Back to results
US 5,178,367 AGranted
Structure for an inflatable lift device
OwnerJack F. Vaugheninventor
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
OwnerJack F. Vaugheninventor
Estimating the term…
In an inflatable lifting device comprising an upper platform to support a load, a lower base platform and a flexible, fluidtight diaphragm interposed between the two platforms for inflation to lift the load, the improvement comprising a diaphragm of truncated conical configuration. In some practices of the invention, two such diaphragms are effectively stacked on top of each other to increase the jacking height of the device. Constructuion of the conical diaphragm provides approximately uniform strength of the diaphragm around its entire periphery. Safety means are provided to prevent over-pressurization of the diaphragm at its maximum lifting height. Means are also provided to prevent collapse of the loaded device in the event the fluid supply line should inadvertantly be disconnected.
In a device to lift a load comprising:
In an inflatable lifting device which is pressurized through at least one inlet port, check valve means to prevent back flow through said inlet port comprising;
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
In a device to lift a load comprising:
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
Term ended 23 Jul 2010 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
This application describes and claims a number of improvements over my previously issued patent Ser. No. 3,799,504 titled "Pneumatically Operated Lift Device" which issued on Mar. 26, 1974.
The previously issued patent cross-referenced above explained the advantages of using a truncated conical inflatable diaphragm as the lifting element in an inflatable lifting device. Subsequent operating experience has proven the validity of the advantages claimed for this design.
The manufacture and use of these lifting devices has resulted in a number of innovations in the manufacture of the conical diaphragms and their mountings to adjacent structure. These improvements are described and claimed herein.
In the drawings, which are to be regarded as merely illustrative:
FIG. 1 is a partial planview of one inflatable lifting device having a single-stage truncated conical diaphragm.
FIG. 2 is a cross-sectional view of one inflatable lifting device comprising a single-stage truncated conical diaphragm mounted in fluidtight manner between two nominally parallel platforms.
FIG. 1 is a partial planview and FIG. 2 is a diametrical cross-section through a single annular pressurized lifting device which constitutes the first embodiment of the invention. This device is shown in the fully inflated condition. A truncated conical diaphragm 1 forms a fluidtight flexible envelope between a first, lower base plate 2 and a second, upper load bearing plate 3. This load bearing plate may be of either rigid or flexible construction. A rigid plate might be made of metal for example while a flexible plate might be made of cloth-inserted rubber. This load bearing plate can have any planform shape but a circular plate is shown in FIG. 1. The larger diameter edge 4 of conical diaphragm 1 is attached by suitable fluidtight means to base platform 2. As shown in FIG. 2, an integral circumferential structural ridge 5 projects upward from the face of base 2. This ridge is preferably circular in planview as shown in FIG. 1. Outer edge 4 of conical diaphragm 1 is attached to the outer vertical surface of ridge 5 preferably by bonding. Ridge 5 is concentrically encompassed by ring 6 which is circular in planview and is of larger diameter than ridge 5. Both ridge 5 and ring 6 are preferably of less vertical height than the elevated portions 7 and 8 of base platform 2. Therefore, when the inflatable device is collapsed, the underside of load plate 3 rests on top of elevated portions 7, 8 of the base plate clearing both ridge 5 and ring 6. Note that the top surface of elevated angular portion 8 preferably has radial grooves 9 cut across its width to facilitate inflation when the lifting device is in its collapsed position. Also, note in FIG. 1 that outer ring 6 may be fitted with outward facing horizontal tabs 10 which have holes drilled through them (and on through base plate 2) to accomodate screws for attaching the inflatable lifting device to other structure. Outer ring 6 may also be fitted with a number of inward facing horizontal tabs 11 equally spaced around its inner periphery. Each of these tabs has a hole drilled through it to fit over an attaching screw 12. Each of these screws projects through base plate 2 and is flush mounted thereto so the screw head does not protrude beyond the face of the base plate. A nut 13 on each attaching screw 12 bears against the surface of each tab 11 to secure ring 6 against base plate 2. Typically, from eight to twelve attaching screws are used to attach the outer ring to the base plate. However, additional flush head screws are also installed in the annular space between ridge 5 and outer ring 6. These screws are typically spaced approximately one and one-half inches apart and are equally spaced circumferentially between tabs 11. No nuts are required on these intermediate screws. A fillet of suitable sealing material 20 is applied around the outer periphery of outer ring 6 where its edge bears against base plate 2. The base plate is then placed on a level surface and the annular cavity between ridge 5 and outer ring 6 is filled with rigid-setting plastic. This plastic material 14 unites the diaphragm, the base plate and the outer ring into one integral structural assembly after the plastic flows around the attaching screws and hardens. The inner edge 15 of conical diaphragm 1 is attached concentrically to a cloth disk 16. This attachment may be by vulcanizing; or alternatively, the parts may be bonded together and stitched by multiple concentric rows of stitches 17. If stitches are used, they should be sealed over inside the inflatable cavity to prevent leakage through the needle holes. Cloth disk 16 is then attached, preferably by bonding, to load plate 3 to complete the assembly. Lifting fluid can be introduced into the interior of the device as shown by arrow 18 through an inlet port 21. Inflation is preferably accomplished through a pressure regulating valve (not shown). Any suitable working fluid can be employed including air, steam, gas, water or oil.
