1. A switching valve for a pressure-type filtration device provided with a plurality of filtration chambers, the switching valve comprising: 5 a valve box having a cylindrical sidewall part, a lid part covering the top end of the sidewall part and a bottom part covering the bottom end of the sidewall part, wherein N raw water outlets, which are to be individually connected to raw water introducing ports of the filtration chambers and are arranged so as to be N-fold 10 symmetrical with respect to the center of the sidewall part, are disposed on the sidewall part, a washing waste water port for discharging washing waste water is disposed on the bottom part, and one or more raw water introducing ports for introducing raw water to be filtered into the valve box are disposed on the lid part or 15 a part of the sidewall part higher than the raw water outlets; a columnar valve element housed in the valve box in such a manner as to be movable vertically and rotatable; and a position control means for controlling the vertical position and orientation of the valve element within the valve box, 20 wherein the valve box has a shape that allows the valve element to be lowered down in such a manner that the upper surface position of the valve element becomes a first position which is lower than lower ends of the N raw water outlets, N channels are provided in the valve body in such a manner as 25 to face the N raw water outlets of the valve box when the upper surface position of the valve element is a second position, at least one of the N channels is a washing waste water channel which communicates the side surface and the lower surface of the valve body, 30 each channel among the N channels excluding the washing waste water channel is a raw water channel which communicates the side surface and the upper surface of the valve body, and the position control means has a function of controlling the 25 vertical position of the valve element within the valve box such that the upper surface position of the valve element is the first position, and a function of controlling the vertical position and orientation of the valve element within the valve box such that the upper surface position of the valve element is the second position 5 and an opening of the washing waste, which is formed on the side surface of the valve body, faces a desired raw water outlet of the valve box.

2. The switching valve according claim 1, wherein 10 the position control means includes: a vertical driving means for vertically moving the valve element such that the upper surface of the valve element moves within a range from the first position to the second position; and a movement conversion means for converting the vertical 15 movement of the valve element to rotational movement around the center axis of the valve element, and whereby rotating the valve element by an angle of 360/N degrees per one reciprocating movement of the valve element, and the valve element is housed in the valve body in such a manner 20 that N channels opened to the side surface of the valve element faces the N raw water outlets when the upper surface position thereof is the second position by being moved upward by the vertical driving means. 25

3. The switching valve according claim 2, wherein the movement conversion means includes a cylindrical member which is fixed to either one of the valve element and the valve body and has a cam groove provided at the side surface thereof, and a cam follower fixed to the other of the valve element and the valve body so as to move 30 in the cam groove of the cylindrical member.

4. The switching valve according to claim 2 or 3, wherein the vertical driving means moves the valve element vertically by means 26 of hydraulic pressure, pneumatic pressure or motor.

5. The switching valve according to any one of claims 1 to 4, wherein the washing waste channel is a channel cross-sectional area of which is larger than the raw water channel.

FIELD]
[0001] The present invention relates to a switching valve, specifically relates to a switching valve used to construct a 5 pressure-type filtration device including a plurality of filtration chambers.
[BACKGROUND]
[0002] A pressure-type filtration device (closed type 10 filtration apparatus) is known as a filtration apparatus to purify water by filtering raw water. In order to keep performance of the pressure-type filtration device, it is necessary to periodically perform water discarding which is for cleaning of filtering material and for stabilization of filtering material particles. 15 One of the washing methods of filtering material is backwashing.
[0003] A system (see e.g., PTL1) has been therefore developed which includes a plurality of pressure-type filtration devices and which is configured in such a manner that each pressure-type filtration device can be backwashed by filtered water obtained by 20 the other pressure-type filtration devices.
[Citation List]
[Patent Literature]
[0004]
[PTL 1] Japanese patent laid-open publication No. 2003-93808. 25
[Summary]
[Technical Problem]
[0005] The above-described system requires a large number of valve devices (three-way valves and so on). 30
[0006] It is therefore the object of the present invention to provide a switching valve capable of constructing a pressure-type filtration device more easily (in such a manner that less number of valve devices are required), which includes individually
2
cleanable filtration chambers.
[MEANS TO SOLVE THE PROBLEM]
[0007] To accomplish the above object, a switching valve for a pressure-type filtration device provided with a plurality of 5 filtration chambers according to the present invention comprises: a valve box having a cylindrical sidewall part, a lid part covering the top end of the sidewall part and a bottom part covering the bottom end of the sidewall part, wherein N raw water outlets, which are to be individually connected to raw water introducing ports 10 of the filtration chambers and are arranged so as to be N-fold symmetrical with respect to the center of the sidewall part, are disposed on the sidewall part, a washing waste water port for discharging washing waste water is disposed on the bottom part, and one or more raw water introducing ports for introducing raw 15 water to be filtered into the valve box are disposed on the lid part or a part of the sidewall part higher than the raw water outlets; a columnar valve element housed in the valve box in such a manner as to be movable vertically and rotatable; and a position control means for controlling the vertical position and orientation of the 20 valve element within the valve box. Further, the valve box in the switching valve according to the present inventions has a shape that allows the valve element to be lowered down in such a manner that the upper surface position of the valve element becomes a first position which is lower than lower ends of the N raw water outlets, 25 N channels are provided in the valve body in such a manner as to face the N raw water outlets of the valve box when the upper surface position of the valve element is a second position, at least one of the N channels is a washing waste water channel which communicates the side surface and the lower surface of the valve 30 body, each channel among the N channels excluding the washing waste water channel is a raw water channel which communicates the side surface and the upper surface of the valve body, and the position control means has a function of controlling the vertical position 3
of the valve element within the valve box such that the upper surface position of the valve element is the first position, and a function of controlling the vertical position and orientation of the valve element within the valve box such that the upper surface position of the valve element is the second position and an opening of the 5 washing waste, which is formed on the side surface of the valve body, faces a desired raw water outlet of the valve box.
