U.S. patent application number 14/174103 was filed with the patent office on 2015-08-06 for vehicle roof structure.
This patent application is currently assigned to HONDA MOTOR CO., LTD.. The applicant listed for this patent is HONDA MOTOR CO., LTD.. Invention is credited to Christopher Hinz, Masahiro Ishikawa.
Application Number | 20150217812 14/174103 |
Document ID | / |
Family ID | 53754170 |
Filed Date | 2015-08-06 |
United States Patent
Application |
20150217812 |
Kind Code |
A1 |
Hinz; Christopher ; et
al. |
August 6, 2015 |
VEHICLE ROOF STRUCTURE
Abstract
A vehicle assembly includes a roof structure having a roof panel
formed of aluminum or an aluminum-based alloy and a vehicle body
formed of steel or a steel alloy supporting the roof structure. The
vehicle body includes a pair of laterally spaced side panels, a
front roof rail and a rear roof rail. A bracket formed of steel or
a steel alloy secures the roof structure to the vehicle body. The
bracket has a first portion fastened to the roof panel and a second
portion extending away from the roof structure and welded to the
vehicle body. An adhesive located inward of the connection of the
vehicle body and second portion of the bracket bonds the second
portion to the vehicle body. The adhesive seals the connection of
the roof panel and bracket first portion and reduces thermal
distortion of the attached roof panel relative to the vehicle
body.
Inventors: |
Hinz; Christopher; (Dublin,
OH) ; Ishikawa; Masahiro; (Dublin, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HONDA MOTOR CO., LTD. |
TOKYO |
|
JP |
|
|
Assignee: |
HONDA MOTOR CO., LTD.
TOKYO
JP
|
Family ID: |
53754170 |
Appl. No.: |
14/174103 |
Filed: |
February 6, 2014 |
Current U.S.
Class: |
296/210 ;
228/175 |
Current CPC
Class: |
B62D 25/06 20130101;
B62D 27/04 20130101; B62D 29/008 20130101 |
International
Class: |
B62D 27/02 20060101
B62D027/02; B23K 31/02 20060101 B23K031/02 |
Claims
1. A vehicle assembly comprising: a roof structure including a roof
panel formed of aluminum or an aluminum-based alloy; a vehicle body
including a pair of laterally spaced side panels, a front roof rail
and a rear roof rail, each roof rail spanning between the side
panels, the vehicle body supporting the roof structure, the vehicle
body formed of steel or a steel alloy; at least one bracket
securing the roof structure to the vehicle body, the bracket having
a first portion fastened to the roof panel and a second portion
extending away from the roof structure and welded to the vehicle
body, the bracket formed of steel or a steel alloy; and an adhesive
located inward of the weld connection of the vehicle body and
second portion of the bracket for bonding the second portion to the
vehicle body, the adhesive sealing the fastened connection of the
roof panel and first portion of the bracket from moisture to
prevent galvanic corrosion between the dissimilar materials of the
roof panel and bracket, the adhesive further reducing thermal
distortion of the attached roof panel relative to the vehicle body
when the vehicle assembly is heated in a paint bake oven during the
manufacture of the vehicle assembly.
2. The vehicle assembly of claim 1, wherein the roof panel includes
an upper horizontal surface connected to a flange structure
provided at a peripheral edge portion of the upper horizontal
surface, the flange structure being defined by a vertical wall and
a lower horizontal surface, the bracket first portion being
fastened to the vertical wall, the adhesive bonding the bracket
second portion to the lower horizontal surface.
3. The vehicle assembly of claim 2, wherein the first portion of
the bracket is a vertical leg and the second portion of the bracket
is a horizontal leg, the vertical leg being connected to an
interior of the roof panel vertical wall.
4. The vehicle assembly of claim 3, wherein the horizontal leg has
a stepped configuration including an upper section and a lower
section.
5. The vehicle assembly of claim 4, wherein the upper section of
the horizontal leg is bonded to the lower horizontal surface of the
roof panel, and the lower section extends outward beyond the lower
horizontal surface and is welded to the vehicle body.
6. The vehicle assembly of claim 4, wherein the lower section of
the horizontal leg is bonded to the lower horizontal surface of the
roof panel, and the upper section extends outward beyond the lower
horizontal surface and is welded to the vehicle body.
7. The vehicle assembly of claim 2, wherein the bracket includes a
pair of side brackets for connecting the side panels to the roof
panel flange structure, a front bracket for connecting the front
roof rail to the roof panel flange structure and a rear bracket for
connecting the rear roof rail to the roof panel flange structure,
together the four brackets extending approximately an entire
perimeter of the roof panel.
8. The vehicle assembly of claim 7, wherein the second portion of
the front bracket is bonded to an end portion of a windshield.
9. The vehicle assembly of claim 1, wherein the bracket provides
for a continuous vertical spacing between the roof panel and the
vehicle body of approximately 4 mm to approximately 6 mm, the
adhesive being provided in the spacing.
