Joints and connections – Interfitted members – Enlarged head in complementary recess – e.g. – dovetail – etc.
Reexamination Certificate
1999-03-05
2001-04-24
Knight, Anthony (Department: 3626)
Joints and connections
Interfitted members
Enlarged head in complementary recess, e.g., dovetail, etc.
C403S293000, C220S684000
Reexamination Certificate
active
06220779
ABSTRACT:
BACKGROUND
1. The Field of the Invention
The present invention is related to an improved joint for connecting two or more segments of a structure. More particularly, the present invention is related to a joint for use in connecting extruded segments to form the body portion of a pressure vessel, such as a tank for storing liquid propane.
2. Technical Background
Pressure vessels are widely used to store liquids and gases under pressure. The storage capacity of a pressure vessel depends on the internal volume of the pressure vessel and the pressure the vessel is capable of safely containing. In addition to its storage capacity, the size, internal shape, external shape, and weight of the pressure vessel are often important.
One growing application of pressure vessels is their use in the storage of alternative fuels, such as propane, for use in vehicles such as automobiles. Propane is increasingly viewed as preferable to gasoline for fueling vehicles. Accordingly, approaches have been devised for converting gasoline-fueled vehicles to propane-fueled vehicles by retrofitting them to use propane instead of gasoline. Additionally, vehicles are now being built which are designed to operate using propane as fuel.
Typical propane storage tanks are cylindrical in shape. Positioning cylindrical storage tanks in the envelope utilized for a fuel tank in most vehicles results in substantial limitations in the amount of propane a vehicle can carry. Hence, storage tanks have been devised which utilize a plurality of arcuate outer wall segments which are connected by internal web segments to form a multi-cell pressure vessel. Such multi-cell pressure vessels have a generally uniform cross section, thereby enabling the outer wall segments to be formed by extrusion.
One disadvantage associated with such multi-cell pressure vessels is the difficulty of obtaining a secure and inexpensive joint for connecting adjacent segments. Typically, adjacent segments are connected by welding them together. One disadvantage to the use of such a welded joint is the high manufacturing cost resulting from welding multiple joints to form a single multi-cell pressure vessel.
Another disadvantage to the use of a welded joint is that welding the joint generally results in heat treating the edges of the wall segments, thereby reducing the strength of the wall segments adjacent the weld. When tested for burst strength, such welded pressure vessels frequently fail in the wall segments that were exposed to the heat from the welding process.
From the foregoing, it will be appreciated that it would be an advancement in the art to provide an improved joint for use in a multi-cell pressure vessel that would be inexpensive to manufacture and assemble.
It would be a further advancement in the art to provide an improved joint for use in a multi-cell pressure vessel which does not suffer from the reduced strength implications arising from heating the pressure vessel during welding.
Such a joint for use in a multi-cell pressure vessel is disclosed and claimed herein.
BRIEF SUMMARY AND OBJECTS OF THE INVENTION
The present invention is directed to a novel joint for use in constructing a body portion of a multi-cell vessel, such as a pressure vessel which may be used for the storage of compressed natural gas or liquid propane. Through the use of the present invention, segments may be extruded out of aluminum or other extrudable material and combined to form vessels having a variety of shapes and useful for a number of functions. Being extruded, the body portion of the vessel has a substantially uniform cross section.
A typical vessel having joints made according to the present invention comprises a number of arcuate outer wall segments connected with at least one internal web segment. Thus, in one embodiment, the joint of the present invention attaches adjacent ends of two arcuate outer wall segments and the end of one internal web segment.
The joint of the present invention is best defined by reference to its cross-sectional geometry. Thus, in cross section, one embodiment of the joint includes a tab configured at the end of each arcuate outer wall segment. The tabs of adjacent ends are symmetrical to each other and are configured for contiguous engagement, thereby forming an exposed seam. A sealing weld extends along the seam to attach adjacent tabs at the seam.
Each tab has a straight, back portion which is in contiguous engagement with the corresponding back portion of the adjacent tab. Together, the tabs form a boss having a proximate neck portion and a distal body portion. The neck portion of the boss has a width smaller than the width of the body portion of the boss, with the boss having a perimeter which is configured in a curvilinear shape.
The joint also includes a retaining member which is configured at the end of the internal web. The retaining member has two lobes which are symmetrical to each other and which extend about the body portion of the boss and terminate at the neck portion of the boss. The retaining member is configured to capture the boss formed at the adjacent ends of the two arcuate outer wall segments with the lobes of the retaining member positioned substantially contiguous to the entire exterior contour of the boss.
In an alternative embodiment of the present invention, a joint is provided for connecting at least a first and a second segment of a structure having a substantially uniform cross section. The segments are preferably formed of an extruded material, such as aluminum. The joint has the capability of bearing a tensile load applied to the segments along a load axis. In cross section, the joint includes a retaining member configured at the end of the first segment. The retaining member has a perimeter configured in a curvilinear shape and is configured with a first and a second pair of inwardly projecting lobes, each having a load bearing surface positioned at an angle with respect to the normal to the load axis. The angle of the load bearing surfaces of the first pair of lobes with respect to the normal to the load axis is opposite to the angle of the load bearing surfaces of the second pair of lobes with respect to the normal to the load axis. The retaining member is preferably configured to be symmetrical about the load axis.
The joint also includes a boss configured at the end of the second segment. Like the retaining member, the boss is preferably symmetrical about the load axis. The boss includes a proximate neck portion and a distal body portion, with the neck portion of the boss having a width smaller than the width of the body portion of the boss. The body portion of the boss is configured with a first and a second pair of outwardly projecting lips each having a load bearing surface.
Thus, the retaining member is configured to capture the boss. In its captured position, the load bearing surfaces of the first pair of lips are in engagement with the respective load bearing surfaces of the first pair of lobes of the retaining member and the load bearing surfaces of the second pair of lips are in engagement with the respective load bearing surfaces of the second pair of lobes of the retaining member. The first pair of lobes of the retaining member are positioned at a distal end of the first segment and are configured to mate with the boss at the neck of the boss. Additionally, the load bearing surfaces of the first pair of lobes extend inwardly towards the first segment, thereby providing a load bearing surface which counteracts the load applied at the load bearing surface of the second pair of lobes.
The retaining member includes two arms which extend about the body portion of the boss and terminate at the neck portion of the boss. The arms of the retaining member are symmetrical to each other about the load axis and are positioned in the joint to be substantially contiguous to the entire exterior contour of the boss.
The retaining member and boss are preferably configured such that the angle of the load bearing surfaces of the first pair of lobes with respect to the normal to the load axis
Blair Michael D
Warner Mark J.
Cordant Technologies Inc.
Knight Anthony
Pickard Alison K.
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