US3253667A - Multiple elevation air bearing device - Google Patents

Description

y 1966 H. A. MACKIE 3,253,667

MULTIPLE ELEVATION AIR BEARING DEVICE Filed Aug. 6, 1965 ATTOR N EY United States Patent 3,253,667 MULTIPLE ELEVATION AIR BEARING DEVICE Harry A. Mackie, Birmingham, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Aug. 6, 1963, Ser. No. 300,256 8 Claims. (Cl. 180-7) This invention relates to load supporting devices for producing substantially frictionless omnidirectional mobility and more particularly to devices of the type supported relative to the ground by means of a low pressure free air cushion.

The present invention is specifically, although not exclusively, directed to improvements in air cushion devices of the type shown in copending application Serial No. 4,465 Mackie et al., assigned to General Motors Corporation.

The indicated copending application discloses a flexible plenum chamber type low pressure air bearing device in which a rigid annulus and a flexible annulus are secured together peripherally and centrally ina manner forming an annular chamber between the diaphragm and the platform. The annular chamber is subjected to superatmospheric pressure causing the diaphragm to bulge downwardly and form a central plenum cavity between the diaphragm and the ground. The plenum communicates with the annular cavity through a central opening formed in the flexible annulus so that a low pressure cushion of air is developed in the latter operable to support the device and any load thereon in frictionless relation with the ground.

An inherent characteristic of the device described is that under operating conditions the flexible annulus or diaphragm tends to assume a cross-sectional contour wherein the outer portion thereof develops a relatively sharp radius which merges into a substantially flat in clined inner portion rather than tending to assume a semicircular configuration between the outer and inner margins thereof. This characteristic is considered to be due to the fact that the opposite surfaces of all of the diaphgram inboard of the throttling gap formed between the ground and the lowermost portion of the diaphragm are subjected to equal superatmospheric pressure, whereas the radius portion of the diaphragm is subjected to both differential pressure within the annular chamber and atmosphere and to the venturi effect of air discharging from the plenum through the throttling gap.

While this characteristic has the advantage of affording a relatively large effective ground support area, i.e., the area over which superatmospheric pressure within the plenum cavity is effective, where it is desirable to provide a greater physical clearance between the rigid annulus and the ground, the obvious expedient of increasing the depth of convolution of the diaphragm results in significant loss of effective ground support area.

That is, the radius at the outer portion of the diaphragm increases considerably and since the lowermost portion of the radius determines the effective ground support area of the plenum cavity, this area is appreciably reduced for a given platform area in comparison to a diaphragm of shallow convolution applied to a corresponding platform area.

An object of the present invention is to provide an improved air bearing device.

Another object is to provide an improved flexible plenum chamber type air bearing device.

A further object is to provide in an air bearing device of the type described, means for increasing the physical clearance between the platform and ground without appreciably reducing the effective ground support area thereof.

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A still further object is to provide a multiple elevation air bearing device.

Still another object is to produce selectively operable means for increasing the elevation level of a low pressure air bearing device.

A yet further object is to produce a fluid pressure energized compound elevation device and low pressure air bearing.

Still a further object is to provide a novel and improved unitary fiexible element for use in a device of the type described.

These and other objects, advantages and features of the invention will become more fully apparent as reference is had to the accompany specification and drawings wherein:

FIGURE 1 is an elevational view, partly in section, of a device constructed in accordance with the invention;

FIGURE 2 is a partially exploded sectional elevational view of a modification of the device shown in FIGURE 1; and

FIGURE 3 is a sectional elevational view of another modification of the invention.