10. The vehicle assembly of claim 1, wherein each of the side
panels, front roof rail and rear roof rail includes an outer panel
and an inner panel, the bracket second portion being welded to the
respective outer panel of each of the side panels, front roof rail
and rear roof rail.
11. The vehicle assembly of claim 10, wherein the outer panel of
each of the side panels, front roof rail and rear roof rail
includes a flange structure having a horizontal wall, the bracket
second portion being welded to the horizontal wall of each of the
side panels, front roof rail and rear roof rail.
12. A vehicle assembly comprising: a vehicle roof structure
including a roof panel, the vehicle roof structure is formed of
aluminum or an aluminum-based alloy; a vehicle body including a
pair of laterally spaced side panels and a front roof rail and a
rear roof rail spanning between the side panels, the side panels
together with the front and rear roof rails support the vehicle
roof structure, the vehicle body is formed of steel or a steel
alloy; and a pair of side brackets connecting the side panels to
roof panel, a front bracket connecting the front roof rail to the
roof panel, and a rear bracket connecting the rear roof rail to the
roof panel, each bracket having a first portion fastened to the
roof panel and a second portion extending outwardly of the roof
panel and welded to the vehicle body, each bracket formed of steel
of a steel alloy; wherein each of the brackets provides a
continuous vertical spacing between the roof panel and the vehicle
body of approximately 4 mm to approximately 6 mm, the vehicle roof
structure is bonded to the vehicle body via an adhesive provided in
the spacing, the adhesive sealing the fastened connection of the
roof panel and first portion of the bracket from moisture to
prevent galvanic corrosion between the dissimilar materials of the
roof panel and bracket, the adhesive further reducing thermal
distortion of the attached roof panel relative to the vehicle body
when the vehicle assembly is heated in a paint bake oven during the
manufacture of the vehicle assembly.
13. The vehicle assembly of claim 12, wherein the roof panel
includes a flange structure provided at a peripheral edge portion,
the flange structure being defined by a vertical wall and a
horizontal surface, each bracket first portion being fastened to
the vertical wall, the adhesive bonding each bracket second portion
to the horizontal surface.
14. The vehicle assembly of claim 13, wherein each bracket is
substantially L-shaped and the first portion of the bracket is a
vertical leg and the second portion of the bracket is a horizontal
leg, the vertical leg being connected to an interior of the roof
panel vertical wall, the horizontal leg having a stepped
configuration including an upper section and a lower section.
15. The vehicle assembly of claim 14, wherein for each of the side
panel brackets and the rear bracket, the upper section of the
horizontal leg is bonded to the horizontal surface of the flange
structure, and for the front bracket the lower section of the
horizontal leg is bonded to the horizontal surface of the flange
structure.
16. The vehicle assembly of claim 13, wherein together the four
brackets extend approximately an entire perimeter of the roof
panel.
17. A method of assembling a vehicle comprising: providing a
vehicle body formed of steel or a steel alloy, the vehicle body
includes a pair of laterally spaced side panels, a front roof rail
and a rear roof rail, each roof rail spans between the side panels;
providing a vehicle roof structure formed of aluminum or an
aluminum-based alloy, the vehicle roof structure includes a roof
panel having a flange structure provided at a peripheral edge
portion, the flange portion including a vertical wall and a
horizontal surface; applying an adhesive on the horizontal surface
of the flange structure around an entire perimeter of the roof
panel; providing a pair of side brackets, a front bracket and a
rear bracket, each bracket formed of steel or a steel alloy, and
positioning each of the brackets on the flange structure such that
the adhesive is between each bracket and the flange structure;
positioning the vehicle roof structure together with the brackets
on the vehicle body; fastening each of the brackets to the vertical
wall of the flange structure; welding the side brackets to the side
panels, the front bracket to the front roof rail and the rear
bracket to the rear roof rail; and heating the vehicle body
together with the vehicle roof structure and the brackets to a
predetermined temperature to cure the adhesive.
18. The method of claim 17, further including providing a
continuous vertical spacing between the roof panel and the vehicle
body of approximately 4 mm to approximately 6 mm by use of the side
brackets, front bracket and rear bracket, and providing the
adhesive in the spacing.
19. The method of claim 17, further including positioning the
fastened connection between the brackets and the flange structure
inwardly of the adhesive, and positioning the welded connection
between the brackets and the vehicle body outwardly of the
adhesive.
20. The method of claim 17, wherein each bracket is substantially
L-shaped and includes a vertical leg and a horizontal leg having a
stepped configuration including an upper section and a lower
section, and the method includes clinching the vertical leg of each
bracket to an interior of the flange structure vertical wall, and
for each of the side panel brackets and the rear bracket, bonding
the upper section of the horizontal leg to the horizontal surface
of the flange structure, and for the front bracket bonding the
lower section of the horizontal leg to the horizontal surface of
the flange structure.
