Claims:I Claim,
1. A method of cleaning a filter (30) in a water purifier (100), said water purifier (100) comprises an accumulator (40) between said filter (30) and a purifier-water delivery valve (50), said method comprises
? measuring pressure difference across said filter (30);
? closing said purified-water delivery valve (50) when said pressure difference is more than a first threshold value;
? continuing supply of water through said filter (30) so as to fill water in said accumulator (40);
? checking if water pressure at the outlet of said filter (30) reaches a second threshold value;
? stopping feed pump (10) to stop supply of water and opening a drain valve (65) of said filter (30) based on the checking result; and
? supplying water from said accumulator (40) back to said filter (30) for back washing of said filter (30).

2. The method of claim 1 further comprises ejecting backwashed water from said filter (30) through said drain valve (35).

3. The method of claim 1 wherein the feed pump (10) is stopped and the drain valve (65) is opened, if water pressure at the outlet of said filter (30) reaches the second threshold value.

4. A water purifier (100) comprises
? a primary filter (20) to purify water supplied from an input line (15);
? a secondary filter (30) to purify water supplied from said primary filter (20);
? an accumulator (40) connected to a purified-water delivery line (35) and placed between the secondary filter (40) and a purified-water delivery valve (50); characterized in that
? a controller (70) adapted to
? close said purified-water delivery valve (50), when pressure difference measured across the secondary filter (30) reaches a first threshold value; and
? stop a water feed pump (10) and open a drain valve (65) of said secondary filter (30), when pressure at outlet of said secondary filter (30) reaches a second threshold value.

5. The water purifier (100) of claim 4, wherein the controller (70) allows supply of water from the input line (15) till the pressure at the outlet of said secondary filter (30) reaches the second threshold value.

6. The water purifier (100) of claim 4 further comprises
? a primary pressure sensor (55) placed between said primary filter (20) and said secondary filter (30);
? a secondary pressure sensor (60) between said secondary filter (30) and said accumulator (40); and
? said controller (70) is connected to said primary pressure sensor (55) and said secondary pressure sensor (60) to measure pressure difference across the secondary filter (30).

7. The water purifier (100) of claim 4 wherein said accumulator (40) comprises an inner vessel (42) for collecting purifier water supplied from the secondary filter (30) and an outer vessel (44) filled with pressurized-air.

