Abstract:
An apparatus and method for removing air from a tube to improve the impregnation of the tube with a curable resin or other viscous fluid used in cured-in-place pipe rehabilitation. Also, a perforated needle for use in vacuum impregnation and a method of evacuating air from a flexible tube, particularly a lining tube used for rehabilitation of underground conduits.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an apparatus and method for removing air from a tube to improve the impregnation of the tube with a curable resin or other viscous fluid used in cured-in-place pipe rehabilitation. The invention is further directed to a perforated hollow needle for use in vacuum impregnation. In a particular embodiment, the invention is directed to a method of evacuating air from a flexible, hollow tube, particularly a lining tube used for rehabilitation of underground conduits. 
     2. Description Of The Related Art 
     The present invention constitutes an improvement over prior methods and apparatus for removing air from a tube to improve the impregnation of the tube with a resin or other viscous fluid used in cured-in-place pipe rehabilitation. 
     Prior methods and apparatus used single and multiple cups to draw a vacuum through a window or slit cut in the tube. Other methods and apparatus involved the use of needles thereby eliminating the need for pre-cutting the tube by creating the opening upon insertion of the needle. Such prior needles had a single opening in the end through which air was drawn. 
     These prior systems were limited in the manner in which one could use them to withdraw air from tubes. For example, these prior systems did not provide a simple way to select the location or locations within the tube for the withdrawal of air from the tube. Further, these prior systems did not provide a way to adjust the rate or intensity of withdrawal of air from a particular portion of the tube. The present invention may overcome one or more of any shortcomings that may be present in the prior systems. 
     SUMMARY OF THE INVENTION 
     The present invention is directed generally to an apparatus and method for vacuum impregnation of a flexible, hollow tube. The apparatus includes a device for removing air from a tube, comprising a hollow tubular member having sidewalls defining an inner chamber and at least one aperture in the sidewalls to provide for the passage of air to the inner chamber through the aperture. The apparatus may additionally comprise a vacuum source, operably connected to the hollow tubular member to draw air through the aperture. 
     In another aspect, the invention is directed to a method for removing air from a flexible, hollow tube. The method broadly comprises inserting a suction apparatus into a tube, the suction apparatus comprising a needle having a sidewall with at least one aperture in the sidewall, and drawing air from the tube. The method may additionally include varying at least one location along the tubular member through which air may be drawn. 
     Advantageously, a specific embodiment of the invention provides for evacuation of a localized portion of the liner layers of the tube being impregnated with fluid. Accordingly, one may select and/or determine before or after placing the device within the tube being impregnated which portion or portions of the liner layers of the tube being impregnated will be evacuated. However, one may select such portion or portions while the device is in place, thus enabling one to provide a more localized and concentrated vacuum. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings, briefly described below, show various specific embodiments of the invention. 
     FIG. 1 is a perspective view of a vacuum impregnation device. 
     FIG. 2 is a partial, cross-section view of an outer tubular member and an inner tubular member of a specific embodiment of the present invention. 
     FIG. 3 is a perspective view of a hollow tubular member of the present invention. 
     FIG. 4 is a perspective view of a vacuum impregnation device, showing an alternative embodiment of the present invention. 
     FIG. 5 is a perspective view of a vacuum impregnation device, showing another alternative embodiment of the present invention. 
     FIG. 6 is a perspective view of a vacuum impregnation device, showing yet another alternative embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In a broad aspect, the present invention is directed to an improved method and apparatus for removing air from a tube. The method may be carded out in connection with the apparatus, and/or the method may be carded out in connection with other apparatus. Likewise, the apparatus may be utilized in connection with the method or the apparatus may be utilized in connection with other methods. Various embodiments and aspects of the apparatus are shown in FIGS. 1-6, where like reference numerals refer to like parts. 
     The method of this invention includes the step of inserting a suction apparatus into a tube, the suction apparatus comprising a needle having a sidewall with at least one aperture in the sidewall. The aperture may be any type of opening, including a perforation, window, slit, slot, hole, or any means by which air can be withdrawn from the tube. It should also be noted that the term &#34;needle&#34; as used herein refers to a generally elongated member having a chamber through which air may be withdrawn. Accordingly, the needle may be any size, shape or configuration, and is defined similar to the term tubular member, as defined elsewhere in this specification. 
     A specific embodiment of the method may include the step of depositing fluid, preferably a curable resin, within the tube and providing a force to the fluid, thereby causing the fluid to be deposited within the tube. The force may be applied directly to the fluid such as by means of a piston or plate directly in contact with the fluid, indirectly by elevating the fluid such that a gravitational force will act upon the fluid, by providing rolling means to the tube, or by any other means or combination of means which would cause the fluid to flow through the tube. It should be noted that the fluid can be any viscous substance capable of impregnating the body of the tube. 
     A specific embodiment of the method may include the step of selecting a location along the needle for withdrawing air from the tube. This selection may further comprise the step of moving an inner tubular member having an inner aperture within an outer tubular member having an outer aperture whereby the inner and outer apertures are substantially aligned. Advantageously, the aligned apertures may comprise a location for withdrawing air from a tube. 
     The apparatus in a broad aspect includes a vacuum device for removing air from a tube, comprising a hollow tubular member having sidewalls defining an inner chamber and at least one aperture in the sidewalls to provide for the passage of air to the inner chamber through the aperture. In a specific embodiment, the apparatus may include a vacuum source, operably connected to the hollow tubular member to draw air through the aperture. 
