HK1076418A - Filter device - Google Patents

Description

Filter device

Technical Field

The present invention relates to a filter device for filtering a liquid such as water. More particularly, the present invention relates to a filter device having a filter medium cleaning mechanism in the interior thereof.

Background

If the filter device is used for a long time, the filter medium (filter sand) in the filter tank of the filter device becomes clogged. This hinders the efficiency of filtration and deteriorates the quality of the filtered liquid such as water. For this reason, clogging is eliminated by removing dirt adhering to the filter medium. In order to operate efficiently, it is desirable to perform a process of removing contaminants from a filter medium, i.e., a cleaning process, in a short time using several steps. And it is also desirable to perform the cleaning process without taking up additional space. For this purpose, it is considered to provide a filter sand cleaning device (filter medium cleaning mechanism) in the filter tank. Providing a cleaning mechanism within the filter canister enables effective cleaning of the filter media in a short period of time without removing the filter media from the filter canister.

There are known filtration devices such as those disclosed in Japanese patent No.31491 and Japanese unexamined utility model publication No.63(1998) — 98704, from which they have been developed. The filter device disclosed in japanese patent No.31491 includes a center pipe (cleaning tank) suspended by a frame (support portion). The lower end of the central tube is opened in the filter cavity (filter tank). The lower end of the interior of the central tube is provided with a propeller. Above the impeller is arranged a tube with jet discharge openings, slightly above the upper edge of the central tube, which is connected to the impeller and rotates therewith for ejecting the cleaning fluid in a transverse direction by centrifugal force. During the filtration, water containing contaminants (hereinafter referred to as "raw water") is supplied from above and filtered by passing through filter sand provided on an open-pore false bottom (filter bed). During cleaning, the impeller is rotated so that the filter sand is sucked into the center tube through the lower opening of the center tube. The filtering sand is raised by the center pipe and then discharged in a horizontal direction by the cleaning fluid being jetted from the jet discharge opening. The filter sand is now cleaned by dirt separating from it.

The filtration apparatus disclosed in japanese unexamined utility model publication No.63(1998) -98704 includes an elevator tube (cleaning tank) standing upright therein and a spiral water elevator provided in the elevator tube. During filtration, water is discharged through the water dispersion pipe in the filter sand. The treated water that has been filtered by passing through the filter sand from below is discharged from above the filter sand. During the filter sand cleaning, the spiral water elevator rotates and lifts the filter sand, which has captured dirt from the lower portion of the spiral water elevator. The dirt is separated from the filter sand by using centrifugal force. The filter sand is discharged through a filter sand discharge opening provided at an upper portion of the elevation pipe. The filter sand is then returned to the interior of the filter tank.

As another example of the known filter device, a filter device is disclosed in Japanese unexamined patent publication No.8(1996) -215509. The configuration of the filter device is similar to that of the filter device disclosed in japanese unexamined utility model publication No.63-98704 in that raw water is filtered by moving upward the upward filter tank. A cylinder containing a screw conveyor is suspended in the upper part of the filtration tank. The filter sand is cleaned during its transport from the lower end to the upper end of the cylinder by the screw conveyor. The filter sand, which has been conveyed upwards, is further agitated in a separate chamber provided in the upper part of the cylinder in order to remove dirt therefrom. The cleaned filter sand is then returned to the upper surface of the filter media layer. In this filter device, raw water flows upward from the bottom thereof during cleaning. That is, filtering is performed continuously without interruption.

Conventionally, in a filter device of a type in which raw water is supplied from above and permeates through to a lower portion thereof, a configuration is known in which a gravel layer of a large diameter is disposed on a filter bed, and fine sand is disposed on top of the gravel layer.

There are cases where cleaning of the filter medium is performed daily, for example before work starts or after work. In the case of a filter device operating 24 hours a day, the degree of clogging of the dirt can be automatically detected with a sensor in order to perform the necessary cleaning. Alternatively, there are cases where cleaning is automatically performed based on a timer that runs every predetermined time interval before the occurrence of a blockage.

Conventionally, there have also been cases where a large number of particles are compressed to such an extent that spaces still exist between the particles so as to function as a filter.

In particular, the filtering apparatus disclosed in Japanese unexamined patent publication No.8-215509 does not stop the filtration even during cleaning. Thus, the fine light sand is pressed upward while the coarse sand remains at the lower portion thereof. If the filter medium in this state is lifted by the spiral water elevator (auger), a coarse sand lower layer of the filter sand is lifted and then discharged to a sand layer. Coarse sand sinks to the bottom while fine light sand remains in the upper part. The problem is therefore that only coarse sand is cleaned, while fine sand is still contaminated. For this reason, a filtering apparatus that performs continuous filtering is not put to practical use. In addition, since the clean water is not backwashed upward from the filter bed, the discharge of the separated contaminants is not efficiently performed, which results in a time-consuming cleaning operation.

In the case where a fine sand layer is provided on top of a large-diameter gravel layer, the fine sand is prevented from sinking to the bottom by the large-diameter gravel. There are other advantages as the holes in the distributed large diameter gravel bed are less likely to become plugged and the flow of liquid is more uniform. However, when cleaning the filter medium disposed in such a manner, there are the following problems.

In the case where cleaning is performed only by backwashing cleaning in which cleaning water is sprayed from the filter bed, the cleaning water is sprayed upward through a passage that is not clogged with dirt in the filter medium. Therefore, the filter sand at the periphery of the passage moves, so that the gravel layer is uneven, that is, unevenness is generated on the surface of the gravel layer. Then, when the filtration is performed following the cleaning, the raw water flowing through the filter medium is not uniformly sprayed since the passage is thereby deflected by the unevenness. Therefore, the filtering efficiency is deteriorated or the filtering effect is unstable. In the case of cleaning the filter sand on top of the gravel layer using the auger, there is a possibility that the rotation of the auger will affect the upper portion of the gravel layer to cause unevenness therein.

In addition, in the case where a sand layer is provided on top of a gravel layer, three to four layers of gravel and sand having gradually decreasing particle diameters are provided. This will ensure that fine sand does not fall into the large gravel layer. In this case, each layer must be about the same thickness. Therefore, the entire layer thickness is large, whereby the height of the filter tank is increased. Accordingly, if installed indoors, there is a limit to the installation location of the filtering apparatus. In addition, maintenance and management, such as cleaning, of many different types of filter media becomes difficult.

In addition, similar filters in which a large number of particles are compressed are prone to becoming clogged with dirt, and it is difficult to remove the dirt causing the clogging.

Disclosure of Invention

The present invention has been made in view of the above problems. The object of the present invention is to provide a filter device in which clogging does not easily occur, unevenness (inevenness) does not occur in a filter medium, and stable filter characteristics are maintained for a long time.

Another object of the present invention is to provide a filtering apparatus in which cleaning and rinsing operations of a filtering medium can be efficiently performed in a short time, thereby facilitating maintenance and management thereof.

The filter device according to the invention comprises: a filter canister having a filter bed for supporting a first layer of granular filter media; and a cleaning mechanism, the cleaning mechanism comprising: a vertically positioned hollow cleaning tank disposed within the filter tank, a cleaning device for conveying a first filter medium upwardly within the cleaning tank while cleaning the filter medium, and a dirt discharge device for discharging dirt separated from the first filter medium to the outside of the filter tank during cleaning; wherein during normal cleaning, liquid that has been filtered by the filter media is drained through the filter bed; the filter bed comprises two vertically separated filter beds; the upper filter bed includes a plurality of liquid passage sections sized such that the first filter media cannot pass through the liquid passage sections; and a second filter medium layer is arranged between the two filter beds, and the size of the second filter medium layer is larger than that of the first filter medium layer.

It is preferable to adopt a configuration in which the cleaning means comprises a screw conveyor suspended at an upper portion of the filter tank; and the screw conveyor is configured to be rotated by a driving part provided at an upper portion of the filter tank. Preferably, the lower end of the auger rotating shaft is shaped as an arcuate surface. It is to be noted that the lower end of the rotating shaft of the screw conveyor may be supported from below.