Description
BACKGROUND
[0001] The substitution of aluminum or aluminum-based alloy roof
panels for the low-carbon steel or steel alloy roof panels most
commonly used in motor vehicles is an attractive option for vehicle
mass reduction. Often, however, the remainder of the vehicle body
structure continues to be fabricated of steel. Joining an aluminum
roof panel to a steel body panel is difficult due to the thermal
expansion considerations of the dissimilar materials. The
combination of the aluminum roof panel attached to the steel body
may create compressive stresses in the aluminum roof panel when the
body is subjected to elevated temperatures such as those required
to cure or bake the paint applied to the body. These stresses may
lead to unacceptable appearance features in the visible segment of
the roof panel.
[0002] Manufacturers currently secure the aluminum roof panel to
the steel body panel after the weld process in assembly. This
process typically includes an adhesive bonding operation.
Self-piercing rivets can also be used to secure the aluminum roof
panel to the steel body panel. This approach, though appealing from
a vehicle mass-reduction viewpoint, raises issues due to the
significantly different coefficients of thermal expansion of
aluminum and steel (about 22.5.times.10.sup.-6 m/m K for aluminum
and about 13.times.10.sup.-6 m/m K for steel). The adhesive must be
able to absorb the distortion caused by the thermal expansion
difference between the roof panel and the steel body panel.
Further, because the steel and aluminum are permanently joined
together by the rivets, this difference in thermal expansion of
steel and aluminum will develop stresses in the aluminum and steel
whenever the vehicle body temperature differs from the temperature
at which the joint was made. The highest temperature experienced by
the vehicle body is during manufacture, when the assembled body is
painted. Automotive paint consists of a number of layers, applied
separately and then cured at an elevated temperature. The paint is
cured by passing the painted body through one or more paint bake
ovens to raise the body temperature to about 180-200.degree. C. and
maintain it at that temperature for at least 20 minutes. This
elevated temperature may be sufficient to initiate plastic
deformation in the aluminum roof panel. Since plastic deformation
is not reversed on cooling, any such deformation may result in an
appearance feature such as a crease or buckle in the roof panel
which could be unacceptable to the customer.
[0003] Further, having the roof and vehicle body panels in contact
or electrically connected can create galvanic corrosion. The risk
for this corrosion is increased when water is present, such as in
the roof gutter areas. As it relates to the adhesive, the current
joining process uses the paint bake ovens to cure the adhesive
bonding the aluminum roof panel to the steel body panel. However,
the heat from the paint bake ovens can cause distortion of the
aluminum roof panel relative to the steel body, creating a bowing
effect. If left unconstrained, the roof panel would bow enough to
break the adhesive bond between the roof panel and vehicle
body.
BRIEF DESCRIPTION
[0004] In accordance with one aspect, a vehicle assembly comprises
a roof structure including a roof panel formed of aluminum or an
aluminum-based alloy and a vehicle body supporting the roof
structure and formed of steel or a steel alloy. The vehicle body
includes a pair of laterally spaced side panels, a front roof rail
and a rear roof rail. Each roof rail spans between the side panels.
At least one bracket secures the roof structure to the vehicle
body. The bracket has a first portion fastened to the roof panel
and a second portion extending away from the roof structure and
welded to the vehicle body. The bracket is formed of steel or a
steel alloy. An adhesive located inward of the weld connection of
the vehicle body and second portion of the bracket bonds the second
portion to the vehicle body. The adhesive seals the fastened
connection of the roof panel and first portion of the bracket from
moisture to prevent galvanic corrosion between the dissimilar
materials of the roof panel and bracket. The adhesive further
reduces thermal distortion of the attached roof panel relative to
the vehicle body when the vehicle assembly is heated in a paint
bake oven during the manufacture of the vehicle assembly.
[0005] In accordance with another aspect, a vehicle assembly
comprises a vehicle roof structure including a roof panel and a
vehicle body. The vehicle roof structure is formed of aluminum or
an aluminum-based alloy. The vehicle body includes a pair of
laterally spaced side panels and a front roof rail and a rear roof
rail spanning between the side panels. The side panels together
with the front and rear roof rails support the vehicle roof
structure. The vehicle body is formed of steel or a steel alloy. A
pair of side brackets connects the side panels to roof panel, a
front bracket connects the front roof rail to the roof panel, and a
rear bracket connects the rear roof rail to the roof panel. Each
bracket has a first portion fastened to the roof panel and a second
portion extending outwardly of the roof panel and welded to the
vehicle body. Each bracket is formed of steel of a steel alloy. The
vehicle roof structure is bonded to the vehicle body via an
adhesive. Each of the brackets provides a continuous vertical
spacing between the roof panel and the vehicle body of
approximately 4 mm to approximately 6 mm, and the adhesive is
provided in the spacing. The adhesive seals the fastened connection
of the roof panel and first portion of the bracket from moisture to
prevent galvanic corrosion between the dissimilar materials of the
roof panel and bracket. The adhesive further reduces thermal
distortion of the attached roof panel relative to the vehicle body
when the vehicle assembly is heated in a paint bake oven during the
manufacture of the vehicle assembly.
