Receptacles – Closures – Removable closure guided in rotary movement
Reexamination Certificate
2001-06-06
2003-05-27
Pascua, Jes F. (Department: 3727)
Receptacles
Closures
Removable closure guided in rotary movement
C220S293000, C220S298000, C220SDIG003
Reexamination Certificate
active
06568553
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of and priority from Japanese Applications No. 2000-169913 filed Jun. 7, 2000 and No. 2001-98077 filed Mar. 30, 2001, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tank cap to close a tank opening member and a tank cap apparatus with the tank cap attached thereto.
2. Description of Related Art
In conventional practice, tank caps are configured such that a fuel supply port is closed by rotating a fuel cap fitted with a gasket several times relative to a filler neck connected to a fuel tank. Since rotating the fuel cap a plurality of times sometimes fails to result in a tight fit, closing the fuel supply port of a filler neck with a fuel cap merely by turning the cap through a predetermined angle (for example, about 90°) has been proposed as a way of overcoming this shortcoming.
FIG. 24
is a diagram depicting the state existing before a fuel cap is mounted over a filler neck. The fuel cap
100
comprises a casing main body
102
for opening and closing the fuel supply inlet FNb of a filler neck FN, a cover
104
mounted on the casing main body
102
, and a gasket GS mounted in the upper portion of the casing main body
102
. A ratchet mechanism (not shown) is interposed between the casing main body
102
and the cover
104
to ensure that the cover
104
idles relative to the casing main body
102
when excessive torque is applied between the cover
104
and the casing main body
102
.
A casing engagement element
102
a
is also formed in the lower portion of the outer circumference of the casing main body
102
. An opening engagement element FNc is further formed in the inner circumferential portion of the filler neck FN. Part of the area around the inside of the opening engagement element FNc is provided with a neck insertion notch FNd for allowing the casing engagement element
102
a
of the fuel cap
100
to be inserted in the axial direction.
FIG. 25
is a diagram depicting the manner in which the fuel cap
100
is mounted over the filler neck FN. The opening engagement element FNc is tapered by a prescribed inclination &agr; in the axial direction, and the guide surface
102
b
of the casing engagement element
102
a
is tapered to match this angle.
The manner in which the inlet FNb of FN is closed with the fuel cap
100
will now be described. The casing engagement element
102
a
is positioned in the neck insertion slot FNd, and the fuel cap
100
is turned through a predetermined angle (about 90°) while the fuel cap
100
is inserted into the filler neck FN. By this, the fuel cap
100
is mounted over the filler neck FN as a result of the fact that the casing engagement element
102
a
is caused to align with and engage the opening engagement element FNc. At the same time, the gasket GS is compressed between the casing main body
102
and the filler neck FN, forming a seal. If rotated further, the cover
104
will idle due to the presence of the ratchet mechanism, signaling that the limit has been reached and indicating that the fuel cap
100
fits tightly over the inlet FNb.
Reducing the inclination &agr; of the opening engagement element FNc during the closure of the fuel cap
100
will increase the operating angle of the fuel cap
100
, not only making the cap more difficult to operate but also allowing the fuel cap
100
to occasionally rotate through an angle greater than 180° and come off. Conversely, increasing the inclination &agr; will increase the tightening rate of the gasket GS (that is, the extent to which the gasket GS is compressed) and will enhance the rubber recoil of the gasket GS. For this reason, the rotational torque will increase and the cover will be idled by the ratchet mechanism before the gasket GS is adequately compressed, making it impossible to form a tight seal.
This approach is thus disadvantageous in the sense that it is difficult to cause the gasket GS to form a tight seal by rotating the fuel cap
100
through a narrow operating angle (about 90°). In addition, considerable load is applied between the opening engagement element FNc and the corner
102
c
of the casing engagement element
102
a
when the corner
102
c
is pressed against the opening engagement element FNc. A greater rotational torque is therefore needed to close the fuel cap
100
, sometimes making it impossible to close the cover properly and form a tight seal.
SUMMARY OF THE INVENTION
One aspect of the present invention provides a tank cap apparatus in which a seal member can form a better seal with a small operating angle.
In accordance with one embodiment of the present invention, a tank cap apparatus comprises a tank opening member having an opening engagement element and a cap constructed and arranged to close the tank opening member through rotation. The cap includes a cap engagement element for engaging the opening engagement element and a gasket interposed between the cap and a sealing surface of the tank opening member and constructed and arranged to seal the gap therebetween. The opening engagement element is inclined at a predetermined angle relative to a direction orthogonal to an axial direction for closing the cap and the cap engagement element has a guide surface for engaging the opening engagement element by a rotation of the cap in a closing direction while the cap is inserted into the tank opening member. An angle of the guide surface decreases with a rotation of the cap in the closing direction.
In the tank cap apparatus according to the present invention, inserting the cap into the tank opening member and rotating the cap in the closing direction will seal the gap between the cap and the tank opening member. This is because a cap engagement element will engage and fit over an opening engagement element, and the seal member interposed between the cap and the tank opening member will be compressed.
During cap closure, the guide surface of the cap engagement element aligns with and engages the opening engagement element. The guide surface is configured such that the angle thereof diminishes as the cap is rotated in the closing direction during this process. Specifically, the configuration is selected such that the inclination is greater in the initial stage. Despite the fact that the inclination of the guide surface is thus increased in the initial stage and the tightening rate is kept at a higher level, the torque is prevented from becoming excessively high and the seal member can be provided with an adequate tightening margin because the seal member produces only a weak reaction force during the initial compression stage of the seal member. When the seal member is compressed past the initial stage, the guide surface acquires a lesser angle and becomes capable of consistently providing a better seal in a state in which the tightening rate of the seal member is reduced.
Accordingly, aligning the steeply inclined guide surface with the opening engagement element during the initial compression stage of the seal member makes it possible to provide the seal member with an adequate tightening margin (and hence to obtain a tight seal) without creating a strong reaction force even in the case of a narrow rotation angle.
As a preferred embodiment of such a guide surface, a simple structure can be formed by providing a first inclined portion configured at an inclination whose angle with respect to the direction orthogonal to the axial direction is greater than the angle of the opening engagement element, and providing a second inclined portion formed as a continuation of the first inclined portion and inclined at an angle substantially equal to the aforementioned predetermined angle. The cap engagement element can be easily formed with high precision by being injection-molded monolithically with the casing main body despite being configured with a slightly varying incline in order to obtain the first and second inclined portions. In addition to the configuration in which the second inc
Hagano Hiroyuki
Nakagawa Masayuki
Pascua Jes F.
Posz & Bethards, PLC
Toyoda Gosei Co,., Ltd.
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