Sludge scraper

Abstract

To provide an inexpensive mud raking device.SOLUTION: A mud raking device comprises: a drive shaft 16; a first pull rod 14a arranged on one end side of the drive shaft 16, a first raking member 12a being coupled; a second pull rod 14b arranged on the other end side of the drive shaft 16, a second raking member 12b for raking mud being coupled thereto; a first link mechanism 15a connected to one end part of the drive shaft 16 thereto; and a second link mechanism 15b connected to the other end part of the drive shaft 16, wherein the drive shaft 16 has a driven sprocket 182, to which rotary drive force of a motor 17 is transmitted, fixed between the one end part and the other end part, and is supported rotatably on its axis by two first bearings 162 provided between the one end part and a transmitted part and two second bearings 162 provided between the other end part and the transmitted part, and also coupled between the two first bearings 162 by a first coupling 163 and between the two second bearings 162 by a second coupling 163.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a sludge scraper that is provided in a sedimentation tank where sludge contained in received suspended solids settles on the bottom of the tank, and scrapes up the sludge that has settled on the bottom of the tank. [Background technology]

[0002] A so-called reciprocating sludge scraper is known, which is equipped with a scraper member that moves back and forth at the bottom of a sedimentation basin, and by repeatedly moving the scraper member in the reciprocating direction, it gradually scrapes up sludge that has settled on the bottom of the basin (see, for example, Patent Document 1). In the sludge scraper of Patent Document 1, a motor installed on the ground is rotated in both directions to move a piston rod up and down, and a roughly triangular angle arm connected to the lower end of the piston rod swings around the swing center axis, causing the pull rod to move linearly in the reciprocating direction. The scraper member attached to the pull rod then moves back and forth repeatedly together with the pull rod, scraping up sludge that has settled on the bottom of the basin.

[0003] Some sedimentation tanks have multiple waterways arranged in parallel. When the sludge collector described in Patent Document 1 is used to collect sludge settled on the bottom of such a sedimentation tank with multiple waterways, a sludge collector is installed for each waterway. This results in a cost equal to the number of waterways multiplied by the price of each sludge collector. Even in a sedimentation tank with only one waterway, multiple sludge collectors may be installed across the width of the tank if the tank is wide. In this case, as with a sedimentation tank with multiple waterways, the number of sludge collectors increases, resulting in a corresponding increase in cost. In response to this problem, attempts have been made to reduce the cost of sludge collectors installed in such a sedimentation tank by extending the central axis of the oscillation in the direction of the tank width and using one motor to move two pull rods in the reciprocating direction, thereby reducing the number of motors. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-180247 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because the swinging shaft rotates in different directions as the pull rod moves forward and backward, an alternating load is applied to the swinging shaft, with the load direction repeatedly fluctuating. Therefore, the long swinging shaft extending between two pull rods spaced apart across the width of the tank must have a significantly thicker shaft diameter to withstand the alternating load, making the shaft expensive. Furthermore, transporting a long, heavy swinging shaft to the sedimentation tank and installing it there is extremely difficult, resulting in high transportation and installation costs. As a result, even if the number of motors can be reduced, other costs increase, ultimately making the sludge collector expensive. On the other hand, splitting the swinging shaft midway and connecting the split sections with a coupling during installation in the sedimentation tank could reduce the transportation and installation costs to the sedimentation tank. However, using a coupling requires an expensive coupling that is resistant to disconnection even when subjected to alternating loads, which still makes the sludge collector expensive.

[0006] SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an inexpensive sludge scraper. [Means for solving the problem]

[0007] The sludge scraper of the present invention, which solves the above-mentioned object, is A sludge scraper is provided in a sedimentation tank where sludge contained in received suspended solids settles on the bottom of the tank, and scrapes up the sludge that has settled on the bottom of the tank, a drive shaft extending in the width direction of the pond; a motor that rotates the drive shaft; a first pull rod connected to a first scraper member disposed on one end of the drive shaft and configured to scrape up sludge settled on the bottom surface of the pond by repeatedly moving in a reciprocating movement direction perpendicular to the pond width direction; A second pull rod is connected to a second scraper member that is disposed on the other end of the drive shaft and scrapes up sludge that has settled on the bottom surface of the pond by repeatedly moving in the reciprocating movement direction; a first conversion device connected to one end portion of the drive shaft and configured to convert rotational motion of the drive shaft in one direction into linear motion in the reciprocating direction of the first pull rod; a second conversion device connected to the other end of the drive shaft and configured to convert the rotational motion of the drive shaft in one direction into linear motion in the reciprocating direction of the second pull rod, The drive shaft has a transmitted part fixed between the one end portion and the other end portion to which the rotational driving force of the motor is transmitted, is supported so as to be freely rotatable around the axis by two first bearings provided between the one end portion and the transmitted part and two second bearings provided between the other end portion and the transmitted part, and is connected between the two first bearings by a first coupling and between the two second bearings by a second coupling. [Effects of the Invention]

