FIELD OF INVENTION
This invention relates to an improved D-piliar of vehicle to reduce torsional
stresses. The D-pillar constitutes extension side body outer.
BACKGROUND/PRIOR ART
D-pillar of vehicle (Extension Side Body Outer) forms a major component of
rear end of BIW assembly. The component provides stiffness to the rear end
structure and has a major contribution in the torsional rigidity of vehicle.
D-pillar of vehicle as shown in fig. 1 and 1A comprising of an outer panel (1)
and inner panel (2) joined with a flange (3) by spot welding. The D-pillar (D) is
placed symmetrically on both right hand side (RHS) and left hand side (LHS) at
the back of vehicle.
In order to satisfy the torsional rigidity targets in a vehicle, the most evident
solution is to increase the surface area/cross sectional area at section A-A (fig.
1). However increase in surface area/cross sectional area has an adverse effect
on the-following parameters.
1. Lateral visibility as seen from inside the vehicle from IRVM (Inner Rear
View Mirror) and
2. Upper luggage insertion width.
-3-
The above can be observed from fig. 2 in which it can be clearly seen that the
section AA has more width and section modulus with less upper luggage
insertion width and obstruction in lateral visibility. Therefore, in order to
enhance the lateral visibility and upper luggage insertion width, D-pillar (Ext
SBO) section A-A width is limited. Thus, a sharp curvature is provided between
roof and D-pillar for clear lateral visibility while driving and to satisfy upperluggage
insertion width.
However, slender design of Ext SBO section A-A does not provide enough
stiffness and hence, high bending is observed. This causes very high stress in
the D pillar region and the spot welds are highly prone to failure in physical
testing (as in fig. 3). Thus high torsional stresses is caused on the outer panel
and on the flange of the D-pillar at the corner due to sharp curvature. This
leads to spot cracks on the flange and cracks/deformation of the outer panel,
which finally creates noise due to collision between the inner panel and outer
panel. Further, development of cracks degrades aesthetic value of vehicle and
reduces life-span of D-pillar. This in turn increases recurring cost.
Now, reference may be made to the following patents.
US20140225399: A vehicle body top structure for enhancing the rigidity and
strength of the intersections of side rails and a front rail. The vehicle body top
structure is provided with left and right side rails to extend in the front-andrear
direction at the top part of a vehicle body side part, and a
-4-
front rail extending left and right, one end part of which is joined to the left side
rail, and the other end of which is joined to the right side rail. Thin-plate parts
having a smaller plate thickness than thick-plate parts and thick-plate parts
are disclosed at the one end and the other end of the front rail. The thin-plate
parts are each connected to the left and right side rails.
The above is directed to A-pillar of vehicle.
IN 1384KOL2011: A side sill structure for vehicle including a door hinge
reinforcement arranged on a front side of a door aperture of a vehicle side
surface and which extends in a vertical direction, a side sill which forms a
doorsill of the door aperture, and is joined at a front end near a bottom end of
the door reinforcement, wherein the side sill includes, a side sill strengths
which extends in a vehicle longitudinal direction and includes a cross section
of a substantial hat-shape convex towards the vehicle exterior, a first side sill
reinforcement which includes a flat part substantially parallel to a vehicle side
surface, and a flange which extends to the vehicle interior continuously from a
front end and upper and lower ends of the flat part, a front surface of the
flange projects forward further than a front end of the side sill strengths, and is
joined to the vehicle interior side near a lower end of the door hinge
reinforcement, and an upper surface and lower surface of the flange are
connected to an inner surface of a convex part of the side sill strengths, and a
second side sill reinforcement, arranged on a rear side of the first side sill
reinforcement and which is joined to an inner surface of the side sill strengths.
None of the above can fulfill the requirements of invention, for which it is
designed. Therefore, an improved D-pillar has been introduced which can
address the aforesaid issues effectively.
-5-
QBJECTS OF THE INVENTION
Primary object of the present invention is to provide an improved D-pillar of
vehicle to reduce torsional stresses which overcomes drawbacks associated
with the prior art.
Another object of the present invention is to provide an improved D-pillar of
vehicle to reduce torsional stresses on the outer panel and flange without
increasing width and cross sectional area of the D-pillar.
Further object of the present invention is tc provide an improved D-pillar of
vehicle to reduce torsional stresses which is cost effective.
Yet another object of the present invention is to provide an improved D-pillar of
vehicle to reduce torsional stresses which reduces weight resulting in improved
fuel efficiency.
SUMMARY OF THE INVENTION
According to this invention, there is provided an improved D-pillar of vehicle to
reduce torsional stresses comprising of an outer panel and inner panel joined
with a flange wherein said outer panel is provided with a bead.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from
the ensuing description when read in conjunction with the accompanying
drawings of exemplary embodiments of invention and wherein:
Fig. 1,shows: Conventional D-pillar of vehicle.
