U.S. patent application number 11/010920 was filed with the patent office on 2006-06-15 for ratcheted fuel cap.
Invention is credited to James Dehn.
Application Number | 20060124644 11/010920 |
Document ID | / |
Family ID | 36582608 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060124644 |
Kind Code |
A1 |
Dehn; James |
June 15, 2006 |
Ratcheted fuel cap
Abstract
A fuel tank cap that is engageable with a neck of a fuel tank.
The fuel tank cap includes a cap shell that has a cover portion and
a substantially cylindrical wall extending from the cover portion
to define a substantially cylindrical chamber. An arm extends from
the cover portion toward the fuel tank. An inner shell is at least
partially disposed within the cylindrical chamber. The inner shell
includes an engagement portion that is engageable with the neck and
a protrusion that is engageable with the arm to selectively couple
the cap shell and the inner shell for rotation in unison.
Inventors: |
Dehn; James; (Brookfield,
WI) |
Correspondence
Address: |
MICHAEL BEST & FRIEDRICH, LLP
100 E WISCONSIN AVENUE
MILWAUKEE
WI
53202
US
|
Family ID: |
36582608 |
Appl. No.: |
11/010920 |
Filed: |
December 13, 2004 |
Current U.S.
Class: |
220/259.3 ;
215/220; 215/221; 220/375 |
Current CPC
Class: |
B60K 15/0406
20130101 |
Class at
Publication: |
220/259.3 ;
220/375; 215/220; 215/221 |
International
Class: |
B65D 43/18 20060101
B65D043/18; B65D 55/16 20060101 B65D055/16; B65D 55/02 20060101
B65D055/02 |
Claims
1. A fuel tank cap engageable with a neck of a fuel tank, the fuel
tank having a fuel chamber adapted to contain fuel, the fuel tank
cap comprising: a cap shell including a cover portion and a
substantially cylindrical wall extending from the cover portion to
at least partially define a substantially cylindrical chamber; an
arm extending from the cover portion toward the fuel chamber of the
fuel tank when the fuel tank cap is installed on the fuel tank; and
an inner shell at least partially disposed within the cylindrical
chamber, the inner shell including an engagement portion that is
engageable with the neck and a protrusion engageable with the arm
to selectively couple the cap shell and the inner shell for
rotation in unison.
2. The fuel tank cap of claim 1, wherein the cap shell includes a
lobe that defines a lobe space, the lobe space disposed near the
arm.
3. The fuel tank cap of claim 2, wherein the arm is substantially
disposed outside of the lobe space when the cap shell and inner
shell are coupled for rotation and the arm is deflected at least
partially into the lobe space to decouple the cap shell and the
inner shell.
4. The fuel tank cap of claim 2, wherein the arm is one of a
plurality of arms and the lobe is one of a plurality of lobes, each
lobe defining a lobe space and each arm disposed near one of the
lobe spaces.
5. The fuel tank cap of claim 4, wherein each of the plurality of
arms is deflectable into the lobe space to decouple the cap shell
and the inner shell such that the cap shell is rotatable relative
to the inner shell
6. The fuel tank cap of claim 1, wherein the engagement portion
includes threads.
7. The fuel tank cap of claim 1, wherein the protrusion includes a
first side engageable with the arm to couple the cap shell and the
inner shell for rotation in unison.
8. The fuel tank cap of claim 7, wherein the first side is
substantially planar.
9. The fuel tank cap of claim 7, wherein the protrusion includes a
second side engageable with the arm to couple the cap shell and the
inner shell for rotation in unison when a torque applied to the cap
shell is at or below an engaged value.
10. The fuel tank cap of claim 9, wherein the second side of the
protrusion engages and displaces the arm to allow the cap shell to
rotate relative to the inner shell when the torque value exceeds
the engaged value.
11. The fuel tank cap of claim 9, wherein the second side is not
planar.