[0008] Namely, the switching valve of the present invention can take the following states.
(1) State where raw water supplied into the switching valve from 10 one or more raw water inlets is supplied to N (>= 3) filtration chambers from the raw water introducing port of each filtration chamber (state where the top surface of the valve element is positioned in the first position)
(2) State where the raw water introducing ports of m (m is natural 15 number smaller than N/2; generally, 1) filtration chambers and the washing waste water port are connected, and raw water supplied into the switching valve is supplied to the remaining “N – m” filtration chambers from the raw water introducing port of each filtration chamber (state where the top surface of the valve element is 20 positioned in the second position and the opening of the washing waste water channel on the side surface of the valve element faces to a desired raw water outlet of the valve box).
[0009] Therefore, with the switching valve of the present invention, it is possible to construct(manufacture) a 25 pressure-type filtration device without using a large number of valve devices, the pressure-type filtration device including N filtration chambers and capable of n filtration chambers being backwashed by filtered water from the other N-m filtration chambers. 30
[0010] On the occasion of actualizing the switching valve of the present invention, it is possible to adopt such configuration that the position control means include: a vertical driving means for vertically moving the valve element such that the upper surface
4
of the valve element moves within a range from the first position to the second position; and a movement conversion means for converting the vertical movement of the valve element to rotational movement around the center axis of the valve element, and whereby rotating the valve element by an angle of 360/N degrees per one 5 reciprocating movement of the valve element, and the valve element is housed in the valve body in such a manner that N channels opened to the side surface of the valve element faces the N raw water outlets when and the upper surface position thereof is the second position by being moved upward by the vertical driving means. 10
[0011] As the movement conversion means, vertical driving means in the vertical driving means having the above function or configuration, various means can be adopted. For example, as the movement conversion means, means including a cylindrical member which is fixed to either one of the valve element or the valve body 15 and has a cam groove provided at the side surface thereof, and a cam follower fixed to the other of the valve element or the valve body so as to move in the cam groove of the cylindrical member may be adopted. Further, as the vertical driving means, means that moves the valve element in the vertical direction by hydraulic 20 pressure, pneumatic pressure or motor (for example, means for moving the valve element vertically by vertically moving a piston that moves vertically and rotates with the valve element in a cylinder by air pressure or hydraulic pressure, means for moving the valve element vertically by vertically moving a spindle that 25 moves vertically and rotates with the valve element by a motor) may be adopted.
[Advantageous Effects of Invention]
[0012] With the switching valve of the present invention, it 30 is possible to construct (manufacture) a pressure-type filtration device including a plurality of filtration chamber more easily than before (in such a manner that the number of valve devices required is less than before). 5
[BRIEF DESCRIPTION OF DRAWINGS]
[0013]
FIG. 1 is a top plan view of the pressure-type filtration device constructed using a switching valve according to an 5 embodiment of the present invention.
FIG. 2 is a front view of the pressure-type filtration device.
FIG. 3 is an explanatory drawing of the internal structure of the pressure-type filtration device.
FIG. 4 is a sectional view of the switching valve cut on a 10 plane passing through the center of the switching valve.
FIG. 5A is a plane view of a valve element in the switching valve.
FIG. 5B is a side view of the valve element.
FIG. 6 is a development view of the shaft part which is a 15 component of the switching valve.
FIG. 7 is an explanatory drawing of the constitution of the switching valve.
FIG. 8 is a section view of the valve element along the VIII-VIII line of Fig.7 viewing from the arrow direction. 20
FIG. 9 is an explanatory drawing of the constitution of the switching valve.
FIG. 10A is an explanatory drawing of paths of raw water and so on in the filtration step of the pressure-type filtration device according to the first embodiment. 25
FIG. 10B is an explanatory drawing of paths of raw water and so on in the backwashing step of the pressure-type filtration device according to the first embodiment.
FIG. 10C is an explanatory drawing of paths of raw water and so on in the water discarding step of the pressure-type filtration 30 device according to the first embodiment.
FIG. 11A is a plane view of a valve element for the switching valve enabling two filtration chambers to be backwashed simultaneously in the backwashing step 6
FIG. 11B is an explanatory drawing of the constitution of the valve element shown in FIG. 11A.
FIG. 12 is a sectional view of a pressure-type filtration device which can be constructed using the switching valve.
FIG. 13 is a top plan view of the pressure-type filtration 5 device shown in FIG. 12.
[Description of Embodiments]
[0014] The embodiments will now be described with reference to the accompanying drawings. 10
[0015] FIG. 1 is a top plan view of a pressure-type filtration device 1 that is constructed using a switching valve according to an embodiment of the present invention. Further, FIG. 2 and FIG. 3 are a front view of the pressure-type filtration device 1 and an explanatory drawing of the internal structure of the 15 pressure-type filtration device 1, respectively.
