TECHNICAL FIELD
The present disclosure generally relates to a fuel tank cap of a vehicle and more particularly to a two-way breathing valve for venting the fuel tank to the atmosphere.
BACKGROUND
A fuel tank cap is commonly employed as a tank closure element to prevent escape of liquid fuel from the fuel tank. The fuel tank is required to be vented in some manner to equalize the pressure within the tank. Accordingly, fuel tanks and fuel tank caps include various types of venting systems intended to provide fuel tank breathing, prevent fuel spillage, relieve excess pressure, and provide thermal venting of the fuel tanks, to prevent damage to the fuel tanks from excessive pressure build-up inside the fuel tank.
Fuel tank caps with venting systems are known in the art. However, the existing fuel tank caps have bulky and complicated construction and are costly to manufacture. In view of the above there is a need to develop a fuel tank cap of a vehicle to increase reliability, ease in assembling and are cheaper to manufacture.
SUMMARY
A cap for a fuel tank is disclosed. The cap has a cover configured to close an opening of the fuel tank. The cover defines a vent path to selectively fluidly connect the opening with the atmosphere. A rib extends from a bottom surface of the cover and forms a loop. The rib together with the cover defines a cavity having a first end fluidly connected to the vent path and a second end fluidly connected to the opening. A diaphragm holder is placed in the cavity. The diaphragm holder is movable between a closed position to restrict flow of fluid through the cavity towards the vent path and an open position to allow flow of fluid through the cavity towards vent path. The diaphragm holder is biased towards the closed position. At

least one first vent is defined by the diaphragm holder. The at least one first vent fluidly connects the fuel tank with the vent path. A diaphragm is positioned on the diaphragm holder to selectively close the at least one first vent. The diaphragm is made of a resiliency flexible material being deformable due to pressure inside the fuel tank acting on the diaphragm. The diaphragm is deformable between a closed state to restrict flow of fluid towards the fuel tank through the at least one first vent and an open state to allow flow of fluid towards the fuel tank through the at least one first vent. The diaphragm is biased towards the closed state.
In an aspect, the diaphragm is in shape of circular disc adapted to abut a surface of the diaphragm holder defining the at least one first vent.
In an aspect, the diaphragm is made of fluorosilicone.
In an aspect, the cap has a cover breather adapted to abut the rib and at least partially define the second end of the cavity and at least one second vent defined in the cover breather. The at least one second vent fluidly connect the cavity with the opening of the fuel tank.
In an aspect, the cap has an inner gasket placed on the diaphragm holder. The inner gasket is configured to sealingly abut a surface defining the second end to seal a gap between the diaphragm holder and the surface.
In an aspect, the cover defines the surface at the second end.
In an aspect, the cap has an outer gasket placed abutting the cover. The outer gasket is configured to seal a gap between the cover and a filler neck of the fuel tank.
In an aspect, the cap has a skirt extending from an outer periphery of the cover, the skirt defines internal threads to engage corresponding outer threads provided on a filler neck of the fuel tank.

In an aspect, the cover breather is in shape of an inverted hat having a crown and a first flange extending from the peripheral edge of the crown. The first flange is configured to abut the rib and at least partially define the second end. The at least one second vent defined on the crown.
In an aspect, the cover breather has a flat base configured to abut the rib to define the second end and a first wall corresponding to the rib to engage the rib to retain the cover breather on the rib.
In an aspect, the cap has a cover breather gasket adapted to be placed between the cover breather and the rib to seal a gap therebetween.
In an aspect, the diaphragm has a stem adapted to be received in a perforation defined on the diaphragm holder for retaining the diaphragm on the diaphragm holder.
BRIEF DESCRIPTION OF FIG.S
FIG. 1 illustrates an exploded view of a fuel tank cap in accordance with an
embodiment of the present disclosure.
FIG. 2 illustrates a cross sectional view of fuel tank cap in accordance with an
embodiment of the present disclosure.
FIG. 3 illustrates a cross sectional view of fuel tank cap along a plane running along
a length of a handle of the cap in accordance with an embodiment of the present
disclosure.
FIG. 4 illustrates a cross-sectional view of a fuel tank cap of FIG. 3 with the
diaphragm holder in open position.
FIG. 5 illustrates a cross-sectional view of FIG. 3 with the diaphragm in open state.
FIG. 6 illustrates a cross-sectional view of a cap in accordance with an alternate embodiment of the present disclosure with the diaphragm holder in open position.

