AA527
- 1 -
DESCRIPTION
Title of Invention: Front Body Structure
5 Technical Field
[0001] This invention relates to a front body
structure for improving the stiffness of an automobile
body.
10 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 sheets are being used to
reduce the thickness of the body structure and thereby
.lighten the weight of the body.
[0003] For example, when using 590 MPa class high
20 strength steel sheets 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 sheets to reduce the thickness of the body structure,
even if the body strength is secured, the torsional
stiffness generally falls.
[0005] That is, in high strength steel sheets, 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,
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the polar moment of inertia of area becomes smaller. As a
result, the torsional stiffness falls. Therefore, when
using high strength steel sheets etc. to maintain the
body strength while-reducing the thickness of the body so
5 as to lighten the weight, it is also necessary to improve
the torsional stiffness.
[0006] Regarding the torsional stiffness of the body,
as art focusing on the front body structure, for example,
art such as shown in PLTs 1 and 2 is disclosed.
10 [0007] Specifically, PLT 1 discloses providing hood
ridge reinforcing parts which extend from front pillars
forward to load input surfaces of strut towers and
imaginary extensions which extend from front ends of the
foot ridge reinforcing parts toward the front so as to
15 pass through the input centers of the load input
surfaces.
[0008] PLT 2 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
20 join them together.
[0009] Further, while not aimed at improvement of the
torsional stiffness, art similar to that which is
described in PLT 1 is disclosed in PLT 3. In PLT 3, the
. bottom ends of the front pillars are joined at the tops
25 of the strut towers with the upper members. The front
pillars and the hinge pillars and upper member which are
positioned at their rears form ring shaped members with
open center parts. Due to this, it is possible to
effectively support the moment load which acts on the
30 bottom ends of the front pillars.
Citations List
Patent Literature
[0010] • PLT 1: Japanese Patent Publication No. 2010-
35 155559A
PLT 2: Japanese Patent Publication No. 2009-078575A
PLT 3: Japanese Patent Publication No. 09-071267A
ft - 3 -
Technical Problem
[0011] In this regard, in the invention which is
described in PLT 1, the hood ridge reinforcing parts
5 which are joined with the front pillars are joined to the
outside edges of the body at the load input surfaces of
the strut towers. Further, in the invention as set forth
in the above PLT 3, the bottom ends of the front pillars
are joined with the upper members at the vehicle outside
10 sides of the strut towers. Therefore, the joined parts of
the hood ridge reinforcing parts or the front pillars are
offset from the input direction of the load from the
struts (members formed from shock absorbers and springs)
to the strut towers (that is, from the axial directions
15 of the struts) to the width direction of the body.
[0012] If a joined part becomes offset from the input
direction of load to a strut tower in this way, when a
load is applied from the strut to the strut tower, a
large moment is generated at the joined part. If the
20 moment becomes larger, the joined part deforms and, as a
result, deformation of the vehicle is invited. For this
reason, with the inventions as set forth in the above
PLTs 1 and 3, sufficient torsional stiffness could not be
obtained.
25 [0013] 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 of the body of an
automobile and in turn a front body structure which uses
30 high strength steel sheets to reduce the thickness and
thereby enable the weight of a body to be efficiently
lightened.
Solution to Problem
35 [0014] To solve this problem, the inventors engaged in
in-depth studies and as a result obtained the following
finding. By providing reinforcing parts joined to the
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front pillars and the strut towers and joining these
reinforcing parts to the strut towers at both the bodyinside
and body-outside from planes extending through the
axes of the struts in the front-rear direction of the
5 body, it is possible to keep a large moment from being
generated at the joined parts of the reinforcing parts to
the strut towers.
[0015] The present invention was made based on the
above finding, and has as its gist the following.
10 (1) A front body structure in a body which has a
passenger compartment and a front compartment which is
arranged at a front side of the passenger compartment,
comprising strut towers which are arranged inside the
front compartment at the two sides of a width direction
15 of the front compartment and to which top edges of front
wheel use struts are attached; front pillars which extend
at the front of the passenger compartment at the two
sides in the width direction from the roof of the
passenger compartment toward the rear top edge of the
20 front compartment; and reinforcing parts with first ends
joined to the strut towers and with other ends joined to
the front pillars, wherein the reinforcing parts are
joined to the strut towers at the two sides of the bodyinside
and body-outside from the planes extending in the
25 front-rear direction of the body through the axes of the
struts which are fastened to the strut towers.