Referring now to the drawings and particularly FIG- URE 1, the reference numeral 2 designates a relatively rigid circular platform, beneath which is disposed a unitary multiple layer element 4 formed of relatively thin flexible substantially fluid impervious material, such as urethane rubber. It will be understood that the greatly exaggerated thickness of the material in the drawings is for purposes of clarity. Element 4 cooperates with platform 2 to form a compound elevation device and low pressure air bearing. Element 4 includes an upper flexible member 6 comprising a substantially fiat lower wall portion 8 having an upturned continuous perimeter 10, the outer margin 12 of which is secured in sealing engagement with the perimeter 14 of platform 2 by an encircling band 16. Centrally thereof, wall 8 has bonded thereto an inverted coneshaped flexible 'web portion 18, the outer periphery 20 of which is mechanically attached to the lower wall 22 of platform 2 by bolts 24. At circumferentially spaced intervals, the intermediate section of web portion 18 is formed with apertures 26 which provide communication between the chamber 28 formed between the wall 8 and platform 2 and the chamber continuation 30 surrounded by Web 18. Near one side thereof, wall 8 has bonded thereto a flexible mellows type conduit 32 having an upper end portion 34 which extends into and is secured in an aperture 36 in platform 2 for a purpose shortly to be described.

Disposed below wall 8 is a flexible member 38 in the form of a relatively shallow single convolution diaphragm having an outer periphery curved upwardly in cross section to form a radius 40. The outer margin 42 of member 38 is bonded to member 6 at the juncture of upturned perimeter 10 and wall 8 and the center 44 thereof is displaced upwardly and bonded to wall 8, thereby forming an annular chamber 46 between flexible member 38 and the wall 8 of flexible member 6 which communicates with opening 36 viabellows conduit 32. At circumferentially spaced intervals along the truncated cone portion 48 inboard of an imaginary circle defined by its lowermost extremity 50, flexible member 38 is formed with apertures 52 providing open communication between the chamber 46 and the plenum cavity 54 formed beneath member 38 and the ground 56 within the support area circumscribed by the imaginary circle previously mentioned.

Formed in platform 2 adjacent aperture 36 is a second aperture 58 which is selectively communicable with chamber 28. In the illustrated embodiment, opening and closing of communication between aperture 58 and chamber 28 is accomplished by a blade closure 60 which is connected to and swingable about the axis of a vertical rod 62 extending through platform 2. When in closed position, blade 60 is maintained in sealing engagement with an O-ring 64 mounted in the lower mouth of aperature 58 by a coil spring 66 compressed between platform 2 and the operating handle 68 secured to the upper end of rod 62. It will be understood that the recess 70 formed in the lower wall of platform 2 is contoured in plan form to permit rotation of the blade 60 from a position totally closing aperture 58 to a horizontally angularly displaced position in which aperture 58 is completely unobstructed.

Mounted on the upper surface of platform 2 is a blower assembly 72 which includes a discharge duct 74 abutting platform 2 in overlapping relation with apertures 36 and 58. Thus, when blower 72 is operated, air delivered thereby into duct 74 is directed into both of the apertures 36 and 58. Assuming an initial condition in which the blade valve 60 has been moved to open position, air entering aperture 58 operates -to inflate the chamber 28 including the continuation chamber 30 within web 18, while air entering aperture 36 passes through bellows conduit 32, initially inflates annular chamber 46 and subsequently passes through openings 52 to create a superatmospheric cushion of air within the plenum cavity 54 which functions to render the entire device capable of frictionless omnidirectional mobility. According to one feature of the invention, the effective clearance 75 between the surface of platform 2 and the ground line is greatly increased over that obtained where the diaphragm 38 is connected directly to the platform 2 as disclosed in the aforementioned Serial No. 4,465, yet little if any decrease in the effective ground support area occurs. By contrast, a single convolution diaphragm having sufficient depth of convolution to produce the same clearance would inherently assume a natural configuration in which the ra- .of blower 72 results in discharge ofair through opening 36 only to accomplish continuous energization of chamber 46 and cavity 54 for frictionless support of the device. In practice, this mode of operation may also be utilized to achieve elevation of the load platform 2 Without providing frictionless support thereto,-or to establish an intermediate elevation level when movement of the load is to be accomplished in interrupted steps. In the latter case, the chamber 28 remains inflated when the blower is deenergized and consequently upon resumption of operation of blower 72, frictionless support is achieved without requiring re-inflation of the chamber 28. Naturally, if blade valve 60 is displaced to the open position after cessation of operation of the blower, the entire platform will descend to a level of proximity with the ground 56 determined solely by the collapsed thickness of the elastic members forming element 4.