FIG. 7 illustrates a cross-sectional view of the cap of FIG. 6 with diaphragm deformed to an open state.
DESCRIPTION OF PRESENT DISCLOSURE
While the invention is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the FIG.s and will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the invention as defined by the appended claims. Before describing in detail embodiments, it may be observed that the novelty and inventive step that are in accordance with the present invention resides in fuel tank cap (10) for vehicles. It is to be noted that a person skilled in the art can be motivated from the present invention and modify the various constructions of assembly, which are varying from vehicle to vehicle. However, such modification should be construed within the scope and spirit of the invention. Accordingly, the drawings are showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such setup or device. In other words, one or more elements in a system or apparatus proceeded by "comprises... a" does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.

A cap (10) for a fuel tank of a vehicle is disclosed. The cap (10) has a two-way breathing valve (12) for facilitating regulation or neutralization of pressure inside the fuel tank. Referring to FIG. 1, the cap (10) as disclosed herein may have a body (14), a ring-shaped outer gasket (16), a spring (18), a diaphragm holder (20), an inner gasket (22), a diaphragm (24), a cover gasket (26), a cover breather (28), and a plurality of screws (30). The body (14) is provided with a handle (32) for a user to hold and turn the cap (10).
As shown in FIG. 1 to FIG. 3, the body (14) has a circular disk-shaped cover (34) and downwardly depending cylindrical skirt (36). An interior surface of the skirt (36) portion defines internal threads (38) that engage outer threads defined on an outer surface of a filler neck of the fuel tank (not shown). Just inside the cylindrical skirt (36) and below the cover (34) of the body (14), the outer gasket (16) is positioned. The outer gasket (16) is adapted for resting on and being compressed between a top surface (98) of the filler neck of the fuel tank and a bottom surface (40) of the cover (34) to provide sealing when the cap (10) is mounted on the filler neck to close an opening of the fuel tank. An inner edge of the ring-shaped outer gasket (16) is positioned nearly abutting a rib (42) extending downwardly and perpendicularly from the bottom surface (40) the cover (34) of the body (14). The rib (42) extends such that the rib (42) forms a loop. In the embodiment as shown in the present disclosure, the rib (42) is shown of a hollow cylindrical shape. The rib (42) and the cover (34) together define a cavity (44) having a first end (46) partly defined by the cover (34) and a second end (48) is fluidly connected to the opening of the fuel tank as shown in FIG 2 and FIG. 3.
The body (14) may have provisions to form a passage for flow of fluid such as fuel vapor or air for venting out any pressure buildup inside the fuel tank. In the embodiment as shown in FIGS. 2-5, a vent path (50) is defined in the body (14). As shown in FIGS. 3-5, the vent path (50) has a vertical path (52) fluidly connecting the interior of the body (14) to a horizontal path (54) of the vent path (50). Further, the horizontal path (54) at one end is fluidly connected to the vertical

