TITLE OF THE INVENTION REGULATED AIRFLOW FABRIC FOR AN AIR GRAVITY CONVEYOR BACKGROUND OF THE INVENTION 1. Field of the Invention: The present invention relates to airflow fabrics that are used in air gravity conveyors ; in particular, the present invention relates to an improved weaving pattern for an airflow fabric.
2. Discussion of Background : Air gravity conveyors are useful in conveying granulated and powdered materials, such as concrete, flour, alumina, barite, and many other dry powders. A typical air gravity conveyor is illustrated in Fig. 1. The air gravity conveyor 200 comprises a hopper 204 that feeds the powdered material 202 onto an airflow fabric, which is enclosed within a chute 208. The airflow fabric separates the upper and lower plenum 210 and 212 of the chute 208 and extends the entire length of the chute 208. Pressurized air is introduced into the lower plenum through the air inlet 206, which is forced through the airflow fabric and flows into the upper plenum 210. Due to an incline of the airflow fabric in conjunction with the air flow, the powdered material 202 flows down the airflow fabric. The rate at which the powdered material 202 is conveyed can be regulated by the porosity and incline of the airflow fabric.
Airflow fabric is constructed using various weaving patterns, depending upon the desired porosity. Prior art weaving patterns showing a high, medium and low porosity are illustrated in Figs. 2,3, and 4, respectively. These weaving patterns have common characteristics: a plurality of filler yarn layers that are woven together by at least two binder yarns. With reference to the high porosity fabric illustrated in Fig. 2, a plurality of filler yarns 302 runs longitudinally the length of the fabric 300 and are held together by a pair of warp yarns 304, which are woven around the filler yam 302 in a sinusoidal manner. The warp yarns 304 weave in opposite directions around the filler yarns 302, much like a two sinusoidal functions that are 180° out of phase. Three layers of the filler yarns 302, with surrounding warp yarn 304, are woven together using binder yarn 306. The binder yarn 306 is woven in the same manner as the warp yarn 304, much like a pair of sinusoidal functions that are 180° out of phase. As can be seen in Figs. 2 and 3, decreasing the porosity of the fabric 300 dramatically increases the number of filler yarns 302 and corresponding warp yarns 304. The weight of the resulting fabric substantially increases, while the fabric becomes less flexible. Unfortunately, the weaving patterns that are
currently employed within the art require a relatively large amount of yarn, which increases manufacturing time and the weight of the resulting fabric.
Therefore, there is a need for a weaving pattern for airflow fabrics that reduces the amount of yarn that is used, but can maintain a tight weave with low porosity.
SUMMARY OF THE INVENTION According to its major aspects and broadly stated, the present invention is an improved weaving pattern for airflow fabric. The pattern uses gut construction positioned between a pair of filler yarn layers. Each filler yarn layer is bound using a pair of warp yarns that weave in opposite directions, much like a pair of sinusoidal functions that are 180° out of phase. With the high and medium porosity fabric, only a single binder yarn surrounds the layers of filler yarn. In low porosity, a pair of binder yarns are used, but the yarns are woven more like sinusoidal functions that are 90° out of phase.
A major feature of the present invention is the weaving pattern, which uses a unique binder arrangement and gut construction. Instead of using a pair of binder yarns, the present invention uses of a single binder yarn to secure the filler yarn. With the use of gut construction, the fabric reduces the layers of filler yarn needed. As a result, the total amount of yarn needed for the fabric is reduced.
A major advantage of the present invention is the use of less yarn to manufacture the fabric. As a result, the manufacturing time to produce the fabric is also reduced. With fewer filler yarns, the fabric can be produce much more quickly and inexpensively.
Other features and advantages of the present invention will be apparent to those skilled in the art from a careful reading of the Detailed Description of a Preferred Embodiment presented below and accompanied by the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, Fig. 1 is a side view of a prior art air gravity conveyor with using an airflow fabric; Fig. 2 is a side cross-sectional view of a high porosity prior art airflow fabric; Fig. 3 is a side cross-sectional view of a medium porosity prior art airflow fabric; Fig. 4 is a side cross-sectional view of a low porosity prior art airflow fabric; Fig. 5 is a side cross-sectional view of a high porosity airflow fabric, according to a preferred embodiment of the present invention; Fig. 6 is a side cross-sectional view of a medium porosity airflow fabric, according to a preferred embodiment of the present invention; and Fig. 7 is a side cross-sectional view of a low porosity airflow fabric, according to a
preferred embodiment of the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the figures, the present invention is an improved weaving pattern for airflow fabric. The weaving patterns showing a high, medium and low porosity are illustrated in Figs. 5, 6, and 7, respectively. For clarity, the fabric is illustrated with the yarns positioned in a spaced-apart manner. It is clear that the yarn will be preferably woven to a tightness that is common in the industry. Although the patterns differ in porosity, each uses gut positioned between at least one pair of filler yarn layers. The binder yarn position in each pattern also differs from the prior art. With the high and medium porosity fabric, only a single binder yarn surrounds the layers of filler yarn. In low porosity, a pair of binder yarns are used, but the yarns are woven more like sinusoidal functions that are 90° out of phase. In order to decrease porosity, additional layers of gut construction are added. Gut construction refers to a mesh that extends longitudinally the length of the fabric.
Referring to Fig. 5, a fabric with high porosity construction is illustrated. A plurality of filler yarns 30 run longitudinally the length of the fabric 10 and are held together by a pair of warp yarns 40, which are woven around filler yarn 30 in a sinusoidal manner. Warp yarns 40 weave in opposite directions around filler yarns 30, much like a pair of sinusoidal functions that are 180° out of phase. Gut construction 20 is positioned between the two layers of filler yarn 30. A single binder yarn 50 is woven around the layers of filler yarn 30 in a sinusoidal manner, such that the binder yarn is wrapped around each filler yarn 30.
Referring to Fig. 6, a fabric with medium porosity construction is illustrated. Again, a plurality of filler yarns 30 run longitudinally the length of the fabric 10 and are held together by a pair of warp yarns 40, which are woven around filler yarn 30 in a sinusoidal manner like a pair of sinusoidal functions that are 180° out of phase. Gut construction 20 is positioned between the two layers of filler yarn 30. In order to decrease porosity, the gut construction 20 is increased in thickness. Again, single binder yarn 50 is woven around the layers of filler yarn 30 in a sinusoidal manner, such that the binder yarn is wrapped around each filler yarn 30. As can be seen by a comparison with Fig. 3, the present invention uses much less yarn to create the desired air flow characteristics.
Referring to Fig. 7, a fabric with low porosity construction is illustrated. Again, a plurality of filler yarns 30 run longitudinally the length of the fabric 10 and are held together by a pair of warp yarns 40, which are woven around filler yarn 30 in a sinusoidal manner like a pair of sinusoidal functions that are 180° out of phase. Two layers of gut
construction 20 are positioned between the three layers of filler yarn 30. In order to decrease porosity, the gut construction 20 is increased in thickness. A first binder yarn 50 and second binder yarn 52 are woven around the layers of filler yarn 30 in a sinusoidal manner, such that the pair of binder yarns 50 and 52 are woven like a pair of sinusoidal functions that are 90° out of phase with each other.
It will be apparent to those skilled in the art that many changes and substitutions can be made to the preferred embodiment herein described without departing from the spirit and scope of the present invention.
