Patent Publication Number: US-7584939-B2

Title: Surge flushing device for wastewater channels and the like

Description:
CLAIM OF PRIORITY 
   Applicants hereby claim the priority benefits under the provisions of 35 U.S.C. § 119, basing said claim of priority on European Patent Application Serial No. 04 029 029.8, filed Dec. 8, 2004. In accordance with the provisions of 35 U.S.C. § 119 and Rule 55(b), a certified copy of the above-listed European patent application will be filed before grant of a patent. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to a flushing device for a channel, and especially to a surge flushing device for a wastewater channel with a flushing blade that can be moved essentially perpendicular to the flow direction of the liquid in the channel, between a lowered position, in which the flushing blade contacts an arc-shaped wall area of the channel wall and related channel cross section, and a raised position, in which the flushing blade releases or opens at least one part of the channel cross section. 
   A surge flushing device for a wastewater channel of the type described above is known from EP 1 219 753 A2. In it, a flushing blade is used that can swivel, is mounted so that it is sealed with respect to the channel wall, is automatically controlled, and is designed with a plate shape. In a mostly empty channel, even with low wastewater flow, this creates banking and allows it to proceed as a flushing surge. The flushing blade is guided to and in the channel by a lever mechanism. A closure is provided that holds the flushing blade in the lowered position and that is unlocked by a mechanism controlled from the head water to release the flushing blade. 
   A surge flushing device for a wastewater channel of the type described above is also known from EP 1 475 484 A2. In that case, a further development of the surge flushing device according to the EP 1 219 753 A2 document is described. It is distinguished in that a lift element works together with the lever arms of a parallel lever, connected in force and movement, for actuating the flushing flap/flushing blade. In the flushing operation, the flushing flap is driven out over the water level in the channel by the lift element. Because of this, the skimming wall effect on the flushing flap is eliminated, and the floating substances that are carried along on the water surface in the wastewater flow can pass the flushing flap unimpeded. 
   SUMMARY OF THE INVENTION 
   The present invention contemplates providing a flushing blade or flushing flap that is formed in such a way that sealing is caused with respect to the channel base and to the lateral channel walls. In this case, an absolute seal is not absolutely necessary. It is adequate if the gasket is designed in such a way that a defined backwater occurs in front of the flushing flap as a result of the inflow. It is also conceivable to provide the waterway of the channel in the area of the flushing flap with a stop for the gasket, against which the flushing flap contacts and/or which acts as a seal along its contour in the lowered position. 
   Another objective of the invention is to further develop a flushing device of the type described above in such a way that a sealed closure between the flushing blade and the channel wall is ensured in all backwater operating positions or conditions of the banking blade, especially with a high banking of liquid in the channel. 
   Yet another objective of the invention is a flushing device of the type described above, wherein the flushing blade has an elastic gasket in its area that comes in contact with the channel wall, whereby the gasket has a base section held in a flushing blade element of the flushing blade and a lip section located outside the flushing blade element to contact the channel wall, whereby the lip section is pointed opposite the flow direction of the liquid, starting from the base section. 
   In regards to the present invention, the designated channel wall is understood not only as the sidewall area of the channel wall, but also the floor area of the channel wall. 
   The flushing device according to the present invention ensures a high degree of sealing between the flushing blade and channel wall. This is the basic prerequisite for banking adequate liquid in the channel in front of the flushing blade to initiate the subsequent flushing process, especially the surge flushing process. The latter requires a fast raising of the flushing blade and thus a sudden release of the water quantities that are banked or collected in front of the flushing blade. The water quantities held back by the flushing blade cause a considerable force to act on the flushing blade. This necessarily has the consequence that the position of the flushing blade changes slightly relative to the channel wall when the flushing blade is actually positioned in the floor area of the channel walls, but is slightly pushed by the liquid masses in its upper end area. It is equally conceivable that the flushing blade is shifted or moved slightly away from the channel wall to the floor area. However, this must not lead to the formation of a gap or slot between the flushing blade and the channel wall, especially a slot that increases continuously as a function of the water pressure. This would result in a situation where the liquid would flow out between the flushing blade and channel wall without the desired flushing effect. 