path (52) and at the other end is fluidly connected to atmosphere. In the embodiment as shown in FIG. 6 and FIG. 7, the vent path (50) only has a vertical path (52) fluidly connecting the cavity (44) with the atmosphere. This way, the interior of the body (14) is fluidly connected to the atmosphere. The rib (42) is positioned on the body (14) such that the first end (46) of the cavity (44) is fluidly connected to the horizontal path (54) of the vent path (50).
In the embodiment as shown in FIGS. 1-5, the cover breather (28) is in form of an inverted hat having a circular crown (56) and a ring shaped first flange (58) extending from the peripheral edge of the crown (56). The cover breather (28) is provided with at least one second vent (60) in the crown (56) to allow passage of air therethrough. As shown, the second vent (60) may be in form of a hole provided in the crown (56) of the cover breather (28). As shown in FIG. 2 and FIG. 3, in assembled state of the fuel tank cap (10), the first flange (58) of the cover breather (28) is positioned underlying and abutting a lowermost surface (62) of the circular rib (42). The cover breather (28) at least partly defines the second end (48) of the cavity (44). As shown in FIG. 3, the cover breather (28) may be secured in position by fastening means such as screws (30). One or more screw holes may be provided in the first flange (58) of the cover breather (28) along with a corresponding bore in the rib (42) to receive a screw for securing the cover breather (28) with the body (14) as shown in FIG. 3.
In the alternate embodiment shown in FIG. and FIG. 7, the cover breather (28) may have a plate (64) and a first wall (66) forming a loop extending from the pate. The plate (64) may be a circular plate (64). The plate (64) is provided with the at least one second vent (60) to facilitate passage of fluid through the plate (64). The first wall (66) is shaped corresponding to the shape of the rib (42) to engage the rib (42). In the embodiment as shown, the first wall (66) is of a hollow cylindrical shape corresponding to the cylindrical wall shape of the rib (42). As shown, the rib (42) and the first wall (66) overlap with each other along a plane perpendicular to a central axis (72) of the cap (10). It may be understood that the cover breather (28)

may be of any suitable shape, size and material. One function of the cover breather (28) in the cap (10) is to support the diaphragm holder (20) and other components placed in the cavity (44) and retain these components inside the cavity (44), while allowing passage of air to and from the cavity (44). In an embodiment, the cover breather (28) may be absent and the rib (42) at the second end (48) itself may be provided with suitable provisions to support and retain the diaphragm holder (20) movably as required.
Further, as shown in FIG. 2 and FIG. 3, a cover gasket (26) may be sandwiched between the cover breather (28) and the rib (42) to seal any gap between the first flange (58) or the first wall (66), and the rib (42) at the second end (48) and prevent passage of fluid through such gap. As shown, the cover gasket (26) may also be provided with screw holes corresponding with the screw holes in the circular rib (42) and the cover breather (28) for securing the cover gasket (26) between the cover breather (28) and the circular rib (42).
In the embodiment as shown, the cavity (44) is defined in between the cover breather (28) and the rib (42) of the body (14) when the cover breather (28) is mounted on the body (14) as shown in FIGS. 2-7. The spring (18), the diaphragm holder (20), the inner gasket (22) and the diaphragm (24) are placed inside the cavity (44).
Further, in the embodiment as shown, the diaphragm holder (20) is of a circular shape having a ring shaped second flange (76) and has a second wall (78) extending from an outer periphery of the second flange (76) of the diaphragm holder (20). The second wall (78) may be adapted to slide against an internal surface (80) of the rib (42). Further, a third wall (82) extends substantially parallel to the second wall (78) from an inner periphery of the second flange (76) of the diaphragm holder (20). A first recess (84) is defined between the second flange (76), the second wall (78) and the third wall (82).

The spring (18) biases the diaphragm holder (20) towards the first flange (58) of the cover breather (28). In assembled state, a bottom end of spring (18) is supported upon the diaphragm holder (20) in the first recess (84). Whereas, a top end of the spring (18) abuts the cover (34).
The diaphragm holder (20) has a base (90) that is in form of a circular disk as shown in FIGS. 1-7. The dimensions of the diaphragm holder (20) and the rib (42) are such that, in assembled state, a gap is provided between the second wall (78) and the internal surface (80) of the rib (42) to allow passage of fluid between the second wall (78) and the rib (42), as described in the following description. At least one first vent (70) is provided on the base (90) of the diaphragm holder (20) to allow passage of fluid through the gap. The first vents (70) may be in form of holes provide in the base (90). Furthermore, the diaphragm holder (20) is provided with a perforation (92) to support and retain the diaphragm (24) on the base (90) of the diaphragm holder (20) as shown in FIG. 2-7. In the embodiment as shown, the perforation (92) is provided on a central portion of the base (90), whereas the first vents (70) are provided around the perforation (92).
The inner gasket (22) is positioned in between the diaphragm holder (20) and the first flange (58) of the cover breather (28) to prevent escape of fuel vapor or air from a gap between the first flange (58) and the second flange (76). A second recess (94) is defined between a peripheral rim (95) extending from the base (90) and the second flange (76) of the diaphragm holder (20) to accommodate an inner edge of the inner gasket (22) and retain the inner gasket (22) on the diaphragm holder (20). In assembled state, the inner gasket (22) retained on the diaphragm holder (20) seals the gap between the second flange (76) and the first flange (58) under biasing force of the spring (18) which acts on the inner gasket (22) via the diaphragm holder (20). The inner gasket (22) may be made of any material suitable for sealing a gap by abutting the diaphragm holder (20) and the cover breather (28) as shown in FIGS. 2-5.

