Water filter with strainer scraping means

A water filter having a strainer mounted on the inside for straining water, and a reciprocating device controlled by a pressure differential controller to reciprocate a disk-like scraper in the strainer, causing it to scrape out dirt from the strainer, the disk-like scraper having a center water hole and a check valve mounted in the center water hole for permitting water to flow downwards in the strainer through the center water hole and stopping water from flowing upwards in the strainer through the center water hole.

BACKGROUND OF THE INVENTION 
The present invention relates to water filters for straining water by a 
strainer, and more particularly to such a water filer which comprises a 
disk-like scraper controlled by a pressure differential controller to 
scrape out dirt from the strainer. 
FIG. 1 shows an industrial water filter according to the prior art. This 
structure of water filter comprises a housing 10, a strainer 11, a suction 
scanner 12, a motor 13, a drain valve 14, a pressure differential switch 
15, a water intake valve 16, and a water outlet valve 17. When a pressure 
drop is detected by the pressure differential switch 15, the pressure 
differential switch 15 immediately provides a signal to start a reverse 
washing operation. The reverse washing operation includes two washing 
procedures, namely the primary washing procedure and the fine washing 
procedure. During the fine washing procedure, the motor 13 is driven to 
propel the suction scanner 12 in the strainer 11. When the drain valve 14 
is opened, a suction force is induced to suck in dirt from the strainer 
11. At the same time, clean water is pumped into the housing 10 by an 
external water pumping device for washing. During the primary washing 
procedure, a stainless steel brush device is driven by a motor to remove 
dirt from the strainer 11, permitting waste matter to be carried with 
water out of the housing 10 through the drain valve 14. The main drawback 
of this structure of water filter is its complicated washing procedures. 
Washing the strainer takes too much time. 
SUMMARY OF THE INVENTION 
According to the preferred embodiment of the present invention, the water 
filter comprises a housing, a strainer mounted inside the housing and 
defining the inside space of the housing into an inner water chamber and 
an outer water chamber around the inner water chamber, a water intake 
valve adapted for guiding water into the housing, a water outlet adapted 
for guiding filtered water out of the housing, and a drain valve connected 
to the housing at a bottom side and adapted for carrying off waste water 
from the housing, wherein a reciprocating device is mounted on the housing 
at a top side and controlled by a pressure differential controller to 
reciprocate a disk-like scraper in the inner water chamber along an inside 
wall of the strainer, causing it to scrape out dirt from the strainer, the 
disk-like scraper comprising a center water hole, and a check valve 
mounted in the center water hole for permitting water to flow downwards in 
the inner water chamber through the center water hole and stopping water 
from flowing upwards in the inner water chamber through the center water 
hole.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 2, 3 and 4A, a water filter in accordance with the 
present invention comprises a cylindrical housing 20, a pressure 
differential controller 21, a strainer 22 mounted within the housing 20, a 
valve control switch 24, a pressure gage 25 connected to the housing 20 
and adapted to measure the inside pressure of the housing 20, a relief 
valve 26, a reciprocating device 27 mounted on the top side of the housing 
20 at the top in a vertical position, a water intake valve 40 connected to 
the housing 20 near its bottom side and controlled to let water flow into 
the housing 20, a water outlet valve 50 connected to the housing 20 near 
its top side and controlled to let filtered clean water flow out of the 
housing 20, and a drain valve 60 mounted on the bottom side of the housing 
20 and controlled by a regulator 61 to drain waste water from the housing 
20. The strainer 22 is mounted on an annular seat 201 inside the housing 
20 in a vertical position, and divides the inside space of the housing 20 
into an inner water chamber 221 and an outer water chamber 222. The 
pressure differential controller 21 has one end connected to the housing 
20 outside the strainer 22, and an opposite end connected to the water 
intake valve 40. A disk-like scraper 30 is moved up and down in the inner 
water chamber 221 along the inside wall of the strainer 22. A vertical 
reciprocating rod 31 is coupled between the disk-like water stopper 30 and 
the reciprocating device 27, and controlled by the reciprocating device 27 
to reciprocate the disk-like scraper 30 in the strainer 22. The disk-like 
scraper 30 has an annular water hole 32 at the center. A check valve 33 is 
mounted in the annular water hole 32 of the disk-like scraper 30 to let 
water flow downwards through the annular water hole 32 and to stop water 
from flowing upwards through the annular water hole 32. 
Referring to FIG. 3 again, when water is pumped into the water intake valve 
40, it flows into the inner water chamber 221 within the strainer 22, then 
flows through the strainer 22 to the outer water chamber 222, and then 
flows out of the housing 20 through the water outlet valve 50. When water 
flows from the inner water chamber 221 through the strainer 22 to the 
outer water chamber 222, a pressure drop is caused to occur, and the 
pressure drop is enhanced with the deposition of sediment in water in the 
inner water chamber 221. When the pressure drop reaches a predetermined 
value, the pressure differential controller 21 is induced to start the 
reciprocating device 27 and simultaneously to close the water intake valve 
40 and the water outlet valve 50. 
Referring to FIGS. 4A and 4B, when the reciprocating device 27 is started 
and the water intake valve 40 and water outlet valve 50 are closed, the 
disk-like scraper 30 is moved downwards along the inside wall of the 
strainer 22 to scrape out dirt. When the disk-like scraper 30 is moved to 
the lower limit, water is forced to flow in a rush from the outer water 
chamber 222 through the strainer 22 into the inner water chamber 221 above 
the disk-like scraper 30, causing the strainer 22 to be washed, and then 
the disk-like scraper 30 is lifted to its former upper limit position. 
When the disk-like scraper 30 is lifted, water is forced to flow downwards 
in the inner water chamber 221 through the water hole 32 of the disk-like 
scraper 30. After washing, waste water is carried away from the housing 20 
through the drain valve 60. 
While only one embodiment of the present invention has been shown and 
described, it will be understood that various modifications and changes 
could be made thereunto without departing from the spirit and scope of the 
invention disclosed.