   In view of these factors, the design according to the present invention provides a flushing blade with a gasket in which the lip section contacts the channel wall with a pre-stress that increases with higher pressure in the liquid, such that the lip section is pressed against the channel wall with higher pressure. The pressure acts on the lip section, which extends in a direction opposite the flow direction of the liquid, starting from the base section of the gasket. With the elastic gasket, the base section thus serves as the mounting for the gasket in the flushing blade element, while the lip section takes over the actual sealing function. 
   It is considered especially advantageous if the flushing blade is designed with a plate shape, while in the area of the face side of the flushing blade, it has a holder for the base section. Naturally the flushing blade could also have a shape other than a plate shape, e.g., as a hollow body, in order to utilize the uplift of the flushing blade when the flushing blade is raised. It is important for the present invention that the gasket provided for contact with the channel wall is continuously active in the area of the flushing blade. 
   It is considered especially advantageous if the flushing blade is designed in such a way that it has an arc shape, and especially a semicircular shape, in its area that acts together with the channel wall. The upper end of the flushing blade thus has an essentially horizontal edge that extends downward from the semicircular contour of the flushing blade. As a consequence, a flushing blade designed in this way acts together with a channel that has a cross section with a semicircular shape. 
   In construction, the flushing device is especially designed in such a way that the channel wall that can be brought into active connection with the flushing blade is a component of a metal wall that is formed by a channel insert part, which consists of stainless steel. In this way, the gasket works together with a metal wall area of the channel. Because of this, a smooth surface of the wall part is ensured and thus a favorable prerequisite for a good seal between the flushing plate and channel wall. 
   According to a special embodiment of the invention, it is provided that the sidewall areas of the channel wall that can be brought into active connection with the flushing blade are slightly convergent or tapered to the floor area of the channel walls. The effect achieved here is that the flushing blade is largely lowered into the channel without the gasket of the flushing blade contacting the channel wall. Just before the flushing blade reaches the completely lowered position, it contacts the sidewall areas because the sidewall areas of the channel walls are arranged so that they are slightly convergent or tapered. Because of this feature, the force is significantly reduced during lowering and lifting of the flushing blade, and the elastic gasket is not stressed. The flushing blade performs or exercises its sealing function only shortly before it reaches the completely lowered position and in the completely lowered position of the flushing blade. 
   Since the flushing device according to the present invention depends on precise arrangement of the gasket with respect to the channel wall, it is suggested that the gasket be mounted in the flushing blade element so that it can be adjusted. It is especially understood that an adjusting capability of the gasket exists in a radial direction with an arc-shaped or circular-shaped design of the flushing blade. 
   The gasket is distinguished by a defined Shore hardness, whereby this is especially true for the lip section. It is considered advantageous if the Shore hardness of the gasket is 40 to 70. The sealing lip is provided with a Shore hardness in the named low range if a relatively small diameter of the channel wall has to be closed by the flushing blade. With an average diameter of the channel wall, preferably a Shore hardness of 60 is used, and with a large diameter, a Shore hardness of 70 is used. Apart from this, the Shore hardness of the gasket should be lower with lower water pressure than with higher liquid pressure that has to be managed. 
   According to a special characteristic of the present invention, it is provided that the elastic gasket is designed so that it is straight before installation in the flushing blade element, and the elastic gasket is pulled into a curve during installation on the flushing blade element. In this way, the elastic gasket can be manufactured very easily as a straight, elongate construction element, the gasket cross section of which is formed by the base section and the lip section. The gasket is not deformed to a curve until it is mounted on the flushing blade element and is stronger toward the inside, with higher stiffness, which means that with the lip section, it is pointed more strongly opposite the flow direction of the liquid. 
