Water purification device and control method

Abstract

The invention relates to the technical field of water purification, particularly provides a water purification device and a control method, and aims at solving the problem that an existing water purification device is poor in adaptability. In order to achieve the purpose, the water purifying device comprises a first filter, a second filter and a valve group, and the valve group can be switched to enable the first filter and the second filter to be arranged in parallel or in series. The first filter and the second filter are controlled by the valve bank to be arranged in parallel, and the first filter and the second filter are put into use at the same time, so that more purified water can be obtained; the valve group is used for controlling the first filter and the second filter to be connected in series, and the first filter and the second filter are put into use at the same time, so that higher purified water quality can be obtained, different water purification requirements are met, and the adaptability of the water purification device is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of water purification, and specifically provides a water purification device and a control method. Background Art

[0002] Household water purification devices have gradually become popular. Water purification devices include pre-filters, purification filters and post-filters. The pre-filter can remove large particles of impurities in tap water, the purification filter can filter tap water to produce pure water, and the post-filter can remove organic impurities such as formaldehyde and urea in pure water. In some purifiers, the post-filter can also add minerals to pure water to improve the drinking taste of pure water.

[0003] In current water purification devices, the pre-filter, purification filter and post-filter are generally of fixed type, and the filtering path of the water flow in the pipeline is fixed, the filtering speed and filtering effect are single, the adaptability is poor, and it is difficult to adapt to the different needs of users.

[0004] Therefore, there is an urgent need for a water purification device and a control method to solve the problem of poor adaptability of existing water purification devices. Summary of the invention

[0005] The present invention aims to solve the above technical problem, that is, to solve the problem of poor adaptability of existing water purification devices.

[0006] In a first aspect, the present invention provides a water purification device, comprising a first filter and a second filter, the water purification device further comprising a valve group, the valve group being capable of switching so that the first filter and the second filter are arranged in parallel or in series.

[0007] In a specific embodiment of the water purification device, the valve group can also be switched to enable the first filter and / or the second filter to be put into operation.

[0008] In a specific embodiment of the above-mentioned water purification device, the first filter is connected to a first water outlet pipe, and the second filter includes a second water inlet pipe; a series pipe is arranged between the first filter and the second filter, one end of the series pipe is connected to the first water outlet pipe, and the other end is connected to the second filter; the valve group includes a first valve, a second valve and a third valve, the first valve is arranged in the first water outlet pipe to control the on-off of the first water outlet pipe, the second valve is arranged in the second water inlet pipe to control the on-off of the second water inlet pipe, and the third valve is arranged in the series pipe to control the on-off of the third valve; the connection point between the series pipe and the first water outlet pipe is located between the first valve and the first filter; when the third valve is closed, the first filter and the second filter are connected in parallel; when the first valve and the second valve are closed and the third valve is opened, the first filter and the second filter are connected in series.

[0009] In a specific embodiment of the above-mentioned water purification device, one end of the series pipe away from the first filter is connected to the second water inlet pipe in the area between the second valve and the second filter; or, the second filter is also connected to a second waste water pipe, and the valve group also includes a fourth valve, which is arranged in the second waste water pipe to control the opening and closing of the second waste water pipe, and one end of the series pipe away from the first filter is connected to the second waste water pipe in the area between the fourth valve and the second filter, and the fourth valve is closed when the third valve is opened.

[0010] In a specific embodiment of the above-mentioned water purification device, the first filter is also connected to the first water inlet pipe, and the valve group also includes a fifth valve, which is arranged in the first water inlet pipe to control the on-off of the first water inlet pipe; when the third valve and the fifth valve are opened and the first valve and the second valve are closed, the first filter and the second filter are arranged in series and put into operation at the same time; when the first valve, the second valve and the fifth valve are opened and the third valve is closed, the first filter and the second filter are arranged in parallel and put into operation at the same time; when the third valve and the fifth valve are closed and the second valve is opened, the second filter is put into operation and the first filter is cut out; when the second valve and the third valve are closed and the fifth valve is opened, the first filter is put into operation and the second filter is cut out.