The diaphragm holder (20) is movable between a closed position and an open position. In the closed position, the diaphragm holder (20) rests on the first flange (58) or first wall (66) of the cover breather (28) as shown in FIGS. 2, 3, 5 and 7. In the closed position, any gap between the first flange (58) (or the first wall (66)) and the second flange (76) is sealed an flow of fluid between the first flange (58) and the second flange (76) from the fuel tank towards the vent path (50) is prevented. In the open position, the diaphragm holder (20) along with the inner gasket (22) moves away from the first flange (58) (or the first wall (66)) as shown in FIG. 4 (or FIG. 6). In normal circumstances, i.e. when the pressure inside the fuel tank is within desirable limits, the diaphragm holder (20) is kept in the closed position under the biasing force of the spring (18).
The diaphragm (24) has a flexible circular disc (96) and a stem (97) extending from a top surface (98) of the circular disc (96) in FIGS. 1, 2 and 3. A projection (99) is provided on the cylindrical outer surface of the stem (97) near a distal end of the stem (97). The dimension of stem (97) is adapted such that the stem (97) is received inside the perforation (92) and the dimension of the projection (99) is kept slightly more than the dimension of the perforation (92) to retain the stem (97) of the diaphragm (24) inside the perforation (92). The diaphragm (24) is mounted to the diaphragm holder (20) by inserting the stem (97) of the diaphragm (24) into the perforation (92) such that the projection (99) is positioned at one side of the base (90) of the diaphragm holder (20) and the circular disc (96) on the other side of the base (90) as shown in FIG. 2 and FIG. 3. The dimensions of the stem (97) and the perforation (92) are kept such that the stem (97) has no play to move in a direction along the central axis (72). Additionally, the stem (97) and the perforation (92) may also be designed to have no or a limited play in a plane perpendicular to the central axis (72) to secure the stem (97) firmly in the perforation (92). Accordingly, the stem (97) of the diaphragm (24) may be held firmly or rigidly by the diaphragm holder (20) to limit any relative movement between the stem (97) and the diaphragm holder (20).

The thin circular disc (96) of diaphragm (24) is positioned below the base (90) of the diaphragm holder (20) and abuts a surface of the base (90) to cover the first vents (70) defined on the base (90) of the diaphragm holder (20). The diaphragm (24) may be molded out of a flexible material such as fluorosilicone or any other polymeric material, whereas the diaphragm holder (20) may be formed of any known hard material, such as plastic, metal, etc. The circular disc (96) of the diaphragm (24) is flexible enough to resiliency deform and allow opening of the first vents (70) when the pressure inside the tank crosses a predetermined or set threshold. The diaphragm (24) is made such that the diaphragm (24) resiliency retains its shape.
The circular disc (96) of the diaphragm (24) is deformable into a closed state and an open state. In closed state the diaphragm (24) is in its normal shape, i.e. the circular disc (96) retaining its circular plate-like shape as shown in FIGS. 2-4 and FIG. 6. In the open state the circular disc (96) is deformed to a concave shape as shown in FIG. 5 and FIG. 7. In open state the outer edge of the circular disc (96) moves away from base (90) of the diaphragm holder (20) to move the circular disc (96) away from the first vents (70), to allow passage of fluid through the first vents (70). The resiliency deformable diaphragm (24) is biased or configured to retain the shape of the diaphragm (24) in the closed state.
The working of the cap (10) according to an embodiment of the present disclosure is described as following. The cap (10) seals the opening of the fuel tank to prevent any undesirable leakage of fluid from the fuel tank. FIG. 2 illustrates the cap (10) in the initial position. In the initial position, the diaphragm holder (20) along with the inner gasket (22) is kept in the closed position, i.e. abutting the first flange (58) (or the first wall (66)) of the cover breather (28) to seal any gap between the first flange (58) and the second flange (76), blocking any movement of fluid from the interior of fuel tank towards the vent path (50).