[0016] The pressure-type filtration device 1 is a pressure-type filtration device to which the principle of the self-backwashing equipment is applied. As illustrated in FIGS. 1 through 3, the pressure-type filtration device 1 comprises a filtration apparatus 20 main body 10, a raw water pipe 20, filtered water pipes 22a - 22c, a water discarding pipe 23, and so on.
[0017] The raw water pipe 20 (FIG. 3) is a pipe to supply water to be purified by the filtration apparatus main body 10 (which will be denoted hereinafter as raw water) to the filtration apparatus 25 main body 10. The filtration apparatus main body 10 is a device that filters raw water supplied through the raw water pipe 20 and output filtration result of raw water (which will be denoted hereinafter as filtered water) from a filtered water outlet 22d (FIG. 2) which is an open end of the filtered water pipe 22a. As 30 illustrated in Figs 1 and 3, in the filtration apparatus main body 10, a raw water chamber 11, six filtration chambers 12 and a purified water chamber 13 are arranged. Moreover, a switching valve 30 is attached to the central part of the upper surface central part of 7
the filtration apparatus main body 10.
[0018] The switching valve 30 according to the present embodiment is a six-way valve that is developed for the pressure-type filtration device 1 (the filtration apparatus main body 10). As illustrated in FIG. 3, the switching valve 30 is 5 formed by a switching valve body part 30a that is housed in an outer shell 10a of the filtration apparatus main body 10 and a drive part 30b that protrudes from the outer shell 10a.
[0019] The switching valve body part 30a is a unit (valve device) where a cylindrical valve element 40 moves vertically and rotates 10 in a cylindrical valve box having an upper lid and a bottom lid. As shown in FIG. 3, at the upper part of the side surface of the valve box of the switching valve body part 30a, six raw water inlets 32a are arranged with a constant angular space. Further, at the part of the side surface of the valve box of the switching valve 15 body part 30a lower than each raw water inlet 32a, six raw water outlets 32b are arranged with a constant angular space. Moreover, an opening 32c, which acts as an outlet of washing waste water (details will be discussed later), is formed on the lower surface of the switching valve body part 30a, and the opening 32c is 20 connected to a waste water pipe 24 extending vertically downward to the outside of the outer shell 10a of the filtration apparatus main body 10.
[0020] Before explaining the details of the switching valve 30 (the switching valve body part 30a and the drive part 30b), 25 constitution of the pressure-type filtration device 1 other than the switching valve 30 will be discussed.
[0021] The raw water chamber 11 (FIG. 3) is a part (vessel) into which raw water is supplied through the raw water pipe 20. The shape of the raw water chamber 11 (shapes of partitions which are 30 components of the raw water chamber 11 and to which the switching valve body part 30a is fitted, and so on) is determined in such a manner that the raw water inlet 32a of the switching valve body part 30a acts as an outlet of the raw water supplied through the
8
raw water pipe 20. Furthermore, it is determined that only six raw water outlet 32b of the switching valve body part 30a are act as outlets of raw water supplied to the switching valve body part 30a from the raw water inlets 32a.
[0022] Each filtration chamber 12 (FIG. 3) is a unit where 5 filtering material 12a is arranged on a water collection board 15 (partition plate formed by strainer and the like for supporting the filtering material 12a, collecting filtered water and scattering backwashing water). Note that, the filtration chamber 12 according to the present embodiment is a unit of which the water 10 collection board 15 functions as the filtered water outlet. Further, although anthracite, manganese sand and filtration gravel are depicted as the filtering materials 12a in FIG. 3, the filtering material 12a is for removing impurities included in raw water, and, kind, particle diameter and uniformity coefficient of the 15 filtering material 12a are determined based on components and density of the removal object.
[0023] As illustrated in FIG. 1, each filtration chamber 12 has shape obtained by the shape dividing the principal part of the inner space of the filtration apparatus main body 10 (outer shell 10a) 20 into six in radial directions from the center of the filtration apparatus main body 10. The switching valve 30 is attached to the filtration apparatus main body 10 in such a manner that raw water can be supplied to each filtration chamber 12 through only corresponding raw water outlet 32b. 25
[0024] The purified water chamber 13 (FIG. 3) is space in the filtration apparatus main body 10 lower than water collection boards 15 in six filtration chamber 12 . As shown in the Figure, In the purified water chamber 13, one end of a filtered water pipe 22b is inserted which extends to the lower surface of the switching 30 valve body part 30a in the form of accommodating the waste water pipe 24 therein. To the part of this filtered water pipe 22b higher than the upper surface of the filtering material 12a, one end of a filtered water pipe 22c which extends approximately horizontally
9
to the outside of the outer shell 10a of the filtration apparatus main body 10 is connected. A filtered water pipe 22a is connected to the other end of the filtered water pipe 22c, and the filtered water supplied to the purified water chamber 13 from each filtration chamber 12 passes the filtered water pipes 22b, 22c and 22a in this 5 order and then flows out from the filtered water outlet 22d.
[0025] Note that, purpose of raising the filtered water to a position above the upper surface of the filter material 12a before flowing out the filtered water is so that there is an amount of water covering the filter material 12a In each filtration chamber 10 12, even if a supply of raw water decreases by some kind of factors.
