Mud raking device

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 in a reciprocating direction at the bottom of a settling basin, and which scrapes up sludge that has settled on the bottom of the basin in stages by repeatedly moving the scraper member in the reciprocating direction (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 repeatedly in the reciprocating direction together with the pull rod, scraping up the sludge that has settled on the bottom of the basin.

[0003] Incidentally, some sedimentation tanks have multiple waterways formed in parallel. When the sludge that has settled on the bottom of a sedimentation tank having multiple waterways is scraped by the sludge scraper described in Patent Document 1, a sludge scraper is provided for each waterway. This results in a cost that is the number of waterways multiplied by the price of one sludge scraper. Even in a sedimentation tank with only one waterway, multiple sludge scrapers may be installed in the width direction of the tank if the tank is wide. In this case, as in the case of multiple waterways, the number of sludge scrapers increases, and the cost increases according to the number of units. In response to this, an attempt has been made to reduce the number of motors by extending the swing center axis in the width direction of the tank and moving two pull rods in the reciprocating direction with one motor, thereby reducing the price of the sludge scraper installed in the sedimentation tank as described above. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-180247 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, since the swinging central shaft rotates in different directions when the pull rod moves in the forward direction and the backward direction, an alternating load is applied to the swinging central shaft, which repeatedly changes the direction of the load. For this reason, the long swinging central shaft extending between the two pull rods separated in the width direction of the pond needs to have a considerably thicker shaft diameter in order to obtain sufficient strength against the alternating load, which makes the shaft expensive. In addition, it is very difficult to transport the long and heavy swinging central shaft to the sedimentation tank and install it in the sedimentation tank, so the transportation and installation costs are also expensive. As a result, even if the number of motors can be reduced, other costs increase, and the sludge scraper ends up being expensive. On the other hand, it is possible to reduce the transportation costs to the sedimentation tank and the installation costs in the sedimentation tank by dividing the swinging central shaft in the middle of the extension direction and connecting the divided parts with a coupling when installing in the sedimentation tank. However, when using a coupling, an expensive coupling that is difficult to come off even when an alternating load is applied is used, so the sludge scraper still becomes expensive.

[0006] 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 is disposed on one end side of the drive shaft, and a first scraping member is connected to the first pull rod, which scrapes up sludge that has 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 side 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 a rotational motion of the drive shaft in one direction into a 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 to which the rotational driving force of the motor is transmitted fixed between the one end portion and the other end portion, is supported for free rotation about an 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, is connected between the two first bearings by a first coupling, and is connected between the two second bearings by a second coupling. Effect of the Invention

[0008] According to the present invention, an inexpensive sludge scraping device can be provided. [Brief description of the drawings]

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

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of this embodiment, an example is used in which a sludge scraper of the present invention is installed in a settling basin provided in a sewage treatment facility. The sludge scraper of this embodiment is a so-called reciprocating type sludge scraper that scrapes sludge by moving scraper members in a reciprocating direction. The sludge scraper of this embodiment is also arranged in a settling basin having two water channels, and the 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 of the lower part of a settling tank in which a sludge scraping device according to one embodiment of the present invention is installed, as viewed from above. Fig. 2 is a view of the settling tank as viewed in 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 settling tank.

[0012] The settling tank 9 shown in FIG. 1 and FIG. 2 is a tank having a substantially rectangular shape in a plan view. In FIG. 1, the downstream portion of the settling tank 9 (the right portion in FIG. 1) is omitted. The settling tank 9 includes a first water channel 9a and a second water channel 9b arranged in parallel in the settling tank 9. The first water channel 9a and the second water channel 9b have substantially 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 receive sewage such as wastewater and rainwater from the conduit on the left side in FIG. 1, and discharge the sewage from the right side in FIG. 1. This sewage corresponds to an example of suspended solids. The sludge contained in the sewage received by the settling tank 9 settles on the first pond bottom surface 91a and the second pond bottom surface 91b shown in FIG. 2 while flowing 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 settling basin 9. Also, hereinafter, the up-down direction in Fig. 1 will be referred to as the basin 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 91a and the second pond bottom 91b are slightly inclined so that the water depth of the second waterway 9b increases toward the upstream side.

[0013] As shown in Fig. 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 to the outside of the settling basin 9 by a sludge pump (not shown).