   The geometric dimensions of the flushing blade with the gasket are to be adapted according to the channel wall. In particular, it is conceived that, in the lowered position of the flushing blade, the sealing lip with its curved outer lip section extends in a direction opposite the flow direction and is pre-stressed relative to its initial straight forward shape. The diameter of the base section of the gasket may be less than the diameter of the channel wall, and the diameter of the lip section may be greater than the diameter of the channel wall. 
   Basically, the gasket could also be designed in such a way that, starting from the base section, it has another lip section extending in the flow direction behind the lip section. This can extend exactly radially or also diagonally, seen in flow direction of the liquid. In this case, the sealing of the gasket would occur not only in the area of the lip section opposite the flow direction of the liquid, but also over the latter lip section(s). However, this is the lip section that extends opposite the flow direction of the liquid. Only this causes the advantageous consequences because of the effect of the water pressure. 
   Further characteristics of the invention are explained in the sub-claims, the description of the figures and the figures themselves, whereby it should be noted that all individual characteristics and all combinations of individual characteristics represent other designs according to the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment will be described in more detail in the following, with reference to the drawings. They show: 
       FIG. 1  shows a cross section through the device, in longitudinal direction of the channel in the lowered position of the flushing blade; 
       FIG. 2  shows a view of the device according to  FIG. 1 , on the head water side, perpendicular to the channel profile, seen in flow direction; 
       FIG. 3  shows a cross section through the device, in longitudinal direction of the channel with the flushing blade released, in suspended state; 
       FIG. 4  shows a view of the device according to  FIG. 3 , on the head water side, perpendicular to the channel profile, seen in flow direction; 
       FIG. 5  shows an illustration of the channel with the channel wall and flushing blade found in the lowered position; 
       FIG. 6  shows a three-dimensional view of the arrangement according to  FIG. 5 , seen diagonally from the top; 
       FIG. 7  shows a cross section through the sealing area between the flushing blade and wall, shown for different positions of the lip section of the gasket; and 
       FIG. 8  shows a cross section through the gasket before the gasket is drawn up into a curve. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   For purposes of description herein, the terms “upper”, “lower”, “right”, “left”, “rear”, “front”, “vertical”, “horizontal” and derivatives thereof shall relate to the invention as oriented in  FIGS. 1 and 2 . However, it is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     FIGS. 1 to 4  show a wastewater channel  1  with a flushing blade assembly  3 , which can also be designated as a flushing flap, guided to and in the channel by lever arms  2  and  2   a  of a parallel lever. The flushing blade assembly  3  is mounted sealed against channel wall  4 . In the lowered position of flushing blade assembly  3 , it is held tight by a closure  5  (not shown in more detail here) so that the incoming wastewater (dry weather inlet) can back up or collect in front of the flushing shield or blade assembly  3 . When a defined back up water level is reached, the flushing blade assembly  3  is actuated from the head water level to release the flushing surge by way of a control mechanism  6  that is not shown in more detail. In front of flushing blade assembly  3 , a lift element  7  is mounted, which is designed, e.g., as two pipe parts lying parallel to each other, whereby the control mechanism operated by the float moves between the pipe parts. 
   The flushing blade assembly  3  is connected by way of the rotary bearings  9  and  9   a  defining a hinge mounting to lever arms  2  and  2   a,  which can be swiveled on the fixed rotary bearings  8  and  8   a.  On the lever arms  2  and  2   a,  the rotary bearings  9   b  and  9   c  are fastened parallel to the rotary bearings  8 ,  8   a  and parallel to the rotary bearings  9 ,  9   a.  On the rotary bearings  9   b  and  9   c,  a vertically oriented operating rod  10  is mounted, which at its lower end holds a float or lift element  7  that is tightly connected to operating rod  10 . However, the lift element  7  can also be designed so that it is elongated toward the top, incorporating operating rod  10  integrally therein to operate directly by way of rotary bearings  9   b,    9   c  with lever arms  2 ,  2   a.    
   In the illustrated embodiment, the rotary bearings  9 ,  9   a,    9   b  and  9   c,  and the rotary bearings  8 ,  8   a,    9   b  and  9   c  form a shifting rhomboidal force parallelogram, or side-by-side, four bar linkages. 
