Internally Threaded Cap

Abstract

A closure assembly for a tank includes a cap shell and a cylindrical insert connected by a lost motion connection defining a first stop and a second stop for relative axial movement. A dome extends inwardly from the cylindrical insert and includes an orifice defining a valve seat. A stem includes a mating edge for engaging the valve seat. The mating edge abuts the valve seat and displaces the dome axially to seal the orifice at the first stop, and is spaced from the valve seat to at the second stop. Opening the valve allows vapor to vent from the tank along a tortuous path defined through an aperture and between the cap shell and the cylindrical insert. The aperture is open or sealed with the valve depending on the relative position of the cap shell and cylindrical insert.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates to a closure assembly for a tank.

2. Description of the Prior Art

Certain tanks, such as fuel tanks, are selectively sealed and accessed through a closure assembly. In addition, known closure assemblies provide a vent passage that selectively allows vapor to escape or enter the tank.

SUMMARY OF THE INVENTION AND ADVANTAGES

The invention provides for a closure assembly including a cap shell having a top wall extending circumferentially about an axis to an outer periphery. A cylindrical insert has a radial periphery facing the top wall of the cap shell and engages a fill neck of the tank. A dome is supported by the cylindrical insert and spaced axially from the radial periphery. An orifice is formed on the dome and defines a valve seat extending circumferentially about the axis for fluid communication with the tank. A stem has a mating edge and is spaced radially inward of the outer periphery and engages the valve seat with the mating edge to form a seal therebetween. The stem displaces the dome axially to form the seal.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a perspective exploded view of a closure assembly according to an exemplary embodiment of the invention;

FIG. 2 is a top view of the closure assembly of the exemplary embodiment;

FIG. 3 is a front view of the closure assembly of the exemplary embodiment;

FIG. 4 is a cross sectional view of the closure assembly taken along line 4-4 of FIG. 2;

FIG. 5 is a cross sectional view of the closure assembly taken along line 5-5 of FIG. 3;

FIG. 6 is a cross sectional view of a cap shell of the closure assembly taken along a line similar to line 4-4 of FIG. 2;

FIG. 7 is a perspective view of a cylindrical insert of the closure assembly;

FIG. 8 is a cross sectional view of the cylindrical insert taken along a line similar to line 5-5 of FIG. 3; and

FIG. 9 is a cross sectional view of a tank detail of the closure assembly taken along a line similar to line 5-5 of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a closure assembly 20 for a tank is generally shown according to an exemplary embodiment in the exploded view of FIG. 1. A cap shell 22 is shown having a top wall extending circumferentially about an axis A to an outer periphery with a skirt depending axially downwardly from the outer periphery of the top wall. A cylindrical insert 24 is shown with a radial periphery 26 extending circumferentially about the cylindrical insert 24 and facing the top wall of the cap shell 22 and a dome 28 supported by the cylindrical insert 24 spaced axially from the radial periphery 26. Referring to FIGS. 4 and 5, the cap shell 22 is engaged with the cylindrical insert 24 to define a tortuous path between the top wall of the cap shell 22 and the radial periphery 26 of the cylindrical insert 24, and will be described in more detail subsequently. The dome 28 has an orifice 30 formed therein and defines a valve seat extending circumferentially about the axis A for selective fluid communication with the tank. A stem 32 with a mating edge 34 disposed at one end thereof is spaced radially inward of the outer periphery of the cap shell 22 and selectively engages the valve seat to form a seal.

A lost motion connection interconnects the cap shell 22 and the cylindrical insert 24, defining a first stop and a second stop. The lost motion connection allows the cap shell 22 to move axially relative to the cylindrical insert 24 between the first stop and the second stop. According to the exemplary embodiment, the lost motion connection includes a first cylindrical wall 36 depending axially downwardly from the top wall of the cap shell 22. Referring to FIG. 6, the first cylindrical wall 36 is spaced radially inward of the skirt and radially outward of the stem 32, and includes a male cap thread 38 having a reverse thread pitch disposed thereabout. Referring to FIGS. 7 and 8, the lost motion connection further includes a female insert thread 40 having a reverse thread pitch disposed about the cylindrical insert 24. Referring again to FIGS. 4 and 5, the female insert thread 40 engages the male cap thread 38 to axially move the cap shell 22 relative to the cylindrical insert 24 along the axis A between the first and second stops in response to rotation of the cap shell 22. Alternatively the lost motion connection could comprise a tab and slot design (not shown) with slots that run circumferentially about the cylindrical insert 24 in a downwardly sloping fashion to achieve relative rotation and axial translation simultaneously, similar to that achieved by the male cap and female insert threads 38, 40. Another alternative could comprise slots than run axially along the length of the cylindrical insert 24, such that only axial translation is needed.