[0006] In accordance with yet another aspect, a method of
assembling a vehicle comprises providing a vehicle body formed of
steel or a steel alloy, the vehicle body includes a pair of
laterally spaced side panels, a front roof rail and a rear roof
rail, each roof rail spans between the side panels; providing a
vehicle roof structure formed of aluminum or an aluminum-based
alloy, the vehicle roof structure includes a roof panel having a
flange structure provided at a peripheral edge portion, the flange
portion including a vertical wall and a horizontal surface;
applying an adhesive on the horizontal surface of the flange
structure around an entire perimeter of the roof panel; providing a
pair of side brackets, a front bracket and a rear bracket, each
bracket formed of steel or a steel alloy, and positioning each of
the brackets on the flange structure such that the adhesive is
between each bracket and the flange structure; positioning the
vehicle roof structure together with the brackets on the vehicle
body; fastening each of the brackets to the vertical wall of the
flange structure; welding the side brackets to the side panels, the
front bracket to the front roof rail and the rear bracket to the
rear roof rail; and heating the vehicle body together with the
vehicle roof structure and the brackets to a predetermined
temperature to cure the adhesive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is an exploded perspective view of a vehicle assembly
including a vehicle body formed of steel or a steel alloy and a
vehicle roof structure formed of aluminum or an aluminum-based
alloy.
[0008] FIG. 2 is a cross-sectional view taken along a side portion
of the vehicle assembly.
[0009] FIG. 3 is a cross-sectional view taken along a forward
portion of the vehicle assembly.
[0010] FIG. 4 is a cross-sectional view taken along a rearward
portion of the vehicle assembly according to one aspect of the
present disclosure.
[0011] FIG. 5 is a cross-sectional view taken along a rearward
portion of the vehicle assembly according to another aspect of the
present disclosure.
[0012] FIGS. 6A, 6B and 6C illustrate thermal distortion of the
attached roof panel relative to the vehicle body when the vehicle
assembly is heated in a paint bake oven during the manufacture of
the vehicle assembly.
DETAILED DESCRIPTION
[0013] It should be understood that the description and drawings
herein are merely illustrative and that various modifications and
changes can be made in the structures disclosed without departing
from the present disclosure. In general, the figures of the
exemplary vehicle roof structure are not to scale. As used herein,
lateral directions are transverse across the vehicle, i.e., left
and right directions. Likewise, longitudinal directions refer to
forward and rearward directions of vehicle travel, and the vertical
directions relate to elevation, i.e., upward and downward
directions. It will also be appreciated that the various identified
components of the exemplary vehicle roof structure disclosed herein
are merely terms of art that may vary from one manufacturer to
another and should not be deemed to limit the present
disclosure.
[0014] Increasingly, low-carbon steel or steel alloys, long the
material of choice for vehicle body construction, is being
displaced by higher strength-to-weight ratio materials such as
aluminum or aluminum-based alloys. This trend is driven by a desire
to reduce vehicle weight for improved fuel economy. An example of
this is the exemplary vehicle assembly 100 which has an aluminum or
aluminum-based alloy roof structure 102 attached to a steel or
steel alloy vehicle body 104. As schematically shown in FIG. 1, the
vehicle body 104 includes a pair of laterally spaced body members
or side panels 112, 114 for defining sides of a passenger
compartment 116 and a front roof rail 118 and a rear roof rail 120
spanning between the side panels. The body members 112, 114 may be
identically constructed, but for their disposition on opposite
sides of the vehicle assembly 100. At least one cross member or
roof bow 122 can be interposed between the front and rear roof
rails 118, 120 and extends between the spaced body members 112,
114. The side panels together with the front and rear roof rails
118, 120 support the roof structure 102 over the passenger
compartment 116. Attached to the vehicle body 104 is the exemplary
vehicle roof structure 102.
[0015] With reference to FIG. 2, the vehicle roof structure 102
includes an aluminum or aluminum-based alloy roof panel 132 which
overlies the passenger compartment 116. The roof panel 132 can
include stiffening ribs 134 adapted to accommodate loads imparted
on the roof panel by articles transported thereon, for example in a
luggage rack. These ribs are commonly used on vehicles such as SUVs
or vans because the roof panels for these vehicles are extensive
and generally flat. The ribs 134 stiffen the roof panel 132 and
help it to maintain its shape. For roof panels used in smaller
vehicles, such as sedans, these ribs are generally not required.
The roof panel 132 is generally rectangular in plan view but
because individual vehicle roof structures are required to conform
to vehicle styling, the roof panel can have alternative shapes. The
roof panel 132 includes a forward end portion 140, a rearward end
portion 142 and opposite side portions 144, 146 which extend
longitudinally between the forward and rearward end portions. The
vehicle roof assembly 102 further includes at least one roof
stiffener which extends between the side portions 144, 146. In the
assembled condition of the vehicle assembly 100, a roof stiffener
(not shown) can overlie the roof bow 122; although the roof
stiffener is not required. As is well known, an opening (not shown)
can be provided in the roof panel 132 for a sunroof assembly (not
shown).