[0011] In a specific embodiment of the above-mentioned water purification device, a first one-way valve is provided on the first water outlet pipe, and the first one-way valve is configured to allow water to flow out from the first filter through the first water outlet pipe; and / or, the second filter is also connected to a second water outlet pipe, and a second one-way valve is provided on the second water outlet pipe, and the second one-way valve is configured to allow water to flow out from the second filter through the second water outlet pipe; and / or, the first filter is also connected to a first wastewater pipe, and a third one-way valve is provided on the first wastewater pipe, and the third one-way valve is configured to allow water to flow out from the first filter through the first wastewater pipe; and / or, the second filter is also connected to a second wastewater pipe, and a fourth one-way valve is provided on the second wastewater pipe, and the fourth one-way valve is configured to allow water to flow out from the second filter through the second wastewater pipe.

[0012] In a specific embodiment of the above-mentioned water purification device, the first filter is any one of a reverse osmosis membrane filter and a nanofiltration membrane filter; and / or, the second filter is any one of a reverse osmosis membrane filter, a nanofiltration membrane filter, an activated carbon filter or a mineralization filter.

[0013] In a specific embodiment of the above water purification device, the water purification device further includes a third filter, the third filter is connected to a third water outlet pipe, and the third water outlet pipe is connected to the first filter and the second filter to supply water to the first filter and the second filter.

[0014] In a second aspect, the present invention provides a control method for a water purification device, the control method comprising: obtaining user demand; and controlling the valve group according to the user demand.

[0015] In a specific implementation of the control method of the above-mentioned water purification device, the user demand is at least any one of a water volume demand, a replacement cycle demand and a water quality demand; "controlling the valve group according to the user demand" includes: if the user demand is a water volume demand, then controlling the valve group so that the first filter and the second filter are connected in parallel and put into use at the same time; if the user demand is a replacement cycle demand, then controlling the valve group so that the first filter and the second filter are connected in parallel and put into use alternately; if the user demand is a water quality demand, then controlling the valve group so that the first filter and the second filter are connected in series and put into use at the same time.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The water purification device provided by the present invention includes a first filter and a second filter, and the water purification device also includes a valve group, and the valve group can switch to set the first filter and the second filter in parallel or in series. By using the valve group to control the first filter and the second filter to be set in parallel, and the first filter and the second filter are put into use at the same time, more purified water can be obtained; by using the valve group to control the first filter and the second filter to be set in series, and the first filter and the second filter are put into use at the same time, higher purified water quality can be obtained, thereby meeting different water purification needs and improving the adaptability of the water purification device.

[0018] Furthermore, the valve group can also switch to put the first filter and / or the second filter into use. By using the valve group to control the first filter and the second filter to be set in parallel, and the first filter and the second filter to be used at the same time, more purified water can be obtained; by using the valve group to control the first filter and the second filter to be set in parallel, and the first filter and the second filter to be used alternately, the service life of the water purification device can be increased, thereby meeting different water purification needs and improving the adaptability of the water purification device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0020] Figure 1 It is a piping diagram of the water purification device provided by the present invention;

[0021] Figure 2 It is a piping diagram of another water purification device provided by the present invention;

[0022] Figure 3 It is a flow chart of the control method of the water purification device provided by the present invention.

[0023] Description of reference numerals:

[0024] 1. The first filter; 11. The first water inlet pipe; 12. The first water outlet pipe; 13. The first waste water pipe; 2. The second filter; 21. The second water inlet pipe; 22. The second water outlet pipe; 23. The second waste water pipe; 3. The third filter; 31. The third water inlet pipe; 32. The third water outlet pipe; 321. The booster pump; 4. The series pipe; 51. The first valve; 52. The second valve; 53. The third valve; 54. The fourth valve; 55. The fifth valve; 56. The first non-return valve; 57. The second non-return valve; 58. The third non-return valve; 59. The fourth non-return valve; 6. The pure water outlet pipe; 61. The second probe; 62. The high-pressure switch; 7. The waste water outlet pipe; 71. The waste water valve; 8. The domestic water pipe; 81. The first probe. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0026] It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0027] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal connection of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In order to solve the problem of poor adaptability of existing water purification devices, the present invention provides a water purification device.