Whenever the temperature in the fuel tank rises beyond a threshold temperature, the fuel gets vaporized. Excess buildup of vaporized fuel inside the fuel tank leads to increase in pressure in the fuel tank. There may be other circumstances that may lead to pressure build up inside the fuel tank, for example movement of vehicle towards higher altitude may also lead to build up of pressure inside the fuel tank due to lower density of air at higher altitudes. Since the cover breather (28) is provided with second vents (60) which fluidly connect the interior of the fuel tank with cavity (44), the pressure inside the fuel tank acts on the diaphragm (24) and the base (90) of the diaphragm holder (20). When the pressure inside the fuel tank crosses a first threshold pressure, the biasing force of the spring (18) on the diaphragm holder (20) is overcome and the diaphragm (24) along with the diaphragm holder (20) and the inner gasket (22) is lifted upwards against the biasing force of the spring (18) to move to the open position. Movement of the diaphragm holder (20) to open position creates a gap between the inner gasket (22) and the first flange (58) (or the first wall (66)) of the cover breather (28). The spring (18) is accordingly configured to keep the diaphragm holder (20) and the inner gasket (22) abutted to the flange until the required first threshold pressure is reached and crossed. The creation of the gap between the inner gasket (22) and the flange allows passage of air or fuel vapour or mixture of air and fuel vapour through the gap between the inner gasket (22) and the flange towards the gap between the internal surface (80) of the rib (42) and the second wall (78), and further towards the vent path (50), and finally to the atmosphere through the vent path (50). Thus, excess pressure inside the fuel tank is released by venting the fuel vapour/air in the atmosphere by movement of the diaphragm holder (20) to the open position.
Further, when the pressure inside the fuel tank is released, and the pressure falls below the first threshold pressure, the diaphragm holder (20) along with the inner gasket (22) moves back to the closed position under force of the spring (18) to seal the gap between the first flange (58) and the inner gasket (22).

Further, pressure inside the fuel tank may also fall due to flowing out of fuel from the fuel tank for supplying fuel to engine, or when a vehicle moves from higher altitude towards a lower altitude. Since the cavity (44) is fluidly connected to the atmosphere via the vent path (50), the atmospheric pressure acts on the top surface (98) of the circular disc (96) through the first vents (70). When the pressure inside fuel tank falls below a second threshold, the flexible circular disc (96) of the diaphragm (24) flexes or deforms to the open state under atmospheric pressure to allow passage of air through vents 44 inside the fuel tank, as shown in FIG. 5 and FIG. 7. This way any fall in pressure inside the fuel tank is compensated by allowing passage of air from atmosphere towards interior of the fuel tank.
As soon as the negative pressure build up inside the fuel tank is neutralized, the force acting on the flexible circular disc (96) due the negative pressure build up decreases and the flexible circular disc (96) flexes to regain its closed state as shown in FIG. 2 to cover the first vents (70) of the diaphragm holder (20).
Further, when the pressure of air entering the flow passage decreases, the diaphragm (24) retracts to the initial position due to resilient properties of the flexible material of the diaphragm (24), covering the first vent (70).
While preferred aspects and example configurations have been shown, and described. It is to be understood that various further modifications and additional configurations will be apparent to those skilled in the art. It is intended that the specific embodiments and configurations herein disclosed are illustrative of the preferred nature of the invention, and should not be interpreted as limitations on the scope of the invention.