According to another feature of the'invention, web portion 18 is formed and arranged so that its conical wall is generated in a path simulating a linear extension of the conical Wall developed by wall portion 48 of member 38. That is, when viewed in cross section, the inclined wall 48 at the left hand side of the device is substantially colinear with the right hand wall of the web 18. In this manner, the anchoring bolt 24 of web 18 functions as a radial tension anchor for the right hand wall portion 48. Asa result of this construction and arrangement, the conical wall 48 is effectively anchored throughout its entire circumference so that radial tension resulting from pressure differential within chamber 46-and atmosphere stabilizes member 38 in the same manner as if the central portion 44 were fixedly secured to the lower wall 22 of platform 2, but nevertheless allows the central portion to actually occupy a substantially spaced relation from the platform. At the same time, web 18 in vertically stressed condition establishes the maximum spacing between platform 2 and wall 8 so that the latter tends to.

remain relatively parallel to the former when inflated.

In FIGURE 2, there is shown a modified form of the invention wherein the composite inflatable upper chamber and lower air bearing device are formed as a unitary flexible element 76 which is not functionally dependent upon the presence of platform 78. That is to say, the element 76 is'capable of operating either directly under a load per se or in combination with a removable platform 78 depending upon the objectives to be accomplished. In the illustrated construction, element 76 is formed of an upper flexible horizontal wall 80 which overlies and is bonded peripherally to an intermediate flexible member 82 having a downwardly generally conically formed central portion 84 merging with a downturned outer periphery 86, the marginal edge 88 of which is bonded to the upper horizontally extending flexible wall portion 90 of air bearing member 92. Member 92 is a unitary hollow body which includes a peripheral portion 94 curved in cross section and a generally conical upwardly deformed lower wall portion 96. The central portion 98 of wall 84 and the central portion 100 of wall portion 96 are bonded to the center 102 of wall 90 for the same purpose previously described with respect to FIGURE 1. Similarly, wall 84 is formed with apertures 104 while wall 96 is formed with apertures 106. Flexible bellows type conduit 108 extends through wall 80 and intermediate member 84 is bonded to wall 90 to effect communication with chamber 110, while communication with chamber 112 is accomplished through sleeve opening 114. When utilized separately, element '76 may be energized by suitably valved air conducting hoses, not shown. Alternatively, the removable platform 78, shown in exploded relation, may be lowered so that openings 116 and 118 receive the sleeved portions of opening 114 and bellows conduit 108. Additionally, any suitable number of molded lugs 120 on wall 80 register with depressions 122 formed in platform 78 to establish sufficient lateral stability between the platform and the load supporting device. In the illustrated embodiment, the rotary type blade valve 60 of FIGURE 1 is replaced by a. linearly movable blade valve 124.

In FIGURE 3, there is shown another modification of the invention wherein the platform 2 is disposed over a single layer diaphragm 126 which is preformed, as by molding, to provide a relatively deep generally vertically extending side wall 128 and a generally conical upwardly deformed lower wall portion 130. The upper or terminal edge 132 of diaphragm 126 is secured peripherally to platform 2 by encircling band 134. Disposed within diaphragm 126 between platform 2 and the lowermost extremity of peripheral inturned portion 136 of the diaphragm is a rigid horizontal wall portion 138, the periphery 140 of which is clamped to the wall of diaphragm 126 by a second encircling band 142. Wall 138 serves to divide the entire chamber formed between platform 2 and diaphragm 126 into inflatable chamber 144 and annular chamber 146. A flexible bellows conduit 148 extends between opening 36 in platform 2 and an opening 150 and wall portion 138 for the same purpose as described with respect to FIGURE 1. Opening 58 corresponds identically to opening 36 in the embodiment shown in FIGURE 1, as do all of the remaining details of the blower and valve assembly not shown in FIGURE 2. In the embodiment shown in FIGURE 3, while the central portion 152 is mechanically secured to wall portion 138, no web portion is required between the wall 138 and platform 2 since the former exhibits no tendency to assume a centrally bulged configuration. Similarly, due to the rigidity of wall 138, ample anchoring of radial tension induced on inclined wall portion 130 is accomplished. While in the illustrated embodiment the portion of diaphragm wall 154 between wall 138 and platform 2 defines a singie outwardly bulged convolution, it will be evident that this side wall convolution may also be formed in an accordion pleated manner on the order of bellows conduit 148 and the inflated depth of the chamber depends only upon the degree of elevation desired.