According to the exemplary embodiment, and referring again to FIG. 1, the lost motion connection also includes a pair of pins 42 that depend axially downwardly from the top wall of the cap shell 22 and adjacent the skirt. A guide track extends circumferentially about the cylindrical insert 24 and receives the pins 42. The guide track is defined between the radial periphery 26 of the cylindrical insert 24 and a radial shelf 44 depending from the radial periphery 26. Referring to FIGS. 7 and 8, the radial shelf 44 also defines a notch 46 extending circumferentially about the cylindrical insert 24 opposite, axially, of the guide track. The notch 46 receives a tank gasket 48, as shown in FIGS. 1 and 4, that contacts the cylindrical insert 24 and the tank and seals a space therebetween. Referring again to FIGS. 7 and 8, the lost motion connection includes a pair of shoulders 50 that have a first side and a second side. The shoulders 50 extend radially from the radial periphery 26 of the cylindrical insert 24 and are spaced 180 degrees circumferentially from one another. The shoulders 50 engage each of the pins 42 against the first side to define the first stop and against the second side to define the second stop. A detent mechanism 52 is provided adjacent each of the shoulders 50 and extends radially into the guide track for maintaining the pins 42 against the shoulders 50 when the pins 42 abut the second side. The lost motion mechanism therefore permits the cap shell 22 and the cylindrical insert 24 to rotate relative to one another between the first and second stops. Additionally, the cap shell 22 rotates together with the cylindrical insert 24 in a cap insertion direction when the pins 42 abut the first side of the shoulders 50, and the cap shell 22 rotates together with the cylindrical insert 24 in a cap removal direction when the pins 42 abut the second side of the shoulders 50.

The lost motion mechanism allows the stem 32 to displace the dome 28 axially to form the seal when the cap shell 22 is moved to the first stop. According to the exemplary embodiment, this occurs when the pins 42 abut the first side of the shoulders 50. The displacement is defined here by a flexing, or deformation, of the dome 28 under pressure from the stem 32. The stem 32 is then spaced from the dome 28 when the cap shell 22 is moved to the second stop, where the pins 42 abut the second side of the shoulders 50.

Referring to FIGS. 4 and 5, the stem 32 of the exemplary embodiment depends axially downwardly from the top wall. A distal edge of the stem 32 defines the mating edge 34, and, as described earlier, the stem 32 is spaced radially inward of the first cylindrical wall 36 and defines an annular fluid chamber extending therebetween. In addition, the dome 28 extends integrally and radially inwardly from the cylindrical insert 24. The stem 32 has a hollow center defining a second cylindrical wall. A cylindrical fluid chamber extends therein and is always in fluid communication with the tank, whether the pins 42 abut the first side or the second side of the shoulders 50.

Referring to FIGS. 4 and 6, according to the exemplary embodiment, the first cylindrical wall 36 of the cap shell 22 includes an aperture 54 between the top wall and the cylindrical insert 24. The aperture 54 helps to define the tortuous path, which flows through the annular fluid chamber, through the aperture 54 and between the top wall of the cap shell 22 and the radial periphery 26 of the cylindrical insert 24, and then out to the environment. The aperture 54 is spaced from the cylindrical insert 24 to permit venting when the pins 42 abut the second side of the shoulders 50, and the aperture 54 is covered by the cylindrical insert 24 to seal the tortuous path when the pins 42 abut the first side of the shoulders 50. To assist the seal, an insert gasket 56 is circumferentially aligned with the radial periphery 26 of the cylindrical insert 24 and is positioned intermediate the radial periphery 26 and the top wall of the cap shell 22. The insert gasket 56 contacts the cap shell 22 to seal the tortuous path when the pins 42 abut the first side of the shoulders 50.