[0008] According to the present invention, an inexpensive sludge scraper can be provided. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a plan view of the lower part of a sedimentation tank in which a sludge scraper according to one embodiment of the present invention is installed, viewed from above. FIG. [Figure 2] 2 is a view of the settling tank as seen in the direction of arrow A in FIG. 1. [Figure 3] FIG. 2 is a side view of the sludge scraper shown in FIG. 1. [Figure 4] 1, showing a plan view similar to FIG. 1, showing the lower part of a settling tank in which a sludge scraper according to a second embodiment is installed, as viewed from above. [Figure 5]5 is a view of the settling tank as seen in the direction of arrow B in FIG. 4. [Figure 6] FIG. 5 is a side view of the sludge scraper shown in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of this embodiment, an example will be used in which a sludge scraper of the present invention is installed in a sedimentation basin provided in a sewage treatment facility. The sludge scraper of this embodiment is a so-called reciprocating sludge scraper that scrapes sludge by moving scraper members in a reciprocating direction. The sludge scraper of this embodiment is installed in a sedimentation basin having two water channels, and sludge scraper members arranged in each of the two water channels are moved in a reciprocating direction by a single motor.

[0011] Fig. 1 is a plan view from above of the lower part of a sedimentation tank in which a sludge scraper according to one embodiment of the present invention is installed. Fig. 2 is a view of the sedimentation tank as seen from the direction of arrow A in Fig. 1. For ease of viewing, the up-down direction of Fig. 2 is aligned with the up-down direction of the sedimentation tank.

[0012] The sedimentation tank 9 shown in Figures 1 and 2 is a pond that is approximately rectangular in plan view. Note that Figure 1 omits the downstream portion of the sedimentation tank 9 (the right portion in Figure 1). This sedimentation tank 9 includes a first water channel 9a and a second water channel 9b arranged in parallel within the sedimentation tank 9. The first water channel 9a and the second water channel 9b have approximately the same shape. The first water channel 9a and the second water channel 9b are separated by a partition wall 90. The first water channel 9a and the second water channel 9b each receive sewage, such as wastewater and rainwater, from the conduits on the left side of Figure 1 and discharge it from the right side of Figure 1. This sewage corresponds to an example of suspended solids. The sludge contained in the sewage received by the sedimentation tank 9 settles on the first pond bottom 91a and the second pond bottom 91b shown in Figure 2 as it flows through the first water channel 9a and the second water channel 9b. Hereinafter, the left side in Fig. 1 will be referred to as the upstream side, the right side in Fig. 1 will be referred to as the downstream side, and the left-right direction in Fig. 1 will be referred to as the longitudinal direction of the sedimentation tank 9. Also, hereinafter, the up-down direction in Fig. 1 will be referred to as the tank width direction, and the direction perpendicular to the paper surface in Fig. 1 will be referred to as the up-down direction. The first pond bottom surface 91a and the second pond bottom surface 91b are slightly inclined so that the water depth of the second water channel 9b increases toward the upstream side.

[0013] As shown in Figure 1, a first sludge pit 92a is provided in the upstream portion of the first waterway 9a. Similarly, a second sludge pit 92b is provided in the upstream portion of the second waterway 9b. The sludge collected in the first sludge pit 92a and the second sludge pit 92b is discharged outside the settling basin 9 by a sludge pump (not shown).

[0014] A sludge collector 1 is installed in the sedimentation basin 9. FIG. 1 shows only the submerged lower portion of the sludge collector 1. The sludge collector 1 of this embodiment includes three first guide rails 11a, a plurality of first collector members 12a, three first slide plates 13a (see FIG. 2), a first pull rod 14a, a first link mechanism 15a, three second guide rails 11b, a plurality of second collector members 12b, three second slide plates 13b (see FIG. 2), a second pull rod 14b, a second link mechanism 15b, a drive shaft 16, a motor 17 (see FIG. 2), and a drive force transmission mechanism 18 (see FIG. 2). The first guide rails 11a, the first collector members 12a, the first slide plates 13a, the first pull rod 14a, and the first link mechanism 15a are arranged on the first waterway 9a side. Additionally, second guide rail 11b, second accumulator 12b, second sliding plate 13b, second pull rod 14b, and second link mechanism 15b are disposed on the second waterway 9b side. First guide rail 11a and second guide rail 11b, first accumulator 12a and second accumulator 12b, first sliding plate 13a and second sliding plate 13b, first pull rod 14a and second pull rod 14b, and first link mechanism 15a and second link mechanism 15b are configured in plane symmetry with respect to the center plane of partition wall 90, which is perpendicular to the pond width direction. In the following explanation, only one of these plane-symmetrical components will be explained, and the explanation of the other may be omitted.

[0015] As shown in FIG. 2, the first guide rail 11a, first collector member 12a, first sliding plate 13a, first pull rod 14a, first link mechanism 15a, and drive shaft 16 are positioned so that they are submerged in the sewage received by the first waterway 9a. Note that in FIG. 2, the thicknesses of the first guide rail 11a, second guide rail 11b, first sliding plate 13a, and second sliding plate 13b are exaggerated. In this embodiment, a total of three first guide rails 11a, one at the center of the pond width and one at each end of the pond width, are fixed to the first pond bottom 91a of the first waterway 9a. The first guide rails 11a are made of, for example, ultra-high molecular weight polyethylene. As shown in FIG. 1, the first guide rails 11a extend in the longitudinal direction of the first waterway 9a.