While several embodiments of the invention have been shown and described, it will be apparent that other changes and modifications may be made therein. It is, therefore, to be understood that it is not intended to limit the invention to the embodiments shown, but only by the scope of the claims which follow.

I claim:

1. A two-stage fluid pressure energized bearing assembly comprising, in combination, an upper load supporting wall, an intermediate inflatable flexible walled chamber and a lower ground proximate fluid cushion device of substantially equal plan form area, collapsible conduit means extending through said intermediate chamber to said fluid cushion device, and fluid pressure generating means arranged in selectively communicating relation with said inflatable chamb r and continuously communicating relation with said fluid cushion through said conduit means.

2. The structure set forth in claim 1 wherein the ground proximate fluid cushion includes a flexible walled annular chamber secured directly to said inflatable chamber in non-communicating relation therewith.

3. The structure set forth in claim 2 wherein said flex ible walled annular chamber is formed with at least one downwardly facing opening located within an imaginary perimeter defined by the lowermost surface of said chamber.

4. The structure set forth in claim 1 wherein said intermediate inflatable flexible wall chamber is formed by a horizontal base portion and an upturned periphery of flexible material hermetically attached to said load sup porting wall.

5. The structure set forth in claim 4 wherein said horizontal base portion is substantially rigid.

6. The structure set forth in claim 4 wherein said hori zontal base portion is formed of flexible material and includes means for restraining the central portion thereof in predetermined spaced relation beneath said platform.

7. The structure set forth in claim 6 wherein said restraining means comprises a perforate web portion integral with said base portion.

8. As an article of manufacture, a first member of thin flexible material having a relatively flat lower wall portion and an upturned perimeter, a supporting web of flexible material secured centrally on the upper surface of said flat wall, a second member of thin flexible material having an upturned perimeter and a lower Wall portion upwardly deformed at its center, said perimeter and upwardly deformed center being hermetically attached on the lower surface of said first member, collapsible conduit means secured to said flat lower wall and providing communication with the space defined between said lower wall and said second member, and means forming openings in the upwardly deformed portion of said lower member.

References Cited by the Examiner UNITED STATES PATENTS 3,095,987 7/1963 Sable Z64-93 3,119,598 1/1964 Petersen et a1. -7

FOREIGN PATENTS 1,278,912 11/1961 France.

BENJAMIN HERSH, Primary Examiner.

M. S. SALES, Assistant Examiner.

Claims (1)

1. A TWO-STAGE FLUID PRESSURE ENERGIZED BEARING ASSEMBLY COMPRISING, IN COMBINATION, AN UPPER LOAD SUPPORTING WALL, AN INTERMEDIATE INFLATABLE FLEXIBLE WALLED CHAMBER AND A LOWER GROUND PROXIMATE FLUID CUSHION DEVICE OF SUBSTANTIALLY EQUAL PLAN FORM AREA, COLLAPSIBLE CONDUIT MEANS EXTENDING THROUGH SAID INTERMEDIATE CHAMBER TO SAID FLUID CUSHION DEVICE, AND FLUID PRESSURE GENERATING MEANS ARRANGED IN SELECTIVELY COMMUNICATING RELATION WITH SAID INFLATABLE CHAMBER AND CONTINUOUSLY COMMUNICATING RELATION WITH SAID FLUID CUSHION THROUGH SAID CONDUIT MEANS.

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