[0016] At least one bracket formed of steel or a steel alloy
secures the roof structure 102 to the vehicle body 104. As will be
described in greater detail below, the at least one bracket has a
first portion fastened to the roof panel 132 and a second portion
extending away from the roof structure 102 and welded to the
vehicle body 104. The roof panel 132 includes an upper horizontal
surface 150 connected to a flange structure 152 provided at a
peripheral edge portion of the upper horizontal surface. According
to one aspect, the flange structure 152 extends about the entire
peripheral edge portion of the upper horizontal surface 150. The
flange structure 152 is generally defined by a vertical wall and a
lower horizontal surface (lower relative to the upper horizontal
surface 150). The bracket first portion is fastened to the vertical
wall and the bracket second portion is adhered or bonded to the
lower horizontal surface.
[0017] Particularly, the at least one bracket includes a pair of
side brackets 160, 162, a front bracket 164 and a rear bracket 166.
The side brackets 160, 162 extend longitudinally on the roof panel
132 between the forward and rearward end portions 140, 142 of the
roof panel 132 and connect the side panels 112, 114 to the
respective side portions 144, 146 of the roof panel 132. The front
bracket 164 extends laterally across the roof panel 132 between the
side portions 144, 146 and connects the front roof rail 118 to the
forward end portion 140 of the roof panel 132. The rear bracket 166
also extends laterally across the roof panel 132 between the side
portions 144, 146 and connects the rear roof rail 120 to the
rearward end portion 142 of the roof panel 132. Each bracket 160,
162, 164, 166 is separate from the roof panel 132 and is fixedly
secured thereto to facilitate attachment of the roof panel and
vehicle body 104. The brackets 160, 162, 164, 166 can be separate
from each other or can be formed as a unitary-one piece member,
such as a single frame. As shown in FIG. 1, together the four
brackets 160, 162, 164, 166 extend approximately an entire
perimeter of the roof panel 132.
[0018] FIG. 2 depicts the side panel 112 connected to the side
portion 144 via the side bracket 160. To simplify the explanation
of the present disclosure, only the construction of the side panel
112 and its connection to the vehicle roof structure 102 will be
discussed, but it should be understood that the side panel 114 can
have the same construction with a similar connection to the vehicle
roof structure 102. The side panel 112 includes an outer panel 170
and an inner panel 172. As is well known, a reinforcement (not
shown) can be interposed between the outer and inner panels. The
outer panel 170 includes a flange structure having vertical wall
176 and a horizontal wall 178. The inner panel 172 also includes a
flange structure having a horizontal wall 182. The respective
horizontal walls 178, 182 of the outer panel 170 and inner panel
172 have complementary forms which nest and are welded together.
The side portion 144 of the roof panel 132 includes a side section
190 of the peripheral flange structure 152 having a vertical wall
192 and a lower horizontal surface 194 (lower relative to the upper
horizontal surface 150). It should be appreciated that the
respective flange structures of the side panel 112 and roof panel
132 define a roof groove 198 having provided therein mounting studs
200 for the attachment of a roof molding (not shown). Each mounting
stud 200 can be fixedly attached (e.g., welded) to the horizontal
walls 178, 182 of the outer panel 170 and inner panel 172.
[0019] The side bracket 160 connects the side panel 112 to the side
section 190 of the peripheral flange structure 152 of the roof
panel side portion 144. The side bracket 160 includes a first
portion 210 and a second portion 212. The first portion 210 is
fastened to the vertical wall 192. The second portion 212 extends
outwardly from the roof panel 132 a distance approximately equal to
a distance or spacing between the outer panel 170 and the roof
panel. This allows the second portion 212 to be both adhered or
bonded to the lower horizontal surface 194 and fixedly attached
(e.g., welded) to the horizontal wall 178 of the outer panel 170.
As depicted in FIG. 2, the side bracket 160 is substantially
L-shaped and the first portion 210 of the side bracket 160 is a
vertical leg 216 and the second portion 212 is a horizontal leg
218. The vertical leg 216 is connected to an interior of the roof
panel vertical wall 192 by any mechanical means known in the art,
such as but not limited to the illustrated clinching of the
vertical leg 216 to the vertical wall 192. For example, it should
be appreciated that the vertical leg 216 can be welded to the
vertical wall 192 or connected by use of self piercing rivets,
bolts, etc. The horizontal leg 218 has a stepped configuration
including an upper section 220 (i.e., a section closer to the upper
horizontal surface 150 of the roof panel 132) and a lower section
222. The upper section 220 of the horizontal leg 218 is adhered or
bonded to the lower horizontal surface 194 of the roof panel 132
via an electrically nonconductive adhesive 230. As such, the
connection between the first portion 210 of the side bracket 160
and the vertical wall 192 of the roof panel 132 is positioned
inwardly of the adhesive 230. The lower section 222 extends outward
beyond an end of the lower horizontal surface 194 and is
dimensioned approximately equal to a dimension of the horizontal
wall 178 of the outer panel 170. This allows the lower section to
be nested with and fixedly attached (e.g., welded) to the
respective horizontal walls 178, 182 of the outer panel 170 and
inner panel 172. The mounting stud 200 can be fixedly attached
(e.g., welded) to the lower section 222.
