FIELD OF INVENTION
This invention relates to back door of vehicle for tilted packaging of spare
wheel. The back door is particularly side opening back door without restricting
scope of the invention to the same.
BACKGROUND/PRIOR ART
Conventionally in (he side opening back door the spare wheel is mounted in
vertically straight position as shown in fig. 1 and fig. 1A.
Now referring to fig. 2, the spare tire (1) is mounted on door outer panel (2).
There is provision of reinforcement (3) behind the outer panel (2), which is
joined with door inner panel (4) .The spare tire is mounted on the mounting
surface of said door outer panel by means of a bracket (5): The spare tire can
be covered by a cover (6) .The back door glass (8) is located above the panel. The
mounting surface of outer panel, bracket and spare tire, all are placed in
straight position.
Therefore, total load of the wheel (mg) acts in vertically downward direction
(towards earth). Thus, the total load (mg) acts in Z-axis and along mounting
direction (X-axis), there is zero load. Hence, the total force (F=mg) due to selfweight
of spare tire acts completely on back door mounting.
The above is associated with the following disadvantages: -
- Chances of endurance/durability failure of spare tire mounting is more
due to entire load of spare tire acting in vertical direction
- Assembly of spare tire is difficult i.e ergonomically not convenient for
assembly operation
- Requirement of thick reinforcements to cater the additional load which
increase the cost and weight of vehicle.
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Some Patents/Publications may be discussed hereinbelow:-
Therc is known to have been available a technology, according to which spare
wheel is mounted on under body. Therefore, ground clearance of vehicle is
compromised in this design. The spare wheel is mounted on a cross member by
means of a bracket and the cross member is connected with shock absorber of
the vehicle. Here, assembly is difficult as tire is mounted in underbody.
A vehicle spare tire carrier is disclosed for the storage and transportation of a
spare tire outside of a vehicle.
This design comprises of back door, spare tire carrier, torsion bar and spare
tire carrier hinge. Torsion bar is used in mechanical connection to a pivotal
arm. Additional hinges are used to mount the spare wheel mounting structure.
Mounting is provided on bumper member as well as back door. Ingress egress
is somewhat difficult because the tire carrier assembly needs to be opened
before opening the back door. It comprises many assembly parts, which
degrades appearance of back view. In this first spare wheel carrier is mounted
on hinges at top and bumper at bottom. Thereafter, the spare tire is mounted
on that carrier. Thus, assembly variations are more as number of child parts is
more. Back door cannot be opened without opening spare wheel tire carrier. It
is particularly applicable for cargo truck.
DE 202013004609: Wheel carrier for a vehicle, comprising a frame having an
upper cross member, a lower member from one end of the upper member
extends at an acute angle, wherein a pivot axis by the free ends of the members
extends, and is defined by upper and lower hinges. Said upper hinge comprises0
a mounting flange for attachment to the belt line of a vehicle body, and wherein
the upper hinge an upwardly open receiving slot defined between the mounting
flange and the pivot axis.
-4-
This design comprises conventional back door, free frame structure, upper
hinge comp and lower hinge comp. Assembly of spare tire is mounted on frame
structure which is folded around vertical axis, using hinges mounted on back
door outer panel. Here, additional bar structure & additional atleast two hinges
are required to hold the spare wheel. Ingress egress is somewhat difficult
because the tire carrier assembly needs to be opened before opening the back
door. This design comprises additional hinges on back door surface which
adversely affects appearance thereof. In this design firstly frame is mounted
along with additional hinges on vehicle. Thereafter spare wheel is mounted on
this frame. Thus, assembly variations are more as number of child parts is
more.
GB267886: The rear sets of a motor vehicle, are arranged to slide
longitudinally, and when moved forwards leave a space for luggage, access to
which is obtained by a door or movable panel in the back of the body, the spare
wheel carrier, when carried at the rear, being mounted on tilting brackets so as
not to hinder access to the.door or panel. A tip-up seat can be used when the
seats are in the rear position.
This patent is regarding rear seat sliding forward to make space for luggage at
back. The spare wheel is mounted on the back with tilted or pivoted brackets
so as not to hinder access to the door or panel.
There is known to have been in existence an accessory kit which is introduced
for aggressive styling. This is placed on a frame on back of vehicle. Thekit
comprises a separate bracket assembled to a mounting on which spare tire is
mounted as shown in fig. 2A.
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However, it is associated with several drawbacks listed herein below:
- It obstructs rear visibility which can't be compromised as it is a
regulatory requirement. Thus homologation requirement of rear visibility
is not met with this design.
Use of additional frame and hinges.
- Ingress egress is somewhat difficult because the tire carrier assembly
needs to be opened before opening the back door.
- This kit is model specific so is styling.
- In this design first frame is mounted along with additional hinges on
vehicle then kit is mounted on frame followed by spare wheel on kit.
- Assembly variations are more as number of child parts is more.
* In order to obviate the aforesaid shortcomings, the instant invention has been
proposed.
OBJECTS OF THE INVENTION
Primary object of the present invention is to provide back door of vehicle for
tilted packaging of spare wheel which overcomes drawbacks associated with
the prior art.
Another object of the present invention is to provide back door of vehicle for
tilted packaging of spare wheel which reduces load acting on the mounting
area of spare tire in vertical direction.