Preferably, the upper filter bed is a wire mesh member having openings constituting the liquid passage portion.

It is preferable to adopt a configuration in which a plurality of filters for discharging filtered liquid are provided at the lower ends of the two filter beds. Preferably, the strainer has an umbrella portion at an upper portion thereof, and a tank for passing liquid is provided in the umbrella portion.

A configuration may be adopted in which the filter device further comprises a liquid ejecting section provided on an outer wall of the filter canister for externally ejecting the second filter medium disposed between the two filter beds; wherein the cleaning liquid is sprayed toward the second filter medium layer through the liquid spraying portion so as to separate the contaminants attached to the second medium by the cleaning liquid flow.

Preferably, the liquid ejecting section is disposed at an angle in a plane substantially perpendicular to the filter bed. Preferably, the liquid ejecting portions are provided at substantially equal intervals along the outer periphery of the filter canister.

A configuration may be adopted in which the vibration device further includes: vibration generating means for applying vibration to a second filter medium disposed between the two filter beds; wherein the vibration generated by the vibration generating means is propagated toward the second filter medium layer to separate contaminants attached to the second filter medium by the vibration applied thereto.

Alternatively, the ultrasonic generator may be mounted to the filter canister and the contaminants attached to the second filter medium may be separated by vibration generated by ultrasonic waves.

The filtering apparatus of the present invention comprises: a filter tank having a filter bed; and a filter media cleaning mechanism, the filter media cleaning mechanism comprising: a hollow cleaning tank; cleaning means within the canister; and a filth discharge device.

The filter bed through which filtered water passes comprises two vertically separated filter beds. The upper filter bed includes a plurality of liquid passage sections sized such that the first filter media cannot pass through the liquid passage sections; a second layer of filter media is disposed between the two filter beds, the second layer of filter media being larger in size than the first layer of filter media. The filtering apparatus of the present invention has the following advantageous effects.

That is, the first and second filter media are separated by two vertically separated filter beds. The first filter medium disposed on the upper filter bed has a smaller diameter than the second filter medium disposed between the two filter beds. Thus, the smaller first filter medium is prevented from falling into the second filter medium by the upper filter bed. Therefore, the filter medium is one in which clogging does not easily occur and a large number of layers are not provided. In addition, the second filter medium disposed between the two filter beds is confined within a predetermined sealed space defined by the two filter beds. Therefore, even when the first filter medium of a smaller diameter is cleaned, unevenness is not generated in the second filter medium of a larger diameter. As a result, consistent filtration can be maintained and the filtration efficiency of the filtration device is improved. Even in the case where a small amount of the first filter medium falls through the upper filter bed into the lower second medium layer, the first filter medium does not pass through the second filter medium. Therefore, there is no possibility that the filter medium becomes mixed into the filtered water. In addition, clogging by dirt is not easily caused in the second filter medium of large diameter.

A configuration may be adopted in which the cleaning device includes a screw conveyor suspended at an upper portion of the filter tank; the screw conveyor is configured to be rotated by a driving part provided at an upper portion of the filter tank. In this case, the first filter medium can be cleaned by scrubbing by the screw conveyor. Therefore, the first filter medium can be easily cleaned, which facilitates maintenance and management. In addition, there is no possibility that unevenness occurs in the second filter medium, which is located below the upper filter bed, even if the first filter medium is cleaned by the rotary screw conveyor two.

A configuration may be adopted in which the upper filter bed is a mesh having meshes constituting the liquid passage portion. In this case, the opening area ratio of the filter bed is large. Therefore, even if the dirt in the raw water is highly concentrated, clogging does not occur. Accordingly, the filtered liquid can effectively pass through the upper filter bed. In addition, during backwashing cleaning, cleaning water can be sprayed uniformly from the filter bed. Therefore, the rinsing efficiency is improved and the rinsing operation can be completed in a short time.

A configuration may be adopted in which a plurality of filters for discharging filtered liquid are provided at lower portions of the two filter beds. In this case, a relatively large portion of the liquid passage through which the larger second filter medium cannot pass may be formed in the filter. Therefore, the filter device can further reduce the possibility of clogging. In addition, when the cleaning water is backwashed, the contaminants caught in the liquid passage portion of the filter can be easily removed.

A configuration may be adopted in which the filter device further comprises a liquid ejecting section provided on an outer wall of the filter canister for externally ejecting the second filter medium disposed between the two filter beds; wherein the cleaning liquid is sprayed toward the second filter medium layer through the liquid spraying portion so as to separate the contaminants attached to the second medium by the cleaning liquid flow. In this case, the second filter medium disposed between the two filter beds can be effectively cleaned in a short time without being discharged from the filter tank. Therefore, the maintenance and the management of the filtering device are greatly convenient.

A configuration may be adopted in which the filter device further includes vibration generating means for applying vibration to the second filter medium disposed between the two filter beds; wherein the vibration generated by the vibration generating means is propagated toward the second filter medium layer to separate contaminants attached to the second filter medium by the vibration applied thereto. Also in such a case, the second filter medium disposed between the two filter beds can be effectively cleaned in a short time and is not removed from the filter tank. Therefore, the maintenance and the management of the filtering device are greatly convenient.

In this way, the filter device of the present invention can perform cleaning and rinsing of the filter medium very efficiently. For example, the filter device of the present invention is capable of performing a cleaning operation in about one third of the time required to separate dirt from the media using only backwash cleaning stream shear (stream shear). Accordingly, in the case where the cleaning operation is performed every day, the difference in the total amount of time spent on the cleaning operation a year, that is, the time that it can be reduced becomes very large. This beneficial effect is very important from the point of view of filtration efficiency and energy consumption for cleaning. Therefore, the filter sand does not float due to the water flow and the dirt can be stably captured.

Drawings

FIG. 1 is a vertical cross-sectional view of a filter apparatus according to a first embodiment of the present invention;

FIG. 2 is a plan view of a filter canister of the filter apparatus of FIG. 1;

FIGS. 3A and 3B show a lower filter bed, wherein FIG. 3A is a plan view of one half of the lower filter bed and FIG. 3B is a cross-sectional view taken along line 3B-3B of FIG. 3A;

FIGS. 4A and 4B show a wire mesh used as an upper filter bed, wherein FIG. 4A is a plan view of one half of the upper filter bed, and FIG. 4B is a sectional view of the main elements of a canister including the wire mesh taken along the line 4B-4B in FIG. 4A;

fig. 5A and 5B show the fitting portions of two sheets of the screen shown in fig. 4, wherein fig. 5A is a partially enlarged view of the fitting portions with screws omitted, and fig. 5B is an enlarged sectional view taken along the line 5B-5B in fig. 5A;

fig. 6A and 6B illustrate a mounting portion of a wire mesh for a filter canister, wherein fig. 6A is a partially enlarged plan view, and fig. 6B is an enlarged sectional view taken along line 6B-6B of fig. 6A;

FIGS. 7A and 7B show a clamping bolt for mounting the screen of FIG. 4, wherein FIG. 7A is an enlarged plan view of the clamping bolt and FIG. 7B is an enlarged side view of the clamping bolt;

FIG. 8 is a vertical cross-sectional view of a filter apparatus according to a second embodiment of the present invention;

FIG. 9 is a schematic view of a complete filtration apparatus of the present invention showing the relationship of the tubes connected to the filtration tank;

FIG. 10 is a timing flow chart showing the relationship between each step from the filtration process to the cleaning process and the operation of each element of the filtration apparatus;

FIG. 11 is a schematic view of a complete filtration apparatus similar to FIG. 9 showing the relationship of the tubes connected to the filtration tank;

FIG. 12 is a timing flow chart showing the relationship between each step from the filtration process to the cleaning process and back to the filtration process and the operation of each element of the filtration apparatus shown in FIG. 11;

FIG. 13 is a vertical cross-sectional view of a variation of the filter apparatus of FIG. 1;

fig. 14 is an enlarged view of the main elements of the filter device shown in fig. 13.