[0016] As shown in FIG. 1, multiple first collector members 12a are arranged at equal or approximately equal intervals along the longitudinal direction of the sedimentation basin 9. Each first collector member 12a extends across the width of the first waterway 9a. Each first collector member 12a is connected to a first pull rod 14a, and as the first pull rod 14a reciprocates in the longitudinal direction, the first collector member 12a reciprocates between the upstream and downstream sides along the first guide rail 11a. Hereinafter, the direction in which the first collector member 12a reciprocates is sometimes referred to as the reciprocating movement direction. This reciprocating movement direction coincides with the longitudinal direction of the sedimentation basin 9. The stroke of the reciprocating movement of the first collector member 12a is set to a distance equal to or greater than the spacing between the first collector members 12a in the reciprocating movement direction. Sludge that has settled on the first pond bottom surface 91a is collected toward the first sludge pit 92a as the first collector member 12a moves upstream. The settled sludge is collected in stages, one stroke at a time, by causing the first collecting member 12a to reciprocate multiple times, and sent to the first sludge pit 92a.

[0017] The first sliding plates 13a connect the multiple first collecting members 12a. Three first sliding plates 13a are provided, one at the center of the pond width direction and one at each end of the pond width direction, and each is in contact with the upper surface of the first guide rail 11a. The first sliding plates 13a are stainless steel plates. The first sliding plates 13a extend over the entire length of the multiple first collecting members 12a in the reciprocating movement direction. Each first sliding plate 13a is fixed to one of the multiple first collecting members 12a. This connects all of the multiple first collecting members 12a. Because each first collecting member 12a is connected by the first sliding plates 13a at the center of the pond width direction and both end portions of the pond width direction, the first collecting members 12a are integrated at the center of the pond width direction and both end portions of the pond width direction, increasing the rigidity of the first collecting members 12a as a whole. This prevents the ends of each first collector member 12a from bending in the direction of their reciprocating movement. If the first collector members 12a were to bend, there is a risk that sludge would remain at the ends of the pond width. When the first collector members 12a move back and forth, the underside of the first sliding plate 13a slides on the first guide rail 11a.

[0018] The first pull rod 14a moves the first collecting member 12a in the reciprocating direction. The first pull rod 14a is positioned in contact with the upper end of the first collecting member 12a at the center of the pond width direction and extends in the reciprocating direction of the first collecting member 12a. The first collecting member 12a and the first sliding plate 13a, positioned in the center of the pond width direction, are fixed to the first pull rod 14a by a fixing mechanism.

[0019] The first link mechanism 15a includes a first drive arm 151a and a first link arm 152a. The first link mechanism 15a is a slider-crank type link mechanism that converts the unidirectional rotational motion of the drive shaft 16 into linear motion in the reciprocating direction of the first pull rod 14a. This first link mechanism 15a corresponds to an example of a first conversion device. In FIG. 1, the first link arm 152a is simplified and indicated by a dashed line. The first drive arm 151a has a plate shape reinforced by ribs. The base end of the first drive arm 151a is fixed to one end of the drive shaft 16 and extends radially from the fixed portion of the drive shaft 16. A shaft is formed at the tip of the first drive arm 151a, parallel to the drive shaft 16 and protruding outward in the pond width direction beyond the drive shaft 16. The upstream end of the first link arm 152a is rotatably attached to the shaft. First link arm 152a is a pipe extending generally in the reciprocating direction. Holes are formed at both ends of first link arm 152a, into which a shaft can be inserted. A shaft formed at the tip of first drive arm 151a is rotatably inserted into the hole at the upstream end of first link arm 152a. A shaft provided at the upstream portion of first pull rod 14a is rotatably inserted into the hole at the downstream end of first link arm 152a.

[0020] The second link mechanism 15b includes a second drive arm 151b and a second link arm 152b. The second link mechanism 15b is a slider-crank type link mechanism that converts the unidirectional rotational motion of the drive shaft 16 into linear motion in the reciprocating direction of the second pull rod 14b. This second link mechanism 15b corresponds to an example of a second conversion device. In FIG. 1, the second link arm 152b is simplified and indicated by a dashed line. The second drive arm 151b has a plate shape reinforced by ribs. The base end of the second drive arm 151b is fixed to the other end of the drive shaft 16 and extends radially from the fixed portion of the drive shaft 16. A shaft is formed at the tip of the second drive arm 151b, parallel to the drive shaft 16 and protruding outward in the pond width direction beyond the drive shaft 16. The upstream end of the second link arm 152b is rotatably attached to this shaft. Second link arm 152b is a pipe extending generally in the reciprocating direction. Holes are formed at both ends of second link arm 152b, into which a shaft can be inserted. A shaft formed at the tip of second drive arm 151b is rotatably inserted into the hole at the upstream end of second link arm 152b. A shaft provided at the upstream portion of second pull rod 14b is rotatably inserted into the hole at the downstream end of second link arm 152b.