Additionally, the cylindrical insert 24 includes a male insert thread 58 with a reverse thread pitch disposed thereabout for threadingly engaging a female neck thread 60 of the tank. Referring to FIGS. 1 and 9, a tank detail 62 is shown having an annular flange 64 for engaging a tank surface. This tank detail 62 may be separately manufactured from the tank body and then attached thereto during final assembly 20. If the parts are constructed of a suitable thermoplastic, they may be sonic welded to complete the assembly 20. The tank detail 62 includes a fill neck 66 extending axially from the annular flange 64 and extends below the tank surface. The fill neck 66 includes the female neck thread 60 threadingly engaging the male insert thread 58 of the cylindrical insert 24. Finally, the fill neck 66 includes a neck flange 68 spaced axially from the annular flange 64 and spaced radially inwardly of the female neck thread 60. A neck gasket 70 is disposed radially on said neck flange 68 for contacting the bottom of the cylindrical insert 24.

The reverse thread pitch as described herein refers to a thread pitch having a flat or acute angle with respect to the thread to which it mates. This configuration helps to resist slippage resulting from axial forces generated by pressure within the tank. A conventional thread under pressure could slip in a cap removal direction resulting in unwanted removal of the closure assembly 20 from the tank. The reverse thread pitch may be alternatively referred to as a buttress thread.

According to the exemplary embodiment, the closure assembly 20 is operated by rotating the cap shell 22 relative to the cap insert in a cap insertion direction to press the stem 32 against the dome 28, engaging the valve seat with the mating edge 34, and displacing the dome 28 axially by flexing it to create a seal for isolating the tank from the tortuous path. The assembly 20 can then be inserted onto the tank details 62 via the male insert threads 58 of the cylindrical insert 24 engaging with the female neck threads 60 lining the fill neck 66. In this position, the tank is sealed from the environment and ready for transportation. The reverse pitch, or buttress, threads 38, 40, 58, 60 prevent pressure buildup from within the tank from inadvertently causing the assembly 20 to rotate out in a cap removal direction. To open the vent, the cap shell 22 is then rotated in a cap removal direction and moves relative to the cylindrical insert 24. This way, the distal edge of the cylindrical insert 24 remains pressed against the neck gasket 70, but the stem 32 is axially spaced from the dome 28 to release the seal. Simultaneously, the aperture 54 of the first cylindrical wall 36 is spaced from the cylindrical insert 24. Vapor within the tank under positive pressure can then escape the tank by flowing through the orifice 30 of the dome 28, through the annular fluid chamber, through the aperture 54 of the first cylindrical wall 36, and between the top wall of the cap shell 22 and the radial periphery 26 of the cylindrical insert 24. This can be used, for example, with a fuel tank for a marine engine where venting is preferred during engine operation. The detent mechanism 52 also maintains the vent in the open position so that vibrations from the engine do not cause the vent to inadvertently close. Finally, to remove completely the closure assembly 20, such as for refueling in the provided example, the cap shell 22 and cylindrical insert 24 can be rotated together by virtue of the pins 42 engaging the second side of the shoulders 50 until the entire assembly 20 is separated from the tank.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the appended claims.

Claims

1. A closure assembly for a tank comprising;

a cap shell including a top wall extending circumferentially about an axis to an outer periphery,

a cylindrical insert having a radial periphery facing said top wall of said cap shell for engaging a fill neck of the tank,

a dome supported by said cylindrical insert spaced axially from said radial periphery,

said dome having an orifice formed therein and defining a valve seat extending circumferentially about said axis for fluid communication with the tank,

a stem having a mating edge and spaced radially inward of said outer periphery for engaging said valve seat with said mating edge to form a seal therebetween, and

said stem displacing said dome axially to form said seal.

2. An assembly as set forth in claim 1 including a lost motion connection between said cap shell and said cylindrical insert defining a first stop and a second stop for moving said cap shell axially relative to said cylindrical insert between said first stop and said second stop wherein said stem axially displaces said dome to form said seal when said cap shell is moved to said first stop and wherein said stem is spaced from said dome when said cap shell is moved to said second stop.

3. An assembly as set forth in claim 2 wherein said top wall of said cap shell and said radial periphery of said cylindrical insert define a tortuous path therebetween when said cap shell is moved to said second stop and wherein said tortuous path is sealed therebetween when said cap shell is moved to said first stop.

4. An assembly as set forth in claim 3 wherein said lost motion connection includes at least one pin depending from said cap shell and a guide track extending along said cylindrical insert for receiving said pin.