[0029] like Figure 1As shown, the water purification device includes a first filter 1, a second filter 2, a third filter 3, a pure water outlet pipe 6 and a waste water outlet pipe 7. The first filter 1 is connected to a first water inlet pipe 11, a first outlet pipe 12 and a first waste water pipe 13. The second filter 2 is connected to a second water inlet pipe 21, a second outlet pipe 22 and a second waste water pipe 23. The third filter 3 is connected to a third water inlet pipe 31 and a third outlet pipe 32. The third water inlet pipe 31 is connected to a water source, which can be tap water or the like. The third outlet pipe 32 can be communicated with the first water inlet pipe 11 and the second water inlet pipe 21 to provide a water source to the first filter 1 and the second filter 2. The first outlet pipe 12 and the second outlet pipe 22 are connected to the pure water outlet pipe 6, and the first waste water pipe 13 and the second waste water pipe 23 are connected to the waste water pipe. A series pipe 4 is provided between the first filter 1 and the second filter 2, one end of the series pipe 4 is connected to the first outlet pipe 12, and the other end is connected to the second filter 2.

[0030] The water purification device also includes a valve group, which includes at least a first valve 51, a second valve 52, a third valve 53, a fourth valve 54 and a fifth valve 55. The first valve 51 is arranged on the first outlet pipe 12 to control the on-off of the first outlet pipe 12. The second valve 52 is arranged on the second inlet pipe 21 to control the on-off of the second inlet pipe 21. The third valve 53 is arranged on the series pipe 4 to control the on-off of the series pipe 4. The fourth valve 54 is arranged on the second waste water pipe 23 to control the on-off of the second waste water pipe 23. The fifth valve 55 is arranged on the first inlet pipe 11 to control the on-off of the first inlet pipe 11. In an embodiment of the present invention, the first valve 51, the second valve 52, the third valve 53, the fourth valve 54 and the fifth valve 55 are solenoid valves. Of course, in other embodiments, the first valve 51, the second valve 52, the third valve 53, the fourth valve 54 and the fifth valve 55 can also be other types of valves, such as manual shut-off valves.

[0031] When the third valve 53 is closed, the first filter 1 and the second filter 2 are arranged in parallel.

[0032] On the basis of the third valve 53 being closed, if the first valve 51 and the fifth valve 55 are opened and the second valve 52 is closed, the first filter 1 is put into operation, the second filter 2 is cut out, the water flowing out of the third filter 3 enters the first filter 1, and the purified pure water flows into the pure water outlet pipe 6 from the first outlet pipe 12. On the basis of the third valve 53 being closed, if the second valve 52 is opened and the first valve 51 and the fifth valve 55 are closed, the second filter 2 is put into operation, the first filter 1 is cut out, the water flowing out of the third filter 3 enters the second filter 2, and the purified pure water flows into the pure water outlet pipe 6 from the second outlet pipe 22. If the first filter 1 and the second filter 2 are any one of a reverse osmosis membrane filter and a nanofiltration membrane filter, as the valve group is switched, one of the first filter 1 and the second filter 2 is put into operation and the other is cut out. When one of the first filter 1 and the second filter 2 is dirty, the dirty filter is cut out and the other filter is put into operation. When both the first filter 1 and the second filter 2 are dirty, the filter element is replaced at the same time to improve the replacement cycle of the water purification device. If the first filter 1 and the second filter 2 are filters of different types, as the valve group is switched so that one of the first filter 1 and the second filter 2 is put into operation and the other is cut out, the water purification device can obtain different purification effects to meet different purification needs.

