Air shaft

Abstract

The present invention is to provide an air shaft comprising a hollow cylinder and a plurality of curved members provided on an outer surface of the hollow cylinder and between both ends thereof, wherein the curved members are adapted to move radially relative to the hollow cylinder and are spaced each other with a gap formed between any two adjacent ones of the curved members. As such, no continuous straight gaps are formed on an outer surface of the hollow cylinder while pushing the curved members. By utilizing the present invention, a web material can be wound on the air shaft directly without the need of mounting a roll on an outer surface of the air shaft, thereby eliminating the drawbacks of the prior art air shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a conventional air shaft prior to inflation;

FIG. 2 is a view similar to FIG. 1 where the air shaft has been inflated;

FIG. 3 is a cross-sectional view of an air shaft according to the invention prior to inflation;

FIG. 4 is a view similar to FIG. 3 where the air shaft has been inflated;

FIG. 5 is a perspective view of the air shaft of FIG. 3 prior to inflation; and

FIG. 6 is a view similar to FIG. 5 where the air shaft has been inflated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 3 and 4, an air shaft in accordance with the invention comprises a hollow cylinder 2, an inflatable airtight bladder 3 in the hollow cylinder 2, a plurality of movable members 4 provided externally of the bladder 3, each movable member 4 having a portion radially passed through the hollow cylinder 2, and a plurality of curved members 5 provided on an outer surface of the hollow cylinder 2 and between both ends thereof. The portion of the movable member 4 radially passed through the hollow cylinder 2 is secured to an outer surface of the curved member 5.

Referring to FIGS. 5 and 6 in conjunction with FIGS. 3 and 4, a plurality of spaced first projections 50 are formed on one sides of the curved members 5. The first projections 50 are disposed axially and overlay the hollow cylinder 2. The curved member 5 further comprises a first slot 52 between any two adjacent first projections 50. A plurality of second slots 56 are formed on the other sides of the curved members 5 lining up with the first projections 50. The second slots 56 are disposed axially and overlay the hollow cylinder 2. A plurality of spaced second projections 54 are formed on the other sides of the curved members 5 lining up with the first slots 52. The second projections 54 are disposed axially and overlay the hollow cylinder 2. Thus, the first projections 50 are adapted to snugly fit into the second slots 56. Also, the second projections 54 are adapted to snugly fit into the first slots 52. That is, the curved members 5 are spaced with a gap formed between two adjacent curved members 5. Prior to inflating the bladder 3, for the curved members 5 tops of the first and second projections 50 and 54 are about flush with tops of the first and second slots 52 and 56 (see FIG. 5). The curved members 5 are pushed outwardly by the movable members 4 after inflating the bladder 3. As an end, tops of the first and second projections 50 and 54 are about flush with tops of the first and second slots 52 and 56.

In view of the above, it is clear that no continuous gaps are formed on an outer surface of the air shaft. Thus, a web material is adapted to wind on the air shaft after inflating the bladder 3. Also, portions of the material will not be pinched by gaps as contrary to that experienced by the prior art outer plates 13. Further, the material will not be pinched by the curved members 5 while deflating the bladder 3 of the air shaft. This eliminates the need of mounting a roll on the outer surface of the air shaft prior to winding the material. As a result, the prior art drawbacks are eliminated. In one embodiment of the invention, each of the movable members 4 comprises a curved inner plate 40 and a sliding member 42 extending outwardly radially from the inner plate 40. The inner plates 40 are provided between two ends of the bladder 3. Each of the inner plates 40 is spaced from a corresponding curved member 5 and lines up therewith radially. One end of the sliding member 42 is formed with the inner plate 40 facing an inner surface of the hollow cylinder 2 and the other end thereof extends through the hollow cylinder 2 to secure to the corresponding curved member 5. A circumferential gap is formed between the inner plates 40 and the hollow cylinder 2 and the curved members 5 overlay the outer surface of the hollow cylinder 2 prior to inflating the bladder 3. In comparison, the inner plates 40 are pushed radially toward a position proximate the inner surface of the hollow cylinder 2 with a circumferential gap formed between the hollow cylinder 2 and the curved members 5 in response to inflating the bladder 3.

