Note: Descriptions are shown in the official language in which they were submitted.
CA 02237029 1998-05-06
BAC~GROUND OF THE INVEN~ION
Field of the Invention
This invention relates to safety ~traps for component~
su~penda~ly ~upported on or u~der motor vehicles.
Especially, the invention relates to safety straps for
gasoline tanks w~ich are supported from the underbody of
motor vehicles usually in a position open to the ground.
Acknow] e~g~ent of Prior Art
Gasoline tanks were, over a ver~ long period of
auto~otive hi~tory, ~anufactured of metal. They h~ve been
supported in convenien~ hollows or cavi~ies of the mo~or
body. These hollows or cavities are usually open to the
ground beneath. One reason for this is that if a gasoline
tank-fractures the ga~oline may run-harmle~sly away with
less ri~k o~ causing fire within the vehicle. Considerable
e~phasis has been laid on back-up supporting sy~tems ~or the
gas tank bec~u9e, should a gas tank should break free of its
prLmary support systems and drag on a road surface, any
resulting sparks may be very dangerous indeed. Therefore,
it ha~ been conventional to provide additional back-up
safety ~traps to hold the gas ta~k, should the primary
support system fail. These back-up ~afety straps have
conventionally been made from metal stampings.
More recently, some gasoline tanks are manuf~c~ured
from ~olded plastic material to mitigate the possibility of
sparks. ~t has, however, been thought nece.~sary to continue
using metal safety straps. The necessity of this is
possibly due to the strength of the strap which ~ay be
required under unu~ually disadvantageous con~itions. T~e
30 weight o~ a ~ull ga~ tank may ea~ily be i~ the region of 150
pounds. This weight must be reliably supported over a long
CA 02237029 1998-OS-06
period of ~ay several years under conditions which may range
from, say., ~ore than 100~F (in sum~er when great heat is
p~oduced from the exha~st or reflected from hot ro~d
s~rface~) to, say, less than -10~F or -20~F (in the depths
of ~inter). In some climates one or both of the~e
temperatures may be even more extreme. Still further, the
ageing of plastic materials results in b~ittleness and lack
of strength.
Thus, it has not been thought prac~icable to use
plastic ~aterials for support straps for gas tanks in spite
of the various difficulties inherent in the use of metal
straps .
The stamped metal saf~ty straps have various problems
associated with them. They are quite expensive to
~5 manufacture in that it is necessary to make a metal
stam~ing, provided with a hinge pin at o~e end by ~eans of
further manufact~ring processes such as riveting or
otherwise fixing a cylindric~l housing for the hinge pin to
one end of the strap and inserting the hinge pin to project
20 fro~ either en~ of the hou~ing. Attachment means must be
provided at the other end of the s~rap, for example an
aperture for a nut and bolt closure with the vehicle body
may be provided. The stamped metal strap must be bent into
a shape conforming to the shape of the gas tank. None of
these ad~itional ~anufacturing steps are as simple as they
first appear. The step of riveting a hinge pin housing to
one end of the strap is e~pensive. The hinge pin itself
tends to fall out of the ho~sing before installation in the
vehicle. This makes handling and storage of the uninstalled
straps somewhat of a problem. The ~tep of ~ending the strap
CA 02237029 1998-05-06
into shaped form with the ~as tank provide~ real proble~s.
The metal has a tendency to ~pring ~ack from the shape in
whic~ it is bent so that the conformation of shape of the
eventually bent strap is never very precise. The process
al~o lead~ to a severe b~lrr problem. As a result it is ~'ery
frequent that a strap must ~e manually stressed or machined
before or during installation by the mechanic installing it.