[0033] On the basis of closing the third valve 53, if the first valve 51, the second valve 52 and the fifth valve 55 are opened, the first filter 1 and the second filter 2 are both put into operation, and the water flowing out of the third filter 3 enters the first filter 1 and the second filter 2 at the same time, and the purified pure water flows into the pure water outlet pipe 6 from the first outlet pipe 12 and the second outlet pipe 22. The first filter 1 and the second filter 2 are any one of a reverse osmosis membrane filter and a nanofiltration membrane filter. The first filter 1 and the second filter 2 are put into operation at the same time, and a large amount of clean water can be obtained to meet the scene of large water demand.

[0034] When the third valve 53 is opened and the first valve 51 and the second valve 52 are closed, the first filter 1 and the second filter 2 are arranged in series and put into use at the same time. The water flowing out of the third filter 3 enters the first filter 1 from the first water inlet pipe 11, and the purified pure water flows out from the first water outlet pipe 12, and then flows into the second filter 2 through the series pipe 4, and flows into the pure water outlet pipe 6 from the second water outlet pipe 22 after being purified by the second filter 2. The first filter 1 is one of a reverse osmosis membrane filter and a nanofiltration membrane filter, and the second filter 2 is any one of a reverse osmosis membrane filter, a nanofiltration membrane filter, an activated carbon filter or a mineralization filter. After the raw water is filtered by the first filter 1 and the second filter 2, a better filtering effect can be obtained to meet the scene with high water quality requirements. Among them, when the second filter 2 is a mineralization filter, it is mainly to improve the taste of pure water.

[0035] In this embodiment, one end of the series pipe 4 away from the first water outlet pipe 12 is connected to the second waste water pipe 23. The position where the series pipe 4 is connected to the first water outlet pipe 12 is located between the first valve 51 and the first filter 1 to ensure that the water flowing out of the first water outlet pipe 12 can enter the series pipe 4. The position where the series pipe 4 is connected to the second waste water pipe 23 is located between the fourth valve 54 and the second filter 2, and the fourth valve 54 is closed when the third valve 53 is opened to ensure that the water flowing out of the series pipe 4 can flow from the second waste water pipe 23 into the second filter 2.

[0036] like Figure 2 As shown, in another possible embodiment, one end of the series pipe 4 away from the first water outlet pipe 12 is connected to the second water inlet pipe 21. The position where the series pipe 4 is connected to the first water outlet pipe 12 is located between the first valve 51 and the first filter 1, so as to ensure that the water flowing out of the first water outlet pipe 12 can enter the series pipe 4. The position where the series pipe 4 is connected to the second water inlet pipe 21 is located between the second valve 52 and the second filter 2, so as to ensure that the water flowing out of the series pipe 4 can flow into the second filter 2 from the second water inlet pipe 21.

[0037] In addition, a first check valve 56 is provided on the first water outlet pipe 12, and the first check valve 56 is provided between the first valve 51 and the pure water outlet pipe 6. The first check valve 56 is configured to allow water to flow out from the first filter 1 through the first water outlet pipe 12, so as to prevent the water in the pure water outlet pipe 6 from flowing from the first water outlet pipe 12 to the first filter 1. A second check valve 57 is provided on the second water outlet pipe 22, and the second check valve 57 is configured to allow water to flow out from the second filter 2 through the second water outlet pipe 22, so as to prevent the water in the pure water outlet pipe 6 from flowing from the second water outlet pipe 22 to the second filter 2. A third check valve 58 is provided on the first waste water pipe 13, and the third check valve 58 is configured to allow water to flow out from the first filter 1 through the first waste water pipe 13, so as to prevent the water in the waste water outlet pipe 7 from flowing from the first waste water pipe 13 to the first filter 1. The second waste water pipe 23 is provided with a fourth one-way valve 59 , which is configured to allow water to flow out of the second filter 2 through the second waste water pipe 23 to prevent water in the waste water outlet pipe 7 from flowing from the second waste water pipe 23 to the second filter 2 .