12. The fuel tank cap of claim 1, wherein the cap shell includes
one of a bead and a recess that extends around the cylindrical
wall, and the inner shell includes the other of the bead and
recess, the bead engaged with the recess to rotationally couple the
cap shell and the inner shell.
13. The fuel tank cap of claim 1, wherein the arm is connected to
the cover portion such that the arm is supported in a cantilever
fashion.
14. A fuel tank cap engageable with a neck that defines a neck
axis, the fuel tank cap comprising: an inner shell rotatable
relative to the neck to move between an engaged position and a
disengaged position; a cap shell including an arm that defines an
arm axis; and a protrusion extending from the inner shell, the
protrusion cooperating with the arm to couple the inner shell and
the cap shell for rotation in unison from the disengaged position
to the engaged position, the protrusion displacing the arm such
that the cap shell rotates independent of the inner shell when
rotated beyond the engaged position, the protrusion engaged with
the arm to couple the inner shell and the cap shell for rotation in
unison from the engaged position to the disengaged position.
15. The fuel tank cap of claim 14, wherein the arm axis is
substantially parallel to the neck axis.
16. The fuel tank cap of claim 14, wherein the inner shell includes
a threaded portion and the neck includes a threaded portion, the
inner shell threadably engageable with the neck.
17. The fuel tank cap of claim 14, wherein the cap shell includes a
cover portion that is substantially normal to the neck axis and
wherein the arm extends in a cantilever fashion from the cover
portion.
18. The fuel tank cap of claim 14, wherein the cap shell includes a
lobe defining a lobe space, and wherein a portion of the arm is
movable into the lobe space.
19. The fuel tank cap of claim 18, wherein the arm is one of a
plurality of arms, and the lobe is one of a plurality of lobes,
each lobe defining a lobe space, at least a portion of each arm
movable into one of the lobe spaces.
20. The fuel tank cap of claim 19, wherein the protrusion is one of
a plurality of protrusions and wherein the number of protrusions is
substantially equal to the number of arms.
21. The fuel tank cap of claim 14, wherein the arm Includes a first
angled surface and the protrusion includes an angled surface
engageable with the first angled surface to couple the cap shell
and the inner shell for rotation.
22. The fuel tank cap of claim 21, wherein the first angled surface
and the angled surface are angled such that when engaged, rotation
of the cap shell produces a force that biases the arm toward the
inner shell.
23. The fuel tank cap of claim 21, wherein the arm includes a
second angled surface and the protrusion includes an arcuate
surface engageable with the second angled surface to couple the cap
shell and the inner shell for rotation.
24. The fuel tank cap of claim 23, wherein the second angled
surface and the arcuate surface are such that when engaged,
rotation of the cap shell produces a force that biases at least a
portion of the arm away from the inner shell.
25. A fuel tank cap engageable with a neck of a fuel tank that
defines a neck axis, the fuel tank also having a fuel chamber
adapted to contain fuel, the fuel tank cap comprising: a cap shell
including a cover portion that is substantially normal to the neck
axis and a substantially cylindrical wall extending from the cover
portion to at least partially define a substantially cylindrical
chamber; an arm extending from the cover portion toward the fuel
chamber of the fuel tank; an inner shell at least partially
disposed within the cylindrical chamber and engageable with the
neck, the inner shell rotatable relative to the neck to move
between a disengaged position and an engaged position; and a
protrusion having a first side and a second side, the first side
engageable with the arm to couple the cap shell and inner shell for
rotation from the engaged position to the disengaged position, the
second side engageable with the arm to couple the cap shell and
inner shell for rotation from the disengaged position to the
engaged position when a rotational torque is below an engaged
value, the second side operable to displace the arm such that the
cap shell rotates independent of the inner shell when the
rotational torque exceeds the engaged value.
26. The fuel tank cap of claim 25, wherein the inner shell includes
a threaded portion and the neck includes a threaded portion, the
inner shell threadably engageable with the neck.