[0026] As illustrated in FIG. 2, at a part of the filtered water pipe 22a near the filtered water outlet 22d, a filtered water valve 27 to permit or stop the outflow of filtered water from the filtered water outlet 22d is arranged. The filtered water pipe 22a is 15 connected to the waste water pipe 24 in the part upstream from the filtered water valve 27 via the water discarding pipe 23. The water discarding valve 28 is mounted on the way of the water discarding pipe 23, which is opened when filtered water flowing within the filtered water pipe 22a is drained from the waste water pipe 24. 20
[0027] Hereinafter, constitution of the switching valve 30 will be discussed with reference to FIG. 4, FIG. 5A, FIG. 5B and FIG. 6 - FIG. 9. Note that, FIG. 4 is a sectional view of the switching valve 30 cut by a plane passing through the center of the switching valve 30. However, hatching is omitted in this sectional view. 25 FIG. 5A and FIG. 5B are a plane view and a side view of the valve element 40, respectively. FIG. 6 is a development view of a shaft part 60 which is a component of the switching valve 30. FIG. 7 is an explanatory drawing of position relations that the valve element 40 and the raw water outlet 32b of the switching valve can 30 take, and FIG. 8 is a section view of the valve element 30 along the VIII-VIII line of Fig. 7 viewing from the arrow direction. FIG. 9 is an explanatory drawing of the constitution of the switching valve 30. 10
[0028] As illustrated in FIG. 4, the switching valve 30 is divided into a switching valve body part 30a and a drive part 30b by an isolation plate 38.
[0029] To start with, constitution of the switching valve body part 30a is described. The switching valve body part 30a comprises 5 the isolation plate 38, a housing 31, the valve element 40 and so on.
[0030] The housing 31 is a member functioning as a valve box of the switching valve body part 30a by being fixed to the isolation plate 38. 10
[0031] At the upper part of the side surface of the housing 31, six circular raw water inlets 32a having the same diameter are arranged with a constant angular space. At the part of the housing 31 lower than the each raw water inlet 32a, six circular raw water outlets 32b having the same diameter are arranged with a constant 15 angular space. The diameter of this raw water outlet 32b is bigger than the diameter of the raw water inlet 32a (in the present embodiment approximately 2.5 times larger than the diameter of raw water inlet 32a). Further, the housing 31, as shown in the Figure, has the shape that allows the valve element 40 therein to be lowered 20 down to a position where the top surface is lower than the lower end of each raw water outlet 32b.
[0032] The valve element 40 is a member having a shape shown in FIG. 5A and FIG. 5B. That is, the valve element 40 is a substantially columnar member. Further, five raw water channels 25 41a communicating between the top and side surfaces of the valve element 40 and a washing waste water channel 41b communicating between the bottom and side surfaces of the valve element 40 are formed in the valve element 40. Hereinafter, the openings of the raw water channel 41a on the side surface and on the top surface 30 of the valve element 40 are referred to as the side surface opening and the upper surface opening of the raw water channel 41a, respectively. Similarly, the openings of the washing waste water channel 41b on the side surface and on the top surface of the valve
11
element 40 are referred to as the side surface opening and the upper surface opening of the washing waste water channel 41b, respectively.
[0033] Each raw water channel 41a formed in the valve element 40 is a channel having approximately the same diameter (in diameter) 5 as the raw water inlet 32a. Further, five raw water channel 41a are in the same shape as shown in FIG. 5A and FIG. 5B.
[0034] The washing waste water channel 41b formed in the valve element 40 is a channel the cross sectional area of which is larger than that of the raw water channel 41a (in the present embodiment, 10 a circular channel the diameter of which is substantially 2.5 times larger than that of the raw water channel 41a). The six channels (five raw water channels 41a and one washing waste water channel 41b) in the valve element 40 are formed in such a manner that center intervals between every two adjacent side surface openings are 15 equiangular intervals (that is, 60 degrees intervals). Further, on the side surface of the valve element 40, O-ring grooves (which has dovetail groove shape) each surrounding the surface side opening are formed, and the valve element 40 is placed within the housing 31 in a condition where an O-ring is inserted in each O-ring 20 groove.
[0035] As illustrated in FIG. 4, a stem 45 for rotating and vertically moving the valve element 40 in the housing 31 is provided at the center part of the valve element 40. The stem 45 extends into the drive part 30b through an opening (bearing part) of the 25 isolation plate 38, and the opening of the isolation plate 38 is configured in such a manner that allows the stem 45 to be rotated and vertically moved while ensuring watertightness and airtightness.
[0036] Hereinafter, the drive part 30b of the switching valve 30 30 will be described. The drive part 30b of the switching valve 30 is a unit for vertically moving and rotating the valve element 40 in the switching valve body part 30a (housing 31). As shown in FIG. 4, the drive part 30b comprises a housing 50, a piston 53
12
and a shaft part 60.
[0037] The housing 50 is formed by a cylindrical cylinder part 52 and a top cover 51 covering the upper end of the cylinder part 52, and so on. The top cover 51 is provided with a compressed air introducing port 51a from which compressed air is introduced when 5 the piston 53 is moved downward. Further, the isolation plate 38 constituting the bottom surface of the drive part 30b is provided with a compressed air introducing port 38a from which compressed air is introduced when the piston 53 is moved upward.
