IN THE DRAWING
FIG. 1 is an elevation view of a tubular structure according to an embodiment of the present invention;
FIG. 2 is a sectional fragmented view of the structure of FIG. 1 taken along lines 2-2;
FIG. 3 is a perspective view of the sleeve of FIG. 1 with the ends unfinished;
FIG. 4 is a sectional view of the structure of FIG. 1 taken along lines 4-4;
FIG. 5 is a plan view of a portion of the wire knit mesh material forming the outermost layer of the structure of FIG. 1;
FIG. 6 is a plan view of a portion of the coknitted wire mesh and fiber forming the middle layer of the structure of FIG. 1;
FIG. 7 is plan view of a portion of woven wire cloth which may form an innermost layer;
FIG. 7
a is a side elevation view of an intermediate layer after folding over juxtaposed with one another to form a two layer structure of coknitted substantially continuous length fibers and wire; and
FIG. 8 is an elevation perspective view of an apparatus utilized in the process for forming the structure of the embodiment of FIG. 1.
In FIG. 1, sleeve 10 is an elongated tubular structure comprising multiple layers which form for example in this embodiment, a muffler packing for an internal combustion engine exhaust system (not shown). The length of the sleeve 10 is determined by a given implementation so that it corresponds in length to the muffler to which it is to be attached. It fits over a perforated exhaust pipe (not shown) and is concentric with the pipe.
In FIGS. 2 and 4, the sleeve 10 comprises multiple concentric tubular layers 12, 14, 16, 18, 20 and 22 which are concentric with longitudinal axis 24. Layer 12 is the outermost layer and layer 22 is the inner most layer. Layer 12 comprises solely knitted wire mesh. Layer 22 comprises knitted wire mesh or woven wire cloth. FIG. 5 illustrates the outer layer 12′ for example as it appears in a top plan, but flattened view. The outer layer 12 in one embodiment comprises stainless steel wire 26 which is knitted on a conventional knitting machine into a wire mesh 28. The wire 26 is knitted into interlocking loops 30. The wire of layer 12 in this embodiment has a diameter of about 0.006 inches to about 0.020 inches (0.152 mm to 0.5 mm). However, this diameter may differ from these values in other embodiments according to a given implementation. The outer layer 12 forms a semi-rigid tube to contain the intermediate layers and keep the fibers of the intermediate layers from breaking loose from the sleeve.
The innermost layer 22, FIG. 2, appears similar to outer layer 12′ in knitted wire mesh configuration, but is knitted preferably from stainless steel wire having a diameter of about 0.011 inches to about 0.028 inches (0.28 mm to 0.71 mm). This tube, which may be, in one embodiment, endless, except for practical purposes, it is cut into sections. The inner layer 22 is cylindrical and is semi-rigid to support the intermediate layers to be described below. The tubular structure forming the inner layer 22 is knitted on a circular knitting machine. The tubular structure is then pulled through a series of dies (not shown) to reshape and form the outer diameter of the structure. The continuous length of tube is flexible and stored for later use for assembly of the structure forming the sleeve 10, FIG. 1.
In the alternative, the inner layer 22 (and also the outer layer 12, FIG. 2, may be formed from woven wire cloth of the same wire as the knitted wire described above. An example of woven wire cloth is shown in FIG. 7. Here stainless steel wire 32 in this embodiment is woven in interleaved relationship as typical in woven structures. This is different than the knitted mesh configuration of FIG. 5 wherein the wire is formed into loops which are interconnected. In the woven style of FIG. 7, the wires are substantially linear except for the fact that they weave over and under each other alternatively in a rectilinear network of wires as shown. The weave forms substantially square openings between the weaves. Either knitted or woven wires thus may be used for the innermost layer 22. The outmost layer 12 is only knitted wire mesh. The type of weave of the inner layer is not important. However, the outer layer should be knitted wire mesh.
What is important is that the inner layer 22, which is tubular, is formed initially and stored for later use as noted above. This layer is solely wire mesh and no non-metal fibers are used in this layer.
The intermediate tubular layers 14, 16, 18 and 20, FIG. 2, are formed on a separate larger circular knitting machine or a weaving machine (not shown). These layers in this embodiment comprise stainless steel wire, for example, from about 0.003 inches to about 0.011 inches (about 0.076 mm to about 0.28 mm) diameter.