8. The water purifier (100) of claim 4, wherein the accumulator (40) supplies back the purified water to backwash said secondary filter (30).
, Description:Field of the invention:
[0001] The invention relates to a water purifier and a method of cleaning a filter of a water purifier. More particularly, it relates to backwashing of the filter in the water purifier.
Background of the invention:
[0002] Water filtration systems to filter raw water for drinking purposes are already known in the prior arts. Normally these water filtration systems use one or more filters to filter out contamination, bacteria etc.
[0003] WO2014138618 discloses a point-of-use water filtration system with backwash function. When a user opens a faucet to get the permeated water, a first pressure drop in a first control line causes a first valve to open and a second pressure drop in the second control line causes the second valve to open so that water from a tank flows in a reverse direction through a first filtration element to backwash the first filtration element.
Brief description of the invention:
[0004] The invention discloses a method of cleaning a filter in a water purifier. The water purifier comprises an accumulator between the filter and a purifier-water delivery valve. The filter cleaning method involves measuring pressure difference across the filter. The purified-water delivery valve is closed when the pressure difference is more than a first threshold value. Water supply through the filter is continued so as to fill the water in the accumulator. A feed pump is stopped to stop the supply of water and a drain valve of the filter is opened when water pressure at the outlet of said filter reaches a second threshold value. Water is then supplied from the accumulator back to the filter for back washing of the filter. The water purifier of the present invention comprises a controller using which the above method/routine for cleaning the filter is executed.
Brief description of the accompanying drawings:
[0005] An embodiment of the invention is described with reference to the following accompanying drawings,
[0006] Fig. 1 shows a circuit diagram of water purifier, in accordance with an embodiment of the invention;
[0007] Fig. 2 shows a schematic diagram of an accumulator of a water purifier, in accordance with an embodiment of the invention;
[0008] Fig. 3 shows a block diagram of a controller connected to other components of a water purifier, in accordance with an embodiment of the invention; and
[0009] Fig. 4 shows a flow chart of a method of cleaning a filter in a water purifier, in accordance with an embodiment of the invention.
Detailed description of the embodiments:
[00010] Fig. 1 shows a circuit diagram of water purifier, in accordance with an embodiment of the invention. Only the important components are shown in the fig.1 and the components which are commonly known are not shown.
[00011] The water purifier 100 comprises a feed pump 10 connected to an input line 15 through which raw water is supplied. A source of raw water such as a tap can be connected to the input line 15. The feed pump 10 draws the water and supplies it to a pre-filter 20. The feed pump 10 runs on electricity supplied from AC mains. The pump 10 can also be run by alternative power sources such as a solar panel, battery, etc. using an inverter.
[00012] The pre-filter 20 filters the water and retains particles of > 5 micron size. Further water is flown through a primary filter 25. Examples of the primary filter 25 can be an activated carbon filter. The primary filter 25 purifies the water supplied from the input line 15 by removing chlorine, hydrocarbons, bad taste and odor.
[00013] Water is then passed from the primary filter 25 to a secondary filter 30. The secondary filter 30 further purifies the water and delivers through a purified-water delivery line 35. Examples of the secondary filter 30 can be an ultra-filter. The secondary filter 30 does not allow particles of more than 0.02 micron size, virus, bacteria, cyst, etc. towards the purified-water delivery line 35. An accumulator 40 is connected to the purified-water delivery line 35 and placed between the secondary filter 30 and a purified-water delivery valve 50. The purified water is flown out through the purified-water delivery valve 50. This delivery valve 50 can be connected to multiple Point-of-Service (POS) terminals, drinking water dispensing tap, a purified water supply tank, etc.
[00014] A primary pressure sensor 55 is placed between the primary filter 25 and the secondary filter 30. Also a secondary pressure sensor 60 is placed between the secondary filter 30 and the accumulator 40.
[00015] Fig. 2 shows a schematic diagram of an accumulator of a water purifier, in accordance with an embodiment of the invention. In an embodiment of the invention, the accumulator 40 is a pressurized accumulator. The accumulator 40 comprises a flexible inner shell 42 for keeping purified water delivered through the purified-water delivery line 35 from the secondary filter 30. An outer shell 44 is provided around the inner shell 42. The outer shell 44 comprises air kept at a particular pressure for e.g. 2 bar. Therefore, the water from the purified-water delivery line 35 completely fills the inner shell 42 of the accumulator 40 only when the pressure of water is more that the air pressure at the outer shell 44.
[00016] Fig. 3 shows a block diagram of a controller connected to other components of a water purifier, in accordance with an embodiment of the invention. The water purifier 100 has a controller 70, which is connected to the pressure sensors 55, 60, the feed pump 10, the purified-water delivery valve 50, and a drain valve 65 of the secondary filter 30. The controller 70 can be a microcontroller chip, in one embodiment or a programmable logic controller in another embodiment and powered by an independent power supply such as a battery. The controller 70 is also capable of transmitting or receiving data through a wired/wireless network.
[00017] The controller 70 computes the pressure difference across the secondary filter 30 based on values output by the primary and secondary pressure sensors 55, 60. When the secondary filter 30 starts clogging, there is a pressure difference created at the input side and output side of the secondary filter 30. The controller 70 closes the purified-water delivery valve 50 when the pressure difference measured across the secondary filter 30 reaches a first threshold value. When the pressure difference across the secondary filter 30 reaches the first threshold value, the controller 50 recognizes the clogging condition of the secondary filter 30. In an embodiment of the invention, the controller 70 closes the purified water delivery valve 50 through an actuator.
[00018] Raw water supply is continued for some time even after closing the purified-water delivery valve 50. As a result, water pressure builds up in the pressurized-water delivery line 35. The pressurized water flows into the inner shell 42 in the accumulator 40 against the pressure of the air and fills the inner shell 42 completely.
[00019] The controller 70 stops the water feed pump 10 to stop the supply of water through the input line 15 and also opens a drain valve 65 of the secondary filter 30, when the pressure at the outlet of the secondary filter 30 reaches a second threshold value for e.g. 4 bar. The pressure at the outlet of the secondary filter 30 is measured by the secondary pressure sensor 60.
[00020] As a result, pressurized water from the accumulator 40 is supplied back to the secondary filter 30 for back-washing. The secondary filter 30 is cleaned and the backwashed water is ejected out through the drain valve 65.
[00021] Fig. 4 shows a flow chart of a method of cleaning a filter in a water purifier, in accordance with an embodiment of the invention. The water purifier 100 comprises an accumulator 40 between the filter 30 and a purifier-water delivery valve 50. The filter 30 can be an ultra-filter. The filter 30 gets clogged over a period of time, because of the impurities and therefore it needs to be detected and cleaned automatically. The cleaning method involves measuring pressure difference across the filter 30 at step S1. The pressure difference across the filter 30 can be measured by a controller 70 with the help of pressure sensors 55, 60 placed on input and output sides of the filter 30, respectively.
[00022] At step S2, the purified-water delivery valve 50 is closed when the pressure difference is more than a first threshold value. For instance, the purified-water delivery valve 50 is closed by an actuator based on signal from a controller 70. Then, at step S3, water supply through the filter 30 is continued further. As a result, water pressure builds up and water is filled in the accumulator 40. The controller 70 checks if water pressure at the outlet of the filter 30 reaches a second threshold value at step S4. The feed pump 10 is stopped to stop the supply of water and a drain valve 65 of the filter 30 is opened at step S5 when water pressure at the outlet of the filter 30 reaches the second threshold value. At step S6, water starts flowing from the accumulator 40 back to the filter 30 for back washing the filter 30. The backwashed water is ejected out through the drain valve 65.
[00023] Then, after a particular time from the completion of backwashing, the controller 70 starts the feed pump 10 to supply the water for filtration. The above cleaning method can be executed with help of the suitable instructions/commands by the controller 70.
[00024] The filter of the water purifier is automatically cleaned whenever it is clogged. Therefore, user’s convenience is improved. Also, the water purifier also has an input panel, through which manual backwashing function can also be selected by the user. The threshold pressure values are factory-set. The water purifier consumes less power and can be operated by various power sources. The water purifier removes bad odors, impurities of to 0.02 micron size, bacteria, virus, etc.
[00025] Clogging of pre-filter can also be detected by using another pressure sensor and the pre-filter can be either cleaned or exchanged. The backwashed water can be used for non-potable requirements such as plant watering, floor cleaning, vehicle wash, etc.
[00026] The critical elements in the system such as the secondary filter membrane & the pump are safeguarded using the following method. A flow switch incorporated in the circuit senses low flow for a pre-set time and the controller switches OFF the feed pump considering no water available at inlet to the feed pump. The primary pressure sensor apart from being used for the backwash function, is also used to provide feedback when pressure overshoots the normal working pressure; As a result the controller switches OFF the pump to safeguard the secondary filter.
[00027] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.