27. The fuel tank cap of claim 25, wherein the cap shell includes a
lobe defining a lobe space, and wherein a portion of the arm is
movable into the lobe space.
28. The fuel tank cap of claim 27, wherein the arm is one of a
plurality of arms, and the lobe is one of a plurality of lobes,
each lobe defining a lobe space, at least a portion of each arm
movable into one of the lobe spaces.
29. The fuel tank cap of claim 28, wherein the protrusion is one of
a plurality of protrusions, the quantity of protrusions being
substantially equal to the quantity of arms.
30. The fuel tank cap of claim 25, wherein the arm includes a first
angled surface and the protrusion includes an angled surface
engageable with the first angled surface to couple the cap shell
and the inner shell for rotation.
31. The fuel tank cap of claim 30, wherein the first angled surface
and the angled surface are angled such that when engaged, rotation
of the cap shell produces a force that biases the arm toward the
inner shell.
32. The fuel tank cap of claim 30, wherein the arm includes a
second angled surface and the protrusion includes an arcuate
surface engageable with the second angled surface to couple the cap
shell and the inner shell for rotation.
33. The fuel tank cap of claim 32, wherein the second angled
surface and the arcuate surface are arranged such that when
engaged, rotation of the cap shell produces a force that biases the
arm away from the inner shell.
Description
BACKGROUND
[0001] The present invention relates to a fuel tank cap, and
particularly to a fuel tank cap that inhibits overtightening and
indicates proper tightening.
[0002] Internal combustion engines are often used to power small
equipment such as lawnmowers, tillers, snow throwers, pressure
washers, generators, and the like. Typically, these engines include
a fuel system that supplies fuel for combustion. The fuel system
includes a tank, in which fuel is stored for use and a cap that can
be removed to add fuel to the tank. The fuel tank cap is typically
threaded on the tank or on a fill spout attached to the tank.
[0003] Generally, small engines include a fuel tank cap that
includes a gasket or resilient component that seals against the
tank fill spout. The gasket is designed to provide a seal when
tightened to a predetermined torque. However, some users tend to
overtighten or undertighten the fuel tank cap. When the cap is
overtightened, the gasket becomes crushed and can become damaged.
The damage can reduce the effectiveness of the gasket, thus
resulting in excess fuel vapor leakage, increased evaporative
emissions, and spillage during operation. If the cap is
undertightened, the gasket cannot provide a proper seal, thus
resulting in excess fuel vapor leakage, increased evaporative
emissions, and spillage during operation.
SUMMARY
[0004] The invention provides a fuel tank cap that is engageable
with a neck of a fuel tank. The fuel tank includes a fuel chamber
that is adapted to contain fuel. The fuel tank cap includes a cap
shell that has a cover portion and a substantially cylindrical wall
extending from the cover portion to define a substantially
cylindrical chamber. An arm extends from the cover portion toward
the fuel chamber of the fuel tank when the cap is installed on the
fuel tank. The arm defines a longitudinal axis that is
substantially orthogonal to the cover portion. An inner shell is at
least partially disposed within the cylindrical chamber. The inner
shell includes an engagement portion that is engageable with the
neck and a protrusion that is engageable with the arm to
selectively couple the cap shell and the inner shell for rotation
in unison.
[0005] The invention also provides a fuel tank cap engageable with
a neck that defines a neck axis. The fuel tank cap includes an
inner shell that is rotatable relative to the neck to move between
an engaged position and a disengaged position. A cap shell includes
an arm that defines an arm axis. A protrusion extends from the
inner shell. The protrusion cooperates with the arm to couple the
inner shell and the cap shell for rotation in unison from the
disengaged position to the engaged position. The protrusion
displaces the arm such that the cap shell rotates independent of
the inner shell when rotated beyond the engaged position. The
protrusion is engaged with the arm to couple the inner shell and
the cap shell for rotation in unison from the engaged position to
the disengaged position.
