Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to caps for fuel tank filler
necks, and more particularly to a novel construction for the
so-called torque-override threaded filler neck cap.
Torque-override threaded fuel tank filler neck caps
are known. There are, for example, the caps of U.S. Patents
3,815,776 and 3,986,634. In these structures, the hand-grip
providing member includes a plurality of ratchet teeth, each
including a locking surface and a torque-override surface.
The closure of that structure is provided with a plurality of
10. pawl fingers extending somewhat concentrically with the wall
upon which the ratchet teeth are formed, and provided at
their ends remote from their connection to the closure
member, with pawl teeth for engaging the ratchet teeth. Each
pawl tooth also includes a locking surface cooperating with
the locking surface of at least one of the ratchet teeth to
provide a driving connection in a cap-removal direction, and
a torque-override surface cooperating with a torque-override
surface of at least one of the ratchet teeth to provide the
torque-limited driving connection in the direction which
20. advances the cap on the filler neck.
The structure of the present invention provides an
alternative to this prior art structure. The inventive
structure is believed to provide better control of the
overriding torque, or so-called "breakaway torque," of the
cap. That is, the structure of the present invention is
believed to provide a better control of the maximum torque to
which the gasket is tightened. Typically, the components of
such a cap are molded from plastic materials and the like.
Unless the components are carefully designed, variations due
30- to the materials used, the molding process, and related
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variables can result in unacceptable variations in breakaway
torque and other cap parameters from batch to batch of the
molded parts.
According to the invention, a fuel tank filler neck
cap comprises a closure member for insertion into a threaded
filler neck to close it, a gasket for sealing against the lip
formed at the axially outer end of the filler neck, and a
shell member providing a hand grip. The gasket is mounted on
the closure member near its axially outer end, and the shell
10. member and closure member include cooperating means providing
a driving connection between the shell and the closure member
in a cap-removal direction and a torque-limited driving
connection between the shell and closure member in the
cap-advancing direction to protect the gasket against
overtightening. The cooperating means includes a plurality
of radially deflectable pawl fingers formed on the shell, the
pawl fingers extending radially from a first radially facing
wall provided on the shell and then generally concentrically
with the first wall, or parallel to the first wall. The pawl
20. fingers are provided at their ends remote from the first wall
with pawl teeth. Each pawl tooth is provided with a first
generally radially and axially extending locking surface and
a second generally chordally and axially extending
torque-override surface. The cooperating means further
includes a second generally radially facing wall on the
closure member. The second wall provides a plurality of
ratchet teeth, with each ratchet tooth including a first
generally radially and axially extending locking surface
cooperating with a locking surface of at least one of the
30- pawl teeth to establish the driving connection between the
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shell and closure in the cap-removal direction. Each
ratchet tooth further includes a second generally chordally
and axially extending torque-override surface cooperating
with at least one of the pawl teeth to establish the
torque-limited driving connection between the shell and
closure in the cap-advancing direction.
The invention may be best understood by referring
to the following description and accompanying drawings which
illustrate the invention. In the drawings:
10. Fig. 1 is a vertical section view of the molded
plastic fuel tank filler neck cap of the instant invention;
and
Fig. 2 is a bottom plan view of the cap of Fig. 1
taken generally along section lines 2-2 thereof.
Referring now to Fig. 1, the fuel tank filler neck
cap 10 of the instant invention includes a closure 12 having
an axially outer portion 14 and an axially inner portion 16.
Cap 10 also includes a shell 18 which provides a hand grip.
A ring 20 fastens shell 18 and closure 12 together.
20. Referring now to Fig. 2, the radially inwardly
facing surface 22 of shell 18 is provided with a plurality of
inwardly extending ribs 24. Ribs 24 engage recesses 28
spaced peripherally about pawl ring 26. A set of equicentric
pawl fingers 30 are connected to a radially inwardly facing
surface 31 of ring 26 by base portions 32. Fingers 30 extend
generally concentrically from their bases, parallel to
surface 31. The distal end of each pawl finger 30 is formed
to provide a tooth 34 having a first generally radially and
axially extending locking surface 36 and a second generally
30- chordally and axially extending torque-override surface 38.
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The axially outermost portion 40 (Fig. 1) of closure 12 is
formed to provide a set of equicentric teeth 44 on a radially
outwardly facing surface 45 thereof. Each tooth 44 has a
first generally radially and axially extending locking
surface 46 and a second generally chordally and axially
extending torque-override surface 48.
Teeth 44 of closure 12 and teeth 34 of pawl fingers
30 are situated for engagement when closure 12 and cap 18 are
rotated relative to one another. If, for example, shell 18
- 10. is rotated in the cap-removal direction (i.e., clockwise as
viewed from the bottom of cap 10 in Fig. 2), the generally
radially and axially extending locking surfaces 36 of teeth
34 and the generally radially and axially extending locking
surfaces of teeth 44 engage in a locking relationship,
rotating closure 12 in the cap-removal direction. This is
- the situation when cap 10 is being loosened. However, if
shell 18 is rotated in the cap-advancing direction (i.e.,
counterclockwise as viewed from the bottom of cap 10 in Fig.