[0038] The piston 53 is formed by sealing a lower end of a 10 cylindrical member 53b having outer diameter slightly smaller than the in diameter of the cylinder part 52 by a disc shaped member 53a. Around the upper and lower sides of the member 53b of the piston 53, O-ring grooves are formed, and the piston 53 is inserted into the housing 50 (cylinder part 52) in a condition where an O-ring 15 is fitted in each O-ring groove.
[0039] Near the upper end of the piston 53 (member 53b), a plurality of (in the present embodiment, six number of) cam followers 54 are attached at equal angular intervals.
[0040] The shaft part 60 is a cylindrical member that is fixed 20 to the housing 50 (top cover 51). A cam groove 61 having the shape shown in FIG. 6 is formed on the outside surface of the shaft part 60.
[0041] Namely, the cam groove 61 on the outside surface of the shaft part 60 has a shape that allows a relative angle of the cam 25 follower 54 to the shaft part 60 to be changed for 30 degrees in a certain direction when the cam follower 54 positioned at the lower end of the cam groove 61 reaches the upper end of the cam groove 61 along the cam groove 61. Further, the cam groove 61 has a shape that allows the relative angle of the cam follower 54 to the shaft 30 part 60 to be changed for 30 degrees in the same direction when the cam follower 54 positioned at the upper end of the cam groove 61 reaches the lower end of the cam groove 61 along the cam groove 61. 13
[0042] Moreover, the switching valve 30 is configured in such a manner that sizes of each part (length in the vertical direction of the cam groove 61, installation angle of the valve element 40 to the stem 45, etc.) satisfies the following conditions.
(1) The upper surface of the valve element 40 becomes a position 5 lower than the lower end of each raw water outlet 32b when the cam follower 54 is positioned at the lower end of the cam groove 61(see FIG. 4).
(2) States shown in FIGS 7 to 9, namely, states where the side surface openings of the channels 41a and 41b are respectively 10 opposed to the raw water outlets 32b of the switching valve body part 30a, are provided when the cam follower 54 is positioned at the upper end of the cam groove 61.
[0043] Hereinafter, function of the pressure-type filtration device 1 will be discussed. Note that, in the following 15 discussion, a control device is defined as a device (a kind of computer) to control the filtered water valve 27, the water discarding valve 28 and the switching valve 30 of the pressure-type filtration device 1. The normal position is a position of the valve element 40 in the housing 31 when the cam follower 54 is positioned 20 at the lower end of the cam groove 61 (see FIG. 4). The backwashing position is a position of the valve element 40 in the housing 31 when the cam follower 54 is positioned at the upper end of the cam groove 61 (see FIG. 9). The backwashing position of a filtration chamber 12 is defined as the backwashing position, among six 25 backwashing positions where the orientations (rotary angles in the housing 31) of the valve element 40 are different, to which the side surface opening of the washing waste water channel 41b is directed.
[0044] In the filtering step of raw water by the pressure-type 30 filtration device 1, the filtered water valve 27, the water discarding valve 28 and the switching valve 30 are controlled by the control device in such a manner that the filtered water valve 27 is opened, the water discarding valve 28 is closed and the
14
switching valve 30 is positioned in the normal position. The state where the filtered water valve 27 is opened, the water discarding valve 28 is closed and the switching valve 30 is positioned in the normal position will be denoted hereinafter as the filtering state.
[0045] The upper surface of the valve element 40 positioned in 5 the normal position is lower than the lower end of each raw water outlet 32b of the housing 31 (FIG. 4). Further, the shape of each raw water outlet 32b is the same. Accordingly, when the filtering state is formed, raw water flowing into the switching valve body part 30a through the six raw water inlets 32a from the raw water 10 chamber 11 is equally distributed to the six filtration chamber 12 through the six raw water outlets 32b in the switching valve body part 30a.
[0046] Further, the filtering state is the state where the filtered water valve 27 is opened and the water discarding valve 15 28 is closed, and therefore filtered water supplied to the purified chamber 13 from each filtration chamber 12 flows out from the filtered water outlet 22d through the filtered water pipe 22 (filtered water pipes 22b, 22c and 22a).
[0047] When a predetermined backwashing start condition, e.g., 20 a backwashing start condition such as "filtration of raw water is performed for a prescribed time(e.g., 24 to 48 hours)" or "filtration resistance rises and reaches the set value" is satisfied, the control device performs backwashing step of the following contents. 25
[0048] The control device, to start with, performs a first control processing to form "a backwashing state where the filtered water valve 27 is closed, and water discarding valve 28 is closed, and the valve element 40 is positioned in the backwashing position for a certain filtration chamber 12". The control performed to 30 the switching valve 30 in the first control processing is control to rotate the valve element 40, which is positioned in the normal position, 30 degrees and thereby raise it to the backwashing position (that is, control to raise the piston 53 positioned at 15
the lower end to the upper end). The control performed to the switching valve 30 in the first control processing may be control in which the rotation angle of the valve body 40 is not 30 degrees, so long as it can move the valve element 40 to the washing position
[0049] When the valve element 40 is positioned in the 5 backwashing position for a filtration chamber 12 (which will be hereinafter denoted as the backwash target filtration chamber 12), the side surface opening of each channel 41a, 41b in the valve element 40 is opposed to each raw water outlet 32b of the housing 31 (see FIG. 9). Further, the raw water channel 41a, the washing 10 waste water channel 41b communicates between the side and upper surfaces of the valve element 40, between the side and lower surfaces of the valve element 40, respectively, and each raw water channel 41a has approximately the same shape.