[0014] A sludge collector 1 is installed in the settling tank 9. In FIG. 1, only the lower part of the sludge collector 1 that is submerged in water is shown. 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 plate 13a, the first pull rod 14a, and the first link mechanism 15a are arranged on the first waterway 9a side. The second guide rail 11b, the second collecting member 12b, the second sliding plate 13b, the second pull rod 14b, and the second link mechanism 15b are arranged on the second waterway 9b side. The first guide rail 11a and the second guide rail 11b, the first collecting members 12a and the second collecting members 12b, the first sliding plate 13a and the second sliding plate 13b, the first pull rod 14a and the second pull rod 14b, and the first link mechanism 15a and the second link mechanism 15b are each configured to be plane-symmetrical with respect to the center plane of the partition wall 90, which is perpendicular to the pond width direction, as the reference plane. In the following description, only one of these plane-symmetrical components will be described, and the description of the other may be omitted.

[0015] As shown in FIG. 2, the first guide rail 11a, the first collecting member 12a, the first sliding plate 13a, the first pull rod 14a, the first link mechanism 15a, and the drive shaft 16 are disposed in positions submerged in the sewage received by the first waterway 9a. In FIG. 2, the thicknesses of the first guide rail 11a, the second guide rail 11b, the first sliding plate 13a, and the second sliding plate 13b are exaggerated. In this embodiment, a total of three first guide rails 11a at the center of the pond width direction and both ends of the pond width direction are fixed to the first pond bottom surface 91a of the first waterway 9a. The first guide rails 11a are made of, for example, ultra-high molecular weight polyethylene. Also, 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, the first collecting members 12a are arranged at equal or approximately equal intervals in the longitudinal direction of the settling tank 9. Each of the first collecting members 12a extends in the width direction of the first waterway 9a. Each of the first collecting members 12a is connected to a first pull rod 14a, and the first pull rod 14a moves back and forth in the longitudinal direction, so that the first collecting members 12a move back and forth between the upstream side and the downstream side along the first guide rail 11a. Hereinafter, the direction in which the first collecting members 12a move back and forth may be referred to as the reciprocating movement direction. This reciprocating movement direction coincides with the longitudinal direction of the settling tank 9. The stroke of the reciprocating movement of the first collecting members 12a is set to a distance equal to or greater than the interval in the reciprocating movement direction in which the first collecting members 12a are arranged. The sludge that has settled on the first pond bottom surface 91a is collected toward the first sludge pit 92a when the first collecting members 12a move upstream. The settled sludge is scraped up stepwise, stroke by stroke, by causing the first scraping member 12a to reciprocate multiple times, and sent to the first sludge pit 92a.

