Reverse osmosis membrane waterway switching structure and water purifier

Abstract

The utility model relates to the technical field of reverse osmosis water purifiers, and discloses a reverse osmosis membrane waterway switching structure and a water purifier, the reverse osmosis membrane waterway switching structure comprises a plurality of reverse osmosis membrane units which are assembled together, a pressure relief pipeline is connected between the water production end and the water inlet end of each reverse osmosis membrane unit, and a pressure relief valve is arranged on the pressure relief pipeline. According to the utility model, the pressure relief pipeline is connected between the water production end and the water inlet end of each reverse osmosis membrane unit, and the pressure relief valve is arranged on the pressure relief pipeline, so that pure water can flow back, the reverse osmosis membrane is filled with mixed water of pure water and tap water, the structure risk of the reverse osmosis membrane is reduced, and the service life of the reverse osmosis membrane is prolonged. Meanwhile, during next water production, the TDS value of the first cup of water is reduced, and the user experience is improved. Besides, only 400 ml / min of water is needed theoretically during whole heating, when the water yield of the system is larger than the flow, pure water can flow back through the pressure release valve, the pressure of a pure water pipeline is reduced, namely, the water inlet pressure of a heating module is stabilized, and the heating system is made to be stable.

Description

[0001] This utility model is a divisional application of the Chinese utility model patent titled "A Reverse Osmosis Membrane Waterway Switching Structure and a Water Purifier", with the application number: 202322799274.9 and the application date: October 18, 2023. Technical Field

[0002] This utility model relates to the technical field of reverse osmosis water purifiers, and particularly to a reverse osmosis membrane waterway switching structure and a water purifier. Background Art

[0003] Currently, during the use of a reverse osmosis (RO) membrane, from the inlet water to the outlet water, the surface pressure of the RO membrane gradually decreases, and the concentration of the wastewater side gradually increases, resulting in a gradual decrease in the water production volume, and there is a risk of scaling and blocking at the end. The utilization rate of the entire RO membrane is uneven, and finally the RO membrane reaches the end of its life and needs to be replaced, increasing the burden on consumers.

[0004] A Chinese invention patent application with the publication number CN 105217732 A discloses a reverse osmosis membrane stack structure with a variable water inlet direction, including a parallel connection of an inlet valve, a reverse inlet valve, an inlet header pipe and a concentrated water header pipe connected to the membrane stack. The inlet valve is connected to the inlet header pipe, the inlet header pipe is connected with a reverse concentrated water valve, the reverse concentrated water valve is connected with a switching pipe, the reverse inlet valve is connected to the concentrated water header pipe, and the concentrated water header pipe is connected with a concentrated water valve. Although this invention adopts the alternate rotation water inlet technology, it can reduce the operating cost to a certain extent and extend the life of the RO membrane. However, the series-parallel connection mode of each RO membrane is fixed, and it is difficult to achieve uniform utilization of each RO membrane, and the effect of extending the life of the RO membrane is not very ideal. Content of the Utility Model

[0005] The purpose of this utility model is to provide a reverse osmosis membrane waterway switching structure with a better effect of extending the life of the RO membrane, to solve one or more technical problems existing in the prior art, and at least to provide a beneficial choice or creation condition.

[0006] To achieve the above purpose, this utility model adopts the following technical solutions.

[0007] A reverse osmosis membrane waterway switching structure includes a number of reverse osmosis membrane units assembled together. Among them, a pressure relief pipeline is connected between the water production end and the water inlet end of each reverse osmosis membrane unit, and a pressure relief valve is provided on the pressure relief pipeline.

[0008] More preferably, a water inlet pump is connected to the water inlet end of each reverse osmosis membrane unit, and the pressure relief pipeline is connected to the water inlet end of the water inlet pump. Preferably, there is one water inlet pump, which can provide water inlet pressure for each reverse osmosis membrane unit at the same time.

[0009] More preferably, a waste water return pipeline is connected between the concentrated water end and the water inlet end of each reverse osmosis membrane unit, and a waste water proportion valve is connected to the waste water return pipeline.

[0010] More preferably, a water inlet pump is connected to the water inlet end of each reverse osmosis membrane unit, and the waste water return pipeline is connected to the water inlet end of the water inlet pump.

[0011] More preferably, there are at least two reverse osmosis membrane units, and each reverse osmosis membrane unit forms a parallel structure; the raw water in the total water inlet pipeline flows through each parallel reverse osmosis membrane unit through the water inlet end of each reverse osmosis membrane unit at the same time, and then the purified water and concentrated water are output from each reverse osmosis membrane unit.