[0050] Therefore, when the valve element 40 is positioned in 15 the backwashing position for the backwash target filtration chamber 12, the raw water flowing into the switching valve body part 30a from the raw water chamber 11 is evenly distributed to five filtration chamber 12 other than the backwash target filtration chamber 12 through five raw water channels 41a of the 20 valve element 40.
[0051] Further, when the valve element 40 is positioned in the backwashing position for the backwash target filtration chamber 12, the raw water introducing port of the backwash target filtration chamber 12 (the raw water outlet 32b from which raw water is supplied 25 to the backwash target filtration chamber 12) is communicated with the waste water pipe 24 by the washing waste water channel 41b of the valve element 40. That is, the backwash target filtration chamber 12 goes into a state where water can flow from the lower part to the upper part because the raw water introducing port is 30 open (raw water is not introduced from the raw water introducing port). Further, when both of the filtered water valve 27 and the water discarding valve 28 are closed, the filtrated water in the purified water chamber 13 cannot flow out to the filtered water
16
pipe 22b.
[0052] Therefore, when the above backwashing state, as schematically shown in FIG. 10B, the backwash target filtration chamber 12 is backwashed with filtered water from five filtration chamber 12 other than the backwash target filtration chamber 12, 5 and washing waste water from the backwash target filtration chamber 12 flows out to the outside through the washing waste water channel 41b and the waste water pipe 24.
[0053] The control device which finished the first control processing of the above contents waits until a backwashing time 10 (e.g., 6 to 7 minutes) passes which is set beforehand as time to perform backwashing.
[0054] When the backwashing time passes, the control device performs control to the switching valve 30 (drive part 30b), the control being to lower the piston 53 positioned at the upper end 15 to the lower end and then raise it to the upper end. When this control (which will be referred to as backwash target change control) is performed, the valve element 40 is positioned in the backwashing position for the filtration chamber 12 next to the filtration chamber 12 that is backwashed, and therefore the control 20 device waits until the backwashing time passes.
[0055] When the backwashing time passes, the control device performs the backwash target change control again, and then waits until the backwashing time passes.
[0056] The control device repeats the above control processing 25 until backwashing of every filtration chambers 12 is completed. When backwashing of every filtration chamber 12 is completed, the control device performs control to the switching valve 30 (drive part 30b), the control being to lower the piston 53 positioned at the upper end to the lower end and then raise it to the upper end, 30 and controls the water discarding valve 28 so as to open.
[0057] When the above control is performed to the water discarding valve 28, "a state where the filtered water valve 27 is closed, the water discarding valve 28 is opened and the valve
17
element 40 is positioned in the normal position" is formed. Therefore, it follows that filtered water from six filtration chambers 12 flows out from the waste water pipe 24 through the water discarding pipe 23 as schematically shown in FIG. 10C.
[0058] The control device that forms the above state (which will 5 hereinafter be termed the water discarding state) by controlling the switching valve 30 and the water discarding valve 28 waits until a time (e.g., ten minutes) set beforehand passes. When that time passes, the control device controls the filtered water valve 27 and the water discarding valve 28 such that the filtered water valve 10 27 is opened and the water discarding valve 28 is closed. Namely, the control device performs control to restore the pressure-type filtration device 1 to the state where raw water is filtered (state where filtered water from six filtration chamber is flowed out from the filtered water outlet 22d). Then, the control device having 15 finished the control enters a state of monitoring whether the backwashing start condition is satisfied.
[0059] As discussed above, by using the switching valve according to the present embodiment, it is possible to construct the pressure-type filtration device 1 where each filtration 20 chamber 12 can be backwashed with filtered water from the other filtration chambers 12. When an apparatus having a similar function to the pressure-type filtration device 1 is constructed without using the switching valve 30, one three-way valve or two two-way valve must be provided at the raw water introducing port 25 side of each filtration chamber. Accordingly, with the switching valve according to the present embodiment, it is possible to construct a pressure-type filtration device including N (>=3)filtration chambers more easily (in such a manner that less number of valve devices are required). 30
[0060] Note that, the pressure-type filtration device 1 described above includes six filtration chambers 12 arranged concentrically and the raw water chamber 11 arranged in the central part of the filtration chambers 12. Moreover, in the pressure-type
18
filtration device 1, raw water is supplied to each filtration chambers 12 from each of the raw water outlets 32b having the same shape provided in the switching valve body part 30a (see FIG. 9). Accordingly, in the pressure-type filtration device 1, substantially uniform amount of raw water is supplied to each 5 filtration chamber 12 in the filtration step.
[0061] Further, the pressure-type filtration device 1 includes the purified water chamber 13 which can act as the filtered water path that introduces filtered water from the filtration chambers 12 other than the backwash target filtration chamber 12 to the 10 filtered water outlet (the water collection board 15) of the backwash target filtration chamber 12. Moreover, this purified water chamber 13 is provided at the central part (just below six filtration chambers 12, see FIG. 3) of six filtration chambers 12. Therefore, in the pressure-type filtration device 1, a total of 15 water filtered in the filtration chambers 12 other than the backwash target filtration chamber 12 is supplied to the backwash target filtration chamber 12 in the backwashing step.