(2) The front body structure as set forth in (1) wherein
the reinforcing parts are integrally shaped members which
are formed from the same blanks as component members
30 forming at least parts of the front pillars.
(3) The front body structure as set forth in (2) wherein
the front pillars comprise outer members which are
arranged at the body-outside and inner members which are
arranged at the body-inside, and the reinforcing parts
35 are integrally shaped members which are formed from the
same blanks at the inner members.
(4) The front body structure as set forth in any one of
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(1) to (3), further comprising a dash panel which
separates the passenger compartment and the front
compartment and a cowl top which extends above the dash
panel in the width direction of the body, wherein the
5 reinforcing parts are joined to the cowl top as well.
(5) The front body structure as set forth in (4) wherein
the reinforcing parts are integrally shaped members which
are formed from the same blanks as component members
which form at least part of the cowl top.
10 (6) The front body structure as set forth in any one of
(1) to (5), further comprising upper members which are
arranged at width ends of the passenger compartment and
extend in the front-rear direction of the body, wherein
the reinforcing parts are joined to the upper members as
15 well.
(7) The front body structure as set forth in (6) wherein
the reinforcing parts are integrally shaped members which
are formed from the same blanks as component members
forming at least parts of the upper members.
20
Advantageous Effects of Invention
[0016] According to all of the front body structures
according to this invention, the reinforcing parts are
joined to the strut towers at both of the body-inside and
25 body-outside of planes extending in the front-rear
direction of the body through the axes of the struts
which are fastened to the strut towers. Due to this, the
load which is transmitted from the struts to the strut
towers is transmitted to the reinforcing parts through
30 joined parts with the reinforcing parts which are
positioned at the vehicle inside from the struts and
joined parts with the reinforcing parts which are
positioned at the vehicle outside from the struts. For
this reason, a large moment is not created between the
35 strut towers and the reinforcing parts and as a result
the torsional stiffness of the body can be raised.
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Brief Description of Drawings
[0017] 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.
5 FIG. 2 is a cross-sectional view of a front pillar 20
which is seen along an arrow II-II of FIG. 1.
FIG. 3 is an enlarged perspective view of a front body
structure of the first embodiment near a bottom end of
one front pillar.
10 FIG. 4 is a side view of part of a front body structure
according to the first embodiment as seen from the bodyinside
.
FIG. 5 is a cross-sectional front view of part of the
front body structure according to the first embodiment.
15 FIG. 6 is a top view of a part of the front body
structure according to the first embodiment.
FIG. 7 is a view which shows an outline of the overall
structure of a body according to a second embodiment of
the present invention.
20 FIG. 8 is an enlarged perspective view of a front body
structure of the second embodiment near a bottom end of
one front pillar.
FIG. 9 is a side view of part of a front body structure
according to the second embodiment as seen from the body-
25 inside.
FIG. 10 is a cross-sectional front view of part of the
front body structure according to the second embodiment.
FIG. 11 is a top view of a part of the front body
structure according to the second embodiment.
30 FIGS. 12 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 XIII-XIII in (A)
35 and shows an outline of generation of a t'orque in a width
direction of the body.
FIG. 13 is a view which shows displacement and the
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torsional angle of a body before and after application of
a torsional torque as seen from line XIII-XIII of FIG.
12(A) .
5 Description of Embodiments
[0018] Below, referring to FIG. 1 to FIG. 5, a first
embodiment of the present invention will be explained.
FIG. 1 is a view which shows a body 1 which has a
front body structure 10 according to a first embodiment
10 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 (left side in FIG. 1)
of the passenger compartment 2. In the present
15 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.
[0019] The front body structure 10 according to the
20 present embodiment is provided with a pair of front side
members 11 which are positioned at the bottom of the
front compartment 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, in the width direction, of
25 the front compartment 3 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, a cowl top 14
30 which extends at the top of this dash panel 13 in the
width direction and forms a closed cross-sectional shape,
and a pair of side panels 17 which extend from the upper
members 12 to the bottom. In addition, the front body
structure 10 is.provided with a roof 19 which is arranged
35 at the top of the passenger compartment 2 and a pair of
front pillars 20 which extend at the front of the
passenger compartment 2 at the two sides in the width
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direction toward the rear top edge of the front
compartment 3.
[0020] The side panels 17 are provided with front
wheel houses 15 and strut towers 16. The front wheel
5 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 thereof, front
wheels (not shown) are arranged.
10 . [0021] 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
15 to the top from ceiling parts of the front wheel houses
15. 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, struts
20 for front wheels (not shown) are arranged. At the strut
setting parts 18 of the strut towers 16 (top surfaces of
strut towers), top ends of the struts for front wheel are
fastened.
[0022] The- front pillars 20, as shown in FIG. 1, have
25 structures which are inclined gradually downward from the
roof 19 of the passenger compartment 2 toward the front
of the body 1 (front compartment 3 side). The bottom ends
of the front pillars 20 are joined to the rear ends of
the upper members 12 and the side ends of the cowl top
30 14.
[0023] FIG. 2 is a cross-sectional view of a front
pillar 20 as seen along the arrow II-II of FIG. 1. As
will be understood from FIG. 2, a front pillar 20 is
provided with an inner member 21 which is arranged at the
35 body-inside and an 'outer member 22 which is arranged at
the body-outside. These inner member 21 and outer member
22 are joined together by welding etc. whereby a closed
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cross-sectional shape is formed. Further, in the example
which is shown in FIG. 2, an outer panel 23 is arranged
at the body-outside of the outer member 22.
[0024] In addition, in the present embodiment,
5 reinforcing parts 25 with first ends joined to the strut
setting parts 18 of the strut towers 16 and with other
ends joined to the front pillars 20 are provided.
[0025] FIGS. 3 give enlarged perspective views of the
front body structure 10 near the bottom end of one front
10 pillar 20. Among these, FIG. 3(A) shows the case where no
reinforcing member 25 is provided, while FIG. 3(B) shows
the case where a reinforcing member 25 is provided. The
reinforcing member 25 is connected at one end to a bottom
end of an outer member 22 which forms the front pillar
15 20. In particular, in the present embodiment, the
reinforcing member 25 and the inner member 21 are
integrally shaped members which are formed from the same
blank.
[0026] On the other hand, as will be understood from
20 FIG. 3(B), the reinforcing member 25 is joined at the
other end to a strut tower 16. In the present embodiment,
the reinforcing parts 25 are joined to the strut towers
16 at both of the body-outside and body-inside from the
planes S which pass through the axes of the struts (not
25 shown) which are fastened to the strut towers 16, and
extend in the front-rear direction of the body 1 (see
cross-sectional front view of FIG. 5 and top view of FIG.
6). That is, the reinforcing parts 25 are provided with
outside parts 25a which are joined to the strut towers 16
30 at the body-outside from the plane S and inside parts 25b
which are joined to the strut towers 16 at the bodyinside
from the planes S. In particular, in the present
embodiment, the bottom ends of the reinforcing parts 25
are joined to the strut setting parts 18 of the strut
35 towers 16.
[0027] As a result, the reinforcing parts 25, as will
be understood from FIGS. 3 to 6, are joined to the strut
- 10 -
setting parts 18 around the load points of the strut
setting parts 18 (that is, points where axes of struts
and planes of strut setting parts 18 intersect). In
particular, in the present embodiment, the bottom ends of
5 the reinforcing parts 25 are arranged on the strut
setting parts 18 and spot welded to the strut setting
parts 18 so as to completely surround the load points of
the strut setting parts 18.
[0028] According to the front body structure 10 of the
10 present embodiment configured in this way, since
reinforcing parts 25 are provided between the front
pillars 20 and the strut setting parts 18 of the strut
towers 16, it is possible to efficiently transmit the
load which is input to the strut towers 16 to the front
15 pillars 20.
[0029] In addition, the reinforcing parts 25 are
joined to the strut setting parts 18 of the strut towers
16 at both the body-inside and body-outside from the
planes S. In this regard, if a reinforcing member 25 were
20 joined to a strut setting part 18 of a strut tower 16 at
only one side of the planes S, if a load were applied
from the strut to the strut setting part 18, a large
moment would be generated at the joined part of the
reinforcing member 25 and the strut setting part 18. If a
25 large moment were generated in this way, the joined part
would deform and deformation of the vehicle would be
invited.
[0030] As opposed to this, in the present' embodiment,
as explained above, the reinforcing parts 25 are joined
30 to the strut setting parts 18 at both the body-inside and
body-outside of the planes S. For this reason, even if a
load is applied from the struts to the strut setting
parts 18, the joined parts of the reinforcing parts 25
and the strut setting parts 18 are not subjected to a
35 large moment. For this reason, the surroundings of the
strut setting parts 18 are kept from locally deforming.
As a result, improvement of the torsional stiffness of
- l i the
body 1 as a whole becomes possible.
[0031] Further, in the present embodiment, the
reinforcing parts 25 are integrally shaped members which
are formed from the same blanks as the front pillars 20.
5 Here, if forming the reinforcing parts and the front
pillars by separate members, these reinforcing parts and
front pillars would be joined in a state superposed in a
direction perpendicular to the load which is applied to
these members. For this reason, if a load were
10 transmitted from the reinforcing parts to the front
pillars, the load would be transmitted in a direction
perpendicular to the direction of the load which was
applied to these members. For this reason, a moment would
be generated between these members and a shear force
15 would be applied to the joined parts of these members.
Therefore, if forming the reinforcing parts and the front
pillars by separate members, due to these moment and
shear force, deformation would easily occur near the
joined parts between these members. As a result, a drop
20 in the torsional stiffness would be invited.
[0032] As opposed to this, as explained above, in the
present embodiment, the reinforcing parts. 25 are
integrally shaped members which are formed from the same
blanks as the front pillars 20. For this reason, the
25 occurrence of a moment or shear force between the
reinforcing parts 25 and the front pillars 20 is
suppressed. As a result, the torsional stiffness of the
body 1 as a whole can be improved.
[0033] In addition, when the reinforcing parts 25 are
30 integrally shaped members which are formed from the same
blanks as the front pillars 20, as explained above,
compared with when forming the reinforcing parts and .the
' front pillars separately and partially superposing them,
it is possible to lighten the weight and streamline the
35 structure of the body 1.
[0034] Note that, in the above embodiment, the
reinforcing parts 25 were joined to the bottom ends of
- 12 -
the inner members 21, but if first ends are joined to the
front pillars 20, the reinforcing parts 25 do not
necessarily have to be joined to the bottom ends of the
inner members 21. Therefore, the reinforcing parts 25 may
5 be joined to the center parts of the inner members 21 or
may be joined to the bottom ends or center parts of the
outer members 22.
[0035] Further, in the above embodiment, the
reinforcing parts 25 were formed from the same blanks as
10 the inner members 21 of the front pillars 20, but they do
not necessarily have to be formed from the same blanks
and may be formed separately. Further, as explained
above, the reinforcing parts 25 may be joined to the
outer members 22 as well. Considering this, the
15 reinforcing parts 21 can be said to be integrally shaped
members which are formed from the same blanks as the
component members which form at least parts of the front
pillars 20 (for example, the outer members 22 and inner
members 21).
20 [0036] Furthermore, in the above embodiment, the
reinforcing parts 25 were joined to the strut setting
parts 18 so that their bottom ends completely surround
the load points of the strut setting parts 18. However,
if the reinforcing parts 25 are partially joined to the
25 strut setting parts 18 at both the body-outside and bodyinside
of the planes S, there is not necessarily a need
to be joined so as to completely surround the load
points. Therefore, the reinforcing parts 25 also do not
need to be closed cylindrical shapes such as shown in
30 FIGS. 3 to 6. They may also be shapes comprised of
pluralities of flat plates.
[0037] Next, referring to FIG. 7 to FIG. 11, a second
embodiment of the present invention will be explained.
FIG. 7 is a view which shows a body 51 which has a front
35 body structure of a second embodiment of the present
invention. Note that, members the same as those of the
first embodiment will be assigned the same reference
- 13 -
notations and detailed explanations will be omitted. The
body 51 is provided with a passenger compartment 52 and a
front compartment 53 which is arranged at the front side
(left side in FIG. 6) of the passenger compartment 52.
5 [0038] FIG. 8 is an enlarged perspective view of a
front body structure 60 of the second embodiment near the
bottom end of one front pillar 20. As will be understood
from FIG. 8, in the front body structure 60 according to
the second embodiment, the reinforcing parts 70 are
10 joined, to the upper members 12 and the cowl top 14. In
particular, in the present embodiment, the body-outside
parts of the reinforcing parts 70 are joined to the upper
members 12 by spot welding, while the body-inside rear
parts of the reinforcing parts 70 are joined to the cowl
15 top 14 by spot welding.
[0039] Further, the reinforcing parts 70, in the same
way as the reinforcing parts 25 of the first embodiment,
are joined to the strut setting parts 18 of the strut
towers 16. The reinforcing parts 70, as shown in FIG. 10
20 and FIG. 11, are joined to the strut setting parts 18 of
the strut towers 16 at both the body-outside and bodyinside
from the planes S. Therefore, the reinforcing
parts 70, as will be understood from FIGS. 8 to 11, are
joined to the strut setting parts 18 around the load
25 points of the strut setting parts 18.
[0040] According to the front body structure 60 of the
present embodiment configured in this way, the load which
is input to the strut setting parts 18 of the strut
towers 16 can be transmitted by the reinforcing parts 70
30 to not only the front pillars 20, but also the upper
members 12 and cowl top 14. For this reason, the load
which is transmitted to the front pillars 20, upper
members 12, and cowl top 14 can be reduced and
accordingly local deformation around the strut towers 16
35 Can be suppressed to a greater degree. Due to this, it
becomes possible to improve the torsional stiffness of
the body 51 as a whole.
- 14 -
[0041] Note that, in the above embodiment, the
reinforcing parts 70 were joined to both the upper
members 12 and the cowl top 14, but it is not necessary
that they be joined to both. They may also be joined to
5 only one.
[0042] Further, the reinforcing parts 70 were joined
by spot welding to the upper members 12 and cowl top 14.
However, the reinforcing parts 70 may also be joined by a
separate joining method to these upper members 12 and
10 cowl top 14. In addition, the reinforcing parts 70 may be
integrally shaped members which are formed from the same
blanks as the component members forming at least parts of
the upper members 12. Further:, they may be integrally
shaped members which are formed from the same blanks as
15 component members forming at least part of the cowl top
14.
[0043] Embodiments of the present invention were
explained, but the present invention is not limited to
the above embodiment. Various changes can be made within
20 a scope not deviating from the gist of the invention.
[0044] For example, in the above embodiments, the case
where the main material of the body was high strength
steel was explained, but all or part of the body may also
be formed from aluminum, FRP, or another material which
25 can generally be used for a body. Further, high strength
steel was used for the reinforcing parts, but aluminum,
FRP, and other materials may also be used.
[0045] Further, the present embodiments were explained
assuming the front compartment mounted a motor or engine
30 or other power unit, but the invention is not limited to
this. It may also be used as a luggage compartment etc.
[0046] Further, the front body structure according to
the present invention can of course be applied to not
only an automobile which mounts an internal combustion
35 engine, but also a hybrid vehicle or an electric vehicle
in which motors are provided at the wheels, etc.
[0047] Further, the shape of the body as a whole is
- 15 -
not limited to the one disclosed in FIG. 1 and FIG. 7. It
may also be a sedan type, station wagon type, minivan
type, SUV type, or other shape.
5 Examples
[0048] Here, to confirm the effect on the present
embodiment, for example, the technique which is shown in
FIG. 12 and FIG. 13 was used to calculate the torsional
stiffness.
10 [0049] Below, first, referring to FIG. 12 and FIG. 13,
the method of measurement and calculation of the
torsional stiffness will be explained. FIG. 12 is a
conceptual view which shows the method of measurement and
calculation of the torsional stiffness of the body-in-
15 white (body) 100, while FIG. 13 is a view for explaining
the torsional stiffness based on the torsion of the front
axle position 100F (position in front-rear direction of
body at which front shaft is arranged) based on the rear
axle position 100R (position in front-rear direction of
20 body at which rear shaft is arranged).
[0050] To measure the torsional stiffness, for
example, as shown in FIG. 12(A), the body-in-white 100 is
fastened at the rear axle position 100R and the average
torsional stiffness GJ which is obtained by application
25 of the torsional torque at the front axle position 100F
is used for evaluation (G: modulus of rigidity, J: polar
moment of inertia of area)
[0051] Specifically, at the rear axle position 100R,
the body-in-white 100 is fastened (for example, the strut
30 setting parts RL and RR of the rear strut towers are
fastened) and the top ends of dummy bars 101 are attached
to the strut 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 are attached is turned
35 about the axis 0.