[0012] More preferably, a water inlet valve is connected to the water inlet end of at least two reverse osmosis membrane units. The concentrated water end of the reverse osmosis membrane unit provided with the water inlet valve is connected to the waste water pipe through a concentrated water on-off pipeline and flows unidirectionally through a one-way pipeline to another reverse osmosis membrane unit provided with the water inlet valve to form a series-parallel selection structure.

[0013] More preferably, there are at least two reverse osmosis membrane units, and each reverse osmosis membrane unit forms a series structure, and the water flow sequentially passes through each reverse osmosis membrane unit.

[0014] More preferably, the raw water in the total water inlet pipeline is respectively connected to the water inlet end of the first reverse osmosis membrane unit and the concentrated water end of the last reverse osmosis membrane unit through two water inlet pipes, and corresponding water inlet valves are respectively arranged on the two water inlet pipes; the water inlet end of the first reverse osmosis membrane unit and the concentrated water end of the last reverse osmosis membrane unit are respectively connected to the waste water pipe through corresponding concentrated water on-off pipelines.

[0015] More preferably, there is one reverse osmosis membrane unit. The raw water in the total water inlet pipeline is respectively connected to the water inlet end and the concentrated water end of the reverse osmosis membrane unit through two water inlet pipes, and corresponding water inlet valves are respectively arranged on the two water inlet pipes. The water inlet end and the concentrated water end of the reverse osmosis membrane unit are respectively connected to the waste water pipe through corresponding concentrated water on-off pipelines.

[0016] On the other hand, the present invention also provides a water purifier having a reverse osmosis membrane water path switching structure as described above.

[0017] The technical solution provided by the present invention has at least the following technical effects or advantages.

[0018] I. By connecting a pressure relief pipeline between the water production end and the water inlet end of each reverse osmosis membrane unit and installing a pressure relief valve on the pressure relief pipeline, pure water can be refluxed, filling the reverse osmosis membrane with a mixed water of pure water and tap water, reducing the structural risk of the reverse osmosis membrane and extending its service life. At the same time, when making water next time, the TDS value of the first glass of water can be reduced, improving the user experience. In addition, when the whole machine is heating, theoretically only 400 ml / min of water volume is required. When the system water production volume is greater than this flow rate, pure water can be refluxed through this pressure relief valve to reduce the pressure of the pure water pipeline, that is, to stabilize the water inlet pressure of the heating module and make the heating system stable.

[0019] II. Combine the pressure relief pipeline and the wastewater reflux pipeline. When the TDS is good, the wastewater is refluxed to the front of the RO membrane, that is, the secondary utilization of the concentrated water, which can reduce the discharge of the concentrated water and improve the recovery rate of the whole machine. When the whole machine is heating, the wastewater can be refluxed to the front of the inlet pump through this wastewater reflux pipeline to increase the flow rate on the membrane surface and reduce the risk of membrane blockage; at the same time, reduce the pressure after the gold water pump, reduce the pump load, and reduce the noise of the whole machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure shows a schematic diagram of the reverse osmosis membrane water path switching structure provided by Embodiment 1 of the present invention.

[0021] Figure 2 The figure shows a schematic diagram of the reverse osmosis membrane water path switching structure provided by Embodiment 2 of the present invention.

[0022] Figure 3 The figure shows a schematic diagram of the reverse osmosis membrane water path switching structure provided by Embodiment 3 of the present invention.

[0023] Figure 4 The figure shows a schematic diagram of the reverse osmosis membrane water path switching structure provided by Embodiment 4 of the present invention.

[0024] Figure 5 The figure shows a schematic diagram of the reverse osmosis membrane water path switching structure provided by Embodiment 5 of the present invention.

[0025] Figure 6 The figure shows a schematic diagram of the reverse osmosis membrane water path switching structure provided by Embodiment 6 of the present invention.

[0026] DESCRIPTION OF THE REFERENCE NUMERALS

[0027] 1: First reverse osmosis membrane unit, 2: Second reverse osmosis membrane unit, 3: Third reverse osmosis membrane unit, 4: First inlet valve, 5: Second inlet valve, 6: First one-way pipeline, 7: Second one-way pipeline, 8: Normally closed valve, 9: Waste water pipe, 10: Waste water valve, 11: Total inlet water pipeline, 12: Pressure relief pipeline, 13: Pressure relief valve, 14: Third inlet valve, 15: Third one-way pipeline, 16: Feed water pump, 17: Waste water return pipeline, 18: Waste water proportion valve, 19: First normally closed valve, 20: Inlet water branch, 21: Fourth inlet valve, 22: Fifth inlet valve, 23: Concentrate water branch, 24: Second normally closed valve. Detailed implementation manners

[0028] The following combines the drawings of the specification to further describe the detailed implementation manners of the present utility model, making the technical solutions and their beneficial effects of the present utility model clearer and more definite. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present utility model, and should not be construed as a limitation to the present utility model.