[0062] Furthermore, the filtration apparatus main body 10 of the pressure-type filtration device 1 has such constitution that 20 the raw water chamber 11 and a plurality of filtration chambers are placed in one outer shell 10 with no gaps therebetween. Accordingly, the pressure-type filtration device 1 can be installed in a smaller area than the pressure-type filtration device to which other constitution is adopted to equalize filtered 25 water supplied to each filtration chamber.
[0063] <>
The switching valve 30 discussed above can be modified in a variety of forms. For example, the drive part 30b of the switching valve 30 may be modified into a unit in which the piston 53 is moved 30 vertically by oil pressure or a unit the piston 53 (stem 45) is moved vertically by a motor. Further, the drive part 30b may be modified into a unit including a vertical movement mechanism to vertically move the valve element 40, and a turning mechanism, which 19
functions independently with the vertical movement mechanism, to turn the valve element 40.
[0064] The shape, the number and the position of the raw water inlets 32a of the switching valve 30 are particularly limited so long as raw water can be supplied into the switching valve body 5 section 30a from above the raw water outlet 32b. Therefore, for example, one relatively big raw water inlet 32a may be provided on the top surface or the side surface of the switching valve body section 30a by altering the shape of drive part 30b.
[0065] The number of the raw water outlets 32b of the switching 10 valve 30 should be three or more. Note that a backwashing water flow rate for the switching valve 30 provided with N raw water outlets 32b is "N - 1" times larger than a filtering speed (hereinafter, backwashing step filtering speed) of each flirtation chamber that acts as a supply source of backwashing water in the 15 backwashing step. Therefore, the number of the raw water outlets 32b is determined based on the backwashing water flow rate required to backwash the filtration chamber and the backwashing step filtering speed of each filtration chamber.
[0066] The switching valve 30 may be modified into a device 20 enabling two filtration chambers to be backwashed simultaneously in the backwashing step. Note that such modification can be made, for example, by changing the valve element 40 to the valve element 40' having the shape shown in Figs 11A and 11B, namely, valve element 40' provided with four raw water channels 41a and two washing waste 25 water channels 41b.
[0067] As described above, in the pressure-type filtration device 1, the switching valve 30 where the diameter of the raw water outlet 32b is approximately 2.5 times larger than the diameter of the raw water inlet 32a and the inner diameter of the washing waste 30 water channel 41b of the valve element 40 is approximately 2.5 times larger than the inner diameter of the raw water channel 41a, is used. Purpose of using the switching valve 30 having such constitution is to prevent that filtered waste quantity that flows
20
backward in the backwash target filtration chamber is limited by channel resistance of the washing waste water channels 41b and the raw water outlets 32b (see. FIG. 9). Further, in order to cause the required amount of filtered water to flow backward in the filtration chamber 12, the cross-section ratio of the washing waste 5 water 41b and the raw water channel 41a may be larger/smaller than the above-mentioned value.
[0068] Using the switching valve 30, the pressure-type filtration device 2 having constitution shown in Figs 12 and 13 may be constructed. Note that FIG. 12 is a sectional view of the 10 pressure-type filtration device 2, and FIG. 13 is a top plan view of the pressure-type filtration device 2.
[0069] Constitution of the pressure-type filtration device 2 will be described. As shown in FIG. 12 and FIG. 13, the pressure-type filtration device 2 is provided with six filtration 15 chambers 70, a raw water chamber 71, a raw water pipe 80 to supply raw water into the raw water chamber 71, etc.
[0070] Each filtration chamber 70 of the pressure-type filtration device 2 is a filtration chamber (filter) having the same configuration, which includes a water collection board 70c 20 and filtering material (in FIG. 12, anthracite manganese sand and filtration gravel) arranged on the water collection board 70c. As shown in FIG. 13, six filtration chambers 70 of the pressure-type filtration device 2 is arranged concentrically centering on the part consisting of the switching valve 30 (switching valve body 25 part 30a), etc.
[0071] As shown in FIG. 12, to the raw water chamber 71, the switching valve 30 is installed in such a manner that the switching valve body part 30a penetrates the upper and lower surface of the raw water chamber 71 and raw water in the raw water chamber 71 flows 30 into each filtration chamber 70 through each raw water inlet 32a. Each raw water outlet 32b of the switching valve body part 30a of the switching valve 30 is connected to the raw water introducing port 70a of a specific filtration chamber 70 by pipe, and a waste
21
water pipe 83 that extends downward vertically and penetrates the purified water chamber 73 is attached to the opening 32c of the switching valve body section 30a.
[0072] The filtered water outlet 70b of each filtration chamber 70 is connected to the purified water chamber 70. In the purified 5 water chamber 73, one end of a filtered water pipe 81a is inserted which extends to the lower surface of the waste water chamber 72 in the form of accommodating the waste pipe 24 therein. To the part of the filtered water pipe 81a higher than the upper surface of the filtering material in each filtration chamber 70, one end 10 of a filtered water pipe 81b the other end of which functions as a filtered water outlet 81d. At the part of the filtered water pipe 81b near the filtered water outlet 81d, a filtered water valve 76 is provided, and the part of the filtered water pipe 81b upstream from the filtered water valve 76 and the waste water pipe 83 are 15 connected via a water discarding pipe 82 provided with a water discarding valve 77.