[0017] The first sliding plate 13a connects the multiple first gathering members 12a. There are three first sliding plates 13a, one at the center of the pond width direction and one at both ends of the pond width direction, and each of them is in contact with the upper surface of the first guide rail 11a. The first sliding plate 13a is a plate-shaped stainless steel plate. The first sliding plate 13a extends over the entire length of the reciprocating movement direction in which the multiple first gathering members 12a are arranged. Each of the multiple first gathering members 12a is fixed to each of the first sliding plates 13a. As a result, the first sliding plate 13a connects all of the multiple first gathering members 12a. Since each of the first gathering members 12a is connected by the first sliding plate 13a at the center of the pond width direction and both ends of the pond width direction, each of the first gathering members 12a is integrated at the center of the pond width direction and both ends of the pond width direction, increasing the rigidity of the first gathering members 12a as a whole. This prevents the first scraping members 12a from bending at both ends in the direction of their reciprocating movement. If the first scraping members 12a bend, there is a risk that sludge will be left behind at the ends in the direction of the pond width. When the first scraping members 12a reciprocate, the lower surface 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 disposed so as to contact 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 disposed at 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 rotational motion of the drive shaft 16 in one direction into a linear motion in the reciprocating direction of the first pull rod 14a. The first link mechanism 15a corresponds to an example of a first conversion device. In FIG. 1, the first link arm 152a is simplified and shown by a dashed line. The first drive arm 151a has a plate shape reinforced by a rib. The base end of the first drive arm 151a is fixed to one end portion of the drive shaft 16, and extends from the fixed portion toward the radial direction of the drive shaft 16. At the tip of the first drive arm 151a, a shaft is formed that is parallel to the drive shaft 16 and protrudes toward the outside of the drive shaft 16 in the pond width direction. 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 movement direction. A hole into which a shaft can be inserted is formed at each end of first link arm 152a. 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 rotational motion of the drive shaft 16 in one direction into a 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 shown by a dashed line. The second drive arm 151b has a plate shape reinforced by a rib. The base end of the second drive arm 151b is fixed to the other end portion of the drive shaft 16, and extends from the fixed portion toward the radial direction of the drive shaft 16. At the tip of the second drive arm 151b, a shaft is formed that is parallel to the drive shaft 16 and protrudes toward the outside of the drive shaft 16 in the pond width direction. The upstream end of the second link arm 152b is rotatably attached to the shaft. Second link arm 152b is a pipe extending generally in the reciprocating movement direction. A hole into which a shaft can be inserted is formed at each end of second link arm 152b. 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 is a shaft extending in the width direction of the pond. The drive shaft 16 passes through a through hole 901 formed in the partition wall 90 and extends from the center of the first water passage 9a in the width direction of the pond to the center of the second water passage 9b in the width direction of the pond. Four bearing pedestals 161 are fixed to the wall on the upstream side of the sedimentation pond 9. The drive shaft 16 is supported rotatably around its axis by bearings 162 provided on each of the bearing pedestals 161. The drive shaft 16 is configured by connecting three shafts with two couplings 163. The drive shaft 16 may be configured as a single long shaft. However, if the drive shaft 16 is configured as a single shaft, the transportation and installation costs will be high when transporting the drive shaft 16 to the sedimentation pond 9 and when installing the drive shaft 16 in the sedimentation pond 9. 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 Fig. 2, the motor 17 is installed in the atmosphere on the ground above the settling tank 9. The motor 17 is for rotating the drive shaft 16. The rotational drive force of the motor 17 is transmitted to the drive shaft 16 via a 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 arranged and the other end where the second link mechanism 15b is arranged. 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 Fig. 1 will be described mainly with reference to Fig. 3. In this explanation of the 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 executed by the drive shaft 16, motor 17, and drive force transmission mechanism 18, will be described, but the second guide rail 11b, second collector member 12b, second sliding plate 13b, second pull rod 14b, and second link mechanism 15b are also simultaneously executed in the same manner by the drive shaft 16, motor 17, and drive force transmission mechanism 18. Since the operation is the same, the latter explanation will be omitted. The first driving arm 151a and the second driving arm 151b may be attached to the drive shaft 16 in a phase shifted manner so that the second collecting member 12b moves backward when the first collecting member 12a moves forward and backward, and the second collecting member 12b moves forward and backward when the first collecting member 12a moves backward. This can 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 scraping device shown in Fig. 1. In Fig. 3, the thicknesses of the first guide rail 11a and the first sliding plate 13a are exaggerated.

[0026] When the output shaft of the motor 17 rotates in one direction, the rotational driving force is transmitted to the driven sprocket 182 via the drive sprocket 181 and the chain 183, and the drive shaft 16 rotates in the same direction as the output shaft of the motor 17. In FIG. 3, the direction in which the drive shaft 16 rotates is indicated by four arc-shaped arrows. As indicated by the two-dot chain line in FIG. 3, when the drive shaft 16 rotates, the upstream end of the first link arm 152a, which is rotatably attached to the first drive arm 151a, rotates. Then, the downstream end of the first link arm 152a, to which the first pull rod 14a is rotatably attached, moves linearly in the reciprocating direction. In detail, when the upstream end of the first link arm 152a rotates above the drive shaft 16, the first pull rod 14a moves downstream, and when the upstream end of the first link arm 152a rotates below the drive shaft 16, the first pull rod 14a moves upstream. That is, when the drive shaft 16 rotates multiple times in one direction, the first pull rod 14a repeats reciprocating motion the same number of times as the rotation. Then, all the first scraping members 12a and the three first sliding plates 13a connected to the first pull rod 14a also move repeatedly in the reciprocating direction. As a result, the sludge that has settled on the first pond bottom surface 91a of the first waterway 9a is scraped stepwise toward the first sludge pit 92a, one stroke at a time, and sent to the first sludge pit 92a. The first scraping member 12a can also be moved linearly in the reciprocating direction by rotating the motor 17 in the reverse direction to rotate the drive shaft 16 in the opposite direction to the arc-shaped arrow shown in FIG. 3. However, the first scraping member 12a has a larger movement load for scraping up sludge when moving upstream than when moving downstream. For this reason, it is preferable to rotate the drive shaft 16 in a direction that reduces the transmission loss of the driving force during the upstream movement. When 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 drive shaft 16 to first pull rod 14a in the moving direction becomes larger when first collector member 12a is moved upstream compared to when 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 drive force of drive shaft 16 can be efficiently converted into a linear motion force of first pull rod 14a.