Detailed Description

The filter device of the present invention is described below with reference to the accompanying drawings. Fig. 1 is a vertical sectional view of a filter device according to a first embodiment of the present invention. Fig. 2 is a plan view of a filter canister of the filter apparatus of fig. 1. The following description is made with reference to fig. 1 and 2.

As shown in fig. 1, a filter device 1 according to a first embodiment of the present invention includes: a canister 2, the canister 2 being generally a cylinder having a sealed top and bottom; horizontally arranged and vertically spaced wire nets (filter beds) 50 and 4 provided at a lower portion of the inside of the filter tank 2; and a filter medium cleaning mechanism 6 (hereinafter simply referred to as "cleaning mechanism") mounted on the curved upper wall 20 of the filter tank 2. The cleaning mechanism 6 includes a motor 26, a brake mechanism 27, a base frame 28, a cleaning tank 38, and an auger 32 (to be described later in detail), which will be described below. The cleaning mechanism 6 further includes a filtered water discharge pipe 46 serving as a dirt discharge means, and a raw water supply pipe 56.

Four support legs 8 (only one shown in figure 1) are mounted on the canister 2. Support legs 8 position the canister 2 on the ground 10. The filter bed 4 is disposed at a distance from the curved bottom wall of the filter tank 2. A plurality of filters 12 for collecting and transferring downward the filtered liquid (filtered water) are provided in the filter bed 4 (refer to fig. 1). It should be noted that the details of the filter bed 4 and the filter 12 will be described later. The raw water supply pipe 56 shown in fig. 1 is located on the right side of the filter tank 2 and is L-shaped with its supply opening facing upward. However, the supply tube may be formed in other shapes.

A layer of the filter medium 14 (filter sand) for filtering the raw water from the raw water supply pipe 56 is provided on the screen 50. The screen 50 has a mesh size smaller than the particles of the filter media 14 so as to prevent the filter media 14 from falling downwardly therethrough. Specifically, the filter media 14 has a particle diameter of substantially 0.4 millimeters to 2 millimeters. Preferably, the filter media 14 has a particle diameter in the range of 0.6 mm to 1 mm. The mesh size is set to a size that does not allow the filter media 14 having a maximum diameter of 2 millimeters to pass downward through it. The detailed structure of the screen will be described later.

A layer of gravel (gradient) having a larger diameter than the filter medium 14, i.e., a layer of filter medium 54 (support layer), is disposed in the space 52 between the wire mesh 50 and the filter bed 4. Filter media 54 serves as a support for supporting filter media 14. Particles having a diameter in the range of about 2 mm to 4 mm are selected for use as the filter media 54. Accordingly, the raw water flowing from above passes through the layer of the filter medium 14, the wire mesh 50, the layer of the filter medium 54 and the filter 12 to flow downward from the filter bed as filtered liquid. The entire layer of filter media 54 is covered by the mesh 50 and is not able to move toward the layer of filter media 14. Therefore, no unevenness is generated therein, the water flow can be dispersed and uniform filtration can be performed. In the case of the present embodiment, the height of the filter tank 2 is approximately 2 meters and the height of the space 52 is approximately 13 centimeters.

A circular mounting opening 22 is formed in a central portion of the upper wall 20 of the canister 2. The cleaning mechanism 6 is mounted to the mounting opening 22 by bolts (not shown). The periphery of the mounting opening 22 is formed as a mounting edge 24. A base frame 28 on which the motor 26 and the brake mechanism 27 are provided is mounted on the rim 24 (refer to fig. 1). A retaining portion 36 including a plurality of bearings 30 is formed within the base frame 28. The shaft 34 of the auger 32 (cleaning device) is supported by the bearing 30 so as to be able to rotate without axial displacement. Note that the motor 26 and the brake mechanism 27 are collectively referred to as a driving portion.

The cleaning mechanism 6 will be described in detail next. The cylindrical cleaning tank 38 of the cleaning mechanism 6 has a mounting wall 29 of a discoid shape or a disk shape at an upper portion thereof. The mounting wall is mounted to the rim 24 with a pedestal 28 by bolts (not shown). In the figure, the bolts will be indicated with centre lines indicating their position. When the upper portion of the cleaning tank 38 is mounted to the rim 24 in this manner, the entirety of the cleaning tank 38 becomes generally suspended to the upper portion of the filter tank 2.

As shown in FIG. 1, the lower portion of the cleaning tank 38 is an open circular lower opening 40. A plurality of vertically extending upper openings 42 are formed at predetermined intervals along the outer periphery of the upper portion of the cleaning tank 38. The positional relationship of the lower opening 40 and the filter media 14 is determined such that the lower opening 40 is located within the filter media 14. The auger 32 is located inside the cleaning tank 38. The shaft 34 of the screw conveyor 32 is constituted by a small diameter portion 34a having a relatively small diameter, and a large diameter portion 34b having a relatively large diameter.

Shaft 34 is connected to motor 26 by coupling 49. The large diameter portion 34b provided for increasing the strength of the shaft 34 is formed as a hollow tube having a sealed lower end 44. Preferably, the lower end 44 is formed as an arcuate surface, such as a spherical surface. By forming the lower end 44 into an arcuate surface, vortices (vortices) are prevented from being generated during rotation of the auger 32 to perform cleaning. Thereby, unnecessary agitation of filter media 14 contacting lower end 44 can be avoided. A helical screw blade 43 is formed on the large diameter portion 34b of the shaft 34. The vane 43 is formed such that it extends to the vicinity of the lower end 44 of the shaft 34.

When the blade 43 of the screw conveyor 32 is disposed in the cleaning tank 38 in such a manner that the upper end of the blade 43 is located in the vicinity of the lower edge 42a of the upper opening 42, as shown in fig. 1. In addition, the lower end portion 35 of the screw conveyor 32 projects downward from the lower opening 40 of the cleaning tank 38, and the lower end 44 of the shaft 34 is located near the screen 50. The reason for this positioning is that efficient upward transport of the filter medium 14 in the vicinity of the screen 50 can be performed during cleaning of the filter medium 14.

The outer edge of the blade 43 is placed to form a slight gap between it and the inner peripheral surface of the cleaning tank 38. The size of the gap is approximately three times the particle diameter of the filter media 14. The gap is provided to reduce the likelihood of the filter media 14 being crushed in the event that the filter media 14 becomes trapped between the vanes 43 and the cleaning tank 38.

Next, elements of the filter device 1 connected to the outside of the filter tank 2 will be described. A downwardly extending filtered water discharge pipe 46 is mounted in the center of the curved bottom wall 9 of the filter tank 2. The liquid which has passed through filter medium 14, wire mesh 50, filter medium 54 and filter 12 and which has been filtered thereby is discharged through filtered water discharge pipe 46. A cleaning water injection pipe 58 (liquid injection section) is installed on the outer wall of the filter tank 2 between the wire net 50 and the filter bed 4. A vent valve 81 for discharging air from the inside of the filter canister 2 is provided in the upper portion of the filter canister 2.

As shown more clearly in fig. 2, the cleaning water spray pipes 58 are installed at four positions along the outer periphery of the filter tank 2, the four positions being shown with equidistant intervals therebetween. The cleaning water injection pipe 58 is installed at an angle with respect to the outer wall of the filter tank 2. The cleaning water is strongly sprayed from the outside of the filter tank 2 toward the inside thereof so as to generate a vortex therein. This strong water flow separates the dirt from the filter media 54 within the space 54 to clean the filter media 54. The cleaning water may be filtered water from a filtered water discharge pipe, or may be cleaning water supplied from a different supply source (not shown). This cleaning will be described in detail later.