[0038] A booster pump 321 is provided on the third water outlet pipe 32 to increase the water pressure of the water flowing from the third water outlet pipe 32 to the first filter 1 and the second filter 2. The third water outlet pipe 32 is also connected to the domestic water pipe 8, and the water after preliminary filtration by the third filter 3 can enter the domestic water pipe 8 to meet the daily water demand. A first probe 81 is provided on the domestic water pipe 8, and the first probe 81 is a TDS (Total dissolved solids) probe, which can detect the total amount of dissolved solids in the water, that is, detect the water quality of the domestic water pipe 8. According to the water quality in the domestic water pipe 8, the degree of dirtiness of the filter element of the third filter 3 can be roughly obtained, so as to facilitate timely replacement. A second probe 61 is provided on the pure water outlet pipe 6, and the second probe 61 can detect the water quality in the pure water outlet pipe 6. According to the water quality in the pure water outlet pipe 6, the degree of dirtiness of the filter elements of the first filter 1 and the second filter 2 can be roughly obtained, so as to facilitate timely replacement.

[0039] The waste water outlet pipe 7 is provided with a waste water valve 71, which can control the flow rate of water flowing out of the waste water outlet pipe 7. The pure water outlet pipe 6 is provided with a high pressure switch 62 to cut off the pure water outlet pipe 6.

[0040] like Figure 3 As shown, the present invention also provides a control method for a water purification device, comprising the following main steps:

[0041] S1. Obtain user demand. User demand is at least one of water quantity demand, replacement cycle demand and water quality demand.

[0042] S2. Control the valve group according to user needs, which specifically includes: if the user demand is a water volume demand, control the valve group so that the first filter 1 and the second filter 2 are connected in parallel and put into use at the same time. Specifically, open the first valve 51, the second valve 52 and the fifth valve 55 and close the third valve 53. The first filter 1 and the second filter 2 are set in parallel and put into use at the same time, which can obtain a larger amount of purified water to meet the scenario of large water volume demand; if the user demand is a replacement cycle demand, control the valve group so that the first filter 1 and the second filter 2 are connected in parallel and put into use alternately. Specifically, close the third valve 53, and on the basis of closing the third valve 53, the first valve 51, the second valve 52 and the fifth valve 55 are opened and the third valve 53 is closed. Valve 52 and the fifth valve 55 switch between a state where the first valve 51 and the fifth valve 55 are open and the second valve 52 is closed, and a state where the first valve 51 and the fifth valve 55 are closed and the second valve 52 is opened, so that the first filter 1 and the second filter 2 are connected in parallel and put into use alternately, so that the water purification device obtains a longer replacement cycle; if the user's demand is water quality demand, the valve group is controlled so that the first filter 1 and the second filter 2 are connected in series and put into use at the same time. Specifically, the third valve 53 is opened and the first valve 51 and the second valve 52 are closed, and the first filter 1 and the second filter 2 are connected in series and put into use at the same time, which can obtain a better filtering effect to meet the demand for high water quality.

[0043] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A water purification device, comprising a first filter (1) and a second filter (2), characterized in that: The water purification device further comprises a valve group, wherein the valve group can be switched so that the first filter (1) and the second filter (2) are arranged in parallel or in series.

2. The water purification device according to claim 1, characterized in that: The valve group can also be switched to enable the first filter (1) and / or the second filter (2) to be put into operation.

3. The water purification device according to claim 1, characterized in that: The first filter (1) is connected to a first water outlet pipe (12), and the second filter (2) comprises a second water inlet pipe (21); a series pipe (4) is provided between the first filter (1) and the second filter (2), one end of the series pipe (4) is connected to the first water outlet pipe (12), and the other end is connected to the second filter (2); The valve group comprises a first valve (51), a second valve (52) and a third valve (53); the first valve (51) is arranged on the first water outlet pipe (12) to control the on-off of the first water outlet pipe (12); the second valve (52) is arranged on the second water inlet pipe (21) to control the on-off of the second water inlet pipe (21); and the third valve (53) is arranged on the series pipe (4) to control the on-off of the third valve (53); The connection point between the series pipe (4) and the first water outlet pipe (12) is located between the first valve (51) and the first filter (1); When the third valve (53) is closed, the first filter (1) and the second filter (2) are connected in parallel; When the first valve (51) and the second valve (52) are closed and the third valve (53) is opened, the first filter (1) and the second filter (2) are connected in series.