     FIGS. 5 to 8  show the structure of the elastically deformable gasket  11  forming a component of the flushing blade assembly  3  and its mounting on flushing blade element portion  13  of flushing blade assembly  3 , as well as the interaction of gasket  11  and channel wall  4 . 
   The flushing blade element  13 , which consists of metal, has a semicircular base shape with respect to the channel cross section, and a rectangular section is connected at the top on the semicircular section. The cross section of channel wall  4 , as can be seen best in  FIG. 5 , is designed according to a semicircular design with straight sections connected on top. 
   The gasket  11  has a base section  14  ( FIGS. 7 and 8 ) held in the flushing blade element  13  and a lip section  15  protruding radially outwardly of the flushing blade element  13 . The latter is used for abutting, sealing contact with the channel wall  4 . The base section  14  has a thickness that remains uniform along the flow direction  16  of the liquid, and is thus designed in a ring shape. The lip section  15 , which narrows conically or tapers starting from base section 14 , is connected to the base section  14 . For example, the lip section  15  encloses an angle α of about 140 degrees with the base section  14 . The length of the lip section  15  is, e.g.,approximately four times as large as the length of the base section, related to the radial extension of base section  14 . The end of the lip section  15 , which is turned away from the base section  14 , is designed so that it is blunt with a face surface  16  that runs parallel to the face surface  17  of the base section  14  turned toward the flushing blade element  13 , relative to the condition of the gasket  11  before installation on the flushing blade element  13 . By means of an adjusting device  18  that has screws connected with the flushing blade element  13 , and a pressure plate designed so that it is curved according to the edge contour of the flushing blade element  13 , the base section  14  is held in the flushing blade element  13  and can be pointed or oriented radially outwardly in it. 
   In order to make the drawing clear,  FIG. 6  shows the gasket  11  over only a short length to show its contact with the channel wall  4 . The flow direction of the liquid through the channel is indicated by the arrow with reference number  20 . 
     FIG. 7  shows different bending positions of the lip section  15 , and thus the sealing action between gasket  11  and channel wall  4 , whereby two positions of the channel wall  4  are shown. With a distance “y” of the flushing blade element  13  from the channel wall  4 , the lip section  15  is more curved or arcuate with respect to the base section  14 , as shown in position “A”. In this position, the distance “y” is, e.g., 20 millimeters. If the distance between the flushing blade element  13  and the channel wall  4  is greater, e.g., according to the dimension “x”, less curvature occurs between base section  14  and lip section  15 , as shown in position “B”. The distance “x” is, e.g., 35 millimeters. If the lip section  15  does not contact the channel wall  4  at all, the relaxed position of the gasket  11 , as shown in position “C”, occurs, which basically corresponds to the position according to the illustration in  FIG. 8 . 
   It is clear, especially from the illustration in  FIG. 5 , that the illustrated sidewall areas  21  converge or taper outwardly toward the top of channel wall  4 . The consequence of this is that, during lowering of the flushing blade  3 , the gasket  11  does not contact the channel wall  4  at first, but only contacts it shortly before the lowest position is reached. During further lowering of the flushing blade assembly  3  into the completely lowered position, the position of the lip section  15 , as shown as “A”, in  FIG. 7  is assumed. Because of the elasticity of gasket  11 , in this position, it presses with especially high force against channel wall  4  with distance dimension “y”. If the flushing blade  3  is raised slightly, especially as a result of the high liquid pressure that is present, this results in the displacement of the flushing blade  3  into the position “B” shown in  FIG. 7 . Even in this case, a seal between flushing blade  3  and channel wall  4  would be ensured by the gasket  11 , and the relatively high water pressure that acts in flow direction  20  presses the lip section  15  against the channel wall  4  with an additional force. 
   The channel wall  4 , which works together with gasket  11 , is especially designed of stainless steel. The channel section assigned to this channel wall represents a separate channel insert part. 
   In the foregoing description, it will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed herein. Such modifications are to be considered as included in the following claims, unless these claims by their language expressly state otherwise.