[0020] FIG. 3 depicts the front roof rail 118 connected to the
forward end portion 140 of the roof panel 132 via the front bracket
164. The front roof rail 118 includes an outer panel 240 and an
inner panel 242. As is well known, a reinforcement (not shown) can
be interposed between the outer and inner panels. The outer panel
240 includes a flange structure having vertical wall 246 and a
horizontal wall 248. The horizontal wall 248 can have stepped
configuration and includes a depressed section 250 extending from
the vertical wall 246. The inner panel 242 also includes a flange
structure having a horizontal wall 152. The depressed section 250
of the outer panel horizontal wall 248 is fixedly attached (e.g.,
welded) to the inner panel horizontal wall 252. The forward end
portion 140 of the roof panel 132 includes a forward section 260 of
the peripheral flange structure 152 having a vertical wall 262 and
a lower horizontal surface 264 (lower relative to the upper
horizontal surface 150). The lower horizontal surface 264 extends
beneath an end portion of a windshield 270 mounted to the vehicle
body 104.
[0021] The front bracket 164 connects the front roof rail 118 to
the forward section 260 of the peripheral flange structure 152 of
the roof panel forward end portion 140. The front bracket 164
includes a first portion 280 and a second portion 282. The first
portion 280 is fastened to the vertical wall 262. The second
portion 282 extends outwardly from the roof panel 132 a distance
approximately equal to a distance the horizontal wall 248 of the
outer panel 240 extends outwardly from the roof panel 132. This
allows the second portion 282 to be both adhered or bonded to the
lower horizontal surface 264 and fixedly attached (e.g., welded) to
the horizontal wall 248 of the outer panel 240. As depicted in FIG.
3, the front bracket 164 is substantially L-shaped and the first
portion 280 of the front bracket 164 is a vertical leg 286 and the
second portion 282 is a horizontal leg 288. The vertical leg 286 is
connected to an interior of the roof panel vertical wall 262 by any
mechanical means known in the art, such as but not limited to the
illustrated clinching of the vertical leg 286 to the vertical wall
262. For example, it should be appreciated that the vertical leg
286 can be welded to the vertical wall 262 or connected by use of
self piercing rivets, bolts, etc. The horizontal leg 288 has a
stepped configuration including an upper section 290 (i.e., a
section closer to the upper horizontal surface 150 of the roof
panel 132) and a lower section 292. The lower section 292 of the
horizontal leg 288 is aligned with the depressed section 250 and is
adhered or bonded to the lower horizontal surface 264 of the roof
panel 132 via the electrically nonconductive adhesive 230. This
positions the connection between the first portion 280 of the front
bracket 164 and the vertical wall 262 of the roof panel 132
inwardly of the adhesive 230. The upper section 290 extends outward
beyond an end of the lower horizontal surface and is fixedly
attached (e.g., welded) to the horizontal wall 248 of the outer
panel 240. The end portion of the windshield 270 is adhesively
bonded to the upper section 290 of the front bracket 164.
[0022] FIG. 4 depicts the rear roof rail 120 connected to the
rearward end portion 142 of the roof panel 132 via the rear bracket
166. The rear roof rail 120 includes an outer panel 300 and an
inner panel 302. As is well known, a reinforcement (not shown) can
be interposed between the outer and inner panels. The outer panel
300 includes a flange structure having vertical wall 306 and a
horizontal wall 308. An end portion 310 of the horizontal wall 308
can be angled; although, this is not required. The inner panel 302
also includes a flange structure having a horizontal wall 312 which
is fixedly attached (e.g., welded) to the outer panel horizontal
wall 308. The rearward end portion 142 of the roof panel 132
includes a rearward section 320 of the peripheral flange structure
152 having a vertical wall 322 and a lower horizontal surface 324
(lower relative to the upper horizontal surface 150).
[0023] The rear bracket 166 connects the rear roof rail 120 to the
rearward section 320 of the peripheral flange structure 152 of the
roof panel rearward end portion 142. The rear bracket 166 includes
a first portion 330 and a second portion 332. The first portion 330
is fastened to the vertical wall 322. According to one aspect shown
in FIG. 4, the second portion 332 extends outwardly from the roof
panel 132 a distance approximately equal to a distance the
horizontal wall 308 of the outer panel 300 extends outwardly from
the roof panel 132. The rear bracket 166 is substantially L-shaped
and the first portion 330 of the rear bracket 166 is a vertical leg
336 and the second portion 332 is a horizontal leg 338. The
vertical leg 336 is connected to an interior of the roof panel
vertical wall 322 by any mechanical means known in the art, such as
but not limited to the illustrated clinching of the vertical leg
336 to the vertical wall 332. For example, it should be appreciated
that the vertical leg 336 can be welded to the vertical wall 322 or
connected by use of self piercing rivets, bolts, etc. The
horizontal leg 338 has a stepped configuration including an upper
section 340 (i.e., a section closer to the upper horizontal surface
150 of the roof panel 132) and a lower section 342. The lower
section 342 of the horizontal leg 338 can be angled to match the
angled end portion 310 of the outer panel horizontal wall 308.