Next, the filter bed 4 will be described with reference to fig. 3A and 3B. Fig. 3A and 3B show the filter bed 4, wherein fig. 3A is a plan view of one half of the filter bed 4 and fig. 3B is a cross-sectional view of the filter bed 4 taken along line 3B-3B in fig. 3A. The filter bed 4 is made of, for example, four stainless steel plates. That is, the filter bed 4 is constituted by a pair of half-moon shaped portions 4a and 4b (only half of the half-moon shaped portions 4a and 4b are shown in fig. 3A) and a pair of substantially rectangular shaped portions 4c (only one substantially rectangular shaped portion 4c is shown in fig. 3A). Accordingly, the filter bed 4 is discoidal or disc-shaped and is linearly symmetrical with respect to the diameter shown in fig. 3A. One side of each substantially rectangular portion 4c is formed as an arc-shaped portion 47.

A plurality of holes 60 are provided in the filter bed 4. The filter 12 is disposed within the bore 60. In addition, a plurality of small holes 62 for fastening screws therein are provided along the outer periphery of each of the portions 4a, 4b and 4 c. Meanwhile, an annular mounting ring 64 is provided along the inner periphery of the filter canister 2. A threaded hole 63 corresponding to the small hole 62 is formed in the mounting ring 64. In addition, a support beam 66 having a T-shaped cross-section is mounted inside the filter tank 2 along the seams of the sections 4a, 4b and 4 c. Threaded holes 63 are also formed in the support beam 66. Screws 61 are threaded through apertures 62 into threaded holes 63 to secure portions 4a, 4b and 4c and thereby mount ring 64 and support beam 66.

A support beam 67 having a T-shaped cross section is connected to the support beam 66 and is disposed perpendicularly thereto at the center of a portion corresponding to the diameter of the filter tank 2. Threaded holes 63 are also formed in the support beam 67. The portion 4c is fixed to the support beam 67 by the screw hole 63. The support beams 68 are also disposed on either side of the support beam 67 in fig. 3B. However, the support beam 68 is only used to support the load of the sections 4a and 4b, and the sections 4a and 4b are not fixed to the support beam 68.

Next, a filter provided in the filter bed 4 will be described. The filter 12 is commercially available under the product name "AB" filter and is made of ABS resin. The filters 12 are formed as tubes, their ends 18 being formed as hollow umbrellas. A plurality of narrow concentric grooves 19 (liquid passage portions) are formed in each umbrella portion 18, and the filter media 54 cannot pass through the grooves 19. The slots 19 only allow filtered liquid to pass down through the filter bed 4.

It should be noted that the tank 19 is shown only in the central filter 12 in fig. 3B. The thread is formed in the pipe portion. A nut 65 threadably engages the threads of the tube portion and cooperates with the umbrella portion 18 to secure the strainer 12 to the filter bed 4. The flutes 19 are sized to not allow passage of the filter media 54 and they are larger than the filter media 14. Therefore, the groove 19 is formed to have a width in which clogging by dirt is unlikely to occur. The advantageous effects obtained by forming the grooves 19 in the umbrella part 18 will be described later.

The screen 50 is described in detail next with reference to fig. 4A, 4B, 5A, 5B, 6A, 6B, 7A, and 7B. Fig. 4A and 4B show the wire mesh 50 installed in the filter canister 2, wherein fig. 4A is a plan view of half of the wire mesh 50, and fig. 4B is a sectional view of the main elements of the filter canister including the wire mesh 50 taken along the line 4B-4B in fig. 4A. Fig. 5A and 5B show the fitting portion of the two sheets of screens 50, in which fig. 5A is a partially enlarged view of the fitting portion with the screws omitted, and fig. 5B is an enlarged sectional view taken along the line 5B-5B in fig. 5A. Fig. 6A and 6B show a mounting portion of the wire net 50 for the canister, in which fig. 6A is a partially enlarged plan view, and fig. 6B is an enlarged sectional view taken along line 6B-6B in fig. 6A. Fig. 7A and 7B show a clamping bolt for mounting the screen 50, wherein fig. 7A is an enlarged plan view of the clamping bolt, and fig. 7B is an enlarged side view of the clamping bolt.

First, referring to fig. 4A, the screen 50 is composed of three flat stainless steel portions. That is, the screen 50 is made up of two half moon shaped portions 50a and 50b and a single generally rectangular portion 50c, the generally rectangular portion 50c being shown with opposed arcuate portions 53. Each of the sections 50a, 50b and 50c has a lattice-like mesh 51 (liquid passage section) and a stainless steel frame 70 along its periphery. The mating portions 71 are identical for all parts, and the frame 70 of each of the portions 50a, 50b and 50c abuts at the mating portions 71. Thus, the mating portion 71 between the portions 50a and 50c will be described with reference to fig. 5A and 5B.

As shown in fig. 5A, opposing semicircular cutouts 72 are formed in the frame 70 of section 50a and in the frame 70 of section 50c so that they are aligned with each other. A circular opening 73 is formed in the adjoining frame 72 by the cutout 72. A screw 74 having a rectangular flange 75 is inserted into the opening 73 from the underside of the screen 50. A frame pressure plate 76 extending along the length of the frame 70 is mounted to the screws 74. The frame pressing plate 76 has a screw hole 77, and the screw 77 is inserted into the screw hole 77. A washer 79 and a nut 80 are mounted to the screw 74 to secure the screw 74 to the frame 70. Thereby, the portion 50a and the portion 50c are integrally joined.

The circular wire mesh 50 constructed in this manner is then installed into the filter canister 2. The structure of this mounting configuration will be described with reference to fig. 6A, 6B, 7A, and 7B. As shown in fig. 6A, inwardly protruding protrusions 82 are formed at predetermined intervals on the outer peripheral frame 70 of the screen 50. A long hole 83 extending in the radial direction of the screen 50 is formed in each of the projections 82. The screen 50 is secured to the filter canister 2 by fitting clamping bolts 84 onto these projections 82.

The clamp bolt 84 is rectangular in plan view as shown in fig. 7A, and has an L-shaped head 85 when viewed from the side as shown in fig. 7B. A circular opening 86 is formed in the head 85. The bolts are welded into the openings 86 to form the clamping bolts 84, which are shown in their entirety in fig. 7A and 7B. The jaw or neck 87 of the clamping bolt 84 is formed as a square block.

Referring again to fig. 6A and 6B, a mounting ring 88 (see fig. 6B) is provided along the inner periphery of the filter canister 2. The clamping bolts 84 are mounted to the frame 70 of the screen 50. At this time, the clamping bolt 84 is mounted to the frame 70 so that the projecting portion 85a of the head 85 is oriented away from the mounting ring 88. The mounting ring 88 is sandwiched between the clamping bolt 84 and the screen 50, the washers 89 and 90 are installed and the nuts 91 and 92 secure the screen 50 to the mounting ring 88. A square protrusion 89a located inside the long hole 83 is provided on the lower surface of the washer 89. With this configuration, the frame 70 is positioned in the radial direction of the filter canister 2 corresponding to the clamp bolt 84. Thereby, the wire mesh is held within the filter canister 2 and does not move in the radial direction.

A modification of the filter device 1 shown in fig. 1 is described below with reference to fig. 13 and 14. FIG. 13 is a vertical cross-sectional view of a variation of the filter apparatus of FIG. 1; fig. 14 is an enlarged view of the main elements of the filter device 200 shown in fig. 13. The modified filter apparatus 200 includes a filter canister 202; a filter media cleaning mechanism 206; a cleaning tank 238 connected to the filter media cleaning mechanism 206; and an auger 232 disposed within the cleaning tank 238. The filter device 200 mainly differs from the filter device 1 shown in fig. 1 in that the auger 232 and the cleaning tank 238 are engaged with each other at their lower ends. In other words, the lower end 235 of the auger 232 is supported by the support 207 provided at the lower end of the cleaning tank 238. In this modification, axial displacement and vibration during rotation of the auger 232 are prevented because the auger 232 is supported by the support 207.

The support structure of the auger 232 will be further described with reference to fig. 14. A metal shaft 236 is welded to the lower end 233 of the auger 232. The shaft 236 includes: a discoid or disk-shaped base 237; and a shaft 239 integrally formed with the base 237 at the center thereof. The central axes of the shaft 239 and the auger 232 are coaxial.