Truncated conical diaphragm 1 is preferably constructed from a number of angular segments like that shown in FIG. 3. Each of these segments is cut from coated fabric with the threads 18 of the fabric oriented parallel and perpendicular to the center line of the segment. The curved edges of the segment are circular arcs having a common center 19. The inner edge has radius r and the outer edge has radius R as shown. The distance (R-r) is the radial width of the segment and becomes the slant height of the conical diaphragm when assembled. The angular width (2.alpha.) of the segment determines how many segments are required to make up one conical diaphragm. The additional angular width (.beta.) represents the area of overlap of the segments when they are assembled together. FIG. 4 is a flat pattern for one conical diaphragm showing how it is assembled from the angular segments of FIG. 3. These angular segments are overlapped along their radial edges and are attached together either by vulcanizing or by bonding and stitching. Bonded and stitched construction is shown in FIG. 4 with the segments attached together by multiple rows of radial stitches 19. To provide uniform radial strength of the diaphragm around its entire periphery, the threads 18 of each angular segment are oriented parallel and perpendicular to the center line of the segment as shown. FIG. 5 is a perspective view of the diaphragm of FIG. 4 showing the truncated conical form it takes after the edges of all segments are attached together. If stitches are used as shown, the stitches must be sealed on the inside of the diaphragm to prevent leakage through the needle holes. Note that the overlap areas of a cone constructed from angular segments in this manner extend the full radial width of the cone and have double the strength of the remainder of the cone. Since they are radially disposed in the cone and are evenly spaced around its periphery, these overlapped areas act as natural limit stops to establish the maximum inflation height of the cone.
FIG. 6 is a planview and FIG. 7 is a diametrical cross-sectional view of a multi-layer conical diaphragm 1 a,b,c and its cloth mounting disk 16 mounted to a load plate 3. All of the cloth parts are made of fluidtight coated fabric and may be attached together either by vulcanizing or by bonding and stitching. Stitched construction is indicated in FIG. 6 with both radial stitches 19 and circumferential stitches 17 shown in partial view. The radial stitches must be sealed from the inside of the diaphragm by covering them with a suitable sealing material between dashed boundry lines 22. Similarly, circumferential stitches 17 must be sealed from the inside of the diaphragm by covering them with a suitable sealing material between dashed boundary lines 23. This sealing material may be a thin, fluidtight plastic or rubber film for example, or it may be a chemical sealant such as room temperature vulcanizing rubber (RTV). In any case, all stitches should be covered so no leakage can occur through the needle holes. If multiple cones are nested together to form a multi-layer diaphragm as shown in FIG. 7, it is necessary to only seal the threads of the innermost cone. This prevents leakage from the interior of the diaphragm when inflated but allows trapped fluid to escape from between successive layers of the diaphragm by passout through their needle holes. Typically, when sealing the radial stitches 19 of the innermost cone, a small margin of width "D" along the outermost edge of the cone is protected from the sealing material. This facilitates later bonding of this outer edge to adjacent structure. If multiple cones are employed as shown in FIG. 7, the successive cones should be staggered in azimuth relative to each other so that the radial stitches of the entire assembly are equally spaced in azimuth like the spokes of a wheel (when seen in planview). This provides approximately uniform radial strength of the multi-layer cone assembly around its entire periphery while retaining maximum flexibility for the assembled diaphragm. It should also be noted that successive cones in this multi-layer construction are preferably attached to each other only by circumferential stitches 17 and by their peripheral mounting to adjacent structure at margin "D". Since the individual conical layers remain free of each other between these two concentric circumferential areas, the entire assembly maintains its flexibility. It is therefore capable of collapsing to a very low, flat profile when the diaphragm is deflated.