Multiple-disc type filter with extensible support

A multiple-disk type filter including a stack of filter disks disposed in a housing and an extensible support for the stack of filter disks, the extensible support including first and second end elements and a multiplicity of rod members joining the first and second end elements in sliding relationship, the multiplicity of rod members being arranged in slidable engagement with at least one of the first and second end elements, and stop apparatus for limiting extension of the support.

FIELD OF THE INVENTION 
The present invention relates to filters and particularly to multiple-disc 
type filters useful in filtering particles from water and in many other 
applications. 
BACKGROUND OF THE INVENTION 
Multiple-disc type filters generally include a housing in which the filter 
body within the housing is in the form of a stack of like, 
centrally-apertured, filter discs of substantially uniform thickness along 
their widths and having grooved side faces defining filtering channels 
between the adjacent discs in the stack. In some applications of such 
filters, the outer face of the stack of filter discs constitutes the 
upstream side of the filter, in which case the fluid being filtered passes 
from the outer face to the inner face of the stack. In other applications 
of such filters, the inner face of the stack constitutes the upstream side 
of the filter, in which case the fluid being filtered passes from the 
inner to the outer face through the filter stack. 
Multiple-disc type filters have a number of advantages over other known 
types of filters, for example, the cylindrical-screen type filter. Thus, 
the multiple-disc filter has a larger capacity for removing and retaining 
dirt particles, since these may be retained also between the side faces of 
the discs, in addition to being retained on the upstream surface as in the 
cylindrical-screen type filter. Another advantage in the multiple-disc 
filter is that it is not as easily ruptured as the screen type and 
therefore there is less danger that because of a malfunction, unfiltered 
water may pass through and clog sprinklers or other devices downstream of 
the filter. The latter advantage is particularly important in 
self-cleaning filters wherein the upstream face of the filter is cleaned 
by a cleaning nozzle which, in the case of a screen-type filter, may 
rupture the screen by particles becoming wedged between the cleaning 
nozzle and the filter screen. 
The stack of discs in the multiple-disc type filter has hitherto been 
supported internally by a cylinder pierced with holes so as to allow the 
fluid being filtered to flow therethrough. Since the stack is held in 
position by fastening members at each end, as for example by annular 
screws which move about threaded extensions of the cylinder at each end 
thereof, the removal of discs for inspection or replacement can be a 
laborious process. The necessity for the threaded extensions adds to the 
size and cost of the equipment and is not practical for non-in line 
systems. 
SUMMARY OF THE INVENTION 
The present invention relates to a novel form of support for the stack of 
discs in a multiple-disc type filter which overcomes the disadvantages of 
the cylindrical kind of support. 
There is thus provided in accordance with an embodiment of the present 
invention, a multiple-disc type filter comprising a stack of filter disks 
disposed in a housing, an extensible support for the stack of filter 
disks, the extensible support including first and second end elements and 
a multiplicity of rod members joining at least one of the first and second 
end elements in sliding relationship, and stop apparatus for limiting the 
extension of the support. 
According to one embodiment of the invention, the multiplicity of rod 
members are arranged for fixed engagement with the first end element and 
for slidable supporting engagement with the second end element. According 
to another embodiment of the invention the rod members are arranged for 
slidable supporting engagment with both the first and second end elements. 
According to a preferred embodiment of the invention, the second end 
element defines a plurality of slidable mounting channels for accomodating 
the rod members, a plate portion defining a central fluid flow aperture 
and a stop engagement portion. 
According to one embodiment of the invention, the first end element is 
constructed to be identical to the second end element. 
Additionally in accordance with an embodiment of the present invention 
there is provided a spacer support which fixedly joins the multiplicity of 
rod members intermediate the first and second end elements. 
Further in accordance with an embodiment of the present invention, the stop 
apparatus comprises an elongated rod extending axially through the stack 
and having transverse extensions adjacent at least one end thereof for 
engaging the stop engagement portions of the second end element for 
preventing disengagement of the second end element from the rods. 
Further in accordance with an embodiment of the invention, the outer extent 
of the spacer support corresponds to the inner radius of the stack of 
filter disks. 
According to an alternative embodiment of the present invention, the outer 
extent of the spacer support corresponds to the outer radius of the stack 
of filter disks.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring now to FIGS. 1-3, there is seen a filtration unit constructed and 
operative in accordance with a preferred embodiment of the present 
invention. The filtration unit comprises first and second end assemblies 
10 and 12, which are typically identical, a plurality of support rods 14, 
which are slidably mounted in a generally cylindrical pattern on the first 
and second end assemblies and a stack of filter discs 16 which are 
supported between end assemblies 10 and 12 on support rods 14. 
The first and second end assemblies 10 and 12 each typically comprise a 
generally planar end portion 18 having a central aperture 20. A plurality 
of ribs 22 extend from planar end portion 18. Each rib includes a first 
axial portion 24 which defines a rod support, and an inwardly directed 
portion 26. The inwardly directed portions 26 of the individual ribs 22 
terminate at a cylindrical collar 28. 
A central rod or shaft 30 extends axially along the entire length of the 
filter disc stack and through respective collars 28 on the first and 
second end assemblies. Stopper sleeves 32 are formed adjacent the ends of 
the central rod or shaft 30 at both ends thereof, outwardly of respective 
collars 28 to restrict the amount that the first and second end assemblies 
10 and 12 may be axially separated along the longitudinal axis 34 of the 
filtration unit. 
A spacer 36 is fixedly mounted onto central shaft 30 and to rods 14 
approximately halfway between first and second end assemblies 10 and 12. 