Meanwhile, an annular plate, i.e., a ring 208, is fixed by welding to the lower end of the cylindrical cleaning tank 238. A plurality of threaded holes 205 are disposed at uniform intervals along the circumference of ring 208. The support 207 is mounted to a ring 208. The support 207 includes: an annular mounting ring 213 in which a hole 209 corresponding to the threaded hole 205 is formed; a housing 248 for accommodating the shaft 239; and a plurality of radial struts (stabs) 249 connecting housing 248 with mounting ring 213. The support 207 is secured by screws 210 into threaded holes 205 of a ring 208.

The housing 248 has a recess 255, the recess 255 being defined by an upwardly open circular inner wall and a bottom wall 248 a. The center of the recess 255 matches the center of rotation of the auger 232. Cylindrical bearings 258 are disposed flush with the inner wall of recess 255. The inner diameter of the bearing 258 is sized to matingly couple with the shaft 239. An annular stepped portion 260 is formed at an open end of the recess 255, and a seal 262 in close contact with the shaft 239 is provided on the annular stepped portion 260. An annular flange 264 is formed on the outer periphery of the upper end of the housing 248. A pressure plate 266 is secured to flange 264 by screws (not shown) to prevent the seal 262 from coming out. An opening 265 for receiving the shaft 239 is formed in the platen 266. Therefore, the platen 266 does not interfere with the auger 232.

The auger 232 is supported by the support 207 in the manner described above. Thus, when the auger 232 rotates, the shaft 239 rotates while being supported by the bearing 258, thereby preventing axial displacement of the lower end portion 239. Preferably, the lower end 239a of the shaft 239 is spaced from the bottom wall 248 a. This configuration is preferred because no downward load is applied to the shaft 239 and separation from the bottom wall 248a prevents frictional resistance during rotation.

Preferably, the bearing 258 is formed of tetrafluoroethylene resin (ethylene trafluoride resin) with a filler material, such as oils Glitron F^TM. However, the material may be any other suitable synthetic resin or metal. The tetrafluoroethylene resin has high wear resistance and a low friction coefficient, and is suitable as a bearing for the filter device 200. In addition, tetrafluoroethylene resin is in accordance with the food hygiene law. Therefore, it is very suitable for the case where the filtered water is used as drinking water or the like.

Next, referring again to fig. 1, a manner in which filtration is performed in the refilter tank 2 will be described. First, raw water is supplied from the raw water supply pipe 56 into the filtration tank 2. When the level of the raw water rises, the air in the filter tank 2 is discharged through the vent valve 81. In the present embodiment, the water level is set to be higher than the raw water supply pipe 56 and reaches the upper portion of the filter tank 2. That is, the water level is set so that the entire filter tank 2 is substantially filled with water 16 (raw water). The raw water permeates through the filter medium 14. Raw water also enters the cleaning tank 38 through the upper opening 42 to permeate through the filter media 14 within the cleaning tank 38, thereby enabling filtration within the cleaning tank 38 as well.

The water that has permeated through the filter medium 14 and has been filtered thereby passes through the wire mesh 50, permeates through the layer of the filter medium 54, passes through the filter bed 4 via the filter 12, and is discharged to the outside through the filtered water discharge pipe 46 at the lower portion of the filter tank 2 so as to be provided for use.

Next, a method for cleaning the filter medium 14 when clogging occurs in the filter medium 14 after a long period of use will be described. First, filtered water is backwashed from filtered water discharge pipe 46 so that the filtered water is sprayed into filter medium 14 through filter medium 54. The flow of filtered water causes the filter media 14 to float. Thereby reducing the load on motor 26 during start-up. Next, the motor 26 is driven, and the screw conveyor 32 is rotated. The filter medium 14 is pressed up into the cleaning tank 38 by the blades 43 of the screw conveyor 32, particularly by the portion of the blades 43 that protrudes below the cleaning tank 38.

The backwashing of the filtered water is continued at the initial stage of the rotation of the screw conveyor 32. This is because, due to the centrifugal force of the screw conveyor 32, the mixing of the filter media 14 at the radially inner and outer portions of the cleaning tank 38 is promoted by the rotation of the screw conveyor 32 in the backwashing cleaning state. At the same time, the entire filter medium 14 is completely cleaned by this movement. Thereafter, the backwash of the filtered water continues at an extremely low speed by reducing the flow rate to a level that does not allow the contaminants to fall into the filter 12. The rotation of the auger 32 continues to clean the filter media 14.

The particles of the filter medium 14 are conveyed upward while being rubbed and scrubbed against each other by the rotation of the auger 32, and discharged from the upper opening 42 to the outside of the cleaning tank 38. The separation of the contaminants from the filter medium 14 is enhanced by the collision of the filter medium 14 with the surface of the water within the filter tank 2. The filter medium 14 that has fallen back into the filter tank 2 is repeatedly conveyed upward into the cleaning tank 38 and scrubbed therein. In this manner, dirt is separated from the filter media 14 by repeated cleaning within the cleaning tank 38. As shown in fig. 1, the lower end 44 of the auger 32 is positioned adjacent the screen 50. Accordingly, the filter medium 14 near the screen 50 is also conveyed upward, thereby completely cleaning the entire filter medium 14.

When the cleaning is completed, the filtered water is backwashed again from the filtered water discharge pipe 46 so that the rinsing operation is performed. The backwashing rinsing operation is continued after the rotation of the screw conveyor 32 is stopped. The backwash liquid from the filtered water discharge pipe 46 is sprayed through the slots 19 of the filter 12 in the filter bed 4 into the layer of filter media 54. The liquid further passes through the screen 50 and rises into the filter media layer 14. Dirt that has been trapped in the filter 12 is also easily removed by backwashing of the liquid through the tank 19.

The filth separated from the filter medium 14 floats and is discharged to the outside with the water containing the filth. The cleaning water is also efficiently backwashed through the inside of the cleaning tank 38 by passing through the gaps of the blades 43. Therefore, the dirt in the cleaning tank 38 is also discharged. During the backwash rinse, the cleaning water sprayed from the basin 19 of the filter 12 permeates the layer of filter media 54 uniformly. That is, the groove 19 is formed in the umbrella portion 18 of the filter 12. Therefore, the cleaning water is sprayed over a wide range at various angles on the periphery of the strainer 12. For this reason, the cleaning operation and the rinsing operation can be effectively performed.

During the rinsing operation, the cleaning water is intensively sprayed between the two filter beds 50 and 4 of the filter tank 2 from the cleaning water supply pipe 58. The sprayed clean water forms a vortex within the layer of filter media 54. Contaminants adhering to the filter media 54 are separated therefrom by the vortex exposed to the water. The separated dirt passes through the wire mesh 50 and flows upward. Dirt is prevented from falling below the filter bed 4 because filtered water from the filtered water discharge pipe 46 is being sprayed through the filter 12. The cleaning water sprayed from the tank 19 at this time is also useful in effectively discharging the contaminants separated from the filter media 54 upward. All the soil is removed from the filter tank 2 by continuous backwash rinsing for the necessary time. It should be noted that specific steps of each step extracted from the filtering process to the cleaning process and back to the filtering process will be described later.

In the case of the modified filter device 200 shown in fig. 13 and 14, the filter medium 14 is cleaned by the same cleaning process as that used for the filter device 1 shown in fig. 1. However, the behavior of the filter media during cleaning is slightly different. Therefore, the differences will be described below.

In the case of the auger 232 of the filtering apparatus 200, the lower end portion thereof protrudes downward from the cleaning tank 238. To this end, a rectangular lower opening 241 (refer to fig. 14) is formed at the lower portion of the cleaning tank 238 in order to facilitate the suction of the filter media 14 into the cleaning tank 238. A predetermined number of lower openings 241 are formed at the periphery of the cleaning can 238 at equal intervals.