[0006] The invention also provides a fuel cap that is engageable
with a neck of a fuel tank that defines a neck axis. The fuel tank
also includes a fuel chamber adapted to contain fuel. The fuel cap
includes a cap shell that has a cover portion that is substantially
normal to the neck axis and a substantially cylindrical wall that
extends from the cover portion to define a substantially
cylindrical chamber. An arm extends from the cover portion toward
the fuel chamber of the fuel tank. An inner shell is at least
partially disposed within the cylindrical chamber and is engageable
with the neck. The inner shell is rotatable relative to the neck to
move between a disengaged position and an engaged position. A
protrusion has a first side and a second side. The first side is
engageable with the arm to couple the cap shell and inner shell for
rotation from the engaged position to the disengaged position. The
second side is engageable with the arm to couple the cap shell and
inner shell for rotation from the disengaged position to the
engaged position when a rotational torque is below an engaged
value. The second side is operable to displace the arm such that
the cap shell rotates independent of the inner shell when the
rotational torque exceeds the engaged value.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The detailed description particularly refers to the
accompanying figures in which:
[0008] FIG. 1 is a perspective view of an engine including a fuel
tank cap;
[0009] FIG. 2 is a perspective view of the fuel cap and fill neck
of FIG. 1;
[0010] FIG. 3 is an exploded perspective view of the fuel tank cap
of FIG. 1;
[0011] FIG. 4 is a section view of the fuel cap of FIG. 2 taken
along line 4-4 of FIG. 2;
[0012] FIG. 5 is an exploded view of a portion of the fuel tank cap
of FIG. 2;
[0013] FIG. 6 is a bottom view of a portion of the fuel tank cap of
FIG. 2 in a loosening position; and
[0014] FIG. 7 is a bottom view of a portion of the fuel tank cap of
FIG. 2 in a tightening position.
DETAILED DESCRIPTION
[0015] With reference to FIG. 1, an engine 10 including a fuel tank
15 with a fuel tank cap 20 is illustrated. The fuel tank 15
includes a fill neck 25 (shown in FIG. 2) that extends from the
tank 15 and provides an opening to the tank fuel chamber that is
adapted to contain fuel. Generally, the fill neck 25 includes
external threads 30 and the cap 20 includes internal threads 35
(shown in FIG. 3) that allow the cap 20 to threadably engage the
fill neck 25.
[0016] As shown in FIG. 3, the fuel cap 20 includes a cap shell 40
or outer shell that includes a cover portion 45 and a substantially
cylindrical wall 50 that extends away from the cover portion 45 to
define a cylindrical chamber 55. In most constructions, the
cylindrical wall 50 is orthogonal to the cover portion 45 and
substantially parallel to a neck axis 60 defined by the fill neck
25. However, other angles could also be employed if desired. A
plurality of lobes 65 extend radially outward from the cylindrical
wall 50 to form a more ergonomic grip surface. The construction
illustrated herein includes five lobes 65 that each define a
substantially hollow lobe space 70 and that are spaced around the
cylindrical wall 50. The five lobes 65 illustrated in FIG. 2 are
spaced approximately seventy-two degrees apart from one another. Of
course other constructions may include fewer lobes 65 or more lobes
65. In addition, the lobes 65 could be spaced apart by non-equal
angles to further improve the ergonomic shape of the cap shell 40
if desired.
[0017] With continued reference to FIG. 3, the cap shell 40
includes a plurality of arms 75 that extend from the cover portion
45 toward the fuel tank 15 and define longitudinal axes 80 that are
preferably substantially parallel to the cylindrical wall 50. The
arms 75 are supported in a cantilever fashion such that they are
only supported at one end. As illustrated in FIGS. 6 and 7, some
constructions include arms 75 that are supported substantially in a
cantilever fashion but that include a thin wall 76 extending along
at least one side of the arm. The thin wall 76 inhibits twisting
and non-radial deflection of the arm 75 but does not significantly
change the stiffness of the arms 75 in the radial direction. In
other constructions, the arms 75 extend from the cover portion 45
but are not parallel to the cylindrical walls 50. In addition,
constructions that support the arms 75 in a manner other than a
cantilever fashion are also contemplated by the invention.
