AU2016240717B2 - Switching valve - Google Patents

Abstract

Disclosed is a switching valve for constructing a pressure-type filtration device including a plurality of filtration chambers. This switching valve (30) has a structure capable of taking: a state in which raw water supplied from raw water inlets (32a) to the interior is discharged from N raw water outlets (32b); and a state in which the raw water supplied to the interior is discharged from N-1 raw water outlets (32b) via N-1 raw water flow paths (41a) in a valve body (40) and the remaining raw water outlet (32b) is discharged from an opening (32c) via a cleaning drainage flow path (41b) in the valve body (40).

Description

SWITCHING VALVE [FIELD]

[0001] The present invention relates to a switching valve,

specifically relates to a switching valve used to construct a

pressure-type filtration device including a plurality of

filtration chambers.

[BACKGROUND]

[0002] A pressure-type filtration device (closed type

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.

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

the other pressure-type filtration devices.

[Citation List]

[Patent Literature]

[0004]

[PTL 1] Japanese patent laid-open publication No. 2003-93808.

[Summary]

[Technical Problem]

[0005] The above-described system requires a large number of

valve devices (three-way valves and so on).

[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 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

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 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 water to be filteredinto 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 controlmeans for controlling the vertical position and

orientation of the 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, 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 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 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 secondposition and an openingofthe washingwaste, whichis 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

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

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

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

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.

[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 of the valve element moves within a range from the first position to the second position; and a movement conversion means for converting the verticalmovement ofthe 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 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.

[0011] As the movement conversion means, verticaldrivingmeans

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

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

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

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

is possible to construct (manufacture) a pressure-type filtration

device includingaplurality offiltration chambermore easily than

before (in such a manner that the number of valve devices required is less than before).

[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

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

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

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.

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.

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

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

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

device shown in FIG. 12.

[Description of Embodiments]

[0014] The embodiments will now be described with reference to

the accompanying drawings.

[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

pressure-type filtration device 1, respectively.

[0016] The pressure-type filtration device lis 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 comprises a filtration apparatus

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

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

illustrated in Figs 1 and 3, in the filtration apparatus main body

10, a raw water chamber 11, six filtration chambers 12 and apurified

water chamber 13 are arranged. Moreover, a switching valve 30 is attached to the central part of the upper surface central part of 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

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 switchingvalve bodypart 30ais aunit (valve device)

where a cylindrical valve element 40 moves vertically and rotates

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 ofthe switchingvalve body part 30a, six raw waterinlets

32a are arranged with a constant angular space. Further, at the

part of the side surface of the valve box of the switching valve

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

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),

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

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 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

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

collection board 15 functions as the filtered water outlet.

Further, althoughanthracite, manganese sand and filtration gravel

are depicted as the filteringmaterials12ain FIG. 3, the filtering

material12ais for removingimpurities includedin raw water, and,

kind, particle diameter and uniformity coefficient of the

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 obtainedby the shape dividing the principalpart ofthe inner

space of the filtration apparatus main body 10 (outer shell 10a)

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.

[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

valve body part 30a in the form of accommodating the waste water

pipe 24 therein. To the part ofthis filteredwater pipe 22bhigher

than the upper surface of the filtering material 12a, one end of a filtered water pipe 22c which extends approximately horizontally 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 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

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 topermit or stopthe outflowof filteredwater fromthe filtered

water outlet 22d is arranged. The filtered water pipe 22a is

connected to the waste water pipe 24 in the part upstream from the

filtered water valve 27 via the water discarding pipe 23. Thewater

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.

[0027] Hereinafter, constitution of the switchingvalve 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.

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

take, and FIG. 8 is a section view of the valve element 30 along

the VIII-VIIIline ofFig. 7 viewing fromthe arrow direction. FIG.

9 is an explanatory drawing of the constitution of the switching

valve 30.

[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

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.

[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

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

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

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

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 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

is a channel having approximately the same diameter (in

diameter) 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,

a circular channel the diameter ofwhichis 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

equiangular intervals (that is, 60 degrees intervals). Further,

on the side surface of the valve element 40, 0-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 31in a condition where an O-ring is inserted in each O-ring

groove.