In another embodiment of the invention, each of the movable members 4 comprises a curved inner plate 40 and a sliding member 42 extending outwardly radially from the inner plate 40. The inner plates 40 are provided airtight in the bladder 3 and between two ends thereof. Each of the inner plates 40 is spaced from a corresponding curved member 5 and lines up therewith radially. One end of the sliding member 42 is formed airtight in the inner plate 40 facing an inner surface of the bladder 3 and the other end thereof extends through the bladder 3 and the hollow cylinder 2 to secure to the corresponding curved member 5. A circumferential gap is formed between the inner plates 40 and an inner surface of the hollow cylinder 2 and the curved members 5 overlay the outer surface of the hollow cylinder 2 prior to inflating the bladder 3. In comparison, the inner plates 40 are pushed radially toward a position proximate the inner surface of the hollow cylinder 2 with a circumferential gap formed between the hollow cylinder 2 and the curved members 5 in response to inflating the bladder 3.

In view of the above, the first projections 50 are adapted to snugly fit into the second slots 56. Also, the second projections 54 are adapted to snugly fit into the first slots 52. That is, no continuous straight gaps are formed by the curved members 5 prior to pushing the curved members 5. Thus, portions of the material will not be pinched by gaps in the winding process of the material. Also, the material will not be pinched by the curved members 5 while deflating the bladder 3 in the unwinding process of the material. As a result, the prior art drawbacks are eliminated.

While the invention herein disclosed has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.

Claims

1. An air shaft comprising: a hollow cylinder;an inflatable airtight bladder in the hollow cylinder;a plurality of movable members provided externally of the bladder, each of the movable members having a portion radially passed through the hollow cylinder; anda plurality of curved members provided on an outer surface of the hollow cylinder and between both ends thereof, the portion of the movable member radially passed through the hollow cylinder being secured to an outer surface of the curved member; whereineach of the curved members comprises a first projections formed on one side, the first projections being disposed axially and overlaid the hollow cylinder, a first slot between any two adjacent ones of the first projections, a second slot formed on the other side and lined up with the first projection, the second slot being disposed axially and overlaid the hollow cylinder, and a second projection formed on the other side and lined up with the first slots, the second projection being disposed axially and overlaid the hollow cylinder;the first projections are adapted to fit into the second slots, and the second projections are adapted to fit into the first slots; andprior to inflating the bladder, tops of the first and second projections are substantially flush with tops of the first and second slots, and the curved members are pushed outwardly by the movable members after inflating the bladder such that the tops of the first and second projections are substantially flush with the tops of the first and second slots.

2. The air shaft of claim 1, wherein each of the movable members comprises: a curved inner plate provided between two ends of the bladder, the inner plates being spaced from a corresponding one of the curved members and lined up therewith radially, a circumferential gap being formed between the inner plates and the hollow cylinder prior to inflating the bladder, and the inner plates being pushed radially toward a position proximate an inner surface of the hollow cylinder in response to inflating the bladder; anda sliding member extended outwardly radially from the inner plate and having one end formed with the inner plate facing the inner surface of the hollow cylinder and the other end extended through the hollow cylinder to secure to the corresponding curved member, the inner plates being pushed radially toward a position proximate the inner surface of the hollow cylinder in response to inflating the bladder, and the curved members being brought inwardly toward the hollow cylinder by the sliding members in response to deflating the bladder.

3. The air shaft of claim 1, wherein each of the movable members comprises: a curved inner plate provided airtight in the bladder and between two ends thereof, the inner plates being spaced from a corresponding one of the curved members and lined up therewith radially, a circumferential gap being formed between the inner plates and the inner surface of the hollow cylinder prior to inflating the bladder, and the inner plates being pushed radially toward a position proximate the inner surface of the hollow cylinder in response to inflating the bladder; anda sliding member extended outwardly radially from the inner plate and having one end formed airtight in the inner plate facing an inner surface of the bladder and the other end extended through the bladder and the hollow cylinder to secure to the corresponding curved member.