LIST OF REFERNCE NUMERALS
Cap (10)
Two way breathing valve (12)
Body (14)
Outer gasket (16)
Spring (18)
Diaphragm holder (20)
Inner gasket (22)
Diaphragm (24)
Cover gasket (26)
Cover breather (28)
Screws (30)
Handle (32)
Cover (34)
Skirt (36)
Internal threads (38)
Bottom surface (40)
Rib (42)
Cavity (44)
First end (46)
Second end (48)
Vent path (50)
Vertical path (52)
Horizontal path (54)
Crown (56)
First flange (58)
Second vent (60)
Lowermost surface (62)
Plate (64)
First wall (66)
First vent (70)

Central axis (72) Second flange (76) Second wall (78) Internal surface (80) Third wall (82) First recess (84) Base (90) Perforation (92) Second recess (94) Rim(95) Circular disc (96) Stem (97) Top surface (98) Projection (99)

We claim:
1. A cap (10) for a fuel tank comprising:
a cover (34) configured to close an opening of the fuel tank, the cover (34) defining a vent path (50) to selectively fluidly connect the opening with the atmosphere;
a rib (42) extending from a bottom surface (40) of the cover (34), the rib (42) forming a loop and together with the cover (34) defining a cavity (44) having a first end (46) fluidly connected to the vent path (50) and a second end (48) fluidly connected to the opening;
a diaphragm holder (20) placed in the cavity (44), the diaphragm holder (20) movable between a closed position to restrict flow of fluid through the cavity (44) towards the vent path (50) and an open position to allow flow of fluid through the cavity (44) towards vent path (50), the diaphragm holder (20) biased towards the closed position;
at least one first vent (70) defined by the diaphragm holder (20), the at least one first vent (70) fluidly connecting the fuel tank with the vent path (50)
a diaphragm (24) positioned on the diaphragm holder (20) to selectively close the at least one first vent (70), the diaphragm (24) being made of a resiliency flexible material deformable due to pressure inside the fuel tank acting on the diaphragm (24), the diaphragm (24) deformable between a closed state to restrict flow of fluid towards the fuel tank through the at least one first vent (70) and an open state to allow flow of fluid towards the fuel tank through the at least one first vent (70), the diaphragm (24) biased towards the closed state.
2. The cap (10) as claimed in claim 1, wherein the diaphragm (24) is in shape
of circular disc (96) adapted to abut a surface of the diaphragm holder (20)
defining the at least one first vent (70).

3. The cap (10) as claimed in claim 1, wherein the diaphragm (24) is made of fluorosilicone.
4. The cap (10) as claimed in claim 1, comprising:
a cover breather (28) adapted to abut the rib (42) and at least partially define the second end (48) of the cavity (44); and
at least one second vent (60) defined in the cover breather (28), the at least one second vent (60) fluidly connecting the cavity (44) with the opening of the fuel tank;
5. The cap (10) as claimed in claim 1, comprising an inner gasket (22) placed on the diaphragm holder (20), the inner gasket (22) configured to sealingly abut a surface defining the second end (48) to seal a gap between the diaphragm holder (20) and the surface.
6. The cap (10) as claimed in claim 5, wherein the rib (42) defines the surface at the second end (48).
7. The cap (10) as claimed in claim 1, comprising an outer gasket (16) placed abutting the cover (34), the outer gasket (16) configured to seal a gap between the cover (34) and the filler neck.
8. The cap (10) as claimed in claim 1, comprising a skirt (36) extending from an outer periphery of the cover (34), the skirt (36) defining internal threads (38) to engage corresponding outer threads provided on the filler neck.
9. The cap (10) as claimed in claim 4, wherein the cover breather (28) is in shape of an inverted hat comprising a crown (56) and a first flange (58) extending from the peripheral edge of the crown (56), the first flange (58) configured to abut the rib (42) and at least partially define the second end (48), the at least one second vent (60) defined on the crown (56).

10. The cap (10) as claimed in claim 4, wherein the cover breather (28) has a flat base (90) configured to abut the rib (42) to define the second end (48) and a wall shaped corresponding to the rib (42) to engage the rib (42) to retain the cover breather (28) on the rib (42).
11. The cap (10) as claimed in any one of claim 9 or claim 10, comprising a cover breather (28) gasket adapted to be placed between the cover breather (28) and the rib (42) to seal a gap therebetween.
12. The cap (10) as claimed in claim 1, wherein the diaphragm (24) has a stem (97) adapted to be received in a perforation (92) defined on the diaphragm holder (20) for retaining the diaphragm (24) on the diaphragm holder (20).