[0027] According to this embodiment, the first pull rod 14a and the second pull rod 14b move linearly in the reciprocating movement direction in response to the rotational motion of the drive shaft 16 in one direction, so that no alternating load in the torsional direction is applied to the drive shaft 16 in the normal sludge scraping operation. As a result, the drive shaft 16 does not need to have strength that takes the alternating load into account, so that the shaft diameter of the drive shaft 16 can be made thin. In addition, since no alternating load is applied to the coupling 163, it is possible to use an inexpensive coupling 163. Furthermore, since a link mechanism is used, the rotational motion of the drive shaft 16 can be converted into linear motion with a simple configuration. In addition, since the drive shaft 16 has the driven sprocket 182 fixed between one end side where the first link mechanism 15a is arranged and the other end side where the second link mechanism 15b is arranged, the bending moment applied to the drive shaft 16 is smaller than when the driven sprocket 182 is fixed outside the positions where they are arranged, and the shaft diameter of the drive shaft 16 can be made thin. As a result, it is possible to inexpensively configure the sludge collector 1. Furthermore, by reducing the shaft 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 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, showing the lower part of the sedimentation tank in which the sludge scraping device of the second embodiment is installed, viewed from above. FIG. 5 is a view of the sedimentation tank as viewed from the direction of the arrow B in FIG. 4. FIG. 6 is a side view of the sludge scraping device shown in FIG. 4. For ease of viewing, the up-down direction of FIG. 5 coincides with the up-down direction of the sedimentation tank. In addition, in FIG. 5 and FIG. 6, the thicknesses of the first guide rail 11a and the first slide plate 13a are exaggerated, and in FIG. 5, the thicknesses of the second guide rail 11b and the second slide plate 13b are also exaggerated. In addition, in FIG. 4 and FIG. 6, the downstream part of the sedimentation tank 9 is omitted.

[0030] The sludge collector 1 shown in Figs. 4 to 6 differs from the sludge collector 1 shown in the previous embodiment in that a first swing mechanism 21a, a third link mechanism 23a, a second swing 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 disposed on the ground. As shown in Fig. 4, the settling basin 9 has a first water passage 9a and a second water passage 9b in parallel, each having a substantially identical shape. The first water passage 9a and the second water passage 9b are separated by a partition wall 90. As shown in Fig. 5, the first swing mechanism 21a and the third link mechanism 23a are disposed on the first water passage 9a side, and the second swing mechanism 21b and the fourth link mechanism 23b are disposed on the second water passage 9b side. In the second embodiment, the first rocking mechanism 21a and the third link mechanism 23a correspond to an example of a first conversion device, and the second rocking 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 scraping members 12a and the second scraping members 12b, the first sliding plate 13a and the second sliding plate 13b, the first pull rod 14a and the second pull rod 14b, the first rocking mechanism 21a and the second rocking mechanism 21b, and the third link mechanism 23a and the fourth link mechanism 23b are each configured to be plane-symmetrical with respect to the center plane of the partition wall 90, which is perpendicular to the pond width direction, as the reference plane. 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 FIG. 5 and FIG. 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 is a mechanism that converts the up-down movement of the first piston rod 232a provided in the third link mechanism 23a into a linear movement 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 central shaft 2112a that is stretched between the pair of first frames 2111a. The pair of first frames 2111a have their base portions fixed to the upstream wall of the first water passage 9a, and their tip portions protrude toward the downstream side. The first swing central shaft 2112a is fixed to the tip portions 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 pivot shaft 2112a so as to be freely swingable. The first angle arm 212a is formed of a frame body having a roughly triangular shape when viewed from the pond width direction. A lower joint shaft having an axis oriented in the pond width direction is fixed to the lower end of the first angle arm 212a. An upper joint shaft having an axis 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 reciprocating movement direction. A hole into which a shaft can be inserted is formed at each of both ends of the first link arm 213a. 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 part 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 simplified and indicated by a dashed line, and in FIG. 5, the first link arm 213a is omitted.