The filtered water is sprayed in an initial step of the cleaning process to float the filter media 14. Then, the auger 232 rotates. At this time, the floating filter media 14 enters the cleaning tank 238 through the lower opening 241. The filter media 14 having entered through the lower opening 241 are conveyed upward by the vane 243 while being rubbed and scrubbed with each other. During the backwash rinse, filtered water from between struts 249 also enters cleaning tank 238 through lower opening 241. As a result, the filter media within filter canister 238 also floats. The other operations of the filter device 200 are the same as the filter device 200 of fig. 1.

Next, a filter device according to a second embodiment of the present invention will be described with reference to fig. 8. Fig. 8 is a vertical sectional view of a filter device 100 according to a second embodiment of the present invention. It should be noted that the same elements of the filter device 100 as those in the first embodiment are denoted by the same reference numerals. The filter device 100 of the second embodiment is mainly different from the filter device 1 of the first embodiment shown in fig. 1 in that a vibration generator 102 is installed between the two filter beds 50 and 4 on the outer wall of the filter tank. It should be noted that only one vibration generator is shown in fig. 8.

The vibration generator 102 is mounted to the filter canister 2 via a mounting base 104. When the vibration is generated by the vibration generator 102, the vibration propagates from the outer wall of the filter tank 2 to the layer of the filter medium 54 and vibrates the filter medium 54. As a result, the contaminants adhered to the filter medium 54 are separated therefrom. That is, the filter media 54 is cleaned by vibration. The vibration occurs during the backwashing rinsing operation. That is, the vibration occurs while the filtered water is being backwashed from the filtered water discharge pipe 46. Dirt separated from the filter media 54 passes through the wire mesh 50, the filter media 14 and is discharged through the raw water supply pipe.

Any vibration generators may be used as long as they provide vibrations of a frequency and amplitude effective in separating dirt from the filter media 54. Preferably, a plurality of generators, such as two or three generators, are positioned at equidistant intervals along the outer periphery of filter canister 2 so as to propagate vibrations toward the center of the layer of filter media 54. The vibration generator 102 may be used alone or in combination with the clean water injection tube 58.

Next, specific examples of each step from the filtering process common to the first and second embodiments to the cleaning process and back to the filtering process will be described with reference to fig. 9 and 10. Fig. 9 is a schematic view of the entire filter device 1' of the present invention, showing the relationship of the pipes connected to the filter canisters 2. Fig. 10 is a graph showing the relationship between each step taken from the filtering process to the cleaning process and back to the filtering process and the operation of each element of the filter device 1'.

First, the connection relationship of each pipe and the canister 2 will be described with reference to fig. 9. The pipe 110 connected to the raw water pump P1 is connected to the raw water supply pipe 56 of the filter tank 2. A raw water valve V1 that opens and closes a flow path is installed in the pipe 110. In addition, a tube 114 extending to the drain tank 112 is connected to the tube 110. A discharge water valve V3 is disposed within tube 114. A pipe 116 having a filtered water valve V2 is connected to the filtered water discharge pipe 46 at the center of the lower end of the filter tank 2. Filtered water is discharged from pipe 116. It should be noted that each of the valves shown in fig. 9 is driven by a motor denoted by "M". In addition, a flow meter provided in the flow path is denoted by "F".

The pipe 118 connected to the backwash pumps P2 and P3 is connected to the pipe 116. A backwash valve V4 is mounted in the pipe 118. The pipes 118a and 118b are connected to a remote location of the pipe 118, and backwash pumps P2 and P3 are connected to the pipes 118a and 118b, respectively. A pipe 120 having a water level regulating valve V5 connects the pipe 116 and the pipe 114 so as to communicate the pipe 116 and the pipe 114 with each other. At least one drain pipe 5 is provided on the side wall 3 of the filter tank 2 at a position above the filter bed 4. The pipe 122 having the water level regulating valve V6 is connected to the discharge pipe 5. Tube 122 is connected to tube 120. In addition, a pipe 124 having a waste water valve V7 is provided between the pipe 116 and the pipe 120 so as to communicate the pipe 116 and the pipe 120 with each other.

Each step from the filtration process to the cleaning process and back to the filtration process is described next. First, the operation state of each element of the filtering apparatus 1' during normal filtration will be described with reference to fig. 10. Note that, in fig. 10, hatched portions indicate that the respective elements are in an operating state, and horizontal lengths of the hatched portions represent the passage of time. As can be understood from fig. 10, both the raw water valve V1 and the filtered water valve V2 are open during normal filtration, and the raw water pump P1 is in operation. That is, referring to fig. 9, the raw water 16 is supplied to the pipe 110 by the raw water pump P1, passes through the open raw water valve V1, and is supplied to the filter tank 2 through the raw water supply pipe 56. The raw water 16 supplied to the filter tank 2 passes through the layers of the filter media 14 and the filter media 54 to be filtered thereby, and is discharged from the filtered water discharge pipe 46. The discharged filtered water passes through the pipe 116, passes through the opened filtered water valve V2, and is discharged. During the filtration, the raw water 16 is higher in level than the supply opening 56a of the raw water supply pipe 56. The filtration tank 2 may be filled with raw water 16.

Next, when switching from the normal filtering process to the cleaning process, the water level is previously adjusted as shown in fig. 10. The water level adjustment process lowers the water level in the filter tank 2 so as to effectively perform cleaning of the filter media 14 and the filter media 54. The raw water valve V1 and the filtered water valve V2 are closed during the level adjustment process. In addition, the operation of the raw water pump P1 is stopped. Thereby, the supply of the raw water 16 and the discharge of the filtered water are stopped. Therefore, the filter tank 2 is in a state in which liquid such as raw water 16 is stored therein. The valves V1 and V2 are motor-driven, and therefore, a certain amount of time is required for their operations to be completed.

Thereafter, the drain water valve V3, the water level adjustment valve V5, and the water level adjustment valve V6 are opened substantially simultaneously. When the discharge water valve V3 is opened, the raw water 16 located above the raw water supply pipe 56 passes through the pipe 110 and the pipe 114 to be discharged to the discharge water tank 112. In addition, when the water level regulating valves V5 and V6 are opened, the filtered water flows from the filtered water discharge pipe 46 and 5 to the pipes 116 and 122, and is discharged into the discharge water tank 112 through the pipe 120 and the pipe 114.

As shown in fig. 9, the water level regulating valve V5 is electrically connected to the water level gauge "LS". The water level regulating valve V5 is configured to close when the water level reaches a predetermined level. That is, the water level regulating valve V5 is closed at a time point shown by a dotted line 128 in fig. 10. Thereafter, the filtered water is discharged only in a small amount through the water level regulating valve V6. Note that air from the outside is introduced into the filter tank 2 through the vent valve 81 during the lowering of the water level. The introduction of air prevents the reduction of the water level lowering speed by preventing the inside of the filter tank 2 from becoming a negative pressure region. By simultaneously opening the discharge water valve V3, the water level regulating valve V5, and the water level regulating valve V6 in this manner, the discharge of the liquid can be conveniently performed, for example, in about two minutes. The water level can be lowered quickly and efficiently. The reduced water level is now below the level suitable for cleaning.

Next, as shown in fig. 10, the backwash valve V4 is opened and the backwash pump P2 is operated immediately after the water level adjustment valve V5 is closed. That is, filtered water passes from backwash pump P2 through pipes 118a, 118 and 116 and through filtered water discharge pipe 46 into filter tank 2. The backwash pump P2 has a large capacity. Thus, the backwash filtered water is sprayed into the filter media 14 with great force, causing the filter media 14 to float up near the cleaning tank 38. The process of flotation of the filter media 14 is a primary backwash process. As shown in fig. 10, after the backwash pump P2 is driven so as to reduce the resistance against the rotation of the auger 32, the motor 26 is driven to start the rotation of the auger 32.