2), the generally chordally and axially extending
20. torque-override surfaces 38 of teeth 34 will engage the
generally chordally and axially extending torque-override
surfaces 48 of teeth 44, exerting a rotating pressure on
closure 12. This is the situation when cap 10 is being
tightened on the filler neck.
Thus, the instant invention provides a cap in which
overtightening is eliminated by the slippage of the second
generally chordally and axially extending torque-override
surfaces 38, 48 of teeth 34, 44. Upon loosening of the cap,
the generally radially and axially extending locking surfaces
30- 36, 46 of teeth 34, 44 engage in a locking relationship in
1~37447
which there is no slippage. The overriding torque required
to permit slippage in the cap-advancing direction
(counterclockwise in Fig. 2) is determined by the flexibility
of pawl fingers 30 and base members 32, and the inclination
of the chordally extending surfaces 48.
Referring now to Fig. 1, a fuel tank filler neck
54 has threads 56 which engage threads 58 of the axially
inner portion 16 of closure 12. A radially extending wall 60
of closure 12 retains an O-ring gasket 62 adjacent an axially
10. inwardly facing surface of axially outer portion 14 of
closure 12. When cap 10 is threaded onto neck 54, gasket 62
seats against flange 64 of neck 54, creating a seal between
closure 12 and neck 54. A principal consideration in
determining the desirable overriding torque between closure
12 and shell 18 is gasket 62. The overriding torque must be
so determined to prevent excessive compression of gasket 62
against flange 64 of neck 54, and resulting damage to
gasket 62.
Closure 12 includes a pressure-vacuum vent valve
20. housing 68 which supports a pressure-vacuum vent valve
assembly 70. Assembly 70 controls the venting of fuel vapors
at a predetermined pressure out of the fuel tank through
housing orifice 72 and between closure 12 and shell 18 to the
atmosphere. Assembly 70 also controls the venting of air
through orifice 72 of housing 68 into the fuel tank when the
pressure in the tank decreases to a predetermined level.
Assembly 70 includes pressure-venting disc 74 having an
axially inwardly facing circwnferential bead 76 which seats
against housing 68 and a central aperture 78. Stem 80 of
vacuum venting disc 82 is loosely received within aperture 78
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of pressure disc 74. Vacuum disc 82 includes a
circumferential valve bead 84 which seats against the axially
inward surface of pressure disc 74. A spring 86 is disposed
between housing 68 and vacuum disc 82 to maintain vacuum disc
82 in a seating relationship against pressure disc 74. A
spring 90 is disposed between a spring retainer cup 92 and a
spring retainer 94 to maintain pressure disc 74 in a seating
relationship with housing 68. Cup 92 rests on the axially
outward surface of pressure disc 74 and retainer 94 is
10. press-fitted into a recess provided in axially outermost
portion 40 of closure 12.
Shell 18 includes a peripheral and axially inwardly
extending skirt 100. Skirt 100 is circumscribed by a
peripheral groove 102 and a pointed lip 104. Retainer ring
20 includes a radially outer, axially outwardly extending
portion 110 and a radially inner, axially outwardly extending
portion 112 joined by an axially inner radially extending web
portion 114. Portion 112 is provided at its axially outer
extent with a surface 116 for supporting axially outer
20. portion 14 of closure 12. As shown in Fig. 2, axially outer
portion 14 of closure 12 is provided with fingers 118
separated by spaces 120. Fingers 118 rest upon axially outer
surface 112 of retainer ring 20. An axially inwardly
projecting spacer ring 121 is formed on the axially inner
surface 123 of shell 18. The axially inner end of ring 121
is closely spaced to ring 26 to insure the axial alignment of
all of the cap 10 components. Spaces 120 between fingers 118
provide for communication between the atmosphere and
pressure-vacuum vent valve assembly 70. Referring again to
30- Fig. 1, a radially inwardly extending flange 122 extends
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about the inner periphery of the radially outer, axially
outwardly extending portion 110 of ring 20. Flange 122
engages lip 104 of skirt 100 in a locking relationship to
retain ring 100 on shell 18. Thus, ring 20 acts as a
radially inward extension of skirt 100 to hold axially outer
portion 14 of closure 12 within shell 18. This structure is
described in considerable detail in U.S. Patent 4,091,955.
It may be noted that shell 18, ring 20, pawl ring
26, and closure 12 are all susceptible of manufacture by the
10. molding of high impact plastics. In this regard, it may be
appreciated that the retention of flange 122 by lip 104 can
be a snap fit if plastics are used.
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