Liquid purification or separation – Filter – Medium – cleaner or agitator moved by fluid
Reexamination Certificate
2000-03-02
2001-09-04
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
Filter
Medium, cleaner or agitator moved by fluid
C210S108000, C210S411000, C210S488000, C055S302000
Reexamination Certificate
active
06283305
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a filter apparatus with a backwashing mechanism in which clogging is removed by backwashing a filter by causing wash fluid to flow in a reverse direction to fluid to be filtered.
DESCRIPTION OF THE RELATED ART
Conventionally, there are known apparatuses having various structures as a filter apparatus that can carry out backwashing by using backwash fluid. In general, in a filter apparatus in which a porous filter face is formed of metal material and the like, when backwashing by using backwash fluid starts and foreign matter that has accumulated on a part of the filter is removed for the first time, flow-rate resistance at that part reduces significantly. Therefore, after that, the backwash fluid passes mainly through the part from which the foreign matter has been removed and pressure of the backwash fluid does not effectively act on the other part. As a result, it is impossible to remove the foreign matter uniformly from the entire filter face.
The above problem makes it difficult to automatically backwash the filter without maintenance of the filter. In other words, conventionally, it is necessary to remove the foreign matter that cannot be removed satisfactorily by backwashing by manual work and the like when a plurality of filters are disposed side by side and the filter is backwashed without stopping the entire apparatus by replacing the filters the filters with each other. Therefore, backwashing of the filter cannot be completely automated, and as a result, requires manpower.
On the other hand, there is a filter disclosed in Japanese Patent Application Laid-open No. 10-272315, in which a thread-shaped body constituting meshes of a filter main body includes groups of thread respectively positioned on an outer periphery side and an inner periphery side and phases of both the groups of thread are displaced from each other in a peripheral direction to change a size of meshes. In this filer, cuttings which have clogged the meshes can be removed by increasing the size of the meshes. However, because the size of the meshes is changed by displacing the phases of the groups of thread on the outer periphery side and the inner periphery side from each other, the size of the meshes can be changed only in a limited range and the filter does not necessarily meet user demands depending on objects to be filtered.
SUMMARY OF THE INVENTION
It is a technical object of the present invention to provide a filter apparatus with a backwashing mechanism for uniformly, satisfactorily, and automatically removing foreign matter that has accumulated on the filter.
It is another technical object of the invention to provide a filter apparatus with a backwashing mechanism for stabilizing filtering gaps in backwashing and for arbitrarily setting a degree of expansion of the filtering gaps according to object to be filtered by forming the filter of a large number of piled resilient filter chips.
It is yet another technical object of the invention to provide a filter apparatus assembly for automatic backwashing of the filter without necessity of maintenance and without manpower by replacing a plurality of filter apparatuses disposed side by side with each other in use of the assembly.
To achieve the above objects, according to the invention, there is provided a filter apparatus with a backwashing mechanism basically including: a housing having an inflow portion and an outflow portion for fluid to be filtered; a filter formed into a cylindrical shape from a plurality of piled resilient filter chips, having a filtering gap for passage of the fluid to be filtered between the respective filter chips, and positioned between the inflow portion and the outflow portion in the housing; a backwashing channel for causing wash fluid to flow through the filter in a direction reverse to the fluid to be filtered; and gap expanding means for expanding the filtering gap of the filter in backwashing by the wash fluid.
As a more concrete structure of the invention, in the first filter apparatus, the filter is formed of spring wire rod wound into a coil shape, a plurality of notches for forming the filtering gaps are formed on the spring wire rod, and the gap expanding means is formed of an actuator for driving the spring wire rod in such a direction as to move opposite ends of the spring wire rod away from each other.
As another concrete structure of the invention, in the second filter apparatus, the filter is formed by piling a plurality of annular leaf spring members, each the leaf spring member is formed with a spring portion for expanding a gap between the leaf spring member and adjacent leaf spring member by resilient force and a projecting portion for forming the filtering gap of fixed size between respective leaf spring members by functioning as a stopper when the filter is compressed, the gap expanding means is formed of an actuator, and the actuator compresses the piled leaf spring members against biasing force of the spring portions in filtering and cancels the compression in backwashing.
As a yet another concrete structure of the invention, in the third filter apparatus, the filter is formed by alternately piling a plurality of annular leaf spring members and filtering plates, each the leaf spring member is in a wave shape in a thickness direction, flattened to have a plate shape in compression, and restores the wave shape in non-compression to form a gap between the leaf spring member and the adjacent filtering plate, each the filtering plate has on front and back opposite faces thereof a large number of filtering grooves in radial directions, the gap expanding means is formed of an actuator, and the actuator pushes the leaf spring members against biasing force of the spring members in filtering and cancels the pushing in backwashing.
The first filter apparatus may include one or more intermediate retaining plates attached to an intermediate portion of the filter and gap adjusting means for stopping the intermediate retaining plates in such a position as to uniformalize the filtering gaps in expansion of the filter by operation of the actuator.
Each the filter apparatus preferably includes a differential pressure sensor for detecting clogging based on a difference between pressures on primary and secondary sides of the filter and a controller for controlling the gap expanding means based on output of the differential pressure sensor.
The filter apparatus with the backwashing mechanism of the invention with the above structure is usually used by arranging the plurality of apparatuses in parallel, using any of them all the time, and recycling one that is not used by backwashing for reuse. Otherwise, a single filter apparatus is used by recycling the apparatus by backwashing during an idle time of a machine cycle, because time required for backwashing is only few seconds or less.
In use of the filter apparatus, predetermined filtering gaps are formed in the cylindrical filter. In backwashing, on the other hand, the filtering gaps are expanded by means for expanding the filtering gaps of the filter or by biasing force of the large number of piled resilient filter chips. Therefore, when the backwash fluid is caused to flow through the backwashing channel, removal of the foreign matter that has accumulated on respective parts of the filter by the backwash fluid is facilitated and removal of the foreign matter by manual work or the like is unnecessary. In expanding the filtering gaps in backwashing, if positions of the intermediate retaining plates provided to the intermediate portions of the filter are adjusted by the gap adjusting means such that the entire filtering gaps are substantially uniformalized, the backwashing can be carried out further effectively.
By forming the filter of the plurality of piled resilient filter chips, the filtering gaps can be stabilized in backwashing and the degree of expansion of the filtering gaps can be set arbitrarily according to the object to be filtered.
In the filter formed of coil-shaped spring wire rod in the first filt
Endo Go
Ishihara Takayuki
Maeda Yoshihisa
Drodge Joseph W.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
SMC Corporation
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