5. An assembly as set forth in claim 4 wherein said lost motion connection includes a detent mechanism for maintaining said cap shell against said second stop to prevent inadvertent sealing of said valve seat.

6. An assembly as set forth in claim 5 wherein said lost motion connection includes a shoulder for maintaining engagement between said cap shell and said cylindrical insert to prevent separation.

7. A closure assembly for a tank as set forth in claim 2 wherein said stem depends axially downwardly from said cap shell to a distal edge defining said mating edge.

8. A closure assembly for a tank comprising;

a cap shell including a top wall extending circumferentially about an axis to an outer periphery,

a cylindrical insert having a radial periphery facing said top wall of said cap shell for engaging a fill neck of the tank,

a dome supported by said cylindrical insert spaced axially from said radial periphery,

said dome having an orifice formed therein and defining a valve seat extending circumferentially about said axis for fluid communication,

a stem having a mating edge and spaced radially inward of said outer periphery for engaging said valve seat with said mating edge to form a seal therebetween,

a lost motion connection between said cap shell and said cylindrical insert defining a first stop and a second stop for moving said cap shell axially relative to said cylindrical insert between said first stop and said second stop,

said stem displacing said dome axially to form said seal and prevent fluid communication through said orifice when said cap shell is moved to said first stop, and

said stem spaced from said dome to allow fluid communication through said orifice when said cap shell is moved to said second stop.

9. An assembly as set forth in claim 8 wherein said lost motion connection includes at least a pair of pins depending from said top wall of said cap shell and a guide track extending along said cylindrical insert for receiving said pins.

10. An assembly as set forth in claim 9 wherein said guide track extends circumferentially along said cylindrical insert to allow relative rotation between said cap shell and said cylindrical insert when translating said cap shell between said first and second stops.

11. An assembly as set forth in claim 10 wherein said lost motion connection includes a first cylindrical wall depending axially downwardly from said top wall of said cap shell and spaced radially inwardly from said outer periphery and spaced radially outwardly from said stem defining an annular fluid chamber extending cylindrically therebetween and including a male cap thread disposed thereabout and wherein said cylindrical insert includes a female insert thread engaging said male cap thread for axially moving said cap shell relative to said cylindrical insert along said axis in response to rotation of said cap shell between said first and second stops.

12. An assembly as set forth in claim 11 wherein said stem depends axially downwardly from said top wall of said cap shell to a distal edge defining said mating edge.

13. An assembly as set forth in claim 12 wherein said dome extends integrally and radially inwardly from said cylindrical insert.

14. An assembly as set forth in claim 12 wherein said stem includes a hollow center defining a second cylindrical wall and a cylindrical fluid chamber in fluid communication with the tank when said cap shell is moved to both said first and second stops.

15. An assembly as set forth in claim 11 wherein said male cap thread and said female insert thread each has a reverse thread pitch for resisting rotational slippage resulting from axial pressure.

16. An assembly as set forth in claim 11 wherein said first cylindrical wall includes an aperture formed therein helping to define a tortuous path between said cap shell and said radial periphery of said cylindrical insert.

17. An assembly as set forth in claim 16 wherein said aperture is covered by said cylindrical insert when said cap shell is moved to said first stop to seal said tortuous path and wherein said aperture is spaced axially from said cylindrical insert when said cap shell is moved to said second stop to allow fluid communication across said tortuous path.

18. An assembly as set forth in claim 17 wherein said pins depend axially downwardly from said top wall and wherein said guide track includes a radial shelf depending from said radial periphery for axially engaging said pins.

19. An assembly as set forth in claim 18 wherein said lost motion connection includes a pair of shoulders each having a first side and a second side and extending radially from said radial periphery of said cylindrical insert and spaced circumferentially from one another for engaging each of said pins on said first side when said cap shell is moved to said first stop and for engaging each of said pins on said second side when said cap shell is moved to said second stop.

20. An assembly as set forth in claim 19 wherein said lost motion connecting includes a detent mechanism adjacent said second side of each of said shoulders and extending radially into said radial shelf for maintaining said pins against said shoulders when said cap shell is moved to said second stop.

21. An assembly as set forth in claim 20 wherein said mating edge of said stem abuts said valve seat when said pins abut said first side of said shoulders and wherein said mating edge of said stem is spaced from said valve seat when said pins abut said second side of said shoulders.