[0021] The drive shaft 16 extends in the width direction of the pond. It passes through a through-hole 901 formed in the partition wall 90 and extends from the center of the first waterway 9a in the width direction of the pond to the center of the second waterway 9b in the width direction of the pond. Four bearing pedestals 161 are fixed to the upstream wall of the sedimentation tank 9. The drive shaft 16 is rotatably supported around its axis by bearings 162 provided in each of the bearing pedestals 161. The drive shaft 16 is composed of three shafts connected by two couplings 163. The drive shaft 16 may be composed of a single long shaft. However, if the drive shaft 16 is composed of a single shaft, the transportation and installation costs for the drive shaft 16 to and from the sedimentation tank 9 will be high. For this reason, it is preferable to divide the drive shaft 16 into multiple shafts and connect them with couplings. As described above, the first link mechanism 15a is connected to one end of the drive shaft 16. The other end of the drive shaft 16 is connected to the second link mechanism 15b.

[0022] As shown in Figure 2, motor 17 is installed in the atmosphere on the ground above sedimentation tank 9. This motor 17 rotates drive shaft 16. The rotational driving force of motor 17 is transmitted to drive shaft 16 via drive force transmission mechanism 18.

[0023] The driving force transmission mechanism 18 includes a driving sprocket 181, a driven sprocket 182, and a chain 183. The driving sprocket 181 is fixed to the output shaft of the motor 17. The driven sprocket 182 is fixed to the drive shaft 16 between one end where the first link mechanism 15a is disposed and the other end where the second link mechanism 15b is disposed. The driven sprocket 182 corresponds to an example of a transmitted part. The chain 183 is wound around both the driving sprocket 181 and the driven sprocket 182. In FIG. 2, the chain 183 is indicated by a dashed line.

[0024] Next, the operation of the sludge collector 1 shown in Figure 1 will be described mainly with reference to Figure 3. In this explanation of operation, the operation of the first guide rail 11a, first collector member 12a, first sliding plate 13a, first pull rod 14a, and first link mechanism 15a, which is performed by the drive shaft 16, motor 17, and drive force transmission mechanism 18, will be described. However, the same operation is also simultaneously performed by the drive shaft 16, motor 17, and drive force transmission mechanism 18 on the second guide rail 11b, second collector member 12b, second sliding plate 13b, second pull rod 14b, and second link mechanism 15b. Since the operation is the same, the latter explanation will be omitted. It is also possible to shift the attachment phase of the former first drive arm 151a and the latter second drive arm 151b to the drive shaft 16 so that when the former first accumulator member 12a moves forward, the latter second accumulator member 12b moves backward, and when the former first accumulator member 12a moves backward, the latter second accumulator member 12b moves forward. This makes it possible to average out the load on the motor 17 and extend the life of the motor.

[0025] Fig. 3 is a side view of the sludge scraper shown in Fig. 1. In Fig. 3, the thicknesses of the first guide rail 11a and the first slide plate 13a are exaggerated.

[0026] When the output shaft of motor 17 rotates in one direction, the rotational driving force is transmitted to driven sprocket 182 via drive sprocket 181 and chain 183, causing drive shaft 16 to rotate in the same direction as the output shaft of motor 17. In FIG. 3, the direction in which drive shaft 16 rotates is indicated by four arc-shaped arrows. As indicated by the two-dot chain line in FIG. 3, when drive shaft 16 rotates, the upstream end of first link arm 152a, which is rotatably attached to first drive arm 151a, rotates. The downstream end of first link arm 152a, to which first pull rod 14a is rotatably attached, moves linearly in the reciprocating direction. Specifically, when the upstream end of first link arm 152a rotates above drive shaft 16, first pull rod 14a moves downstream. When the upstream end of first link arm 152a rotates below drive shaft 16, first pull rod 14a moves upstream. That is, when the drive shaft 16 rotates multiple times in one direction, the first pull rod 14a reciprocates the same number of times. All of the first collector members 12a and the three first slide plates 13a connected to the first pull rod 14a also reciprocate repeatedly. As a result, the sludge that has settled on the first pond bottom 91a of the first waterway 9a is gradually collected toward the first sludge pit 92a, one stroke at a time, and sent to the first sludge pit 92a. The first collector member 12a can also be moved linearly in the reciprocating direction by rotating the motor 17 in the opposite direction to the arc-shaped arrow in FIG. 3 . However, the load on the first collector member 12a to collect sludge increases when moving upstream compared to moving downstream. Therefore, it is preferable to rotate the drive shaft 16 in a direction that minimizes the transmission loss of driving force during the upstream movement. When the drive shaft 16 is rotated in the direction of the arc-shaped arrow shown in FIG. 3, the component of the driving force transmitted from the drive shaft 16 to the first pull rod 14a in the direction of movement becomes larger when the first collector member 12a is moved upstream compared to when the first collector member 12a is moved downstream, and the transmission loss of the driving force is reduced.In other words, when the connection portion between first drive arm 151a and first link arm 152a is located below drive shaft 16, the height position of that connection portion becomes closer to the height position of the connection portion between first link arm 152a and first pull rod 14a, so that the rotational driving force of drive shaft 16 can be efficiently converted into a linear motion force of first pull rod 14a.