[0035] As illustrated in FIG. 4, a stem 45 for rotating and

verticallymoving the valve element 40in the housing 31is 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

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 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

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

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

cylindricalmember 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, 0-ring grooves are formed, and the piston 53 is inserted

into the housing 50 (cylinder part 52) in a condition where an O-ring

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

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

follower 54 to the shaft part 60 to be changed for 30 degrees in

a certain direction when the camfollower 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

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.

[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

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

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

discussion, a control device is defined as a device (a kind of

computer) to control the filtered water valve 27, the water

discardingvalve 28 and the switchingvalve 30 of the pressure-type

filtration device1. The normalpositionis aposition ofthe valve

element 40 in the housing 31 when the cam follower 54 is positioned

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

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

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

switchingvalve 30is positionedin the normalposition. 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

normalposition willbe denotedhereinafter as the filtering state.

[0045] The upper surface of the valve element 40 positioned in

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

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

28 is closed, andtherefore filteredwater 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.,

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.

[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

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 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

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

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

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

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 chamber12 (the rawwater outlet 32b fromwhichrawwater

is supplied 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 open (raw water is not introduced from the raw water

introducing port). Further, when both of the filtered water valve

27 and the water discardingvalve 28 are closed, the filtratedwater

in the purified water chamber 13 cannot flow out to the filtered

water 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,

andwashingwaste water fromthe backwashtarget 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

(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

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 chamber12 thatis backwashed, and therefore the control

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

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,

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 element 40 is positioned in the normal position" is formed.

Therefore, it follows that filtered water from six filtration

chambers 12 flows out fromthe waste waterpipe 24 throughthe water

discarding pipe 23 as schematically shown in FIG. 10C.

[0058] The controldevice that forms the above state (whichwill

hereinafter be termed the water discarding state) by controlling

the switchingvalve 30 and the water discardingvalve 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 discardingvalve 28 such that the filtered water valve

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

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

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

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).

[0060] Note that, the pressure-type filtration device 1

described above includes six filtration chambers 12 arranged concentrically and the raw water chamber 11arrangedin the central part ofthe filtration chambers 12. Moreover, in the pressure-type 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

filtration chamber 12 in the filtration step.

[0061] Further, the pressure-type filtration device 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

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

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

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

water supplied to each filtration chamber.

[0063] <<Modified Mode>>

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 maybe modified into a unit in which the piston 53 is moved

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 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

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

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) ofeach flirtation

chamber that acts as a supply source of backwashing water in the

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

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'havingthe shape showninFigs11Aand11B, namely, valve element

40' provided with four raw water channels 41a and two washing waste

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

water channel41b ofthevalve element 40is approximately2.5 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 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 chamber12, the cross-section ratio ofthe washingwaste 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

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

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

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

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

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 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

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

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

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

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

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

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 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.

[DESCRIPTION OF THE REFERENCE NUMERALS]

[0075]

1, 2 pressure-type filtration device

filtration apparatus main body

10a outer shell

11, 71 raw water chamber

12a filtering material

12, 70 filtration chamber

13, 73 purified water chamber

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

23, 82 water discarding pipe

24, 83 waste water pipe

27, 76 filtered water valve

28, 77 water discarding valve

switching valve

30a switching valve body part

30b drive part

31, 50 housing

32a raw water inlet

32b raw water outlet

32c opening

38a, 51a pressurized air introducing port

38 isolation plate

valve element

41a raw water channel

41b washing waste water channel

stem

52 cylinder part

53 piston

54 cam follower

shaft part

61 cam groove

70a raw water introducing port

70b filtered water outlet

70c water collection board

Claims (5)

1. A switching valve for a pressure-type filtration device

provided with a plurality of filtration chambers, the switching

valve comprising:

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

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 apart of the sidewallparthigher than the rawwater outlets;

a columnar valve element housed in the valve box in such a

manner as to be movable vertically and rotatable; and

a position controlmeans for controlling the verticalposition

and orientation of the valve element within the valve box,

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 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,

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 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 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

the position control means includes:

a vertical driving means for vertically moving the valve

element such that the upper surface ofthe valve elementmoves 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 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 Nrawwater outlets when the upper surface position thereof

is the second position by being moved upward by the vertical driving

means.

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 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 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.