Further object of the present invention is to provide back door of vehicle for
tilted packaging of spare wheel which leads to reduction in weight 85 cost of
reinforcement resulting in high fuel efficiency of vehicle.
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Yet another object of the present invention is to provide back door of vehicle for
tilted packaging of spare wheel which distributes the load efficiently.
SUMMARY OF THE INVENTION
According to this invention, there is provided back door of vehicle for tilted
packaging of spare wheel comprising of back door outer panel connected to
inner panel with reinforcement there between, wherein outer panel mounting
surface for spare tire is provided at an inclination for tilted mounting of said
spare tire.
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. land
1A shows: Conventional mounting of spare tire on vehicle.
Fig. 2 shows: mounting arrangement of spare tire in the prior art.
Fig. 2A shows: A known kit for mounting spare tire on vehicle. <
Fig. 3 shows: Mounting arrangement of spare tire according to present
invention.
Fig. 4 shows: Components of force due to weight of spare tire acting in X
and Z direction.
Fig. 5 shows: Graph between angle of inclination of spare tire (9) and load
acting on the mounting area in vertical direction (Fz).
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS
The invention makes disclosure which teaches a novel design regarding back
door of vehicle for tilted packaging of spare tire.
-7-
Now reference may be made to fig. 3 wherein the back door inner panel (1) is
spot welded and hemmed with outer panel (2). Reinforcement (3) is placed
behind the outer panel. The invention lies in the tilting of outer panel mounting
surface on which the spare tire (4) is mounted. As can be observed from the
figure, the mounting surface (M) on the back door outer panel is tilted on which
spare tire is mounted in tilted position along with the spare tire mounting
bracket (5). The complete assembly can be covered with spare tire cover (6).
The back door glass (7) is above the panel.
Thus, according to this invention, spare wheel assembly mounting surface on
door outer panel is modified to give a tilt to spare wheel. The mounting surface
is integrated with the outer panel.
The angle of tilt depends on the packaging space available between said inner
panel and outer panel, wherein location of the inner panel is derived from
ergonomics.
Due to the titled position of the spare tire, the load on the mounting area in
vertical direction is less as compared to prior art because the load is
distributed in two directions i.e. along length of vehicle (X-direction) and along
height; of vehicle (Z-direction).
In respect of this, reference may be made to fig. 4 in which the spare tire with
bracket is orthogonal to the mounting surface. Force due to weight of spare
wheel (F=mg) on mounting is distributed into the following two components.
Fx=mg Sin.9; Fx= force along length of vehicle
Fz=mg CosG; Fz= force along height of vehicle (load on the mounting area in
vertical direction)
Wherein m= mass of spare wheel; g= acceleration due to gravity. (Refer figure 4)
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An example of working out the vertical load on the mounting area is given
herein below:
Force on the mounting area (Fz)=mgCos0
Where m=24 kg; g=9.81m/sec2;0=lO°
Fz=24X9.81XCos 10°
= 231.87 N
According; to conventional design
F= mg (Force on the mounting area)
= 24X9.81 N
= 235.44 N
Thus, it can be observed that the load on the mounting area is reduced due to
provision of present invention.
The load (mgCosB) decreases with the increase in angle of inclination, which
can be noticed from the below table:
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The above has been reflected in the graph between tilt angle (9) and load (Fz) in
fig. 5.
Advantageous Features:
- Chances of endurance/durability failure are less owing to less stress on
the rnounting area in vertical direction.
Easy assembly of spare tire as tilt assists the mounting once tire is
located in bolts.
- Redaction in reinforcement thickness as less load acts in vertical
,. direction.
- Meeting of homologation requirement of rear visibility.
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. Back door of vehicle for tilted packaging of spare wheel comprising of
back door outer panel connected to inner panel with reinforcement there
between, wherein outer panel mounting surface for spare tire is provided
at an inclination for tilted mounting of said spare tire.
2. Back door of vehicle for tilted packaging of spare wheel as claimed in
claim 1 wherein the angle of inclination relies on the packaging space
available between the inner panel and outer panel.
3. Back door of vehicle for tilted packaging of spare wheel as claimed in
claim 1 or 2 wherein the spare tire is mounted in tilted position along
with the spare tire mounting bracket on the mounting surface of outer
panel. ., •
4. Back door of vehicle for tilted packaging of spare wheel as claimed in any
of the preceding claims wherein the mounting surface is integrated with
the outer panel.
5. Back door of vehicle for tilted packaging of spare wheel as claimed in any
of the preceding claims wherein force due to the weight of spare tire on
mounting is distributed in two directions.
6. Back door of vehicle for tilted packaging of spare wheel as claimed in any
of the preceding claims wherein the force along height of vehicle (load on
the mounting in vertical direction) is mgCos9 and force along length of
vehicle is mgSinO.
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7. Back door of vehicle for tilted packaging of spare wheel as claimed in any
of the preceding claims wherein the load on the mounting in vertical
direction i.e. mgcos0 is less than mg.
8. Back door of vehicle for tilted packaging of spare wheel as claimed in any
of trie preceding claims is associated with the advantageous features
such as herein described.
9. Back door of vehicle for tilted packaging of spare wheel substantially as
herein described with reference to the accompanying drawings.