[0027] According to this embodiment, first pull rod 14a and second pull rod 14b move linearly in the reciprocating direction in response to the unidirectional rotational motion of drive shaft 16. Therefore, no torsional alternating load is applied to drive shaft 16 during normal sludge scraping operations. This eliminates the need for drive shaft 16 to have strength designed to withstand alternating loads, allowing the shaft diameter of drive shaft 16 to be reduced. Furthermore, because no alternating load is applied to coupling 163, an inexpensive coupling 163 can be used. Furthermore, the use of a link mechanism allows the rotational motion of drive shaft 16 to be converted into linear motion with a simple configuration. In addition, because drive shaft 16 has driven sprocket 182 fixed between one end where first link mechanism 15a is located and the other end where second link mechanism 15b is located, the bending moment applied to drive shaft 16 is smaller than when driven sprocket 182 is fixed outside the positions where these mechanisms are located, allowing the shaft diameter of drive shaft 16 to be reduced. As a result, it is possible to inexpensively configure the sludge scraper 1. Furthermore, by reducing the diameter of the drive shaft 16, the moment of inertia of the drive shaft 16 is reduced, and therefore the amount of power required to rotate the motor 17 can also be reduced.

[0028] Next, a sludge scraping device 1 according to a second embodiment will be described. In the following description, components having the same names as components described so far will be assigned the same reference numerals as those used so far, and duplicate descriptions may be omitted.

[0029] FIG. 4 is a plan view, similar to FIG. 1, of the lower portion of a sedimentation tank in which a sludge scraper according to a second embodiment is installed, viewed from above. FIG. 5 is a view of the sedimentation tank as viewed in the direction of arrow B in FIG. 4. FIG. 6 is a side view of the sludge scraper shown in FIG. 4. For ease of viewing, the vertical direction of FIG. 5 coincides with the vertical direction of the sedimentation tank. Furthermore, in FIGS. 5 and 6, the thicknesses of the first guide rail 11a and the first sliding plate 13a are exaggerated, and in FIG. 5, the thicknesses of the second guide rail 11b and the second sliding plate 13b are also exaggerated. Additionally, the downstream portion of the sedimentation tank 9 is omitted from the illustrations of FIGS. 4 and 6.

[0030] The sludge collector 1 shown in Figures 4 to 6 differs from the sludge collector 1 shown in the previous embodiment in that a first swinging mechanism 21a, a third link mechanism 23a, a second swinging mechanism 21b, and a fourth link mechanism 23b are provided instead of the first link mechanism 15a and the second link mechanism 15b in the previous embodiment, and that the drive shaft 16 is located on the ground. As shown in Figure 4, the settling basin 9 has a first water channel 9a and a second water channel 9b arranged in parallel, each having a substantially identical shape. The first water channel 9a and the second water channel 9b are separated by a partition wall 90. As shown in Figure 5, the first swinging mechanism 21a and the third link mechanism 23a are located on the first water channel 9a side, and the second swinging mechanism 21b and the fourth link mechanism 23b are located on the second water channel 9b side. In the second embodiment, the first swing mechanism 21a and the third link mechanism 23a correspond to an example of a first conversion device, and the second swing mechanism 21b and the fourth link mechanism 23b correspond to an example of a second conversion device. The first guide rail 11a and the second guide rail 11b, the first and second collector members 12a and the second collector members 12b, the first and second slide plates 13a and 13b, the first and second pull rods 14a and 14b, the first swing mechanism 21a and the second swing mechanism 21b, and the third and fourth link mechanisms 23a and 23b are configured in plane symmetry with respect to the center plane of the partition wall 90, which is perpendicular to the pond width direction. In the following description, only one of these plane-symmetrical components will be described, and the description of the other may be omitted.

[0031] As shown in Figures 5 and 6, the first swing mechanism 21a includes a first bracket 211a, a first angle arm 212a, and a first link arm 213a. The first swing mechanism 21a converts the up-and-down movement of the first piston rod 232a provided in the third link mechanism 23a into linear motion in the reciprocating direction of the first pull rod 14a. The first bracket 211a includes a pair of first frames 2111a that are A-shaped when viewed from the pond width direction, and a first swing center shaft 2112a that spans between the pair of first frames 2111a. The pair of first frames 2111a have their bases fixed to the upstream wall of the first waterway 9a and their tips protruding toward the downstream side. The first swing center shaft 2112a is fixed to the tip of the pair of first frames 2111a, with its axis oriented in the pond width direction. The first angle arm 212a is attached to a first swing center shaft 2112a so as to be able to swing freely. The first angle arm 212a is configured as a frame body having a roughly triangular shape when viewed in the pond width direction. A lower joint shaft, whose axis is oriented in the pond width direction, is fixed to the lower end of the first angle arm 212a. An upper joint shaft, whose axis is oriented in the pond width direction, is fixed to the upper end of the first angle arm 212a. The first link arm 213a is a pipe extending roughly in the direction of reciprocation. Holes are formed at both ends of the first link arm 213a, into which shafts can be inserted. The lower joint shaft is rotatably inserted into the hole at the upstream end of the first link arm 213a. A shaft fixed to the upstream portion of the first pull rod 14a is rotatably inserted into the hole at the downstream end of the first link arm 213a. In FIG. 4, the first link arm 213a is simply shown by a dashed line, and in FIG. 5, the first link arm 213a is not shown.