After the driving of the backwash pump P2 is started, the motor 26 for rotating the screw conveyor 32 is driven for about five seconds. By driving the backwash pump P2, the water level in the filter tank 2 rises and reaches a level suitable for cleaning the filter medium 14 approximately 10 seconds after the start of driving. The water level at this point is 10 cm to 20 cm above the surface of the layer of filter media 14. This water level is lower than the supply opening 56a of the raw water supply pipe 56, which prevents the filter medium from being discharged through the raw water supply pipe 56 during a cleaning operation, which will be described later.

As shown in fig. 10, the cleaning process starts when the liquid in the filter tank 2 reaches a certain level. In this process, the operation of the backwash pump P2 is stopped and the backwash pump P3 having a lower capacity than the backwash pump P2 is driven. The water level regulating valve V6 is kept open, and thus the filtered water supplied by the backwash pump P3 is discharged from the discharge pipe 5. The filtered water discharged from the discharge pipe 5 passes through the water level adjustment valve V6 and is discharged into the discharge water tank 112. At this time, the filth at the bottom of the filter tank 2 and the filth separated from the filter media 54 are discharged from the discharge pipe 5 together with the filtered water. The amount of filtered water supplied by the backwash pump P3 and the amount of liquid discharged by the water level adjustment valve V6 are substantially the same. The motor 26 is continuously driven during the cleaning process and dirt is separated from the filter media 14 by the scrubbing action caused by the rotation of the auger 32. The cleaning process lasts about one minute.

Next, following the cleaning process, a process of rinsing the cleaned filter media 14 and 54, i.e., a secondary backwashing process, is started. In this process, the drain water valve V3 and the backwash valve V4 remain open, but the water level adjustment valve V6 is closed. The backwash pump P3 is stopped from driving and the high capacity backwash pump P2 is driven. Thereby, filtered water is again sprayed into the filter tank 2 from the filtered water discharge pipe 46 with a large force, and rinsing of the filter media 14 and 54 is started. After the drive of the backwash pump P2 is started, the motor 26 for rotating the screw conveyor 32 is stopped from being driven for about five seconds. The secondary backwash process lasts about five minutes. The filtered water flowing into the filter tank 2 from the backwash pump P2 passes through the raw water supply pipe 56, the pipe 110 and the pipe 114 to be discharged to the discharge water tank 112 together with the filth floated by the rinsing operation. At this time, the auger 32 is not driven, and thus there is no possibility that the filter medium 14 is agitated and flows out from the raw water supply pipe 56.

When the rinsing process, i.e., the secondary backwashing process, is completed, the wastewater process is started. In this process, the drain water valve V3 and the backwash valve V4 are closed and the backwash pump P2 is stopped from being driven. Thereby, the injection of the filtered water into the filter tank 2 and the discharge of the filtered water including the filth through the raw water supply pipe 56 are stopped. Next, the raw water valve V1 and the waste water valve V7 are opened, and the raw water pump P1 is driven. Thereby, the raw water 16 is supplied again from the raw water supply pipe 56 into the filtration tank 2. The filtered water in filter tank 2 passes through filtered water discharge pipe 46, pipe 124, waste water valve V7 and exits through pipe 120 and pipe 114 to a drain sump. This allows dirt floating on the bottom of the canister 2 to be discharged. The wastewater process may last from two minutes to twenty minutes depending on the purpose of the process.

It should be noted that during the wastewater process, the amount of raw water 16 flowing in is substantially the same as the amount of water flowing out through the pipe 124, and the raw water 16 is discharged relatively slowly. This is because if the raw water outflow speed is too fast, in other words, if the outflow is larger than the inflow, bubbles are generated in the filter medium 14 due to the negative pressure. If these bubbles are generated, they remain in the following filtration process and there is a possibility that the filtration through the filter medium 14 cannot be performed efficiently. The wastewater process completely discharges dirt, sludge, and the like remaining in the filter tank 2.

When the wastewater process is completed, the operation of the filtering apparatus is returned to the filtering process. That is, after the waste valve V7 is closed, the filtered water valve V2 is opened. The raw water valve V1 remains open and the raw water pump P1 is continuously driven, whereby the raw water 16 supplied from the raw water supply pipe 56 is discharged through the pipe 116.

Next, other specific examples of each step from the filtering process to the cleaning process and back to the filtering process, which are common to both the first and second embodiments, are described with reference to fig. 11 and 12. Fig. 11 is a general schematic view of a filter device 1 "similar to the filter device 1' in fig. 9, showing the relationship of the pipes connected to the filter canisters 2. Fig. 12 is a graph similar to fig. 10 showing the relationship between each step taken from the filtration process to the cleaning process and back to the filtration process and the operation of each element of the filter device 1 "in fig. 11. Note that, in the description, the same elements as those in fig. 9 are described with reference to the same reference numerals.

First, the connection relationship of each pipe to the canister 2 different from that in fig. 9 will be described with reference to fig. 11. In the filter device 1 "shown in fig. 11, the waste water valve V7 and the backwash pump P3 of the filter device 1" are eliminated, and the pipe 122 is formed straight. Further, valves capable of adjusting the degree of opening are used as the back washing valve V4 'and the water level adjusting valve V5', whereby the flow rate therethrough can be adjusted. As for the other elements, they are the same as those of the filter device 1' shown in fig. 9.

In more detail, only the high capacity backwash pump P2 is provided to the pipe 116, the pipe 116 is connected to the filtered water discharge pipe 46, and the low capacity backwash pump P3 is not used. Accordingly, only tube 118 and one-way valve 130 are used. Additionally, in the previous example, a pipe 124 having a waste valve V7 was disposed between pipe 116 and pipe 120. However, these elements are not used in this example.

This example is the same as the previous example in that the pipe 122 having the water level regulating valve V6 is connected to the discharge pipe 5, and the pipe 122 is connected to the pipe 120. However, the present example differs from the previous example in that the tube 122 includes an upright portion 122a extending upward. The highest portion of the upright portion 122a is set to be located at the same position as the preferred water level in the filter tank 2 during cleaning. Thereby, the water level during cleaning is always kept in this position. As mentioned above, this example reduces the initial capital cost of the filtration unit 1 "by eliminating the backwash pump P3 and waste valve V7.

Next, each step from the filtration process to the cleaning process and back to the filtration process will be described. First, referring to fig. 12, during normal filtration, the operation is the same as the previous example in that the raw water valve V1 and the filtered water valve V2 are open and the raw water pump P1 is in operation. That is, at this time, the raw water 16 is supplied from the raw water supply pipe 56 to the filtration tank 2. The raw water 16 supplied to the filter tank 2 passes through the layers of the filter media 14 and the filter media 54 to be filtered thereby, and is discharged from the filtered water discharge pipe 46. The discharged filtered water passes through the pipe 116, passes through the opened filtered water valve V2, and is discharged.

Next, when switching from the normal filtering process to the cleaning process, as shown in fig. 12, the water level adjustment is the same as that in the previous example. During the water level adjustment process, the raw water valve V1 and the filtered water valve V2 are closed. In addition, the operation of the raw water pump P1 is stopped. Therefore, the filter tank 2 is in a state in which liquid such as raw water 16 is stored therein. Thereafter, the drain water valve V3, the water level adjustment valve V5' and the water level adjustment valve V6 are opened substantially simultaneously. The raw water 16 passes through the pipe 110 and the pipe 114 to be discharged into the discharge water tank 112. The filtered water flows from the filtered water discharge pipe 46 and the discharge pipe 5, and is discharged into the discharge water tank 112 through the pipe 120 and the pipe 114. Then, as shown in fig. 11, when the liquid in the filter tank 2 reaches a certain level, the level regulating valve V5' is closed. That is, the water level regulating valve V5' is closed at a time point shown by a dotted line 128 in fig. 12. Thereafter, the filtered water is discharged only in a small amount through the water level regulating valve V6.