4. The water purification device according to claim 3, characterized in that: One end of the series pipe (4) away from the first filter (1) is connected to the second water inlet pipe (21) in the area between the second valve (52) and the second filter (2); or, The second filter (2) is also connected to a second waste water pipe (23), and the valve group further comprises a fourth valve (54), wherein the fourth valve (54) is arranged on the second waste water pipe (23) to control the opening and closing of the second waste water pipe (23); an end of the series pipe (4) away from the first filter (1) is connected to the second waste water pipe (23) in an area between the fourth valve (54) and the second filter (2); and the fourth valve (54) is closed when the third valve (53) is opened.

5. The water purification device according to claim 3, characterized in that: The first filter (1) is also connected to a first water inlet pipe (11), and the valve group further comprises a fifth valve (55), wherein the fifth valve (55) is arranged on the first water inlet pipe (11) to control the opening and closing of the first water inlet pipe (11); When the third valve (53) and the fifth valve (55) are opened and the first valve (51) and the second valve (52) are closed, the first filter (1) and the second filter (2) are arranged in series and are put into operation at the same time; When the first valve (51), the second valve (52) and the fifth valve (55) are opened and the third valve (53) is closed, the first filter (1) and the second filter (2) are arranged in parallel and are put into operation at the same time; When the third valve (53) and the fifth valve (55) are closed and the second valve (52) is opened, the second filter (2) is put into operation and the first filter (1) is cut out; When the second valve (52) and the third valve (53) are closed and the fifth valve (55) is opened, the first filter (1) is put in and the second filter (2) is cut out.

6. The water purification device according to claim 3, characterized in that: The first water outlet pipe (12) is provided with a first one-way valve (56), and the first one-way valve (56) is configured to allow water to flow out from the first filter (1) through the first water outlet pipe (12); and / or, The second filter (2) is further connected to a second water outlet pipe (22), the second water outlet pipe (22) being provided with a second one-way valve (57), the second one-way valve (57) being configured to allow water to flow out of the second filter (2) through the second water outlet pipe (22); and / or, The first filter (1) is further connected to a first waste water pipe (13), the first waste water pipe (13) being provided with a third one-way valve (58), the third one-way valve (58) being configured to allow water to flow out of the first filter (1) through the first waste water pipe (13); and / or, The second filter (2) is also connected to a second wastewater pipe (23), and a fourth one-way valve (59) is provided on the second wastewater pipe (23). The fourth one-way valve (59) is configured to allow water to flow out from the second filter (2) through the second wastewater pipe (23).

7. The water purification device according to any one of claims 1 to 6, characterized in that: The first filter (1) is any one of a reverse osmosis membrane filter and a nanofiltration membrane filter; and / or, The second filter (2) is any one of a reverse osmosis membrane filter, a nanofiltration membrane filter, an activated carbon filter or a mineralization filter.

8. The water purification device according to any one of claims 1 to 6, characterized in that: The water purification device further comprises a third filter (3), the third filter (3) being connected to a third water outlet pipe (32), the third water outlet pipe (32) being in communication with the first filter (1) and the second filter (2) so as to supply water to the first filter (1) and the second filter (2).

9. A control method for a water purification device according to any one of claims 1 to 8, characterized in that: The control method comprises: Obtain user needs; The valve group is controlled according to the user demand.

10. The control method of the water purification device according to claim 9, characterized in that: The user demand is at least any one of a water quantity demand, a replacement cycle demand and a water quality demand; "Controlling the valve group according to the user's needs" includes: If the user demand is a water demand, the valve group is controlled so that the first filter (1) and the second filter (2) are connected in parallel and put into use at the same time; If the user demand is a replacement cycle demand, the valve group is controlled so that the first filter (1) and the second filter (2) are connected in parallel and put into use alternately; If the user demand is a water quality demand, the valve group is controlled so that the first filter (1) and the second filter (2) are connected in series and put into use at the same time.

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