[0032] As shown in FIG. 5, the third link mechanism 23a includes a third drive arm 231a and a first piston rod 232a. The third link mechanism 23a is a slider-crank type link mechanism that converts the unidirectional rotational movement of the drive shaft 16 into the vertical movement of the first piston rod 232a. The third drive arm 231a is plate-shaped and reinforced by ribs. The base end of the third drive arm 231a is fixed to one end of the drive shaft 16 and extends radially from the fixed portion of the drive shaft 16. A shaft is formed at the tip of the third drive arm 231a, parallel to the drive shaft 16 and protruding outward in the pond width direction beyond the drive shaft 16. The first piston rod 232a is a pipe that extends vertically from the ground to near the first pond bottom surface 91a. Holes into which the shafts can be inserted are formed at the upper and lower ends of the first piston rod 232a. A shaft formed at the tip of the third drive arm 231a is rotatably inserted into a hole at the upper end of the first piston rod 232a, and an upper joint shaft of the first angle arm 212a is rotatably inserted into a hole at the lower end of the first piston rod 232a.

[0033] The second swing mechanism 21b includes a second bracket 211b, a second angle arm 212b, and a second link arm 213b (see FIG. 4). The second swing mechanism 21b converts the up-and-down movement of the second piston rod 232b provided in the fourth link mechanism 23b into linear motion in the reciprocating direction of the second pull rod 14b. The second bracket 211b includes a pair of second frames 2111b that are A-shaped when viewed from the pond width direction, and a second swing central shaft 2112b that spans between the pair of second frames 2111b. The pair of second frames 2111b have their bases fixed to the upstream wall of the second waterway 9b, and their tips protrude toward the downstream side. The second swing central shaft 2112b is fixed to the tip of the pair of second frames 2111b, with its axis oriented in the pond width direction. The second angle arm 212b is attached to a second swing center shaft 2112b so as to be able to swing freely. The second angle arm 212b is configured as a frame body having a roughly triangular shape when viewed from the pond width direction. A lower joint shaft, whose axis is aligned with the pond width direction, is fixed to the lower end of the second angle arm 212b. An upper joint shaft, whose axis is aligned with the pond width direction, is fixed to the upper end of the second angle arm 212b. The second link arm 213b is a pipe extending roughly in the direction of reciprocation. A hole into which a shaft can be inserted is formed at each end of the second link arm 213b. The lower joint shaft is rotatably inserted into the hole at the upstream end of the second link arm 213b. A shaft fixed to the upstream portion of the second pull rod 14b is rotatably inserted into the hole at the downstream end of the second link arm 213b. In FIG. 4, the second link arm 213b is simply shown by a dashed line, and in FIG. 5, the second link arm 213b is not shown.

[0034] The fourth link mechanism 23b includes a fourth drive arm 231b and a second piston rod 232b. The fourth link mechanism 23b is a slider-crank type link mechanism that converts the unidirectional rotational motion of the drive shaft 16 into the vertical motion of the second piston rod 232b. The fourth drive arm 231b is plate-shaped and reinforced by ribs. The base end of the fourth drive arm 231b is fixed to the other end of the drive shaft 16 and extends radially from the fixed portion of the drive shaft 16. A shaft is formed at the tip of the fourth drive arm 231b, parallel to the drive shaft 16 and protruding outward in the pond width direction beyond the drive shaft 16. The second piston rod 232b is a pipe that extends vertically from the ground to near the second pond bottom surface 91b. Holes into which the shafts can be inserted are formed at the upper and lower ends of the second piston rod 232b. A shaft formed at the tip of the fourth drive arm 231b is rotatably inserted into a hole at the upper end of the second piston rod 232b, and an upper joint shaft of the second angle arm 212b is rotatably inserted into a hole at the lower end of the second piston rod 232b.

[0035] As shown in Figure 6, the drive shaft 16, motor 17, and drive force transmission mechanism 18 are installed in the atmosphere on the ground above the sedimentation basin 9. The drive shaft 16 extends above ground from the center of the first water channel 9a in the width direction of the pond to the center of the second water channel 9b in the width direction of the pond. The driven sprocket 182 of the drive force transmission mechanism 18 is located directly above the partition wall 90. Furthermore, since the drive shaft 16 and motor 17 are located closer to each other than in the previous embodiment, the chain 183 is shorter than in the previous embodiment.

[0036] Next, the operation of the sludge collector 1 shown in Figures 4 to 6 will be described mainly with reference to Figure 6. In this explanation of operation, the operation of the first guide rail 11a, first collector member 12a, first sliding plate 13a, first pull rod 14a, first swinging mechanism 21a, and third link mechanism 23a, which is performed by the drive shaft 16, motor 17, and drive force transmission mechanism 18, will be described. However, the same operation is also simultaneously performed by the drive shaft 16, motor 17, and drive force transmission mechanism 18 for the second guide rail 11b, second collector member 12b, second sliding plate 13b, second pull rod 14b, second swinging mechanism 21b, and fourth link mechanism 23b. Since the operation is the same, the latter explanation will be omitted. It is also possible to shift the attachment phase of the former third drive arm 231a and the latter fourth drive arm 231b to the drive shaft 16 so that when the former first accumulator member 12a moves forward, the latter second accumulator member 12b moves backward, and when the former first accumulator member 12a moves backward, the latter second accumulator member 12b moves forward. This can average out the load on the motor 17 and extend the life of the motor.

[0037] When the output shaft of the motor 17 rotates, the rotational driving force is transmitted to the driven sprocket 182 via the drive sprocket 181 and the chain 183, causing the drive shaft 16 to rotate in the same direction as the output shaft of the motor 17. The motor 17 and drive shaft 16 rotate in only one direction, either clockwise or counterclockwise, as viewed in FIG. 6. When the drive shaft 16 rotates, the upper end of the first piston rod 232a, which is rotatably attached to the third drive arm 231a, rotates, and the lower end, to which the upper joint shaft of the first angle arm 212a is rotatably attached, moves up and down. As shown by the two-dot chain line in FIG. 6, the up and down movement of the lower end of the first piston rod 232a causes the first angle arm 212a of the first swing mechanism 21a to swing around the first swing central axis 2112a. In FIG. 6, the swing direction is indicated by an arc with arrows at both ends. When the first angle arm 212a swings, the upstream end of the first link arm 213a, which is rotatably attached to the first angle arm 212a, also swings. The downstream end of the first link arm 213a, to which the first pull rod 14a is rotatably attached, moves linearly in the reciprocating direction. Specifically, when the first piston rod 232a moves upward, the first angle arm 212a swings counterclockwise in FIG. 6, and the first pull rod 14a advances upstream (moves forward). Conversely, when the first piston rod 232a moves downward, the first angle arm 212a swings counterclockwise in FIG. 6, and the first pull rod 14a retreats downstream (moves backward). That is, when the drive shaft 16 rotates multiple times in one direction, the first pull rod 14a repeats reciprocating motion in the reciprocating direction the same number of times as the drive shaft 16 rotates. All of the first scraper members 12a and the three first slide plates 13a connected to the first pull rod 14a also repeatedly move back and forth in the same manner, causing the sludge that has settled on the first pond bottom surface 91a of the first waterway 9a to be scraped stepwise, one stroke at a time, toward the first sludge pit 92a and sent to the first sludge pit 92a.

[0038] The sludge scraper 1 of the second embodiment also provides the same effects as the previous embodiment.

[0039] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. For example, in this embodiment, the sludge scraper 1 is installed in a settling basin 9 having two waterways, extending across the two waterways and scraping sludge from each of the two waterways. However, this sludge scraper 1 may also be applied to a settling basin in which the first scraper member 12a and the second scraper member 12b are arranged in parallel in a single waterway. Furthermore, the coupling 163 may be omitted, and a long drive shaft 16 may be used. Furthermore, in this embodiment, the sludge scraper is installed in the settling basin of a sewage treatment facility. However, the sludge scraper of the present invention may also be installed in the settling basin of a water purification facility that purifies raw water taken from a river or the like. When the sludge scraper of the present invention is installed in the settling basin of a water purification facility, the raw water corresponds to an example of suspended solids.

[0040] Note that even if a component is included only in the description of the embodiment or modified example described above, that component may be applied to other embodiments or other modified examples.

[0041] The sludge scraper described above has the following features: A sludge scraper is provided in a sedimentation tank where sludge contained in received suspended solids settles on the bottom of the tank, and scrapes up the sludge that has settled on the bottom of the tank, a drive shaft disposed in a position submerged in water and extending in the width direction of the pond; a motor installed on the ground to rotate the drive shaft; a driving force transmission mechanism that transmits the rotational driving force of the motor to the drive shaft; a first pull rod connected to a first scraper member disposed on one end of the drive shaft and configured to scrape up sludge settled on the bottom surface of the pond by repeatedly moving in a reciprocating movement direction perpendicular to the pond width direction; A second pull rod is connected to a second scraper member that is disposed on the other end of the drive shaft and scrapes up sludge that has settled on the bottom surface of the pond by repeatedly moving in the reciprocating movement direction; a first conversion device connected to one end portion of the drive shaft and configured to convert rotational motion of the drive shaft in one direction into linear motion in the reciprocating direction of the first pull rod; and a second conversion device connected to the other end of the drive shaft for converting the rotational motion of the drive shaft in one direction into linear motion in the reciprocating direction of the second pull rod.

[0042] Also, a sludge scraper is provided in a sedimentation tank where sludge contained in received suspended solids settles on the bottom of the tank, and scrapes up the sludge that has settled on the bottom of the tank, a drive shaft extending in the width direction of the pond; a motor that rotates the drive shaft; a first pull rod connected to a first scraper member disposed on one end of the drive shaft and configured to scrape up sludge settled on the bottom surface of the pond by repeatedly moving in a reciprocating movement direction perpendicular to the pond width direction; A second pull rod is connected to a second scraper member that is disposed on the other end of the drive shaft and scrapes up sludge that has settled on the bottom surface of the pond by repeatedly moving in the reciprocating movement direction; a first conversion device disposed on one end of the drive shaft and configured to convert rotational motion of the drive shaft in one direction into linear motion in the reciprocating direction of the first pull rod; The rotary motion of the drive shaft may be converted into linear motion in the reciprocating direction of the second pull rod by a second conversion device disposed on the other end of the drive shaft.

[0043] With this sludge collector, the first pull rod and the second pull rod move linearly in the reciprocating direction in response to the unidirectional rotation of the drive shaft, so no alternating load is applied to the drive shaft in the torsional direction. This means that the diameter of the drive shaft does not need to be particularly large, and when a coupling is used, it is not necessary to consider alternating loads, making it possible to use an inexpensive coupling, and as a result, the sludge collector can be provided at low cost.

[0044] In addition, in this scraping device, the first conversion device includes a first link mechanism that converts the rotational motion of the drive shaft in one direction into linear motion in the reciprocating movement direction of the first pull rod, The second conversion device may include a second link mechanism that converts unidirectional rotational motion of the drive shaft into linear motion in the reciprocating direction of the second pull rod.

[0045] By employing the first link mechanism and the second link mechanism, it is possible to convert the unidirectional rotational motion of the drive shaft into linear motion of the first pull rod and the second pull rod with a simple configuration. The drive shaft may be disposed in a position submerged in water.

[0046] In addition, in this scraping device, the first conversion device includes a third link mechanism having a first piston rod extending in a vertical direction and converting unidirectional rotational movement of the drive shaft into vertical movement of the first piston rod, and a first swing mechanism converting the vertical movement of the first piston rod into linear movement in the reciprocating movement direction of the first pull rod, The second conversion device may include a fourth link mechanism having a second piston rod extending in an up-down direction and converting unidirectional rotational movement of the drive shaft into up-down movement of the second piston rod, and a second swing mechanism converting the up-down movement of the second piston rod into linear movement in the reciprocating movement direction of the second pull rod.

[0047] Even with this configuration, the unidirectional rotational motion of the drive shaft can be converted into linear motion of the first pull rod and the second pull rod. The drive shaft may be installed in the atmosphere. The first and second swing mechanisms may be submerged in water.

[0048] In addition, in this scraping device, The drive shaft may have a transmitted part fixed between the one end side where the first conversion device is arranged and the other end side where the second conversion device is arranged, to which the rotational driving force of the motor is transmitted.

[0049] This reduces the bending moment applied to the drive shaft, thereby increasing the durability of the drive shaft. [Explanation of symbols]

[0050] 1 Sludge scraper 9 Sedimentation tank 12a First scraper member 12b Second scraper member 14a No. 1 pull rod 14b No. 2 pull rod 15a First link mechanism 15b Second link mechanism 16 drive shaft 17 Motor 91a No. 1 pond bottom 91b Second pond bottom

Claims

[Claim 1] A sludge scraper is provided in a sedimentation tank where sludge contained in received suspended solids settles on the bottom of the tank, and scrapes up the sludge that has settled on the bottom of the tank, a drive shaft extending in the width direction of the pond; a motor that rotates the drive shaft; a first pull rod connected to a first scraper member disposed on one end of the drive shaft and configured to scrape up sludge settled on the bottom surface of the pond by repeatedly moving in a reciprocating movement direction perpendicular to the pond width direction; a second pull rod connected to a second scraper member disposed on the other end of the drive shaft and configured to scrape up sludge settled on the bottom surface of the pond by repeatedly moving in the reciprocating movement direction; a first conversion device connected to one end portion of the drive shaft and configured to convert the rotational motion of the drive shaft in one direction into linear motion in the reciprocating direction of the first pull rod; a second conversion device connected to the other end of the drive shaft and configured to convert the rotational motion of the drive shaft in one direction into linear motion in the reciprocating direction of the second pull rod, A sludge scraper device characterized in that the drive shaft has a transmitted part fixed between the one end portion and the other end portion to which the rotational driving force of the motor is transmitted, and is supported so as to be freely rotatable around its axis by two first bearings provided between the one end portion and the transmitted part and two second bearings provided between the other end portion and the transmitted part, and is connected between the two first bearings by a first coupling and between the two second bearings by a second coupling.

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