[0018] Each arm 75 is disposed near one of the lobe spaces 70 such
that a radially outward force applied to the arm 75 will deflect
the arm 75 into the lobe space 70. The cap shell 40 also includes a
circumferential groove 85 and a clearance space 90 that extend
around the interior of the cylindrical wall 50.
[0019] In addition to the cap shell 40, the fuel tank cap 20
includes an inner shell 95 and a gasket 100. The inner shell 95,
best illustrated in FIG. 5, includes a cylindrical portion 105 that
defines an outer surface 110 and an inner surface 115. The outer
surface 110 includes a circumferential bead 120 that surrounds the
outer surface 110 and is sized to engage the groove 85 of the cap
shell 40. Once engaged, the position of the inner shell 95 relative
to the cap shell 40 is fixed along the neck axis 60. However, the
inner shell 95 remains free to rotate about the neck axis 60
relative to the cap shell 40. It should also be noted that while
the illustrated construction includes a circumferential bead 120 on
the inner shell 95 and a corresponding groove 85 in the cap shell
40, the location of the bead 120 and groove 85 could be reversed.
In addition, there is no requirement that the bead 120 and groove
85 extend completely around the inner shell 95 and the cap shell
40.
[0020] The outer surface 110 also includes a plurality of
protrusions 125 that extend radially outward from the outer surface
110. In most constructions, there is one protrusion 125 for each
arm 75. Thus, in the illustrated constructions, there are five
protrusions 125 extending from the outer surface 110. Of course,
other constructions may employ fewer protrusions 125 than arms 75,
or more protrusions 125 than arms 75 if desired. For example, one
construction may include two protrusions 125 for each arm 75.
[0021] The inner surface 115 of the inner shell 95 includes threads
35 that correspond with the threads 30 of the fill neck 25. Thus,
when the cap 20 is installed on the fuel tank 15, the inner shell
95 engages the fill neck 25 and is rotated relative to the fill
neck 25 to loosen or tighten the cap 20.
[0022] As shown in FIG. 3, a second cylindrical wall 130 extends
from the inner shell 95 and defines a chamber 135 that is sized to
receive an additive container 140. The additive container includes
a fuel additive such as a rust inhibitor, an anti-oxidant, and/or a
metal deactivator and is described in greater detail in U.S. patent
application Ser. Nos. 10/209,687 and 10/465,499 both of which are
fully incorporated herein by reference. The chamber 135 includes an
engagement surface 145 (shown in FIG. 4) that engages the additive
container 140 and holds the container 140 in place, while still
allowing for the removal and replacement of the container 140. A
puncture device 150 is formed within the chamber 135 and is
positioned to punch a hole in the additive container 140 to provide
a vent that improves additive container function. While the
construction of FIG. 3 includes an additive container 140, the
container 140 is not necessary for the invention to function.
[0023] The inner shell 95 includes a substantially planar flange
155 that extends around the end of the cylindrical portion 105 and
cooperates with the cap shell 40 to trap a tether 160 as shown in
FIG. 4. The tether 160, best illustrated in FIG. 3, includes a
first cylindrical lobe 165 that is sandwiched between the flange
155 and the cap shell 40, and a second cylindrical lobe 170 that
attaches to the fuel tank 15 or the engine 10. The tether 160
maintains an attachment between the fuel tank 15 or engine 10 and
the fuel tank cap 20 even when the cap 20 is removed from the fill
neck 25. This attachment reduces the likelihood that the user would
lose the cap 20. Of course not all fuel caps 20 employ a tether 160
and its use is not critical to the function of the invention.
[0024] The gasket 100 (sometimes referred to as a liner or seal)
fits within the inner shell 95 and cooperates with the fill neck 25
to form a seal. As illustrated in FIG. 3, the liner is a generally
flat resilient component that can deform or compress slightly as
the cap 20 is tightened onto the fill neck 25. The gasket 100 can
be coupled to the inner shell 95 using any suitable means including
adhesive, welding, threading, keys, cams, fasteners, and the like.
Generally, the gasket 100 is formed from a softer material than the
inner shell 95. This allows the gasket 100 to compress as it makes
contact with the fill neck 25 to form a better seal. As the gasket
100 compresses, increased torque is required to continue turning
the cap 20.
[0025] In another construction, the gasket 100 cooperates with the
inner surface of the inner shell 95 to define a tapered
neck-receiving space. Because the neck-receiving space is tapered,
the torque required to tighten the fuel tank cap 20 is not
constant. Rather, the torque that must be applied to tighten the
cap 20 continues to increase as the cap 20 is tightened and the
fill neck 25 extends into the more narrow portions of the
neck-receiving space. The fill neck 25 compresses the gasket 100 as
it moves into the neck-receiving space to establish a seal between
the cap 20 and the fill neck 25.
[0026] In another construction, the gasket 100 and inner shell 95
are formed together as a single component. This construction has
the advantages of reducing the number of components and the
complexity of the assembly. However, it is not possible to use
different materials in this construction. As such, the seal
achievable with this construction may not be suitable in all
applications.
[0027] With reference to FIGS. 6 and 7, the details of the arms 75
and the protrusions 125 will be described. While FIGS. 6 and 7
illustrate a single arm 75 and protrusion 125, each arm 75 and
protrusion 125 are substantially the same as those illustrated. As
such, only the one arm 75 and protrusion 125 will be described. In
addition, FIGS. 6 and 7 are bottom views of the fuel tank cap 20.
As such, a movement of the components in a clockwise direction 180
in FIGS. 6 and 7 would be the result of a counterclockwise rotation
of the fuel tank cap 20 relative to the fill neck 25 as perceived
by a user. Thus, a movement of the components in the clockwise
direction 180 (from the bottom view) in FIGS. 6 and 7 would result
in the fuel tank cap 20 loosening from, or being removed from the
fill neck 25 (assuming standard right-hand threads are employed). A
counterclockwise movement 185 (from the bottom view) of the
components results in the tightening of the fuel tank cap 20 onto
the fill neck 25.
[0028] The arm 75 includes a first angled surface 190 on the
clockwise side (from the bottom view) and a second angled surface
195 on the counterclockwise side (from the bottom view). While both
surfaces 190, 195 could be angled such that they are parallel, the
second surface 195 is angled more acutely than the first surface
190. The protrusion 125 includes a planar surface 200 and an
arcuate surface 205. The planar surface 200 is disposed on the
counterclockwise side (from the bottom view) of the protrusion 125
and the arcuate surface 205 is disposed on the clockwise side (from
the bottom view). The planar surface 200 is angled to substantially
match the angle of the first angled surface 190.
[0029] With reference to FIG. 7, the cap shell 40 is shown as it is
being rotated in the counterclockwise direction 185 (from the
bottom view). The protrusions 125 pass through the clearance space
90 formed in the cap shell 40 such that the arcuate surface 205
engages the second angled surface 195 of the arm 75. The arcuate
surface 205 and second angled surface 195 are oriented such that a
force that tends to displace the arm 75 radially outward is
established. However, during the initial tightening of the cap 20,
the friction between the arcuate surface 205 and the arm 75 and the
stiffness of the arm (i.e., the arm's resistance to bending) are
sufficient to allow rotation of both the inner shell 95 and the cap
shell 40 in unison. As the fill neck 25 begins to extend into the
neck-receiving space, additional torque is required to tighten the
cap 20. The additional torque generates a larger force between the
arcuate surface 205 and the second angled surface 195. Eventually,
the force generated by the torque is great enough to displace the
arm 75 and allow the protrusion 125 to pass. At this point, the cap
20 cannot be tightened more, as the cap shell 40 rotates
independent of the inner shell 95.