According to the embodiment of FIG. 4, the upper section 340 is
adhered or bonded to the lower horizontal surface 324 of the roof
panel 132 via the electrically nonconductive adhesive 230. This
positions the connection between the first portion 330 of the rear
bracket 166 and the vertical wall 322 of the roof panel 132
inwardly of the adhesive 230. The lower section 342 extends outward
beyond an end of the lower horizontal surface 324 and is fixedly
attached (e.g., welded) to the end portion 310 of the horizontal
wall 308 of the outer panel 300.
[0024] FIG. 5 shows another aspect of a rear bracket 166' for
connecting a rear roof rail 120' to the peripheral flange structure
152 of the roof panel 132. The rear bracket 166' includes a first
portion 330' attached to the vertical wall 332 of the flange
structure 152. A second portion 332' of the rear bracket 166' is
shorter in length than a horizontal wall 308' of an outer panel
308' of the rear roof rail 120'. This allows a lower section 342'
of the second portion 332' to be nested with and fixedly attached
(e.g., welded) to the respective horizontal walls 308', 312' of the
outer panel 300' and inner panel 302'. An upper section 340' of the
second portion 332' is adhered or bonded to the lower horizontal
surface 324 of the roof panel 132 via the electrically
nonconductive adhesive 230.
[0025] It should be appreciated that the locations of the fastened
connections (e.g., clinching) between the first portion 210, 280,
330 of each of the brackets 160, 162, 164, 166 and the roof panel
132 is generally dictated by the need for the strength of the
attachment between the vehicle roof structure 102 and vehicle body
104 and more, closely-spaced, connections will promote stronger
attachment. However, it should also be appreciated that distortion
of the roof panel 132 can be minimized when fewer connections are
employed, and the brackets 160, 162, 164, 166 together with the
adhesive 230 provides the required attachment strength between the
vehicle roof structure 102 and the vehicle body 104. In addition,
each of the brackets 160, 162, 164, 166 maintains a continuous
spacing or gap between the roof panel 132 of the vehicle roof
structure 102 and the vehicle body 104 of approximately 4 mm to
approximately 6 mm, and the adhesive 230 is provided in the
spacing. As shown, this continuous spacing provided by brackets
160, 162, 164, 166 for the adhesive 230 is in the vertical or
height direction between the roof panel 132 and the second portions
212, 282, 332 of the brackets 160, 162, 164, 166 which connect the
roof panel 132 to the vehicle body 104. According to one aspect,
the continuous vertical spacing between the roof panel 132 and the
vehicle body 104 is approximately 5 mm. This continuous vertical
spacing maintained between the vehicle roof structure 102 and
vehicle body 104 eliminates the concern for galvanic corrosion and
also controls the flow and location of the e-coat on the vehicle
assembly 100. It should also be appreciated that with the
connection of the first portion 210, 280, 330 of each respective
bracket 160, 162, 164, 166 to the roof panel 132 being located
inward of the adhesive 230, the adhesive 230 seals the connection
of the roof panel 132 and each bracket from the intrusion of
water/moisture and dirt debris to prevent galvanic corrosion
between the dissimilar materials of the roof panel 132 and brackets
160, 162, 164, 166.
[0026] As indicated above, rigidly attaching the aluminum-based
alloy vehicle roof structure 102 to the steel vehicle body 104
(i.e., vehicle components with dissimilar coefficients of thermal
expansion--about 22.5.times.10.sup.-6 m/m K for aluminum and about
13.times.10.sup.-6 m/m K for steel) will generate thermal stresses
when the temperature is raised or lowered. On heating, tensile
stresses develop in the lower coefficient of thermal expansion
material and compressive stresses develop in the material with the
higher coefficient of thermal expansion. Thus, the roof panel 132
of the vehicle roof structure attached to the vehicle body 104 will
be subjected to compressive thermal stresses with increase in
temperature, the thermal stresses increasing generally in
proportion to the temperature.
[0027] After assembly, but before attachment of closures such as
doors or hoods, the vehicle assembly 100 is washed and then
painted. The paint must be cured by exposure to elevated
temperatures, requiring that the vehicle assembly 102 to pass
through at least one paint bake oven, subjecting the vehicle
assembly to temperatures of up to 200.degree. C. for a period of
not less than 20 minutes. This temperature establishes the greatest
compressive stress developed in the vehicle roof structure. The
roof panel 132, when subjected to compressive loads or stresses may
deform, forming a buckle. If the buckling stress exceeds the yield
stress of the metal of the roof panel, the buckle will be permanent
and the roof panel 132 will not adopt its original configuration
even after even after the vehicle assembly 100 exits the oven and
cools.