Spacer 36 provides structural stability to the support structure for the 
stack of filter discs. Spacer 36 is constructed to have an inner collar 
member 38 and an outer ring 40 which defines slots for seating of rods 14. 
The inner collar member 38 and outer ring 40 are joined by a plurality of 
spokes 42. 
It is appreciated that in the embodiment of FIGS. 1-3, both of the end 
assemblies are axially slidable with respect to the spacer rods 14 to 
permit spreading apart of the individual filter discs from discs adjacent 
thereto for the purpose of cleaning particles therefrom. 
Reference is now made to FIGS. 4-6 which illustrate another preferred 
embodiment of the invention. Here the filtration unit comprises first and 
second end assemblies 50 and 52, which are normally not identical, a 
plurality of support rods 54, which are arranged in a generally 
cylindrical pattern and fixedly mounted onto the first end assembly 50 and 
slidably mounted onto the second end assembly 52. A stack of filter discs 
56 is supported between end assemblies 50 and 52 on support rods 54. 
First end assembly 50 comprises a planar end portion 51 in which are formed 
a plurality of bores 53 for end seating of rods 54 and a seating collar 55 
which may communicate with an aperture 57 formed in end portion 51. 
The second end assembly 52 typically comprises a generally planar end 
portion 58 having a central aperture 60. A plurality of ribs 62 extend 
from planar end portion 58. Each rib includes a first axial portion 64 
which defines a rod support, and an inwardly directed portion 66. The 
inwardly directed portions 66 of the individual ribs 62 terminate at a 
cylindrical collar 68. 
A central rod or shaft 70 extends axially along the entire length of the 
filter disc stack. Shaft 70 is fixedly seated in collar 55 on end assembly 
50 and extends slidably through collar 68 on the second end assembly. A 
stopper sleeve 72 is formed adjacent the end of the central rod or shaft 
70 at the end thereof which lies outwardly of collar 58 to restrict the 
amount that the first and second end assemblies 50 and 52 may be axially 
separated along the longitudinal axis 74 of the filtration unit. 
A spacer 76 is fixedly mounted onto central shaft 70 and slidably mounted 
onto rods 54 approximately halfway between first and second end assemblies 
50 and 52. Spacer 76 provides structural stability to the support 
structure for the stack of filter discs. Spacer 76 is constructed to have 
an inner collar member 78 and an outer ring 80 which defines holes 82 for 
slidable engagement with rods 54. Ring 80 extends to an outer radius which 
corresponds to the outer dimensions of filter discs 56. The inner collar 
member 78 and outer ring 80 are joined by a plurality of spokes 82. 
It is appreciated that in the embodiment of FIGS. 4-6, only one of the end 
assemblies is axially slidable with respect to the spacer rods 14 to 
permit spreading apart of the individual filter discs from discs adjacent 
thereto for the purpose of cleaning particles therefrom. It is further 
appreciated that any of the features of the embodiment of FIGS. 1-3 may be 
combined with any of the features of the embodiment of FIGS. 4-6 to 
produce a suitable filtration unit, which is also within the scope of the 
present invention. 
Reference is now made to FIG. 7 which illustrates a filter employing a 
filtration unit of the type described in connection with FIGS. 4-6. It is 
appreciated that alternatively, the filtration unit may be of the type 
illustrated in FIGS. 1-3 or have a combination of the features of the two 
embodiments. The filter includes a generally bell-shaped housing 90, which 
is mounted on a mounting base 92. A filtration unit of the type described 
hereinabove is disposed within housing 90. 
A central securing rod 94, having first and second threaded ends 95 and 97, 
is secured to base 92 at threaded end 95 by means of internally threaded 
nuts 96 and 98. A nut 100, threaded at end 97, secures the filtration unit 
onto base 92 and maintains the nut in its non-extended orientation for 
filtering opeation and an additional nut 102 secures housing 90 onto base 
92. 
In the illustrated embodiment, base 92 defines a liquid inlet 104 which 
communicates with the outer cylindrical surface of the filtration unit and 
a liquid outlet 106 which communicates with the inner cylindrical surface 
of the filtration unit. The arrows appearing in FIG. 7 indicate the flow 
of liquid through the unit. It is appreciated that base 92 may readily be 
modified to provide an oppositely directed flow or may be formed with a 
movable baffle or baffles to permit selection of the direction of flow. 
Reference is now made to FIG. 8 which illustrate a double capacity filter 
employing the filtration units of the type described hereinabove in 
connection with FIGS. 4-6. In principle, two units 110, each generally of 
the type illustrated in FIGS. 4-6 are placed end to end in communication 
with a common base 112. A single rod 114 threaded at both ends, traverses 
the entire unit and is operative in cooperation with a pair of threaded 
screws 118 to secure the individual housing elements 116 to base 112. The 
filtration units are mounted onto base 112 by means of a pair of 
compression springs 120 which are seated on the axial inner facing 
surfaces of screws 118 and on the axially outer facing surfaces of 
respective end members 122 of the filtration units. Fluid to be filtered 
enters the apparatus at a port 124 and passes through the stack of filter 
discs from the outer cylindrical surface inwardly to the central cavity 
defined by the discs and out through an outlet port 126, in directions 
indicated by the arrows appearing in FIG. 8. 
It is appreciated that in this and all other embodiment of the present 
invention illustrated herein, the indicated direction of flow of fluid 
therethrough may be changed by suitable modification of the flow paths. 
It will be appreciated by persons skilled in the art that the present 
invention is not limited to what has been shown and described with 
particularity hereinabove. Rather the scope of the present invention is 
defined only by the claims which follow: