U.S. patent application number 09/801995 was filed with the patent office on 2001-09-20 for suspension frame construction.
This patent application is currently assigned to Suzuki Motor Corporation. Invention is credited to Suzuki, Tomoyuki.
Application Number | 20010022437 09/801995 |
Document ID | / |
Family ID | 26587733 |
Filed Date | 2001-09-20 |
United States Patent
Application |
20010022437 |
Kind Code |
A1 |
Suzuki, Tomoyuki |
September 20, 2001 |
Suspension frame construction
Abstract
There is provided a suspension frame construction capable of
increasing rigidity when a braking load, a lateral load, or an
engine mounting load is applied to a suspension frame. In a
suspension frame construction comprising an upper plate and a lower
plate joined to each other to form a suspension frame; and front-
and rear-side suspension arm support portions provided at both
ends, right and left, of the suspension frame, the lower plate 9 is
made up of a pair of side plates 11.sub.1 and 11.sub.2 each
provided with a support portion for supporting at least a rear-side
arm of a suspension arm 10.sub.1, 10.sub.2 and a center plate 12
for connecting the side plates 11.sub.1 and 11.sub.2 to each
other.
Inventors: |
Suzuki, Tomoyuki;
(Hamamatsu-shi, JP) |
Correspondence
Address: |
ALSTON & BIRD LLP
BANK OF AMERICA PLAZA
101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Assignee: |
Suzuki Motor Corporation
|
Family ID: |
26587733 |
Appl. No.: |
09/801995 |
Filed: |
March 8, 2001 |
Current U.S.
Class: |
280/124.134 ;
280/124.1; 280/788 |
Current CPC
Class: |
B60G 7/02 20130101; B60G
2206/82 20130101; B60G 2206/722 20130101; B60G 2206/60 20130101;
B60G 2200/142 20130101; B62D 21/11 20130101; B60G 2206/8102
20130101 |
Class at
Publication: |
280/124.134 ;
280/124.1; 280/788 |
International
Class: |
B60G 001/00; B60G
003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 2000 |
JP |
2000-075088 |
Apr 12, 2000 |
JP |
2000-110141 |
Claims
1. A suspension frame construction comprising an upper plate and a
lower plate joined to each other to form a suspension frame; and
front- and rear-side suspension arm support portions provided at
both ends, right and left, of said suspension frame, wherein said
lower plate is made up of a pair of side plates each provided with
a support portion for supporting at least a rear-side arm of a
suspension arm and a center plate for connecting said side plates
to each other.
2. The suspension frame construction according to claim 1, wherein
the thicknesses of said side plates are made greater than the
thickness of said center plate, and a vehicle body mounting portion
is provided on said side plate.
3. The suspension frame construction according to claim 1 or 2,
wherein said suspension arm support portions are provided on the
front and rear of said right and left side plates, and a side wall
portion is formed on the outside of said side plate.
4. The suspension frame construction according to claim 1 or 2,
wherein bent portions are formed at both ends of said center plate
to form a gap between said center plate and said right and left
side plates, and the distal lower end of said bent portion is
joined to said side plate to form a vertical wall portion for
partitioning the interior of said suspension frame.
5. The suspension frame construction according to claim 4, wherein
said vertical wall portion is arranged in a substantially straight
line with respect to said side wall portion.
6. The suspension frame construction according to claim 3, wherein
said side wall portion provided on said side plate is formed so as
to be close to the vehicle body mounting portion of said suspension
frame.
7. The suspension frame construction according to claim 4, wherein
both end portions of said center plate are lapped partially on said
right and left side plates, the lapped portion is inclined toward
said vertical wall portion, and a gap is formed in said lapped
portion.
8. The suspension frame construction according to claim 7, wherein
the inclined portion of said center plate is extended to at least
the vehicle body mounting portion of said suspension frame.
9. A suspension frame construction comprising an upper plate and a
lower plate joined to each other to form a suspension frame; and
front- and rear-side suspension arm support portions provided at
both ends, right and left, of said suspension frame, wherein said
upper plate is made up of a pair of side plates each provided with
a support portion for supporting at least a rear-side arm of a
suspension arm and a center plate for connecting said side plates
to each other.
10. A suspension frame construction comprising an upper plate and a
lower plate joined to each other to form a suspension frame; and
suspension arm support portions extending to the substantially
front and lateral sides, which are provided at both ends, right and
left, of said suspension frame, wherein said upper plate is made up
of a pair of side plates each provided with a support portion for
supporting at least a rear-side arm of a suspension arm and a
center plate for connecting said side plates to each other, an
outer wall portion is formed in said suspension arm support portion
extending to the substantially front side, and a vertical wall
portion continuous with said outer wall portion is provided on said
center plate.
11. The suspension frame construction according to claim 10 wherein
said center plate comprises inclined portions provided on the
inside of said right and left vertical wall portions, an
intermediate portion connected to said lower plate, which is
provided between said inclined portions, and lapped portions joined
face-to-face to said lower plate, which are each provided between
said vertical wall portion and said inclined portion.
12. The suspension frame construction according to claim 11,
wherein the peripheral edge of said side plate is joined to said
lower plate, and the lower face of said side plate is joined to the
upper end of inclined portion and the upper end of vertical wall
portion of said center plate.
13. The suspension frame construction according to claim 11 or 12,
wherein the lapped portions of said center plate are joined to said
lower plate by penetration welding.
Description
FIELD OF THE INVENTION AND RELATED ART STATEMENT
[0001] The present invention relates to a suspension frame
construction for supporting a suspension lower arm, an engine
mounting member, and the like.
[0002] Generally, the vehicle body constructions of motor vehicles
are broadly divided into a framed construction used for motor
trucks and the like and a frameless construction used for passenger
cars and the like. The frameless construction incorporates side
members and cross members as a part of body in place of a frame to
increase the torsional rigidity. A chassis part is usually attached
directly to the body, but, on some vehicles, it is attached to a
partial frame, what is called a subframe, and then is assembled to
the body.
[0003] The subframe is also referred to as a suspension frame
because suspension lower arms are usually attached to both sides of
the subframe. Hereafter, the subframe and the like are given a
general name of a suspension frame.
[0004] The suspension frame is assembled to the vehicle body as an
assembled part after a suspension lower frame, a stabilizer, and
the like are attached thereto. The suspension frame is generally
composed of an upper plate, a lower plate, and lower arm mounting
brackets as a basic construction.
[0005] FIGS. 21 to 28 show a construction of a conventional
suspension frame (Japanese Patent Provisional Publication No.
7-179180).
[0006] A suspension frame 100 is supported on a pair of side
members 101, 101 at both sides thereof, and suspension lower arms
102, 102 are attached to both sides of the suspension frame 100.
Between the suspension frame 100 and a cross member 103 installed
on the front is provided a center member 104, to which an engine
105 is assembled.
[0007] The suspension frame 100 is usually disposed at the lower
part of an engine room isolated by a dash panel 106, and is fitted
with various fittings. The dash panel 106 is fitted with a steering
knuckle 107 via brackets 108.
[0008] As shown in FIGS. 24 to 26, the suspension frame 100 is
formed by joining an upper plate 109 and a lower plate 110, which
are formed by pressing a steel plate etc., by welding or other
means, and at both sides, right and left, of the suspension frame
100 are provided vehicle body mounting portions h, i and j, and in
the central portion thereof are provided engine mounting member
mounting portions k. At both sides in the vehicle width direction
of the suspension frame 100, a pair of suspension lower arm
mounting portions 100a and 100d are provided. In the suspension
lower arm mounting portion 100a on the front side of the vehicle
body is provided a lower arm mounting bracket 111 in a cantilever
state.
[0009] The lower arm mounting bracket 111 is formed into a
substantially square box shape with one side being open by pressing
or other means, and the opposed wall faces 111a and 111b thereof
are provided with pivotally supporting portions 112, 112 for the
suspension lower arms 102, 102. This lower arm mounting bracket
111, which is supported on the outside of the vehicle body mounting
portions h, i and j in a cantilever manner, has a construction that
provides low rigidity and is disadvantageous in terms of driving
stability and vibration noise.
[0010] To mount the lower arm mounting bracket 111, as shown in
FIG. 26, a distal end portion 109a of the upper plate 109 is lapped
partially on and joined to the upper face of the lower arm mounting
bracket 111. Also, the distal end of the lower plate 110 is
butt-welded to the wall face of the lower arm mounting bracket 111.
Therefore, a reinforcement 113 is installed between the upper plate
109 and the lower plate 110 to reinforce the mounting portion of
the lower arm mounting bracket 111. Further, a flange portion 114
is provided along the open end portion of the lower arm mounting
bracket 111 to increase the rigidity of the bracket 111.
[0011] The suspension frame 100 is subjected to the severest
condition when a longitudinal load is applied thereto (for an
actual vehicle, for example, when the brake is applied or when a
wheel falls into a pothole).
[0012] When a braking load is applied to the suspension frame 100,
as shown in FIG. 27, the mounting portion 100a of the lower arm
mounting bracket 111 is put into a deformation mode of being opened
to the outside while being twisted as indicated by the arrow
{circle over (1)}, and a central portion 100b of the suspension
frame 100 is put into a deformation mode of being sunk as indicated
by the broken line {circle over (2)}.
[0013] The central portion 100b of the suspension frame 100 is also
sunk in the same manner by a load applied by the engine mounting
member at the time of sudden start.
[0014] On the other hand, as shown in FIG. 28, when a load is
applied in the lateral direction, the mounting portion 100a of the
lower arm mounting bracket 111 is twisted to the inside as
indicated by the arrow {circle over (3)}. As a result, one of the
lower arm mounting portions 100d on the vehicle body rear side of
the suspension frame 100 is deformed upward as indicated by the
arrow {circle over (4)} and the other thereof is deformed downward
as indicated by the arrow {circle over (5)}. Also, on both sides of
the central portion 100b of the suspension frame 100, one side is
deformed upward as indicated by the arrow {circle over (4)} and the
other side is deformed downward as indicated by the arrow {circle
over (5)}. Thus, the suspension frame 100 is put into a deformation
mode of being wavy.
[0015] As is apparent from the above-described deformation modes,
the rigidity around the opening portion of the lower arm mounting
bracket 111 is low in the case where the suspension frame 100 is
formed merely by two upper and lower plates joined to each other.
Near the opening portion, the vehicle body mounting portions lie.
If the rigidity of this portion of the suspension frame 100 is low,
therefore, there is a possibility that the first-order natural
frequency of the suspension frame 100 resonates with the vehicle
body.
OBJECT AND SUMMARY OF THE INVENTION
[0016] The present invention has been made to solve the above
problems, and accordingly an object thereof is to provide a
suspension frame construction capable of increasing rigidity when a
braking load, a lateral load, or an engine mounting load is applied
to a suspension frame.
[0017] To solve the above problems, the present invention provides
a suspension frame construction comprising an upper plate and a
lower plate joined to each other to form a suspension frame; and
front- and rear-side suspension arm support portions provided at
both ends, right and left, of the suspension frame, wherein the
lower plate is made up of a pair of side plates each provided with
a support portion for supporting at least a rear-side arm of a
suspension arm and a center plate for connecting the side plates to
each other.
[0018] Also, the present invention is characterized in that the
thicknesses of the side plates are made greater than the thickness
of the center plate, and a vehicle body mounting portion is
provided on the side plate.
[0019] Further, the present invention is characterized in that the
suspension arm support portions are provided on the front and rear
of the right and left side plates, and a side wall portion is
formed on the outside of the side plate.
[0020] Still further, the present invention is characterized in
that bent portions are formed at both ends of the center plate to
form a gap between the center plate and the right and left side
plates, and the distal lower end of the bent portion is joined to
the side plate to form a vertical wall portion for partitioning the
interior of the suspension frame.
[0021] Also, the present invention is characterized in that the
vertical wall portion is arranged in a substantially straight line
with respect to the side wall portion.
[0022] Further, the present invention is characterized in that the
side wall portion provided on the side plate is formed so as to be
close to the vehicle body mounting portion of the suspension
frame.
[0023] Still further, the present invention is characterized in
that both end portions of the center plate are lapped partially on
the right and left side plates, the lapped portion is inclined
toward the vertical wall portion, and a gap is formed in the lapped
portion.
[0024] Also, the present invention is characterized in that the
inclined portion of the center plate is extended to at least the
vehicle body mounting portion of the suspension frame.
[0025] The present invention provides a suspension frame
construction comprising an upper plate and a lower plate joined to
each other to form a suspension frame; and front-and rear-side
suspension arm support portions provided at both ends, right and
left, of the suspension frame, wherein the upper plate is made up
of a pair of side plates each provided with a support portion for
supporting at least a rear-side arm of a suspension arm and a
center plate for connecting the side plates to each other.
[0026] Also, the present invention provides a suspension frame
construction comprising an upper plate and a lower plate joined to
each other to form a suspension frame; and suspension arm support
portions extending to the substantially front and lateral sides,
which are provided at both ends, right and left, of the suspension
frame, wherein the upper plate is made up of a pair of side plates
each provided with a support portion for supporting at least a
rear-side arm of a suspension arm and a center plate for connecting
the side plates to each other, an outer wall portion is formed in
the suspension arm support portion extending to the substantially
front side, and a vertical wall portion continuous with the outer
wall portion is provided on the center plate.
[0027] Further, the present invention is characterized in that the
center plate comprises inclined portions provided on the inside of
the right and left vertical wall portions, an intermediate portion
connected to the lower plate, which is provided between the
inclined portions, and lapped portions joined face-to-face to the
lower plate, which are each provided between the vertical wall
portion and the inclined portion.
[0028] Still further, the present invention is characterized in
that the peripheral edge of the side plate is joined to the lower
plate, and the lower face of the side plate is joined to the upper
end of inclined portion and the upper end of vertical wall portion
of the center plate.
[0029] Also, the present invention is characterized in that the
lapped portions of the center plate are joined to the lower plate
by penetration welding.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a schematic perspective view showing an embodiment
of a suspension frame construction in accordance with the present
invention;
[0031] FIG. 2 is a perspective view of the suspension frame
construction shown in FIG. 1;
[0032] FIG. 3 is a plan view of the suspension frame construction
shown in FIG. 2;
[0033] FIG. 4 is an exploded perspective view of the suspension
frame construction shown in FIG. 2;
[0034] FIG. 5 is a perspective view of a lower plate shown in FIG.
2;
[0035] FIG. 6 is a perspective view of an assembling portion of a
center plate and a side plate;
[0036] FIG. 7 is a plan view of a suspension frame, showing a joint
portion of a center plate;
[0037] FIG. 8 is a bottom plan view of FIG. 7;
[0038] FIG. 9 is a sectional view taken along the line A-A of FIG.
7;
[0039] FIG. 10 is a perspective view of a suspension lower arm
shown in FIG. 1;
[0040] FIG. 11 is a schematic perspective view showing another
embodiment of the suspension frame construction in accordance with
the present invention shown in FIG. 1;
[0041] FIG. 12 is a perspective view of a lower plate in a state in
which a center plate and side plates shown in FIG. 11 are connected
to each other;
[0042] FIG. 13 is a sectional view showing a state in which the
suspension frame shown in FIG. 13 is assembled;
[0043] FIG. 14 is a schematic perspective view showing still
another embodiment of a suspension frame construction in accordance
with the present invention;
[0044] FIG. 15 is a perspective view of the suspension frame
construction shown in FIG. 14;
[0045] FIG. 16 is a plan view of the suspension frame construction
shown in FIG. 15;
[0046] FIG. 17 is an exploded perspective view of the suspension
frame construction shown in FIG. 15;
[0047] FIG. 18 is a plan view of an upper plate and a lower plate
shown in FIG. 15;
[0048] FIG. 19 is a sectional view taken along the line B-B of FIG.
18 in a state in which an upper plate and a lower plate are
assembled to each other;
[0049] FIG. 20 is a perspective view of a suspension lower arm
shown in FIG. 14;
[0050] FIG. 21 is a perspective view of a conventional suspension
frame construction;
[0051] FIG. 22 is a plan view of a conventional suspension frame
construction;
[0052] FIG. 23 is a side view of FIG. 22;
[0053] FIG. 24 is a plan view of a conventional suspension frame
construction;
[0054] FIG. 25 is a perspective view of a conventional suspension
frame construction;
[0055] FIG. 26 is a sectional view taken along the line C-C of FIG.
24;
[0056] FIG. 27 is a perspective view showing a deformation mode of
a conventional suspension frame construction under a braking load;
and
[0057] FIG. 28 is a perspective view showing a deformation mode of
a conventional suspension frame construction under a lateral
load;
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
[0058] Embodiments of the present invention will now be described
in detail with reference to the accompanying drawings.
[0059] FIG. 1 shows the vehicle body front part of a motor
vehicle.
[0060] In an engine room 2 isolated by a dash panel 1, a suspension
frame 5 is installed to front side members 3.sub.1 and 3.sub.2,
which are disposed on both sides of a vehicle body, via brackets 4
on the lower face side of the engine room 2. On the outside of the
front side members 3.sub.1 and 3.sub.2 are provided struts 7 for
suspending right and left wheels 6.
[0061] The construction of the suspension frame 5 will be described
with reference to FIGS. 2 to 9.
[0062] As shown in FIGS. 2 to 6, the suspension frame 5 is formed
into a substantially closed curved surface construction by joining
an upper plate 8 and a lower plate 9', which are formed by
pressing, to each other by welding or other means.
[0063] For the upper plate 8, as shown in FIGS. 2 to 4, the front
and rear end portions of a flat steel plate are bent and extend
downward, and suspension lower arm support portions 8a and 8b for
supporting arms 10a and 10b of suspension lower arms 10.sub.1 and
10.sub.2 are provided on both sides, right and left, of the upper
plate 8 so as to branch and extend to the substantially front and
lateral sides.
[0064] The upper plate 8 is provided with a falling portion 8c that
extends downward ranging from the face on the vehicle body front
side to the inside face of the suspension lower arm support portion
8a. Along the lower edge of the falling portion 8c is provided a
flange portion 8d.
[0065] Also, a flange portion 8e is provided along the lower end of
the face on the vehicle body rear side from the peripheral portion
of the suspension lower arm support portion 8b.
[0066] On the other hand, as shown in FIGS. 4 and 5, the lower
plate 9' is formed into a three-piece construction composed of a
pair of side plates 11.sub.1 and 11.sub.2 and a center plate 12
disposed between these side plates 11.sub.1 and 11.sub.2. The
paired side plates 11.sub.1 and 11.sub.2 and the center plate 12
are joined to each other into a unit. The side plates 11.sub.1 and
11.sub.2 and the center plate 12 each are formed by pressing a
steel plate, and the thicknesses of the side plates 11.sub.1 and
11.sub.2 are greater than thickness of the center plate 12. For the
center plate 12, a band-shaped plate thinner than the conventional
lower plate is used.
[0067] The paired side plates 11.sub.1 and 11.sub.2 each are
provided, on the right and left sides thereof, with suspension
lower arm support portions 11a and 11b for supporting the arms 10a
and 10b of the suspension lower arm 10.sub.1 and 10.sub.2, like the
upper plate 8, in such a manner as to branch and extend to the
substantially front and lateral sides. The suspension lower arm
support portions 11a provided on the paired side plates 11.sub.1
and 11.sub.2 are fitted with right and left lower arm mounting
brackets 14.sub.1 and 14.sub.2, respectively. The lower arm
mounting brackets 14.sub.1 and 14.sub.2 support the arms 10a and
10b of the suspension lower arms 10.sub.1 and 10.sub.2,
respectively, so as to be swayable. The suspension lower arm
support portion 11a is provided with a notch 11c for permitting the
arms 10a and 10b of the suspension lower arms 10.sub.1 and 10.sub.2
to be swayed. Also, a flange portion ld is provided at the front
edge on the vehicle body front side of the side plate 11.sub.1,
11.sub.2. Also, a flange portion 11e is provided ranging from the
suspension lower arm support portion 11b to the rear end on the
vehicle body rear side.
[0068] On the outside face of the suspension frame 5 ranging from
the suspension lower arm support portion 11a to the proximal end
portion of the lateral suspension lower arm support portion 11b, a
side wall portion 11f is erected on the outside of the side plate
11.sub.1, 11.sub.2. The side wall portion 11f is formed by bending
the outer edge portion of the side plate 11.sub.1, 11.sub.2 upward
substantially at right angles.
[0069] As shown in FIGS. 4 to 6, the center plate 12 has a slant
face portions 12c that are each formed by bending a side 12a of the
plate slantwise upward with respect to an intermediate portion 12b.
A vertical wall portion 12d is formed by bending the end portion of
the slant face portion 12c downward substantially at right angles.
The vertical wall portion 12d of the center plate 12 is provided
with a flange portion 12e at the periphery thereof, and the center
plate 12 is connected to the side plate 11.sub.1, 11.sub.2 via this
flange portion 12e.
[0070] The center plate 12 is assembled to the side plates 11.sub.1
and 11.sub.2 so that the vertical wall portions 12d on both sides
each are continuous substantially straight with the side wall
portions 11f of the side plates 11.sub.1 and 11.sub.2. The center
plate 12 is formed integrally with the side plates 11.sub.1 and
11.sub.2 by welding (w1) the lower ends of the vertical wall
portions 12d to the upper faces of the side plates 11.sub.1 and
11.sub.2 by arc welding and by welding (w2) both edges of the
intermediate portion 12b to the upper faces of the side plates
11.sub.1 and 11.sub.2 by arc welding. Between the slant face
portion 12c of the center plate 12 and the upper face of the side
plate 11.sub.1, 11.sub.2 is formed a gap 13, so that a closed cross
section S.sub.1 is formed.
[0071] At both ends, right and left, of the suspension frame 5,
suspension lower arm support portions 5a and 5b are formed by
joining the upper plate 8 and the lower plate 9' to each other.
[0072] The suspension lower arm support portion 5a is formed by
supporting the lower arm mounting bracket 14.sub.1, 14.sub.2 by the
suspension lower arm support portion 8a of the upper plate 8 and
the suspension lower arm support portion 11a of the side plate
11.sub.1, 11.sub.2.
[0073] The lower arm mounting bracket 14.sub.1, 14.sub.2 is formed
substantially into a box shape by pressing or other means, and one
side of this box shape is opened so as to form a support portion
for a sway shaft of the suspension lower arm 10. In each of front
and rear wall faces 14a opposed in the vehicle body longitudinal
direction of this box shape, there is provided a mounting hole 14b
for mounting the sway shaft of the suspension lower arm 10.
[0074] The suspension lower arm support portion 5b is formed by the
suspension lower arm support portion 8b of the upper plate 8 and
the suspension lower arm support portion 11b of the lower plate
9'.
[0075] On the other hand, as shown in FIG. 4, in a substantially
central portion of the suspension frame 5 are provided an engine
mounting member mounting portions 15. Also, the upper plate 8 and
the side plate 11.sub.1, 11.sub.2 of the lower plate 9' are
provided with vehicle body mounting portions 8h, 8i and 8j and 11h,
11i and 11j of the suspension frame 5, respectively. The center
plate 12 is provided with a mounting hole 12i corresponding to the
vehicle body mounting portions 8i and 11i. As shown in FIG. 9,
collars 16 are fitted in and welded to the vehicle body mounting
holes 8h, 8i and 8j and 11h, 11i and 11j. In the portion where the
center plate 12 is provided, the mounting hole 12i is also
connected by the common collar 16. In the portion where the central
plate 12 is provided, the upper plate 8 and the center plate 12 are
joined to each other by penetration welding w3 as shown in FIGS. 7
and 9.
[0076] The joining of the center plate 12 to the side plates
11.sub.1 and 11.sub.2 and the joining of the center plate 12 to the
upper plate 8 can be performed by various joining methods such as
arc welding and spot welding.
[0077] Further, in the suspension lower arm support portion 8b of
the upper plate 8 and the suspension lower arm support portion 11b
of the lower plate 9', there are provided mounting holes 8g and
11g, respectively, for supporting the rear-side arm 10b of the
suspension lower arm 10.sub.1, 10.sub.2 as shown in FIG. 10 (see
FIG. 4). As shown in FIG. 10, the front-side arm 10a of the
suspension lower arm 10.sub.1, 10.sub.2 is supported by a
horizontal shaft, and the rear-side arm 10b thereof is supported by
a vertical shaft. The front-side arm 10a and the rear-side arm 10b
each are provided with a bush 17, and the suspension lower arm
10.sub.1, 10.sub.2 is supported on the suspension frame 5 so as to
be swayed freely by inserting the support shaft in the center of
the bush 17.
[0078] As shown in FIG. 4, the suspension lower arm support portion
5b of the suspension frame 5 is provided with an increased rigidity
by ribs 8k and 11k formed in the vehicle width direction in the
suspension lower arm support portion 8b of the upper plate 8 and
the suspension lower arm support portion 11b of the lower plate 9',
respectively. Further, the suspension lower arm support portion 8b
of the upper plate 8 is formed a step higher so that the distance
between the suspension lower arm support portion 8b of the upper
plate 8 and the suspension lower arm support portion 11b of the
lower plate 9' is increased, by which a support portion for the arm
10b of the suspension lower arm 10.sub.1, 10.sub.2 is formed.
[0079] According to the above-described construction, the lower
plate 9' is formed into a three-piece construction composed of the
paired side plates 11.sub.1 and 11.sub.2 and the center plate 12
disposed between these side plates 11.sub.1 and 11.sub.2, and the
paired side plates 11.sub.1 and 11.sub.2 and the center plate 12
are joined to each other into a unit. The center plate 12 is
thinner and therefore has a lower mass than the conventional lower
plate, so that lighter weight of the suspension frame 5 can be
achieved. On the other hand, the thicknesses of the side plates
11.sub.1 and 11.sub.2 are made greater than the thickness of the
center plate 12 to increase the rigidity of the vehicle body
mounting portions. By making the thicknesses of the side plates
11.sub.1 and 11.sub.2 greater, the natural frequency of the
suspension frame 5 is increased, and thereby what is called a
muffled sound is restrained.
[0080] The center plate 12 is formed integrally with the side
plates 11.sub.1 and 11.sub.2 by welding (w1) the lower ends of the
vertical wall portions 12d to the upper faces of the side plates
11.sub.1 and 11.sub.2 by arc welding and by welding (w2) both edges
of the intermediate portion 12b to the upper faces of the side
plates 11.sub.1 and 11.sub.2 by arc welding. Thus, between the
slant face portion 12c of the center plate 12 and the upper face of
the side plate 11.sub.1, 11.sub.2 is formed the gap 13, so that the
closed cross section S.sub.1 is formed. Therefore, the closed
curved surface of the suspension frame 5 can be reinforced by the
vertical wall portion 12d, so that an increase in rigidity can be
achieved when a braking force, a lateral force, or an engine
mounting load is applied to the suspension frame 5. Also, since the
vehicle body mounting portions are formed by joining two plates of
the side plate 11.sub.1, 11.sub.2 and the center plate 12, and the
mounting portions are provided on the side of the side plate
11.sub.1, 11.sub.2 having a higher rigidity, the surface rigidity
is increased, so that an increase in rigidity of vehicle body
mounting portions can be achieved.
[0081] Further, the suspension lower arm support portion 5b of the
suspension frame 5 is formed with the ribs 8k and 11k in the
vehicle width direction in the suspension lower arm support portion
8b of the upper plate 8 and the suspension lower arm support
portion 11b of the lower plate 9' to increase the rigidity.
Further, the suspension lower arm support portion 8b of the upper
plate 8 is formed a step higher so that the distance between the
suspension lower arm support portion 8b of the upper plate 8 and
the suspension lower arm support portion 11b of the lower plate 9'
is increased, by which the support portion for the arm 10b of the
suspension lower arm 10.sub.1, 10.sub.2 is formed. Thus, the
distance between the upper plate 8 and the lower plate 9' can be
increased only in the mounting portion for the arm 10b of the
suspension lower arm 10.sub.1, 10.sub.2, so that the rigidity of
the suspension frame 5 is not decreased. Since the arm 10b of the
suspension lower arm 10.sub.1, 10.sub.2 is supported between the
upper plate 8 and the lower plate 9', the rigidity can be
increased. In particular, since the suspension lower arm support
portion 8b and the suspension lower arm support portion 11b are
joined to each other on the front and rear end sides and are joined
by the vertical wall portion 12d of the center plate 12 at the
proximal end side, only a pull-out portion for the arm 10b of the
suspension lower arm 10.sub.1, 10.sub.2 is open, so that the
support portion for the arm 10b can be constructed strongly.
[0082] FIGS. 11 to 13 show another embodiment of the present
invention. In this embodiment, explanation is made by applying the
same reference numerals to the same elements as those shown in
FIGS. 1 to 4.
[0083] In this case, of the upper plate 8 and the lower plate 9',
which constitute the suspension frame 5, the lower plate 9' is
subjected to a change in construction.
[0084] A lower plate 9" has a construction such that only the right
and left suspension lower arm support portions for supporting the
rear-side arm 10b of the suspension lower arm 10.sub.1, 10.sub.2
are separated from the intermediate portion.
[0085] The lower plate 9" is composed of side plates 18.sub.1 and
18.sub.2 consisting of a suspension lower arm support portion 18b
and a center plate 19 connected to the side plates 18.sub.1 and
18.sub.2. The center plate 19 is provided with suspension lower arm
support portions 19a at the front ends on both sides.
[0086] The center plate 19 is provided with side wall portions 19f
in the vehicle body longitudinal direction at both sides. The side
wall portion 19f is provided so as to range from the vicinity of
the suspension lower arm support portion 19a to the rear end, so
that it partitions the internal space of the suspension frame 5
into the center plate side and the suspension lower arm support
portion side.
[0087] The side plate 18.sub.1, 18.sub.2 is joined to the outside
lower end of the side wall portion 19f of the center plate 19 by
arc welding or other means.
[0088] The lower plate 9" is joined integrally to the upper plate 8
by joining flange portions 19d and 19e provided on the front and
the rear of center plate 19 and the upper end of the side wall
portion 19f to the upper plate 8 and by joining the side plates
18.sub.1 and 18.sub.2 to the peripheral surfaces of the suspension
lower arm support portions 8b via the peripheral edge portions of
the side plates 18.sub.1 and 18.sub.2 by spot welding or other
means.
[0089] In this case, as the vehicle body mounting portions, the
upper plate 8 is formed with the vehicle body mounting holes 8h, 8i
and 8j, and the lower plate 9" is formed with vehicle body mounting
holes 19h, 19i and 18j. The vehicle body mounting holes 19h and 19i
are formed in the center plate 19, and the vehicle body mounting
hole 18j is formed in the side plate 18.sub.1, 18.sub.2.
[0090] In this embodiment, as in the case of the above described
embodiment, the thicknesses of the side plates 18.sub.1 and
18.sub.2 are made greater than the thickness of the center plate
19, by which the rigidity of the suspension lower arm support
portion 18b can be increased.
[0091] FIGS. 14 to 20 show still another embodiment of the present
invention. In this embodiment, the upper plate has a separated
construction.
[0092] FIG. 14 shows the vehicle body front part of a motor
vehicle. In this figure, the same reference numerals are applied to
the same elements as those shown in FIG. 1.
[0093] In the engine room 2 isolated by the dash panel 1, a
suspension frame 5' is installed to the front side members 3.sub.1
and 3.sub.2, which are disposed on both sides of the vehicle body,
via the brackets 4 on the lower face side of the engine room 2. On
the outside of the front side members 3.sub.1 and 3.sub.2 are
provided the struts 7 for suspending the right and left wheels
6.
[0094] The construction of the suspension frame 5' will be
described with reference to FIGS. 15 to 20.
[0095] As shown in FIGS. 15 to 18, the suspension frame 5' is
formed into a substantially closed curved surface construction by
joining an upper plate 8' and a lower plate 9, which are formed by
pressing, to each other by welding or other means. On the right and
left of the suspension frame 5', the suspension lower arm support
portions 5a and 5b formed by the upper plate 8' and the lower plate
9 are provided so as to branch and extend to the substantially
front and lateral sides.
[0096] The upper plate 8' has a three-piece construction composed
of a pair of side plates 21.sub.1 and 21.sub.2 and a center plate
22 disposed between the side plates 21.sub.1 and 21.sub.2. The
paired side plates 21.sub.1 and 21.sub.2 and the center plate 22
are joined to each other into a unit. The side plates 21.sub.1 and
21.sub.2 and the center plate 22 each are formed by pressing a
steel plate.
[0097] On the other hand, as shown in FIGS. 17 and 18, for the
lower plate 9, the rear end portion of a flat steel plate is bent
and extend upward, and suspension lower arm support portions 9a and
9b for supporting the arms 10a and 10b of the suspension lower arms
10.sub.1 and 10.sub.2 are provided on both sides, right and left,
of the lower plate 9 so as to branch and extend to the
substantially front and lateral sides. The lower plate 9 is
provided with a rising portion 9c at the peripheral edge thereof
ranging from the rear end to the suspension lower arm support
portion 9b, and is provided with a flange portion 9d at the front
end peripheral edge thereof. In the rising portion 9c provided at
the periphery of the suspension lower arm support portion 9b, a
notch 9e for supporting the rear-side arm 10b of the suspension
lower arm 10.sub.1, 10.sub.2 is provided on the front side.
[0098] Also, on the outside face of the lower plate 9 ranging from
the front-side suspension lower arm support portion 9a to the
proximal end portion of the lateral-side suspension lower arm
support portion 9b, an outer wall portion 9f is erected along the
outside edge of the lower plate 9.
[0099] As shown in FIG. 17, the center plate 22 has a slant face
portions 22c that are each formed by bending a side 22a of the
plate slantwise upward with respect to an intermediate portion 22b.
A wall portion 22d is formed by bending the end portion of the
slant face portion 22c downward substantially at right angles. To
the wall portion 22d is connected a lapped portion 22e that is
lapped on the upper face of the lower plate 9. At the side of the
lapped portion 22e is erected a vertical wall portion 22f by
bending the plate upward. The vertical wall portion 22f is provided
so as to be continuous with the outer wall portion 9f of the lower
plate 9 substantially straight in the vehicle body longitudinal
direction. A flange portion at the upper end of the vertical wall
portion 22f, together with a flange portion at the upper end of the
outer wall portion 9f of the lower plate 9, is joined to the lower
face of the side plate 21.sub.1, 21.sub.2. The lapped portion 22e
of the center plate 22 is joined to the upper face of the lower
plate 9 by penetration welding w4. Also, the front end of the
vertical wall portion 22f is joined to the outer wall portion 9f,
and the rear end thereof is joined to the rising portion 9c at the
rear end of the lower plate 9.
[0100] The center plate 22 is assembled to the side plates 21.sub.1
and 21.sub.2 so that the vertical wall portions 22f on both sides
are each continuous substantially straight with side wall portions
21f of the side plates 21.sub.1 and 21.sub.2. The center plate 22
is disposed on the upper face of the lower plate 9 so that the
vertical wall portions 22f are each continuous substantially
straight with the outer wall portions 9f of the lower plate 9, and
the intermediate portion 22b thereof is joined to the lower plate 9
by spot welding w5 or other means.
[0101] The flange portion provided at the upper end of the vertical
wall portion 22f, together with the flange portion provided at the
upper end of the outer wall portion 9f of the lower plate 9, is
joined to the lower face of the side plate 21.sub.1, 21.sub.2. The
lapped portion 22e of the center plate 22 is joined to the upper
face of the lower plate 9 by penetration welding w4.
[0102] Between the slant face portion 22c and the vertical wall
portion 22f of the center plate 22 and the upper face of the side
plate 21.sub.1, 21.sub.2 is formed a gap 23, so that a closed cross
section S.sub.2 is formed.
[0103] The paired side plates 21.sub.1 and 21.sub.2 each are
provided, on the right and left sides thereof, with suspension
lower arm support portions 21a and 21b for supporting the arms 10a
and 10b of the suspension lower arm 10.sub.1 and 10.sub.2, like the
upper plate 9, in such a manner as to branch and extend to the
substantially front and lateral sides.
[0104] The side plate 21.sub.1, 21.sub.2 is assembled to the center
plate 22 by joining an opposed inside edge portion 21c of the side
plate 21.sub.1, 21.sub.2 to the upper end of the slant face portion
22c of the center plate 22 and by joining a front flange portion
21d of the side plate 21.sub.1, 21.sub.2 to the front flange
portion 9d of the lower plate 9.
[0105] The suspension lower arm support portions 9a and the
suspension lower arm support portions 21a provided on the paired
side plates 21.sub.1 and 21.sub.2 are fitted with the right and
left lower arm mounting brackets 14.sub.1 and 14.sub.2,
respectively. The lower arm mounting brackets 14.sub.1 and 14.sub.2
support the arms 10a and 10b of the suspension lower arms 10.sub.1
and 10.sub.2, respectively, so as to be swayable.
[0106] The lower arm mounting bracket 14.sub.1, 14.sub.2 is formed
substantially into a box shape by pressing or other means, and one
side of this box shape is opened so as to form the support portion
for the sway shaft of the arm 10a, 10b of the suspension lower arm
10.sub.1, 10.sub.2. In each of front and rear wall faces 14a
opposed in the vehicle body longitudinal direction of this box
shape, there is provided the mounting hole 14b for mounting the
sway shaft of the suspension lower arm 10.sub.1, 10.sub.2.
[0107] On the other hand, in a substantially central portion of the
suspension frame 5' are provided the engine mounting member
mounting portions 15. Also, the side plate 21.sub.1, 21.sub.2 and
the lower plate 9 are provided with vehicle body mounting holes
21h, 21i and 21j and 9h, 9i and 9j of the suspension frame 5',
respectively, at the corresponding positions. The center plate 22
is provided with mounting holes 22i and 22h corresponding to the
vehicle body mounting portions 21i, 21h, 9i, and 9h.
[0108] Further, in the suspension lower arm support portion 21b of
the side plate 21.sub.1, 21.sub.2 and the suspension lower arm
support portion 9b of the lower plate 9, there are provided
mounting holes 21g and 9g, respectively, for supporting the
rear-side arm 10b of the suspension lower arm 10.sub.1, 10.sub.2
(see FIG. 17).
[0109] As shown in FIG. 19, collars 26 are fitted in and welded to
the vehicle body mounting holes 21h, 21i, 21j, 9h, 9i, 9j and 22h.
Although not shown in the figure, in the portion where the center
plate 22 is provided, the similar collar 26 can also be used in the
mounting hole 22i. In the portion where the central plate 22 is
provided, the lower plate 9 and the center plate 22 are joined to
each other by penetration welding w4 as shown in FIG. 17.
[0110] The joining of the center plate 22 to the side plates
21.sub.1 and 21.sub.2 and the joining of the center plate 22 to the
lower plate 9 can be performed by various joining methods such as
arc welding and spot welding. As shown in FIG. 20, the front-side
arm 10a of the suspension lower arm 10.sub.1, 10.sub.2 is supported
by a horizontal shaft, and the rear-side arm 10b thereof is
supported by a vertical shaft. The front-side arm 10a and the
rear-side arm 10b each are provided with the bush 17, and the
suspension lower arm 10.sub.1, 10.sub.2 is supported on the
suspension frame 5' so as to be swayed freely by inserting the
support shaft in the center of the bush 17.
[0111] Also, the suspension lower arm support portion 21b of the
side plate 21.sub.1, 21.sub.2 is formed a step higher so that the
distance between the suspension lower arm support portion 21b of
the side plate 21.sub.1, 21.sub.2 and the suspension lower arm
support portion 9b of the lower plate 9 is increased, by which the
support portion for the arm 10b of the suspension lower arm
10.sub.1, 10.sub.2 is formed.
[0112] According to the above-described construction, the upper
plate 8' is formed into a three-piece construction composed of the
paired side plates 21.sub.1 and 21.sub.2 and the center plate 22
disposed between these side plates 21.sub.1 and 21.sub.2, and the
lower plate 9 is joined to the center plate 22.
[0113] The center plate 22 is assembled to the side plates 21.sub.1
and 21.sub.2 so that the vertical wall portion 22f on both sides
are each continuous substantially straight with the side wall
portion 21f of the side plate 21.sub.1, 21.sub.2.
[0114] The center plate 22 is disposed on the upper face of the
lower plate 9 so that the vertical wall portions 22f each are
continuous straight with the outer wall portion 9f of the lower
plate 9, and the intermediate portion 22b thereof is joined to the
lower plate 9 by spot welding w5 or other means. The lapped
portions 22e of the center plate 22 are joined to the upper face of
the lower plate 9 by penetration welding w4. The side plates
21.sub.1 and 21.sub.2 are disposed on the lower plate 9 and the
center plate 22, and the opposed inside edge portions 21c of the
side plates 21.sub.1 and 21.sub.2 are each joined to the upper end
of the slant face portion 22c of the center plate 22 by arc welding
w6 or other means, and the front flange portions 21d of the side
plates 21.sub.1 and 21.sub.2 are each joined to the front flange
portion 9d of the lower plate 9 by spot welding w5 or other
means.
[0115] Further, the flange portion at the upper end of the vertical
wall portion 22f of the center plate 22 and the flange portion at
the upper end of the outer wall portion 9f of the lower plate 9 are
joined to the lower face of the side plate 21.sub.1, 21.sub.2.
[0116] According to the above-described construction, the center
plate 22 can be made thinner and therefore can have a lower mass
than the conventional upper plate, so that lighter weight of the
suspension frame 5' can be achieved. On the other hand, the
thicknesses of the side plates 21.sub.1 and 21.sub.2 can be made
greater than the thickness of the center plate 22 to increase the
rigidity of the vehicle body mounting portions. By making the
thicknesses of the side plates 21.sub.1 and 21.sub.2 greater, the
natural frequency of the suspension frame 5', is increased, and
thereby what is called a muffled sound can be restrained.
[0117] Since the lapped portion 22e of the center plate 22 is
joined to the upper face of the lower plate 9 by penetration
welding w4, the lower plate 9 has a two-layer construction in this
portion, and the closed cross-sectional construction is formed
between the lower plate 9 and the side plate 21.sub.1, 21.sub.2. In
particular, therefore, the rigidity of the vehicle body mounting
portions increases, so that an increase in rigidity can be achieved
when a braking force, a lateral force, or an engine mounting load
is applied to the suspension frame 5'.
[0118] Also, the suspension lower arm support portion 21b of the
upper plate 8' is formed a step higher so that the distance between
the suspension lower arm support portion 21b of the upper plate 8'
and the suspension lower arm support portion 9b of the lower plate
9 is increased, by which the support portion for the arm 10b of the
suspension lower arm 10.sub.1, 10.sub.2 is formed. Thus, the
distance between the upper plate 8' and the lower plate 9 can be
increased only in the mounting portion for the arm 10b of the
suspension lower arm 10.sub.1, 10.sub.2, so that the rigidity of
the suspension frame 5', is not decreased. Since the arm 10b of the
suspension lower arm 10.sub.1, 10.sub.2 is supported between the
upper plate 8' and the lower plate 9, the rigidity can be
increased. In particular, since the suspension lower arm support
portion 21b and the suspension lower arm support portion 9b are
joined to each other on the front and rear end sides and are joined
by the vertical wall portion 22f of the center plate 22 at the
proximal end side, only a pull-out portion for the arm 10b of the
suspension lower arm 10.sub.1, 10.sub.2 is open, so that the
support portion for the arm 10b can be constructed strongly.
[0119] The present invention is not limited to the above-described
embodiments. For example, although the lower plate 9' is divided
into three pieces, the paired side plates 111 and 112 and the
center plate 12, in the present invention, the lower plate 9' can
be divided into four or more pieces. Also, although the lower plate
9" is divided into three pieces, the side plates 18.sub.1 and
18.sub.2, which each consist of the suspension lower arm support
portion 18b, and the center plate 19, in another embodiment, the
lower plate 9" may be divided into five pieces by separating the
suspension lower arm support portions 19a.
[0120] Further, in the above-described embodiments, the vehicle
body mounting portion is divided into the thick side plates
11.sub.1 and 11.sub.2 in which all vehicle body mounting portions
are provided and the thin center plate 12, or into the side plates
18.sub.1 and 18.sub.2 in which some vehicle body mounting portions
are provided and the center plate 19. However, any division mode
may be adopted.
[0121] Also, although the upper plate 8' is divided into three
pieces, the paired side plates 21.sub.1 and 21.sub.2 and the center
plate 22, in still another embodiment, the upper plate 8' can be
divided into four or more pieces. Also, the thicknesses of the side
plates 21.sub.1 and 21.sub.2 constituting the upper plate 8' is
made greater than the thickness of the center plate 22, by which
the rigidity of the side plates 21.sub.1, 21.sub.2 in which the
vehicle body mounting portions are provided can be increased. In
this case, by using a band-shaped plate that is thinner than the
conventional upper plate as the center plate 22 constituting the
upper plate 8', the total weight can be decreased.
[0122] Further, a blank material tailored by forming materials with
different thicknesses into one piece by laser welding is used as
the center plate 22 constituting the upper plate 8', by which
lighter weight can be achieved. In this case, it is a matter of
course that a thin portion is used as the intermediate portion 22b
of the center plate 22 constituting the upper plate 8'.
[0123] As described above, the suspension frame construction in
accordance with the present invention can achieve the effects
described below.
[0124] In claim 1, in a suspension frame construction comprising an
upper plate and a lower plate joined to each other to form a
suspension frame; and front- and rear-side suspension arm support
portions provided at both ends, right and left, of the suspension
frame, the lower plate is made up of a pair of side plates each
provided with a support portion for supporting at least a rear-side
arm of a suspension arm and a center plate for connecting the side
plates to each other. Therefore, the rigidity can be increased when
a braking force, a lateral force, or an engine mounting load is
applied to the suspension frame. The increase in rigidity under the
mounting load can eliminate a mass damper.
[0125] In claim 2, the thicknesses of the side plates are made
greater than the thickness of the center plate, and a vehicle body
mounting portion is provided on the side plate. Therefore, in a
state in which the weight is kept low, the rigidity can be
increased when a braking force, a lateral force, or an engine
mounting load is applied to the suspension frame.
[0126] In claim 3, the suspension arm support portions are provided
on the front and rear of the right and left side plates, and a side
wall portion is formed on the outside of the side plate. Therefore,
the rigidity can be increased when a braking force, a lateral
force, or an engine mounting load is applied to the suspension
frame.
[0127] In claim 4, bent portions are formed at both ends of the
center plate to form a gap between the center plate and the right
and left side plates, and the distal lower end of the bent portion
is joined to the side plate to form a vertical wall portion for
partitioning the interior of the suspension frame. Therefore, the
rigidity of the suspension frame can be increased when a braking
force, a lateral force, or an engine mounting load is applied to
the suspension frame.
[0128] In claim 5, the vertical wall portion is arranged in a
substantially straight line with respect to the side wall portion.
Therefore, the rigidity of the suspension frame can be increased
when a braking force, a lateral force, or an engine mounting load
is applied to the suspension frame.
[0129] In claim 6, the side wall portion provided on the side plate
is formed so as to be close to the vehicle body mounting portion of
the suspension frame. Therefore, the rigidity of the vehicle body
mounting portion can be increased.
[0130] In claim 7, both end portions of the center plate are lapped
partially on the right and left side plates, the lapped portion is
inclined toward the vertical wall portion, and a gap is formed in
the lapped portion. Therefore, the rigidity of the suspension frame
can be increased when a braking force, a lateral force, or an
engine mounting load is applied to the suspension frame.
[0131] In claim 8, the inclined portion of the center plate is
extended to at least the vehicle body mounting portion of the
suspension frame. Therefore, the rigidity of the vehicle body
mounting portion can be increased.
[0132] In claim 9, in a suspension frame construction comprising an
upper plate and a lower plate joined to each other to form a
suspension frame; and front- and rear-side suspension arm support
portions provided at both ends, right and left, of the suspension
frame, the upper plate is made up of a pair of side plates each
provided with a support portion for supporting at least a rear-side
arm of a suspension arm and a center plate for connecting the side
plates to each other. Therefore, by adjusting the plate thickness,
light weight can be achieved, and also the rigidity can be
increased when a braking force, a lateral force, or an engine
mounting load is applied to the suspension frame. The increase in
rigidity under the mounting load can eliminate a mass damper.
[0133] In claim 10, in a suspension frame construction comprising
an upper plate and a lower plate joined to each other to form a
suspension frame; and suspension arm support portions extending to
the substantially front and lateral sides, which are provided at
both ends, right and left, of the suspension frame, the upper plate
is made up of a pair of side plates each provided with a support
portion for supporting at least a rear-side arm of a suspension arm
and a center plate for connecting the side plates to each other, an
outer wall portion is formed in the suspension arm support portion
extending to the substantially front side, and a vertical wall
portion continuous with the outer wall portion is provided on the
center plate. Therefore, by adjusting the plate thickness, in a
state in which the weight is kept low, the rigidity can be
increased when a braking force, a lateral force, or an engine
mounting load is applied to the suspension frame.
[0134] In claim 11, the center plate comprises inclined portions
provided on the inside of the right and left vertical wall
portions, an intermediate portion connected to the lower plate,
which is provided between the inclined portions, and lapped
portions joined face-to-face to the lower plate, which are each
provided between the vertical wall portion and the inclined
portion. Therefore, the lower plate is made have a two-layer
construction, and the closed cross-sectional construction can be
formed between the vertical wall portion and the inclined portion
at the right and left, so that the rigidity and driving stability
can be increased, and the rigidity can be increased when a braking
force, a lateral force, or an engine mounting load is applied to
the suspension frame. The natural frequency is increased, and
thereby a muffled sound can be restrained.
[0135] In claim 12, the peripheral edge of the side plate is joined
to the lower plate, and the lower face of the side plate is joined
to the upper end of inclined portion and the upper end of vertical
wall portion of the center plate. Therefore, the closed
cross-sectional construction can be formed, so that the rigidity
and driving stability can be increased, and the rigidity of the
suspension frame can be increased when a braking force, a lateral
force, or an engine mounting load is applied to the suspension
frame.
[0136] In claim 13, the lapped portions of the center plate are
joined to the lower plate by penetration welding. Therefore, the
surface rigidity can be increased.
* * * * *