If it should slip there is a danger of either injuring the
mechanic hi~self o~ damaging the gasoline tank. ~ow that
gasoline tanks are frequently made of molded plastic
materi~l, the danger of damaging the gasoline tan~ and
actually rupturing i~ is quite high. It is also necessary,
whether the gasoline t~nk is a me~al tank or a molded tank,
to provide some padding between the tank surface and the
metal strap. Such padding mitigates friction and resulting
wear of the gas t~nk d~e to ~ubbing of the strap. In the
case o~ molded tanks it may help to prevent the metal strap
actually tearing apart the tank. In the case of metal tanks
it may help prevent sparks
Even though the use of ~etal safety straps has so many
di~ficultie~ associated with it, there has been a very real
acceptance in the industry that these difficulties are
inherent and must be lived with. It has not been thought
possible to make substan~ive changes in the manufacture and
design of safety straps for gasoline tanks and other ~nder-
~ehicle parts such as exhaust systems.
S~MM~RY OF THE INVENTION
The present inventor has addLe~sed the pxoblems in
providing more satisfactory, less expensive safety ~traps
for use ~ith under-vehicle parts. Most surprisingly he
CA 02237029 l998 - 05 - 06
discovered that ~he perceived reasons for the impos~ibility
of using molde~ material safety straps may ~ot apply
especially when the m~lded material i~ selected from those
materials which do not suffer fro~ deterioration under the
extreme conditions which occur underneath a car.
~ccording to the invention there is provided an elon~ate
sa~ty strap constructed and arranged to e~tend beneath an
article supporte~ above the ground by pri~ary support means
depending from a supporting body, the safety strap being
molde~ in a material selected from the group con~isting of
moldable ceramic material, thermosetting plastic~ materials,
and thermoplastics materialY to conform generally with the
shape of an undersurface of ~aid article in the region of
the strap, each end of the strap havi~g a connector molded
thereinto to connect the strap to said body.
Preferabl~ the safety strap is of the type having a
hinqe at one end and closure means at the other so that it
may be open for accessing the component part if neces~ary
and reclosable when d~sired. Conveniently, the hinge may be
the hinge pin extending at right angles to the strap for
location in hinge ~ountings of the structure from which the
article is supported. In particular, the article may be a
gasoline tank, a muffler, other parts of ~n exhau~t ~ystem
or other vehicle compo~ents supported beneath a motor
vehicle.
When the article is, for example, a gasoline tank, the
safety strap may be manufaot~red ~rom reinforced
thermoplastic materials such as nylons, ~or example Celanese
1500 and Zytel 70G43L. Other thermoplastic materials such
CA 02237029 1998-05-06
as li~uid crystal polymers ~vectra B420 ), polyphenylene
sulp~ide, ~tc. may also be u~ed. Nylons, which tend to
harden on ageing may be especially sui~able.
When the article to be supported is, for example, a
muffler system the ~trap may be ~olded from moldable ceramic
material or thermo~etting plastic material. Alternat-vely,
the~moplastic material having a melting point above 4~0~F my
be used. -
The straps should, of course, be of sufficient strength
to support the tank or other article if the primary suppor~should ~ail. Thus, the 6tra~ or straps must be su~ficiently
strong to support loads in the region of 150 lbs depending
on the capacity and content of the tank. Clearly loads
greater than this may b~ envisaged. It may, therefore, be
convenient to form the straps of molded reinforced material.
The reinforcement may be, for example, a fiber reinforcement
either oriented or non-oriented. Examples of fibe~
reinforcement are fibergla~, Kevlar lTrademark) or other
aramid fiber, graphite and the like.
The invention includes a method of injection molding a
back-up safety strap for supporting an article espe~ially a
component of a motor vehicle against ~alling sho~ld its
primary ~upport fail. The injection ~olding method may
comprise forming a mold to conform with the shape of at
least the under side of the article with which the safety
strap is to be used, locating a hinge pin in the mold,
inj ecting moldable material around a mid-portion o~ the
hinge pin and ~emoving the molded article from the mold.
Conveniently, provision may be made in the mold to provide
CA 02237029 1998-05-06
-- 6 --
an aperture at one end of the safety strap for latching with
a ~tructure on ~hich the article is supported by me~ns of a
bolt passing through the aperture and a lock-nut.