[0028] The brackets 160, 162, 164, 166 together with the adhesive
230 reduce thermal distortion of the attached roof panel 132
relative to the vehicle body 104 when the vehicle assembly 100 is
heated in the paint bake oven during the manufacture of the vehicle
assembly. By way of example, FIG. 6A shows a pre-bake condition of
the vehicle assembly 100. FIG. 6B shows the vehicle assembly 100 in
a baking condition. As the roof panel 132 expands upwardly and
outwardly, the adhesive 230 absorbs the expansion. As shown in FIG.
6C, the roof panel 132 returns to the pre-bake condition. Thus, the
continuous spacing or gap provided by the brackets 160, 162, 164,
166 for the adhesive 230 allows the aluminum roof panel 132 to
distort during baking and curing of the adhesive (e.g., during an
e-coat process) and allows shearing of the adhesive without the
adhesive failing and without deformation of either the roof panel
132 or the side panel 112. Again, the adhesive 230 forms the
primary connection between the second portions 212, 282, 332 of the
brackets 160, 162, 164, 166 and the roof panel 132, whereas the
fastened connection (e.g., clinching) of the first portions 210,
280, 330 of the brackets to the roof panel 132 is more for
positioning the roof panel and the brackets together prior to
curing of the adhesive 230. The adhesive 230 provides flexibility
during heating of the vehicle body to help absorb the stress
associated with the different expansion rates of the dissimilar
materials. And the depicted fastened (e.g. clinched) area is in a
dry section because the adhesive 230 seals the connection of the
brackets 160, 162, 164, 166 and the roof panel 132 from moisture to
prevent galvanic corrosion between the dissimilar materials.
[0029] As evident from the foregoing, to prevent distortion of the
vehicle roof structure 102 as described above, the present
disclosure provides a method of assembling a vehicle including the
vehicle body 104 formed of steel or a steel alloy and the vehicle
roof structure 100 formed of aluminum or an aluminum-based alloy.
The method comprises providing the vehicle body 102 including the
pair of laterally spaced side panels 112, 114, the front roof rail
118 and the rear roof rail 120; providing the vehicle roof
structure 102 including the roof panel 132 having the flange
structure 152 provided at a peripheral edge portion; applying the
adhesive 230 on the horizontal surface 194, 264, 324 of the flange
structure 152 around an entire perimeter of the roof panel 132;
positioning each of the brackets 160, 162, 164, 166 on the flange
structure 152 such that the adhesive 230 is between each bracket
and the flange structure; positioning the vehicle roof structure
102 together with the brackets 160, 162, 164, 166 on the vehicle
body 104; fastening each of the brackets 160, 162, 164, 166 to the
vertical wall 192, 262, 322 of the flange structure 152 (e.g., by
clinching, welding, fasteners); welding the side brackets 160, 162
to the side panels 112, 114, the front bracket 164 to the front
roof rail 118 and the rear bracket 166 to the rear roof rail 120;
and heating the vehicle body 104 together with the vehicle roof
structure 102 and the brackets 160, 162, 164, 166 to a
predetermined temperature to cure the adhesive 230.
[0030] The exemplary method further comprises providing a
continuous vertical spacing between the roof panel 132 and the
vehicle body 104 of approximately 4 mm to approximately 6 mm by use
of the side brackets, front bracket and rear bracket, and providing
the adhesive 230 in the spacing; positioning the fastened
connection between the brackets 160, 162, 164, 166 and the flange
structure 152 inwardly of the adhesive 230, and positioning the
welded connection between the brackets 160, 162, 164, 166 and the
vehicle body 104 outwardly of the adhesive 230. The method further
includes clinching the respective vertical leg 216, 286 336 of each
bracket 160, 162, 164, 166 to an interior of the flange structure
vertical wall 192, 262, 322, and for each of the side panel
brackets 160, 162 and the rear bracket 166, bonding the upper
section 218, 340 of the horizontal leg 220, 338 to the horizontal
surface 194, 324 of the flange structure 152, and for the front
bracket 164 bonding the lower section 292 of the horizontal leg 288
to the horizontal surface 264 of the flange structure 152.
[0031] While, for purposes of simplicity of explanation, the method
has steps described as executing serially, it is to be understood
and appreciated that the present disclosure is not limited by the
illustrated order, and some steps could occur in different orders
and/or concurrently with other steps from that shown and described
herein.
[0032] It will be appreciated that various of the above-disclosed
and other features and functions, or alternatives thereof, may be
desirably combined into many other different systems or
applications. Also that various presently unforeseen or
unanticipated alternatives, modifications, variations or
improvements therein may be subsequently made by those skilled in
the art which are also intended to be encompassed by the following
claims.
* * * * *