[0073] The pressure-type filtration device 2 where each of raw water and filtered water for backwashing is uniformly supplied to each flirtation chamber can be constructed also by using the 20 switching valve 30 as described above.
[0074] The reason why the pressure-type filtration device of each embodiment is configured as an apparatus where the number of the filtration chambers is six and one filtration chamber is backwashed in the backwashing step, is that it is assumed that the 25 flow velocity required for backwashing (hereinafter, backwashing step flow velocity) is 1,000 m/day and the filtration speed in the backwashing step (hereinafter, backwashing filtration speed) is 200 m/day. That is, when the backwashing step flow velocity and the backwashing filtration speed are the above values, the flow 30 velocity (filtered water quantity) required to backwash one filtration chamber 70 can be covered by filtered water from five filtration chamber 70. The pressure-type filtration device of each embodiment is therefore configured as an apparatus where the
22
number of the filtration chambers is six and one filtration chamber is backwashed in the backwashing step. However, the number of filtration chambers may not necessarily be six, and the number of filtration chambers that are backwashed in the backwashing step may not necessarily be one. 5
[DESCRIPTION OF THE REFERENCE NUMERALS]
[0075]
1, 2 pressure-type filtration device
10 filtration apparatus main body 10
10a outer shell
11, 71 raw water chamber
12a filtering material
12, 70 filtration chamber
13, 73 purified water chamber 15
15 water collection board (filtered water outlet)
18 maintenance port
20, 80 raw water pipe
22a - 22c, 81a, 81b filtered water pipe
22d filtered water outlet 20
23, 82 water discarding pipe
24, 83 waste water pipe
27, 76 filtered water valve
28, 77 water discarding valve
30 switching valve 25
30a switching valve body part
30b drive part
31, 50 housing
32a raw water inlet
32b raw water outlet 30
32c opening
38a, 51a pressurized air introducing port
38 isolation plate
40 valve element 23
41a raw water channel
41b washing waste water channel
45 stem
52 cylinder part
53 piston 5
54 cam follower
60 shaft part
61 cam groove
70a raw water introducing port
70b filtered water outlet 10
70c water collection board 24

I/We Claim:
1. A switching valve for a pressure-type filtration device provided with a plurality of filtration chambers, the switching valve comprising: 5
a valve box having a cylindrical sidewall part, a lid part covering the top end of the sidewall part and a bottom part covering the bottom end of the sidewall part, wherein N raw water outlets, which are to be individually connected to raw water introducing ports of the filtration chambers and are arranged so as to be N-fold 10 symmetrical with respect to the center of the sidewall part, are disposed on the sidewall part, a washing waste water port for discharging washing waste water is disposed on the bottom part, and one or more raw water introducing ports for introducing raw water to be filtered into the valve box are disposed on the lid part or 15 a part of the sidewall part higher than the raw water outlets;
a columnar valve element housed in the valve box in such a manner as to be movable vertically and rotatable; and
a position control means for controlling the vertical position and orientation of the valve element within the valve box, 20
wherein the valve box has a shape that allows the valve element to be lowered down in such a manner that the upper surface position of the valve element becomes a first position which is lower than lower ends of the N raw water outlets,
N channels are provided in the valve body in such a manner as 25 to face the N raw water outlets of the valve box when the upper surface position of the valve element is a second position,
at least one of the N channels is a washing waste water channel which communicates the side surface and the lower surface of the valve body, 30
each channel among the N channels excluding the washing waste water channel is a raw water channel which communicates the side surface and the upper surface of the valve body, and
the position control means has a function of controlling the 25
vertical position of the valve element within the valve box such that the upper surface position of the valve element is the first position, and a function of controlling the vertical position and orientation of the valve element within the valve box such that the upper surface position of the valve element is the second position 5 and an opening of the washing waste, which is formed on the side surface of the valve body, faces a desired raw water outlet of the valve box.
2. The switching valve according claim 1, wherein 10
the position control means includes:
a vertical driving means for vertically moving the valve element such that the upper surface of the valve element moves within a range from the first position to the second position; and
a movement conversion means for converting the vertical 15 movement of the valve element to rotational movement around the center axis of the valve element, and whereby rotating the valve element by an angle of 360/N degrees per one reciprocating movement of the valve element, and
the valve element is housed in the valve body in such a manner 20 that N channels opened to the side surface of the valve element faces the N raw water outlets when the upper surface position thereof is the second position by being moved upward by the vertical driving means.
25
3. The switching valve according claim 2, wherein the movement conversion means includes a cylindrical member which is fixed to either one of the valve element and the valve body and has a cam groove provided at the side surface thereof, and a cam follower fixed to the other of the valve element and the valve body so as to move 30 in the cam groove of the cylindrical member.
4. The switching valve according to claim 2 or 3, wherein the vertical driving means moves the valve element vertically by means 26
of hydraulic pressure, pneumatic pressure or motor.
5. The switching valve according to any one of claims 1 to 4, wherein the washing waste channel is a channel cross-sectional area of which is larger than the raw water channel.