IMPROVED RETAINING STRUCTURE FOR A FUEL TANK MOUNTED VALVE BODY

Abstract: In a two piece valve assembly (14) comprising a non-weldable lower body portion inserted into the fuel tank through an opening (12) in the tank wall (10), and an upper valve body portion or cover (20) made from a weldable material and designed to be connected to the lower valve body portion (16) and welded to the upper surface of the fuel tank wall (10). An improved assembly structure comprising a plurality of circumferentially-spaced support/retention tabs (26) are formed on the lower valve body (16).

Description: IMPROVED RETAINING STRUCTURE FOR A FUEL TANK MOUNTED VALVE BODY Field of the Invention The present invention is generally in the field of vent valves mounted to automotive fuel tanks, and more particularly relates to structure for securely positioning and retaining such valves in the mounting holes through which they are inserted into the fuel tank. Background of The Invention Automotive fuel tanks are typically supplied with one or more vapor venting valves of different type to selectively vent fuel vapor from the interior of the fuel tank. Commonly used valves include "ORVR" (onboard refueling/vapor recovery) control valves and rollover valves. Fuel tank mounted vapor vent valves typically have a hollow valve body which is inserted through an opening formed in the tank such that a lower part of the valve body is located in the tank, and an upper part or cover of the valve body remains outside the tank. In many cases the lower and upper portions of the valve body are formed separately and are connected mechanically or by known methods such as ultrasonic welding, heat staking or overmolding. The lower portion of the valve body is sized to fit through the opening in the fuel tank, while the upper portion of the valve body is wider to keep the valve assembly from falling through the fuel tank opening. A common method for securing the valve assembly to the tank is to provide a weldable connector portion on the upper valve body made from a weldable material similar to the material of the fuel tank wall. When the valve assembly is inserted through the fuel tank opening, the weldable connector rests on the upper surface of the fuel tank and is welded to the fuel tank wall to secure the valve in place. Examples of valves with weldable connectors are shown in co-owned U.S. Patent No. 5,404,907 issued May 11, 1995. Mechanical connection of the non-weldable and weldable portions of the valve is often preferred, due to its simplicity and low costs. But while the weld between the weldable upper portion of the valve body and the fuel tank wall is highly reliable, the mechanical connection with the lower valve body is often subject to thermal expansion and creep under fuel tank operating conditions, which can loosen the connection between the lower valve body and the upper valve body or cover, destroying the integrity of the mounting arrangement and of seals between the upper and lower portions. The present invention is directed to overcoming this problem. Summary of the Invention The present invention overcomes the difficulties experienced with the mechanical connection between a lower valve body portion inserted through the opening in the tank and the upper portion or cover of the valve body which rests on top of and is welded to the fuel tank. This is generally achieved by providing means on the lower valve body portion which rests on the upper surface of the fuel tank and which interacts with the weldable upper valve body portion such that the welding operation secures both the upper and lower valve portions to the fuel tank wall. In an embodiment of the invention illustrated in detail below, the retention means on the lower valve body comprises a plurality of laterally projecting retaining tabs extending from the upper end of the lower valve body to rest on the upper surface of the fuel tank around the fuel tank opening and within the periphery of the weldable portion of the upper valve body or cover. The retaining tabs make the lower valve body self-supporting on the fuel tank when it is inserted through the fuel tank opening. When the upper valve body or cover is subsequently welded to the upper surface of the fuel tank around the opening, the retaining tabs are firmly sandwiched between the cover's weld "foot" (which melts during welding) and the surface of the tank. The invention eliminates the need for a pre-assembled mechanical interlock between the lower valve body and the upper valve body. However, in a further embodiment of the invention, the lower valve body is provided with conventional mechanical interlock structure which complements and mechanically interacts with the weld- interfacing retaining tabs. These and other features of the invention will become apparent upon a further reading of the specification. Brief Description of the Drawings Figure 1 is an exploded view of a two piece prior art valve assembly with a non-supportive, non-retaining relationship between the lower portion and the fuel tank opening; Figure 2 is a front perspective view of the prior art valve assembly of Figure 1, assembled, inserted in a fuel tank opening, and welded in place; Figure 3 is an exploded view of a two piece weldable valve assembly according to the present invention prior to being inserted in a fuel tank opening; Figure 4 is a front perspective view of the valve assembly of Figure 3, assembled and welded in place on the fuel tank; and, Figure 5 is a bottom (viewed from inside the fuel tank) plan view of the valve of Figure 4 in its assembled condition. Detailed Description of the Illustrated Embodiment Referring now to Figures 1 and 2, a prior art two piece valve assembly 14 is shown in its unassembled and assembled/mounted conditions relative to a fuel tank wall 10 with a valve-receiving fuel tank opening 12. Valve assembly 14 comprises a lower valve body 16 made from a non-weldable plastic material such as nylon, for example, and an upper valve body portion or cover 20 made from a weldable polymer such as polyethylene, for example, which can be welded in known fashion to the similarly-weldable polymer material of fuel tank wall 10. Upper and lower valve body portions 16, 20 are mechanically assembled prior to insertion in the fuel tank, for example via conventional lock tabs 18 formed on the outer sidewall of the lower valve body, and lock fingers 22 extending from upper valve body portion 20 which slide over and snap onto lock tabs 18. Upper valve body portion 20 is illustrated with a laterally extending outlet portion 19 showing some representative internal detail of outlet and other connections which would normally be covered with a cover; these details, however, are not critical to the invention. Once the lower and upper valve body portions 16, 20 are connected, assembled valve 14 is