     In another embodiment, the hollow tubular member may have at least one aperture, preferably on a sidewall of the tubular member, whereby the position of the aperture within a tube can be placed or selected in such a way that air may be removed from a particular portion of the tube. 
     In yet another embodiment of the invention, the hollow tubular member may be an outer tubular member having at least one outer aperture, the vacuum device further comprising an inner tubular member having a sidewall with at least one inner aperture. The inner tubular member may be disposed for movement within the outer tubular member. The inner tubular member may also be slidable and/or rotatable with respect to the outer tubular member. In still another embodiment of the invention, at least one inner aperture may be substantially aligned with at least one outer aperture and the tubular member may be open-ended, closed-ended, and/or pointed. 
     Referring now to the drawings, in FIG. 1, a specific embodiment of the invention includes a vacuum device or suction apparatus 10 which has a hollow tubular member 12, having a pointed tapered tip 14 and at least one aperture 16 in the sidewall of member 12. It should be apparent to one of ordinary skill in the art, that any type of hollow tubular member may be utilized in the vacuum impregnation device. It should be noted that the hollow tubular member may be one-piece in design or may be constructed of any number of pieces, members or segments. Further, the hollow tubular member need not be cylindrical and other tubular shapes may be utilized. For example, the hollow tubular member may be octagonal or ellipsoidal in cross-section and various cross-sections along the length of the member may have different shapes. Further, &#34;vacuum&#34; is defined herein as any pressure less than the pressure of the atmosphere surrounding the exterior surface of the tube. Thus, for example, creating a vacuum, meaning providing a sub-atmospheric pressure, is different than drawing a vacuum, which refers to the removal of air, which may result in either creating or maintaining a vacuum 
     An embodiment of the invention includes multiple apertures 16 arranged at different lengthwise positions on member 12. However, as shown in FIG. 3, a single aperture 16 may also be utilized. Further, referring to FIG. 2, it should be noted that any shape or configuration of aperture 16, 20 may be utilized and the apertures in a particular embodiment may have more than one shape. For example, as shown in FIGS. 4 and 5, the aperture may be a slot 22 in either the inner tubular member 18 or the outer tubular member 13. Further, the shapes and sizes of the apertures 20 may be selected which in turn may provide for a desired level of concentration and localization of the vacuum within an absorbent layer of a lining tube, depending on the thickness, composition, density and/or number of layers making up a lining tube. 
     In a specific embodiment of the invention, the hollow tubular member 12 includes multiple aperture 16 arranged at different points lengthwise and circumferentially. For example, the apertures 16 may be arranged as shown in FIG. 1. In a specific embodiment, the vacuum impregnation device includes an inner tubular member 18 with inner apertures 20, and an outer tubular member 13 with outer apertures 16. However, as shown in FIG. 3, the vacuum device 10 may also include a single hollow tubular member 12 with either an open end 14 or a closed end 14. 
     In the embodiments shown in FIGS. 1, 2, 4, 5, and 6, the inner tubular member 18 is aligned with the outer tubular member 12 such that only one of the apertures 20 in the inner tubular member 18 is aligned with one of the apertures 16 of the outer tubular member 13 at a given time. However, in another embodiment, the alignment may be such that more than one set of apertures may be in alignment so that multiple points of evacuation may be provided. 
     The inner tubular member 18 is preferably disposed for rotatable movement within the outer tubular member 13, being rotatable by mining the upper portion 22 of the inner tubular member 18. However, in another embodiment, as shown in FIG. 6, the inner tubular member 18 may also be disposed for slidable movement within the outer tubular member 13. 
     As shown in FIGS. 1, 2, 4, and 5, in a specific embodiment one may select which set of apertures 16, 20 will draw air from the tube by rotating the inner tubular member 18 so that at least one inner aperture 20 and at least one outer aperture 16 are aligned. Such ability to select which apertures are open enables one to determine the point or points at which air may be drawn, thereby localizing the point and/or points at which air may be drawn and/or concentrating the vacuum pressure at such point or points. It should be noted that the tube may be constructed of any number of materials, including, but not limited to, a liner having single or multiple layers of felt. Air may be drawn from within the chamber of the tube. Further, in the embodiment having a permeable liner made of felt, the air may also be drawn from the interstices or pores of the felt. Similarly, when other materials are used, air may also be drawn from the interstices or pores of such material. Therefore, precise control of the location from which air may be drawn may be important. 
     In a preferred embodiment of the invention, the vacuum impregnation device 10 may be used in drawing a vacuum from a multi-layered liner, preferably a liner used in the repair or rehabilitation of conduits such as sewer pipes. Many of these liners have one or more absorbent layers, particularly felt, which may be impregnated by a viscous fluid such as curable resin. In order to create a vacuum, or otherwise to evacuate a localized portion of one or more of the liner layers, a specific embodiment of the invention, shown in FIGS. 1, 2, 4, and 5, may be utilized by rotating the inner tubular member 18 to align apertures 16, 20 at selected distances from the tip of the needle, thus localizing the point and/or points at which air may be drawn and/or concentrating the vacuum pressure at such point or points. 
     It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials or embodiments shown and described, as obvious modifications and equivalents will be apparent to one skilled in the art. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.