Background Art [2] Generally, invert structures for manholes are bottom structures of manholes to smoothly drain sewage and wastes, drawn into the manholes, without allowing the sewage and waste to be deposited in the manholes, so that odors are prevented from caused.

[3] For example, an invert structure for manholes was proposed in Korean Utility Model Registration NO. 298666, entitled'MANHOLE'. In the conventional invert structure disclosed in NO. 298666, as shown in FIGS. 1 and 2, a bottom 11 of a manhole 10 is inclined downward in a direction toward a drain hole 13 from a plurality of inlets 12 at a predetermined angle. A sewage guide groove 14 having a semicircular cross-section is provided on each of predetermined portions of the bottom 11 of the manhole 10, so that sewages flow along the plurality of sewage guide grooves 14 from the plurality of inlets 12 to the drain hole 13.

[4] To construct the manhole 10 with the conventional invert structure in the ground, an end of a drain pipe 30 is inserted into the drain hole 13, and an end of an inlet pipe 20 is inserted into one of the plurality of inlets 12 which corresponds to a position of the end of the inlet pipe 20. Thus, the inlet pipe 20 and the drain pipe 30 are connected to each other by the manhole 10.

[5] However, in the conventional invert structure for manholes, in case that a position of the end of the inlet pipe 20 is changed, it is very difficult to precisely couple the inlet pipe 20 to the inlet 12 of the conventional invert structure. Furthermore, in case that the position of the end of the inlet pipe 20 dose not correspond to a position of the inlet 12, the conventional invert structure forces a user to interpose an additional connecting unit, such as an elbow and etc. , between the inlet pipe 20 and the inlet 12.

Disclosure of Invention Technical Solution [6] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an invert structure for manholes, which precisely couples an inlet of the invert structure to an inlet pipe, regardless of a position of an end of the inlet pipe.

[7] In order to accomplish the above object, the present invention provides a n invert structure for manholes, which is installed in a manhole having a cylindrical shape of a predetermined diameter to drain sewage. The invert structure includes a bottom plate installed in a lower portion of the manhole, having a drain hole provided on a pre- determined portion of an edge of an upper surface of the bottom plate; a main sewage guide groove extending from the drain hole to a central portion of the upper surface of the bottom plate; and a first guide part provided on a predetermined portion of the upper surface of the bottom plate. The first guide part has a predetermined width and is curved to have an arc shape of a predetermined radius of curvature and a pre- determined central angle. The invert structure further includes a rotating plate having a sectorial appearance and provided on the upper surface of the bottom plate, having at least one subsidiary sewage guide groove having a semicircular cross-section and provided on an upper surface of the rotating plate while extending in a radial direction from a central portion of the rotating plate to a circumferential edge of the rotating plate; and a second guide part provided on a lower surface of the rotating plate to correspond to the first guide part of the bottom plate. The second guide part of the rotating plate engages with the first guide part of the bottom plate so that the second guide part rotates along the first guide part within a predetermined range with both a predetermined radius of curvature and a predetermined rotating angle.

[8] The bottom plate may be removably installed in the manhole.

[9] The upper surface of the bottom plate may be inclined downward in a direction toward the drain hole of the bottom plate.

[10] The invert structure for manholes may further include a pipe coupling unit to allow an outside pipe to communicate with an interior of the manhole. The pipe coupling unit may have a coupling part, with a pipe hole axially provided in the coupling part, a stopper provided on an inner end of the coupling part while being bent outward at the inner end of the coupling part, an angled inserting part integrally provided between the coupling part and the stopper, and a guide piece provided on a predetermined portion of the stopper to guide fluid in a predetermined direction.

Description of Drawings [11] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: [12] FIG. 1 is a perspective view of a conventional invert structure for manholes; [13] FIG. 2 is a sectional view of the conventional invert structure of FIG. 1; [14] FIG. 3 is an exploded perspective view of an invert structure for manholes, according to an embodiment of the present invention; [15] FIG. 4 is a perspective view of the assembled invert structure of FIG. 3; and [16] FIG. 5 is a sectional view showing a manhole in which the invert structure of FIG.

4 is installed.

Best Mode [17] Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.

[18] FIG. 3 is an exploded perspective view of an invert structure for manholes, according to an embodiment of the present invention. FIG. 4 is a perspective view of the assembled invert structure of FIG. 3.

[19] As shown in FIGS. 3 and 4, the invert structure for manholes of the present invention includes a bottom plate 40 which is installed in a lower portion of a manhole 10 having a cylindrical shape of a predetermined diameter. The bottom plate 40 has a drain hole 42 which is provided on a predetermined portion of an edge of an upper surface of the bottom plate 40. The bottom plate 40 further has a main sewage guide groove 41 which has a semicircular cross-section and extends from the drain hole 42 to a central portion of the upper surface of the bottom plate 40. The upper surface of the bottom plate 40 is inclined downward in a drection toward the drain hole 42 of the bottom plate 40, thus easily draining sewage, drawn into the manhole 10, to the outside of the manhole 10.

[20] The bottom plate 40 further has a first guide part 43 which is provided on a pre- determined portion of the upper surface of the bottom plate 40. The first guide part 43 may comprise a first guide projection which has a predetermined width and a pre- determined height and is curved to have an arc shape of a predetermined radius of curvature and a predetermined central angle. Alternatively, the first guide part 43 may comprise a first guide groove which has a predetermined width and a predetermined depth and is curved to have an arc shape of a predetermined radius of curvature and a predetermined central angle.

[21] At this time, the bottom plate 40 may be integrally installed in the lower portion of the manhole 10. Preferably, the bottom plate 40 is removably installed in the lower portion of the typical manhole 10.