Immediately after the water level regulating valve V5' is closed, the backwash valve V4 is opened and the backwash pump P2 is driven as shown in fig. 12. That is, filtered water is supplied from the backwash pump P2 to the filtration tank 2 via the pipe 118a, the pipe 118, the pipe 116, and the filtered water discharge pipe 46. The backwash pump P2 has a large capacity. Thus, the backwash filtered water is sprayed into the filter media 14 with great force, thereby floating the filter media 14 near the cleaning tank 38. After the backwash pump P2 is previously driven so as to reduce the resistance against the rotation of the screw conveyor 32, the motor 26 is driven so as to start the rotation of the screw conveyor 32, as shown in fig. 12. This process is the same as the process of the previous example.

After the driving of the backwash pump P2 is started, the motor 26 for rotating the screw conveyor 32 is driven for about one to twenty seconds. By driving the backwash pump P2, the water level in the filter tank 2 rises and reaches a predetermined level suitable for cleaning the filter medium 14 about five to ten seconds after the start of driving.

When the liquid reaches a predetermined level, the cleaning process starts in a different way than in the previous example, as shown in fig. 12. In this process, the high capacity backwash pump P2 continues to be driven because the low capacity backwash pump P3 is eliminated from the present example. However, since the amount of filtered water supplied by the backwash pump P2 is large, the opening degree of the variable flow rate backwash valve V4' is adjusted, i.e., narrowed, in order to reduce the discharge amount of the drain. In addition, the water level regulating valve V6 is kept open, and thus the filtered water supplied by the backwash pump P2 is discharged from the discharge pipe 5.

The filtered water discharged from the discharge pipe 5 passes through the water level adjustment valve V6 and is discharged to the discharge water tank 112 via the pipe 122. The pipe 122 includes an upright portion 122a, and thus the liquid level in the filter tank 2 is automatically adjusted to a level suitable for cleaning. That is, if the water level is lower than the highest portion of the upright portion 122a, the water is not discharged, and if the water level is higher than the highest portion, the water is automatically discharged together with the contaminants, thereby maintaining the water level substantially uniform. During the cleaning process, the motor 26 is continuously driven. The dirt is thereby separated from the filter medium 14 by a scrubbing action which is produced by the rotation of the screw conveyor 32 in the same manner as in the previous example.

Following the cleaning process, a process of rinsing the cleaned filter media 14 and 54, i.e., a backwashing process, is initiated. In this process, the opening degree of the backwash valve V4' is adjusted (increased), and a large amount of filtered water is supplied from the backwash pump P2 via the filtered water discharge pipe 46. Accordingly, the backwash pump P2 is continuously driven through the cleaning and backwash process. In the same manner as in the previous example, the drain water valve V3 and the backwash valve V4 are still open, but the water level adjustment valve V6 is closed.

When the rinsing process, i.e., the backwashing process, is completed, the wastewater process is started. Since the waste valve V7 is eliminated from the present example, the variable flow level regulating valve V5' is used as a waste valve. In this process, the filtered water must be drained very slowly in order to drain the dirt that has settled on the bottom of the filter tank 2. Therefore, the opening degree of the water level regulating valve V5' is narrowed to discharge the filtered water at a low flow rate. The operation states of the other elements except the water level regulating valve V5' serving as a waste water valve are the same as those in the previous example.

When the wastewater process is completed, the filtering apparatus 1 ″ returns to the normal filtering process. The operating state of the elements at this time is the same as in the previous example.

The process performed by the filtration device is described in detail above. However, the time period values given in each process description are for example only, and the process is not limited to the time periods. For example, in the case where filtered water is used as drinking water, more time must be spent for each process than in the case where filtered water is used for industrial use. In addition, the amount of time allocated to each process can be freely set using a timer. For example, in the above-described embodiment, the timer may be set such that the filtering is performed for a period of time in the range of one to seventy-two hours, the cleaning is performed for a period of time in the range of zero to two minutes, the secondary backwashing is performed for a period of time in the range of one to two minutes, and the wastewater is performed for a period of time in the range of one to thirty minutes. In addition, each process may be performed automatically. Further, it goes without saying that the settable range for each process time period can be expanded.

The preferred embodiments of the present invention have been described. However, the present invention is not limited to the above structure. For example, as a structure for supporting the lower end of the screw conveyor, a configuration different from the modification shown in fig. 13 and 14 may be adopted. That is, the lower end of the screw conveyor 44 may be formed in a conical shape, and a member having a recess for receiving the tip of the conical shape may be provided on the support beam of the wire net 50. This structure can reduce the axial displacement of the screw conveyor. In addition, this structure does not depart from the functions of the present invention.

In addition, glass beads, activated carbon particles, or the like may be used as the filter medium 54. In the case of activated carbon particles, there is a tendency that the particles are easily fixed to each other from their surface to the upper layer during use. That is, the activated carbon granules are connected into a continuous sheet during use. If the activated carbon particles are bonded in a plate shape, the liquid to be filtered permeates down through cracks in the plate or the like. However, the filtering effect is only obtained in the vicinity of the water circuit. Therefore, even if the activated carbon positioned from the intermediate layer to the lower layer still has adsorption characteristics, its function cannot be sufficiently exhibited. For this reason, replacement, calcination and regeneration of activated carbon particles are indispensable.

By providing the cleaning device of the present invention, activated carbon particles can be agitated and cleaned. Thereby, the adhesion of the activated carbon particles can be avoided. Accordingly, the entire layer of activated carbon particles can be effectively utilized. As a result, the performance of the filter device using activated carbon as a filter medium is improved. In addition, contaminants such as organic matter attached to the surface of the activated carbon are separated therefrom during cleaning. Therefore, the interval between activated carbon replacements is significantly increased. Thereby, maintenance and management of the filtration apparatus is facilitated and costs associated therewith are reduced.

Preferably, the position of the upper opening 42 is not too low. The filter media 14 can be scrubbed over a long distance within the cleaning tank 38.

In the case where the diameter of the filtration tanks 2 and 202 is large, a plurality of cleaning tanks 38 and 238 may be provided therein. In this case, filter media 14 can be cleaned more quickly and efficiently.

The above examples can be used for filtering waste liquid, oil, and the like, in addition to water.

Claims (6)

1. A filtration device comprising:

a filter canister having a filter bed for supporting a first layer of granular filter media; and

a cleaning mechanism, the cleaning mechanism comprising:

a vertically positioned hollow cleaning tank disposed within the filtration tank;

a cleaning device for conveying a first filter media upwardly within the cleaning tank while cleaning the filter media; and

a filth discharge device for discharging filth separated from the first filter medium to the outside of the filter canister during cleaning;

wherein:

during normal filtration, liquid that has been filtered by the filter media passes through a filter bed and is discharged through the filter bed;

the filter bed comprises two vertically separated filter beds;

the upper filter bed includes a plurality of liquid passage sections sized such that the first filter media cannot pass through the liquid passage sections; and

a second layer of filter media is disposed between the two filter beds, the second layer of filter media being larger in size than the first layer of filter media.

2. The filtration device of claim 1, wherein:

the cleaning device comprises a screw conveyor, and the screw conveyor is hung at the upper part of the filter tank; and

the screw conveyor is configured to be rotated by a driving part provided at an upper portion of the filter tank.

3. A filter arrangement according to claim 1 or 2 wherein:

the upper filter bed is a mesh having mesh holes constituting the liquid passage portion.

4. A filter arrangement according to any one of claims 1-3 wherein:

a plurality of filters for discharging filtered liquid are disposed at a lower filter bed of the two filter beds.

5. The filtration device of any one of claims 1-4, further comprising:

a liquid ejecting section provided on an outer wall of the filter canister for externally ejecting the second filter medium disposed between the two filter beds; wherein:

the cleaning liquid is sprayed toward the second filter medium layer through the liquid spraying portion so that the contaminants attached to the second medium are separated by the cleaning liquid flow.

6. The filtration device of any one of claims 1-5, further comprising:

vibration generating means for applying vibration to a second filter medium disposed between the two filter beds; wherein:

the vibration generated by the vibration generating means is propagated toward the second filter medium layer to separate contaminants attached to the second filter medium by the vibration applied to the second filter medium.