[0030] In operation, the fuel tank cap 20 is positioned on the fill
neck 25 and rotated to begin tightening the cap 20. The cap shell
40 rotates about the neck axis 60 independent of the inner shell 95
until the arcuate surfaces 205 of the protrusions 125 engage the
second angled surfaces 195, as illustrated in FIG. 7. The cap shell
40 and the inner shell 95 then rotate together in unison until the
fill neck 125 begins to extend into the cap 20 and compress the
gasket 100. As the fill neck 125 compresses the gasket 100, the
torque required to continue turning the cap shell 40 increases. As
the torque increases, additional force is required to maintain the
connection between the cap shell 40 and the inner shell 95. To
generate the additional friction, the arcuate surfaces 205 rotate
further relative to the second angled surfaces 195. The additional
rotation of the arcuate surfaces 205 displaces the arms 75. Thus,
the arms 75 exert an increased reaction force against the arcuate
surfaces 205. The increased reaction forces produce an increase in
the normal forces and thus, the frictional forces between the
arcuate surfaces 205 and the second angled surfaces 195. At a
predetermined torque value, the friction between the arcuate
surfaces 205 and the second angled surfaces 195 is insufficient to
maintain their engagement and the arms 75 are pushed into the lobe
spaces 70. Any efforts to further tighten the fuel tank cap 20
produce free rotation of the cap shell 40 without any rotation of
the inner shell 95. In addition, further rotation will produce a
"clicking" sound that is typically audible to the user and a
tactile sensation, both of which indicate that the cap 20 is
properly installed and tightened. Thus, with a proper choice of the
angle of the second angled surfaces 195 and the shape of the
arcuate surfaces 205, the inner shell 95 can be rotated to a
predetermined torque repeatably, thus improving the likelihood of a
properly seated fuel tank cap 20 each time it is placed on the fill
neck 25.
[0031] As shown in FIG. 6, with the cap shell 40 rotated in the
clockwise direction 180 (loosening) the planar surface 200 engages
the first angled surface 190. The angled surface 140 and planar
surface 200 are arranged such that the force generated between the
contacting surfaces 190, 200 tends to push the arm 75 radially
inward, thus maintaining the arm 75 and protrusion 125 in a locked
arrangement such that the inner shell 95 and cap shell 40 rotate in
unison regardless of the torque applied.
[0032] Thus, to remove the cap 20, the cap shell 40 is rotated in
the clockwise direction 180 (as shown in FIG. 6). The cap shell 40
rotates independent of the inner shell 95 until the planar surface
200 engages the first angled surface 190. Because the planar
surface 200 and the first angled surface 190 are arranged to
maintain the position of the arm 75 and not displace the arm 75
into the lobe space 70, the inner shell 95 and the cap shell 40
remain engaged with one another regardless of the torque applied to
the cap shell 40. Thus, rotation of the cap shell 40 also rotates
the inner shell 95 to allow for the removal of the cap 20.
[0033] The cap arrangement described herein increases the
likelihood that a proper seal between the cap 20 and the fill neck
25 is established each time the cap 20 is installed. In addition,
the cap 20 provides both audible and tactile feedback to the user
that indicates that the cap 20 has been properly tightened.
Furthermore, the arrangement of the arms 75 within the cap 20 (and
displaceable into the lobe spaces 75), allows for a cap 20 that has
a reduced height when compared to other caps. The reduced height is
particularly advantageous when the engine is used with equipment
that includes an engine cover such as riding lawn mowers, snow
throwers, and the like. The reduced height of the cap allows for a
closer fit between the cover and the engine. In addition, tall caps
can be unsightly and thus undesirable, while wide caps are
generally more visually appealing and do not require additional
space as they are typically disposed on top of a wide fuel
tank.
[0034] Although the invention has been described in detail with
reference to certain preferred embodiments, variations and
modifications exist within the scope and spirit of the invention as
described and defined in the following claims.
* * * * *