BRIEF DESCRIPTION OF THE DR~INGS
Embodiment~ o~ the invention are generally illustrated
by way of example in the accompanying drawin~s in which:
Figu~e 1 is an exploded view of an e~emplary prior art metal
strap for back-up support for a gasoline tanki
Figure 2, ~A, 2~ and 2C show a safety strap according to the
1~ invention for back-up suppoLt for a gasoline tanki
Figure 3 shows another safety strap according to the
invention for back-up support on a gasoline tank;
Figure 4 shows a strap accor~ing to the invention for
support of a mu~fler system; and
Figure 5 show~ a section of a ~old for molding a safety
strap as ~hown in Figure ~.
DETAILEI) I;~ESCRI Pl'ION OF PREFERRED EMBODIMENTS
From Figure 1 it can be seen that a large numbex of
parts are necessary in the manufacture of even a very simple
strap stamped fro~ metal. A hinge pin 12 is lo~ated only by
a clamp 14 riveted by rivet 16 to the bo~y 18 of the strap
10. The strap 10 is provided with a fl.ange 20 at t~e end
distan~ from the hinge pin 12. A hole 22 is punched in the
~lange so that the strap may be bolted to the under body 17
of a motor vehicle by bolt 21. A foam pad 11 is provided on
the strap 10.
CA 02237029 1998-05-06
The hinge pin 12 may be located in sockets 13 fixed to
~he underbody 17 of a motor vehicle. A ga~oline tank 15 is
~uppor~ed beneath the underbody 17 by primary supports 19.
~ igures 2, 2A and 2B show a safety strap 30 embodyi~g
the invention w~ich is simple in comparison with a ~trap of
the prior art. Strap 30 is molded in one piece construction
from glass fiber reinforced nylon Zytel 70G43L. The one
piece construction of the strap extends around hinge pin 32
to adhere to hinge pin 32 and locate it fi~mly with respect
to strap 30. Flange 34 is provided at the end of the strap
distant from hinge pin 32 and is molded in the original
molding. It is not necessary ~o provide an extra process
step to bend flange 34 i~to position. Aperture 36 is
provided to accept a ~olt 21 from a under body of a motor
vehicle and, again, may be pro~ided in the original mol~ing.
The gasoline tank 15 i~, as in Figure 1, supported beneath
the underbody ~7 by pri~ary supports 19.
Figure 3 shows more complex shape o~ a safety strap
otherwi~e similar to that of Figure 2. It may, however, be
seen from Figure 3 that the configuration of strap 30 ~ay
follow the shape of gasoline tank 15 to fit indentations in
the tank. This is not convenient or even possible when
using a metal strap of the prior art.
Hinge pin 12, shown separa~ely in Figure 2A, may have a
knurled central portion for better bonding. The strap 30
itself may ~e ribbed for strength. For example it may have
the cross section shown in Figure 2B. Figure 2c ~hows a
rigid washer 54 which is molded into the end of strap 30 as
CA 02237029 1998-05-06
~he flange 34 distant from the hinge. Washer 54 forms a
ba~e ~or attachment to the vehicle body.
Figure 4 ~hows a strap which may be a pri~ary ~upport
strap for a muf~ler ~olded from a ceramic ~oldable material.
Reference numerals in Figures 3 and 4 represent similar
parts to those of Figure 2.
The strap 30~ of Figure 3 has at one end, a washer 54A
~imilar to that of Figure 2C. At the other end a downward
leg ~0 of a bLacket 62 is embedded in the end during
molding. The strap 30B of Figure 4 has washers 54B at eac~
end. Washers 54B are similar to washers 54 and 54~.
Fi~ure 5 is a section through injection mold ~alves to
make a safety strap as shown in Figure 2. The mold includes
a cavity 50 ha~ing a bulbous portion 52 at one end and a
socket ~or location of a hinge pin 32. At the end of the
cavity distant from the bulbous end, a square washex 54 is
located in the cavity. The washer 54 forms a firm base and
has an aperture for an attachment bolt. Since washer 54 is
~olded into, or at least attached to, the strap, there is
red~ed risk of it loss duling transport. The gating for
the injection mold may be provided at any convenient
location.