22. A closure assembly for a tank comprising;

a cap shell including a top wall extending circumferentially about an axis to an outer periphery,

said cap shell including a skirt depending axially downwardly from said outer periphery of said top wall,

a cylindrical insert having a radial periphery extending circumferentially about said cylindrical insert and facing said top wall of said cap shell,

said cap shell engaged with said cylindrical insert to define a tortuous path between said top wall of said cap shell and said radial periphery of said cylindrical insert,

a dome supported by said cylindrical insert spaced axially from said radial periphery,

said dome having an orifice formed therein and defining a valve seat extending circumferentially about said axis for fluid communication with the tank,

a stem having a mating edge disposed at one end thereof and spaced radially inward of said outer periphery for selectively engaging said valve seat with said mating edge to form a seal therebetween,

a lost motion connection between said cap shell and said cylindrical insert for defining a first stop and a second stop and for moving said cap shell axially relative to said cylindrical insert between said first stop and said second stop,

said lost motion connection including a first cylindrical wall depending axially downwardly from said top wall of said cap shell and spaced radially inward of said skirt and including a male cap thread having a reverse thread pitch disposed thereabout,

said lost motion connection including a female insert thread having a reverse thread pitch disposed about said cylindrical insert and engaging said male cap thread of said first cylindrical wall for axially moving said cap shell relative to said cylindrical insert along said axis between said first and second stops in response to rotation of said cap shell,

said lost motion connection including a pair of pins depending axially downwardly from said top wall of said cap shell adjacent said skirt and a guide track extending circumferentially about said cylindrical insert for receiving said pins,

said guide track including said radial periphery of said cylindrical insert and a radial shelf depending from said radial periphery for axially engaging said pins,

said radial shelf of said cylindrical insert defining a notch extending circumferentially about said cylindrical insert opposite of said guide track along said axis for receiving a tank gasket to contact said cylindrical insert and the tank and to seal a space therebetween,

said lost motion connection including a pair of shoulders having a first side and a second side and extending radially from said radial periphery of said cylindrical insert and spaced 180 degrees circumferentially from one another for abutting each of said pins with said first side to define said first stop and for abutting each of said pins with said second side to define said second stop,

said lost motion connection including a detent mechanism adjacent each of said shoulders and extending radially into said guide track for maintaining said pins against said shoulders when said pins abut said second side,

said cap shell and said cylindrical insert rotating relative to one another between said first and second stops and said cap shell rotating together with said cylindrical insert in a cap insertion direction when said pins abut said first side of said shoulders and said cap shell rotating together with said cylindrical insert in a cap removal direction when said pins abut said second side of said shoulders,

said stem displacing said dome axially to form said seal when said pins abut said first side of said shoulders,

said stem spaced from said dome when said pins abut said second side of said shoulders,

said stem depending axially downwardly from said top wall to a distal edge defining said mating edge and spaced radially inward of said first cylindrical wall to define an annular fluid chamber extending therebetween,

said stem having a hollow center defining a second cylindrical wall extending axially therealong and a cylindrical fluid chamber extending therein in fluid communication with the tank when said pins abut said first side and said second side of said shoulders,

said dome extending integrally and radially inwardly from said cylindrical insert,

said first cylindrical wall of said cap shell including an aperture between said top wall and said cylindrical insert helping to define said tortuous path for venting said fluid chamber when said pins abut said second side of said shoulders and said aperture covered by said cylindrical insert to seal said tortuous path when said pins abut said first side of said shoulders,

an insert gasket circumferentially aligned with said radial periphery intermediate said radial periphery and said top wall for contacting said cap shell to seal tortuous path defined when said pins abut said first side of said shoulders and for allowing fluid communication across said tortuous path when said pins abut said second side of said shoulders, and

said cylindrical insert including a male insert thread having a reverse thread pitch disposed thereabout for threadingly engaging a female neck thread of the tank.

23. A closure assembly as set forth in claim 22 including;

a tank detail having an annular flange for engaging a tank surface,

said tank detail including a fill neck extending axially from said annular flange of said tank detail for extending axially below the tank surface,

said fill neck including said female neck thread threadingly engaging said male insert thread of said cylindrical insert, and

said fill neck including a neck flange spaced axially from said annular flange and spaced radially inwardly of said female neck thread and a neck gasket disposed radially thereon for contacting said bottom of said cylindrical insert.