-6-
Fig. 1A shows: Different parts of known D-pillar.
Fig. 2 shows: Different designs of D-pillar according to prior art.
Fig. 3 shows: Stress contours for the existing design under twist loading.
Fig. 4 shows: Design of D-pillar in accordance with present invention.
Fig. 5 shows: Bead of invention. -
Fig. 6 shows: Stress contours under twist loading for D-pillar of invention.
Fig. 7 shows: D-pillar (extension side body outer) in deformed stage
according to existing and new design.
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS
The invention makes a disclosure in respect of improved D-pillar of vehicle.
In order to increase the upper luggage insertion width and lateral visibility from
the IRVM (Inner Rear View Mirror), the upper corner radius (R) on both sides of
the body in the back door opening area is reduced as illustrated in fig. 4. This
deteriorates the torsional rigidity of the vehicle. Therefore, to meet the torsional
rigidity target, the section A-A (fig. 1) of the D-pillar is required to be modified.
This modification constitutes addition of a bead (1) to the outer panel of Dpillar
(2, fig. 4) as best seen in fig. 5.
The bead is integrated to the outer panel of said D-pillar. The bead comprises a
longitudinal member, which is located at a distance (D) from the flange (3)
maintaining required clearance therefrom. This clearance from the flange (on
which weather strip is located) is directed towards inside of vehicle as shown.
The bead is located along whole of the curvature joining roof of vehicle with Dpillar.
The bead ends prior to the mounting (M) of backdoor balancer. Width
and height of the bead are optimized according to torsional stress value.
Therefore, the same varies from model to model.
-7-
The orientation of the bead is kept such that it runs parallel to the adjacent
flange in order to provide maximum stiffness to the structure while body
experiences twist condition (as in fig. 6).
The provision of bead leads to reduction in the deformation/cracks of outer
panel due to stress by 20%. As a result, torsional rigidity of the vehicle is
improved. Thus, the stress in D=pillar satisfies the stress target evaluation
criteria. •
In conjunction with the above, the bending is significantly reduced about
section A-A (fig. 6). As a result, the stress in the spots (spot cracks on flange) is
decreased by 32%. This adds to the overall torsional rigidity of the vehicle as
well.
Thus, the present invention improves torsional rigidity of vehicle and provides
strength to the rear end of the structure when the vehicle is subjected to
torsional/twist loads in dynamic conditions.
The bead of instant invention is provided symmetrically on both LHS and RHS
of vehicle at back door opening area.
Now reference may be made to fig. 7. From the stress contour of the existing
and the new design (E and N) it can be clearly seen that in the D ring area
stress is reduced in the modified design of present invention in comparison to
the existing design.
Advantageous Features:
- Reduction in weight of D-pillar
- Cost effective
-8-
- Adds to fuel efficiency
- High stiffness of D-pillar, which in turn avoids development of spot
cracks on flange and cracks/deformation of outer panel
- Longer life span
- Better section modulus as compared to the current design, which
strengthens the structure and adds to the torsional rigidity of vehicle.
- Maintains clear lateral visibility while driving and satisfies upper luggage
insertion width.
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-

We Claim:
1. An improved D-pillar of vehicle to reduce torsional stresses comprising of
an outer panel and inner panel joined by means of a flange wherein said
outer panel is provided with a bead.
2. An improved D-pillar of vehicle to reduce torsional stresses as claimed in
claim 1 wherein said bead constitutes a longitudinal member, which is
located at a distance from the flange.
3. An improved D-pillar of vehicle to reduce torsional stresses as claimed in
claim 1 or 2 wherein the bead is placed along the curvature joining the
D-pillar with roof of vehicle, in which said bead ends prior to the
mounting of back door balancer.
4. An improved D-pillar of vehicle to reduce torsional stresses as claimed in
any of the preceding claims wherein the bead, width and height of which
are optimized according to torsional stress value.
5. An improved D-pillar of vehicle to reduce torsional stressesas claimed in
any of the preceding claims wherein the bead is preferably parallel to the
adjacent flange.
6., An improved D-pillar of vehicle to reduce torsional stresses as claimed in
any of the preceding claims wherein the bead is integrated with said
outer panel.
7. An improved D-pillar of vehicle to reduce torsional stresses as claimed in
any of the preceding claims wherein the bead is provided symmetrically
on both left hand side and right hand side of vehicle at back door
opening area.
8. An improved D-pillar of vehicle to reduce torsional stresses as claimed in
any of the preceding claims is associated with the advantageous features
such as herein described.
9. An improved D-pillar of vehicle to reduce torsional stresses substantially
as herein described with reference to the accompanying drawings.