Non-metallic fibers, and preferably basalt fibers, which are non-metallic, are coknitted with the knitted or woven wire to form a composite layer of material comprising knitted or woven wires interlaced with the non-metallic basalt fibers. These fibers are continuous in length and can withstand high temperatures such as at least 500° C. FIG. 6 illustrates woven substantially continuous length stainless steel wire 34 in this embodiment coknitted with substantially continuous length basalt fibers 36. This forms a sheet 38 of coknitted wire mesh and basalt fibers. The basalt fibers are preferably about 5 to about 20 microns in diameter. The fibers are assembled into a roving of about 330 bundle tex (g/1000 meters). The roving is then knitted with the wire to form the sheet 38.
While basalt fibers are used in one embodiment, any non-metallic fibers such as glass, carbon or ceramic and the like as known may be used in alternative embodiments according to a given implementation.
Basalt fibers are made from basalt rocks using a single component raw material in a single stage process. The fibers are formed as continuous fibers and later may be converted in a form for their intended use. A basalt roving is produced by assembling a bundle of strands into a single large strand, which is then wound into a stable, cylindrical package. The basalt fiber yarns are covered with a sizing agent as commercially available to provide sufficient integrity required for further processing. The fibers may also be formed into twisted yarn by twisting the roving. The twist provides additional integrity to the yarn prior to weaving.
The basalt fibers have relatively higher operating temperature, higher Young's modulus and greater chemical resistance as compared to fiberglass. Basalt fibers may replace asbestos and carbon fibers due to the basalt properties in comparison to these other fibers. However, any fiber may be used in the sleeve according to other various embodiments.
For example, the properties of basalt fibers of 9 micron diameter include a break tenacity of 35-40 (cN/tex), a density of 2.65 g/cm3, a linear density of 50 tex and moisture recovery of 1.0% having a sizing agent content of 1-2%. The roving has a linear density of about 330+/−10% tex and a breaking load of about 107 N. Basalt fibers are available from Albarrie Canada Limited, Barrie, Ontario, Canada.
The coknitted basalt fibers and wire mesh are woven as a tubular structure and then flattened to form sheet 38, FIG. 6. In FIG. 7a, the flattened sheet 38 is then folded over at fold 40 to form a two layer structure 42 of two juxtaposed layers of coknitted wire and continuous length basalt fibers.
In FIG. 8, the inner tubular layer 22 and the folded over intermediate layer structure 42, in one embodiment, are fed into the larger mouth of a sheet metal cone 44. The cone wraps the intermediate layer structure about the inner layer 22 as they are fed through the cone. The structure 42 has a width sufficient so that it wraps twice about the inner tubular layer 22. The resulting layered tubular structure 46 exiting the cone 44 is fed into a circular knitting machine 48 via a cylindrical sheet metal guide band 50. The machine 48 pulls the inner tubular structure and the overlying intermediate multiple layers of wire mesh and coknitted fibers through the cone. Machine 48 knits the outer wire mesh layer 12, FIG. 2, at this time over these other inner layers. The outer mesh layer 12 is solely wire with no non-metallic fibers. The resulting tubular structure has any desired length as it is produced as a relatively continuous unlimited length tubular composite layered structure.
The resulting structure of a continuous tubular structure of the inner, outer and intermediate layers are then drawn through a series of dies to reshape and form the final internal and external diameters of the tubular structure. This structure is then cut to length as shown in FIG. 3. In FIG. 3, the frayed ends 52 of the fibers are trimmed as necessary.
It will occur to one of ordinary skill that modifications may be made to the disclosed embodiments. For example, the fibers may be glass or other material that is resistant to high temperature environments. While the intermediate layer is preferably flattened into two overlying layers and then wrapped twice about the inner layer, this is exemplary.
The number of coknitted layers is optional and may comprise any number of layers according to a given implementation and may be fewer or more than the four disclosed layers of the disclosed embodiment. What is important is that the intermediate layer serves as a heat or sound insulation for a given application. Depending on the temperatures or sound intensities involved, more or fewer layers of the coknitted mesh may be used than the disclosed four overlying intermediate layers. The fibers may also comprise cotton, plastic, nylon, polyester or any other elongated strands of filaments wound on a spool for example.
While the application for the sleeve described herein in the disclosed embodiments is for a muffler packing, it will occur to those of ordinary skill that such a sleeve may be used for other applications wherein sound or heat insulation for a tubular member is needed. It is intended that the scope of the invention be defined by the appended claims, the description herein being given by way of illustration and not limitation.
Patent Application
20070261914