[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 rotational motion of the drive shaft 16 in one direction into the vertical motion 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 from the fixed part toward the radial direction of the drive shaft 16. At the tip of the third drive arm 231a, a shaft is formed that is parallel to the drive shaft 16 and protrudes toward the outside of the drive shaft 16 in the pond width direction. The first piston rod 232a is a pipe that extends in the vertical direction from the ground to the vicinity of the first pond bottom surface 91a. At the upper end and the lower end of the first piston rod 232a, holes into which the shafts can be inserted are formed. 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 is a mechanism that converts the up-down movement of the second piston rod 232b provided in the fourth link mechanism 23b into a linear movement 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 is stretched between the pair of second frames 2111b. The pair of second frames 2111b have their base portions fixed to the upstream wall of the second water passage 9b, and their tip portions protrude toward the downstream side. The second swing central shaft 2112b is fixed to the tip portion of the pair of second frames 2111b with its axis oriented in the pond width direction. The second angle arm 212b is attached to the second pivot shaft 2112b so as to be able to swing freely. The second angle arm 212b is formed of a frame body having a roughly triangular shape when viewed from the pond width direction. A lower joint shaft having an axis oriented in the pond width direction is fixed to the lower end of the second angle arm 212b. An upper joint shaft having an axis oriented in 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 reciprocating movement direction. A hole into which a shaft can be inserted is formed at each of both ends 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. An axis fixed to the upstream part 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 simplified and indicated by a dashed line, and in FIG. 5, the second link arm 213b is omitted.

[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 rotational motion of the drive shaft 16 in one direction 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 from the fixed part toward the radial direction of the drive shaft 16. At the tip of the fourth drive arm 231b, a shaft is formed that is parallel to the drive shaft 16 and protrudes toward the outside of the drive shaft 16 in the pond width direction. The second piston rod 232b is a pipe that extends in the vertical direction from the ground to the vicinity of the second pond bottom surface 91b. At the upper end and lower end of the second piston rod 232b, holes into which the shafts can be inserted are formed. 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 Fig. 6, the drive shaft 16, motor 17 and drive force transmission mechanism 18 are installed in the atmosphere on the ground above the settling basin 9. The drive shaft 16 extends on the ground from the center of the first water passage 9a in the width direction of the pond to the center of the second water passage 9b in the width direction of the pond. The driven sprocket 182 of the drive force transmission mechanism 18 is disposed directly above the partition wall 90. Also, since the drive shaft 16 and motor 17 are disposed closer to each other than in the previous embodiment, the chain 183 is shorter than that in the previous embodiment.

[0036] Next, the operation of the sludge scraping device 1 shown in Figures 4 to 6 will be described mainly with reference to Figure 6. In this explanation of the operation, the operation of the first guide rail 11a, the first scraping member 12a, the first sliding plate 13a, the first pull rod 14a, the first swinging mechanism 21a, and the third link mechanism 23a, which is executed by the drive shaft 16, the motor 17, and the driving force transmission mechanism 18, will be described, but the second guide rail 11b, the second scraping member 12b, the second sliding plate 13b, the second pull rod 14b, the second swinging mechanism 21b, and the fourth link mechanism 23b are also simultaneously executed in the same manner by the drive shaft 16, the motor 17, and the driving force transmission mechanism 18. Since it is the same operation, the latter explanation will be omitted. The third drive arm 231a and the fourth drive arm 231b may be attached to the drive shaft 16 in a phase shifted manner so that the second collector member 12b moves backward when the first collector member 12a moves forward, and the second collector member 12b moves forward when the first collector member 12a moves backward. 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, a rotational driving force is transmitted to the driven sprocket 182 via the drive sprocket 181 and the chain 183, and the drive shaft 16 rotates in the same direction as the output shaft of the motor 17. The motor 17 and the drive shaft 16 rotate only in one direction, either clockwise or counterclockwise, in FIG. 6. When the drive shaft 16 rotates, the upper end portion of the first piston rod 232a rotatably attached to the third drive arm 231a rotates, and the lower end portion of the first angle arm 212a rotatably attached to the upper joint shaft of the first angle arm 212a moves up and down. As shown by the two-dot chain line in FIG. 6, the first angle arm 212a of the first swing mechanism 21a swings around the first swing central axis 2112a due to the up and down movement of the lower end portion of the first piston rod 232a. In FIG. 6, the swing direction is indicated by a circular 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. And 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. In detail, 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 (moves forward) to the upstream side. 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 (moves backward) to the downstream side. 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 number of rotations. All of the first scraping members 12a and the three first sliding plates 13a connected to the first pull rod 14a also repeatedly move back and forth in the same manner, so that the sludge that has settled on the first pond bottom surface 91a of the first waterway 9a is scraped up step by step toward the first sludge pit 92a, one stroke at a time, and sent to the first sludge pit 92a.