[22] The invert structure further includes a rotating plate 50 which has a sectorial appearance and is provided on the upper surface of the bottom plate 40. The rotating plate 50 has a subsidiary sewage guide groove 51 which has a semicircular cross- section and is provided on an upper surface of the rotating plate 50 while extending from a central portion of the rotating plate 50 to a circumferential edge of the rotating plate 50. At this time, one or more subsidiary sewage guide grooves 51 (three subsidiary sewage guide grooves 51 are provided in the drawings, according to the embodiment of the present invention) are provided on the upper surface of the rotating plate 50 in radial directions. Thus, one of the plurality of subsidiary sewage guide grooves 51 corresponds to an inlet pipe 20 of which an end may be placed at various positions.

[23] The rotating plate 50 has a second guide part 53 which is provided on a lower surface of the rotating plate 50 to correspond to the first guide part 43 of the bottom plate 40. In case that the first guide part 43 comprises the first guide projection, the second guide part 53 comprises a second guide groove. Alternatively, in case that the first guide part 43 comprises the first guide groove, the second guide part 53 comprises a second guide projection. In the meantime, a length of the grooved guide part of the first and second guide parts 43 and 53 is longer than the projected guide part of the first and second guide parts 43 and 53. Therefore, the rotating plate 50 rotates on the bottom plate 40 within a range defined by a difference between the lengths of the grooved guide part and the projected guide part.

[24] To couple the inlet pipe 20 to the manhole 10, the invert structure of the present invention further includes a pipe coupling unit 60, a pipe coupling socket 82, and a pipe support unit 70 having thereon an inserting hole 71. The pipe coupling unit 60 has a coupling part 64, with a pipe hole 63 axially provided in the coupling part 64, and a stopper 65 which is provided on an inner end of the coupling part 64 while being bent outward at the inner end of the coupling part 64. The pipe coupling unit 60 further has an inserting part 66 which has an angled shape, such as a square or hexagonal shape, and is integrally provided between the coupling part 64 and the stopper 65 The pipe coupling unit 60 further has a guide piece 61 which is provided on a lower end of the stopper 65 to guide the sewage drawn into the manhole 10.

[25] To provide the manhole 10 with the invert structure of the present invention, in case of the manhole 10 integrally having the invert structure, the manhole 10 is directly installed in a predetermined position of the ground. In case that the invert structure is separated from the manhole 10, the invert structure is installed in the lower portion of the manhole 10, before the manhole 10 is installed in the ground. Thereafter, the bottom plate 40 is adjusted in the manhole 10 such that the drain hole 42, provided on the bottom plate 40, is aligned with an end of a drain pipe 30.

[26] The rotating plate 50, thereafter, rotates on the bottom plate 40 to align one of the plurality of inlets 52 of the second guide part 50 with the end of the inlet pipe 20. At this time, the rotating plate 50 rotates on the bottom plate 40 while the second guide part 53 rotates along the first guide part 43 within the predetermined range with both a predetermined radius of curvature and a predetermined rotating angle. When the selected one of the plurality of inlets 52 is aligned with the position of the end of the inlet pipe 20, the rotation of the rotating plate 50 is stopped.

[27] Thereafter, a through hole 15 is formed on each of positions of an outer surface of the manhole 10 which respectively correspond to the inlet pipe 20 and the drain pipe 30. In the above state, each of the pipe coupling units 60 is inserted into each of the through holes 15 in the manhole 10, so that the coupling part 64 of each of the pipe coupling units 60 is exposed to the outside of the manhole 10 through each of the through holes 15. Thereafter, each of the pipe support units 70 and each of the sockets 80 are coupled to each of the coupling parts 64 which is projected outward from the outer surface of the manhole 10. Each of the inlet pipe 20 and the drain pipe 30 is, thereafter, coupled to each of the sockets 80.

[28] At this time, the plurality of inlets 52 are provided on the circumferential edge of the rotating plate 50 at regular angular intervals. Thus, the rotating plate 50 is rotated on the bottom plate 40 such that one of the plurality of inlets 52 nearest to the end of the inlet pipe 20 is aligned with the inlet pipe 20. Therefore, the selected one of the plurality of inlets 52 is easily coupled to the inlet pipe 20. As such, the invert structure of the present invention can simply align the inlet 52 with the inlet pipe 20 even when the end of the inlet pipe 20 is placed at any position.

[29] In the invert structure of the present invention, the sewage, drawn into the manhole 10 through the inlet pipe 20, is guided into the subsidiary sewage guide groove 51 along the guide piece 61 of the pipe coupling unit 60 which is associated with the inlet pipe 20. Thereafter, the sewage flows along the subsidiary sewage guide groove 51, which is inclined downward from the inlet 52 toward the central portion of the rotating part 50, to the central portion of the bottom plate 40. Thereafter, the sewage, which has reached the central portion of the bottom plate 40, flows along the main sewage guide groove 41 of the bottom plate 40 to the drain hole 42 of the bottom plate 40. The sewage is, thereafter, is drained to the outside of the manhole 10 through the drain pipe 30.

[30] Since the preferred embodiment of the present invention has been disclosed for il- lustrative purposes, the present invention is not limited in the preferred embodiment.

Particularly, a plurality of inlet pipes 20 may be simultaneously coupled to the manhole 10 having the invert structure of the present invention.

[31] Of course, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Industrial Applicability [32] As described above, the present invention provides an invert structure for manholes, which precisely couples an inlet of the invert structure to an inlet pipe, without using any additional coupling unit, such as an elbow and etc. , thus easing in- stallation of the manhole, reducing working time, and smoothly draining sewage drawn into the manhole to the outside of the manhole without allowing the sewage to be deposited in the manhole.