mounted on the fuel tank by inserting the lower valve body portion 16 through fuel tank opening 12 until upper valve body portion 20 rests on the upper surface of fuel tank wall 10. As illustrated, lower valve body portion 16 is sized to fit through fuel tank opening 12 without interference; if let go it would simply drop into the tank. Upper valve body portion 20, on the other hand, has a greater diameter so that it acts as a stop for its pre-assembled lower valve body portion 16. Once valve assembly 14 has been located in fuel tank opening 12 by upper valve body portion 20, it is welded to the similarly-weldable fuel tank wall 10 to secure the valve to the fuel tank. Typically, the periphery of upper valve body portion 20 is provided with a circumferential weld foot 24 comprising a downwardly- turned bead or flange of weldable material lying radially outward of the fuel tank opening 12. The welding process is applied to weld foot 24, which melts into the fuel tank wall . A disadvantage of the prior art valve assembly of the type illustrated in Figures 1 and 2 is the need for a pre- assembly of the upper and lower valve body portions prior to being mounted on the fuel tank to retain the lower valve body portion in place relative to the opening 12. Another disadvantage is the deterioration of the mechanical interlock and sealing fit between the upper and lower valve body portions due to different rates of thermal expansion and creep in the high temperature, hydrocarbon-saturated environment of the fuel tank. It will be apparent to those skilled in the art that valve assembly 14 can comprise any of a number of different vapor venting valves, for example onboard refueling and vapor recovery (ORVR) control valves, rollover valves, running loss valves and the like. The particular valve structure, typically located in the hollow lower valve body portion 16, is unimportant to the present invention. Often, however, the junction of the upper valve body portion 20 and lower valve body portion 16 will define, at least in part, some sort of valve seat (Figure 5) or vapor outlet (illustrated at 21) selectively opened and closed by a valve element which is pressure-, liquid- or gravity- responsive. Accordingly, not only the mechanical interlock but also the effectiveness of vapor control across the valve seat or vent outlet can be affected by thermal expansion and creep problems between the dissimilar materials of the upper and lower valve body portions. Referring now to Figure 3, the present invention is disclosed as applied to the valve configuration illustrated in Figures 1 and 2. Accordingly, the same reference numerals will be used where the valve structure of Figures 1 and 2 is repeated. In the inventive valve assembly of Figures 3-6, the non-weldable lower portion 16 has been modified with a plurality of support/retaining tabs 26 projecting laterally from the upper end of lower portion 16 to extend beyond the fuel tank opening 12 and rest on the upper surface of fuel tank wall 10 when the lower portion 16 is inserted in the tank. In the illustrated embodiment four evenly-spaced tabs 26 are illustrated, although varying numbers can be used depending on mounting requirements or to accommodate a different number of locking fingers and lock tabs 22, 18. In the illustrated embodiment support/retention tabs 26 are sized to fit snugly between lock fingers 22 when the upper and lower valve body portions are assembled so that they are guided and rotationally secured between fingers 22. Support/retention tabs 26 will rest on the upper surface of fuel tank wall 10 if the lower valve body portion 16 is inserted alone through fuel tank opening 12. This is beneficial in applications where it is desired to assemble the upper and lower valve body portions after the lower valve body portion has been positioned in the fuel tank opening. When the illustrated embodiment of Figures 3-6 is assembled with lock tabs 18 and lock fingers 22, support/retention tabs 26 are inset (Figures 4 and 5) into the interior of the weld foot circumference of upper valve body portion 20, and are preferably flush with the upper inside surface of upper valve body portion 20. Tabs 26 are preferably of a thickness less than the height of weld foot 24. During welding the weld foot 24 melts into the tank wall, effectively lowering the height of weld foot 24 and bringing support/retention tabs 26 into contact with the upper surface of the fuel tank wall 10 as the weld foot melts to sandwich the tabs 26 securely between the upper valve body portion 20 and the surface of fuel tank wall 10. The use of a plurality of circumferentially-spaced tabs 26 cooperating with lock fingers 22 ensures that each tab is individually locked by the melting weld foot on up to three sides (end 26a, sides 26b) . Support/retention tabs 26, with their close fit between lock fingers 22, further serve to align lock tabs 18 on lower valve body portion 16 with lock fingers 22 in a positive fashion upon assembly, whether assembly occurs before or after lower valve body portion 16 is inserted into the tank. This is best illustrated in Figure 5. It will be understood by those skilled in the art that the foregoing illustrated embodiment is exemplary of the invention, and that various changes and modifications can be made without departing from the scope of the invention. I accordingly claim:

Claims: Claims 1. A retaining structure for an automotive fuel tank valve of the type having a body inserted through an opening in the fuel tank, and a weldable cover portion connected to the body and welded to the surface of the fuel tank around the opening, comprising: retaining means on the body for resting on the upper surface of the fuel tank, the retaining means located relative to a weldable portion of the cover such that the welding operation which welds the weldable portion of the cover to the fuel tank also secures the retaining means to the surface of the fuel tank. 2. The apparatus of claim 1, wherein the retaining means on the valve body comprises a plurality of laterally projecting retaining tabs extending from an upper end of the valve body to rest on the upper surface of the fuel tank around the fuel tank opening and within the periphery of the weldable portion of the cover. 3. The apparatus of claim 2, wherein the valve body further includes mechanical interlock structure for engaging separate mechanical interlock portions of the cover, the mechanical interlock structure on the cover being positioned to mechanically mate with the retaining means such that the mechanical interlock means on the cover is properly aligned with the mechanical interlock structure on the valve body.

Inventors: LEADFORD GARY H, LEADFORD, GARY, H.
Applicants: EATON CORP, EATON CORPORATION
Application year: 1998
Main classification: F16K17
IPC codes: B60K15, F02M37, F16K27