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

[0039] The present invention is not limited to the above-mentioned embodiment, and various modifications can be made within the scope of the claims. For example, in the present embodiment, the sludge scraper 1 is installed in a settling tank 9 having two waterways, and extends across the two waterways to scrape sludge in each of the two waterways. However, the sludge scraper 1 may be applied to a settling tank in which the first scraper member 12a and the second scraper member 12b are arranged in parallel in one waterway. Also, the coupling 163 may be omitted, and a long drive shaft 16 may be used. Furthermore, in the present embodiment, the sludge scraper is installed in the settling tank of a sewage treatment facility, but the sludge scraper of the present invention may be installed in the settling tank 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 tank of a water purification facility, the raw water corresponds to an example of suspended water.

[0040] In addition, 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 scraping device described above 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 is disposed in a position submerged in water and extends in the width direction of the pond; A motor installed on the ground for rotating the drive shaft; a driving force transmission mechanism that transmits a rotational driving force of the motor to the drive shaft; A first pull rod is disposed on one end side of the drive shaft, and a first scraping member is connected to the first pull rod, which scrapes up sludge that has 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 side 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 a rotational motion of the drive shaft in one direction into a linear motion in the reciprocating direction of the first pull rod; and a second conversion device connected to the other end portion 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, in a sludge scraper provided in a sedimentation tank where sludge contained in received suspended solids settles on the bottom of the tank, the sludge scraper 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 is disposed on one end side of the drive shaft, and a first scraping member is connected to the first pull rod, which scrapes up sludge that has 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 side 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 side of the drive shaft and configured to convert a rotational motion of the drive shaft in one direction into a linear motion in the reciprocating direction of the first pull rod; and a second conversion device disposed on the other end of the drive shaft for converting rotational motion of the drive shaft in one direction into linear motion in the reciprocating direction of the second pull rod.

[0043] With this sludge collector, the first pull rod and the second pull rod move linearly in the reciprocating direction in response to the rotational movement of the drive shaft in one direction, so no alternating load is applied to the drive shaft in a torsional direction. This means that the diameter of the drive shaft does not need to be very large, and when using a coupling, 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 a low cost.

[0044] In addition, in this scraping device, the first conversion device includes a first link mechanism that converts a rotational motion of the drive shaft in one direction into a 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, the unidirectional rotational motion of the drive shaft can be converted 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 one-way rotational motion of the drive shaft into vertical motion of the first piston rod, and a first swing mechanism converting the vertical motion of the first piston rod into linear motion 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 a vertical direction and converting one-way rotational motion of the drive shaft into vertical motion of the second piston rod, and a second oscillating mechanism converting the vertical motion of the second piston rod into linear motion in the reciprocating movement direction of the second pull rod.

[0047] Even in 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 disposed in positions 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 makes it possible to reduce 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 collecting member 12b Second gathering 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 1st 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 is disposed on one end side of the drive shaft, and a first scraping member is connected to the first pull rod, which scrapes up sludge that has 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 side 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 a rotational motion of the drive shaft in one direction into a linear motion in the reciprocating direction of the first pull rod; a second conversion device connected to the other 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 second pull rod, The drive shaft has a transmitted part between the one end portion and the other end portion to which the rotational driving force of the motor is transmitted, and is supported for free rotation about 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 connected between the two second bearings by a second coupling.

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