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.

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.