[0029] The additional aspects and advantages of the present utility model will become apparent in the following description part, or be learned through the practice of the present utility model.

[0030] Embodiment 1.

[0031] See Figure 1 As shown, a reverse osmosis membrane water path switching structure of a water purifier includes a first reverse osmosis membrane unit 1, a second reverse osmosis membrane unit 2, and a third reverse osmosis membrane unit 3 connected in parallel; a first inlet valve 4 and a second inlet valve 5 are respectively provided at the water inlet ends of the second reverse osmosis membrane unit 2 and the third reverse osmosis membrane unit 3; the concentrated water of the first reverse osmosis membrane unit 1 and the second reverse osmosis membrane unit 2 flows unidirectionally into the water inlet end of the third reverse osmosis membrane unit 3 through a first one-way pipeline 6, and the water outlet end of the first one-way pipeline 6 is connected to the water outlet side of the second inlet valve 5; the concentrated water of the first reverse osmosis membrane unit 1 and the third reverse osmosis membrane unit 3 flows unidirectionally into the water inlet end of the second reverse osmosis membrane unit 2 through a second one-way pipeline 7, and the water outlet end of the second one-way pipeline 7 is connected to the water outlet side of the first inlet valve 4; a pressure relief pipeline 12 is connected between the water production ends of the first reverse osmosis membrane unit 1, the second reverse osmosis membrane unit 2, and the third reverse osmosis membrane unit 3 and the total inlet water pipeline 11, and a pressure relief valve 13 is provided on the pressure relief pipeline 12.

[0032] It should be noted that the unidirectional flow of water in the one-way pipeline is controlled by a number of one-way valves. As for the specific structural form of the one-way pipeline and the number and position arrangement of the one-way valves on the one-way pipeline, they are common technical knowledge mastered by those skilled in the art and will not be elaborated here in detail.

[0033] During operation, by controlling the on-off combinations of the first water inlet valve 4 and the second water inlet valve 5, it is very convenient to achieve the connection of the first reverse osmosis membrane unit 1 and the second reverse osmosis membrane unit 2 in parallel and then in series with the third reverse osmosis membrane unit 3, or the connection of the first reverse osmosis membrane unit 1 and the third reverse osmosis membrane unit 3 in parallel and then in series with the second reverse osmosis membrane unit 2, or the parallel connection of the first reverse osmosis membrane unit 1, the second reverse osmosis membrane unit 2, and the third reverse osmosis membrane unit 3. In the case of poor water quality, it is preferably to use the parallel structure of the first reverse osmosis membrane unit 1, the second reverse osmosis membrane unit 2, and the third reverse osmosis membrane unit 3 for water purification.

[0034] In this way, by changing the series-parallel positions of the first reverse osmosis membrane unit 1, the second reverse osmosis membrane unit 2, and the third reverse osmosis membrane unit 3, the service lives of the second reverse osmosis membrane unit 2 and the third reverse osmosis membrane unit 3 can be effectively balanced, the problem of uneven utilization rate during the use of the reverse osmosis membrane can be solved, the reverse osmosis membrane can consume its service life evenly, the reverse osmosis membrane can be used for a long time, and the user's cost of replacing the filter element can be reduced.

[0035] Particularly, to ensure the normal operation of the water path switching, it is preferably that the concentrated water ends of the second reverse osmosis membrane unit 2 and the third reverse osmosis membrane unit 3 are respectively connected to the waste water pipe 9 through corresponding concentrated water pipelines with normally closed valves 8, and a waste water valve 10 is provided on the waste water pipe 9.

[0036] In this embodiment, the advantages of setting the pressure relief pipeline 12 and the pressure relief valve 13 are that during the heating of the whole machine, theoretically only 400 ml / min of water is required. During the heating process, when the water production of the system is greater than this flow rate, the pure water can be returned through the pressure relief pipeline 12 and the pressure relief valve 13 to reduce the pressure of the pure water pipeline; that is, to stabilize the water inlet pressure of the heating module and make the heating system stable. In addition, this design of the pure water returnable structure can also make the water at the water inlet end a mixture of pure water and tap water, thereby reducing the structural risk of the reverse osmosis membrane, extending the service life of the reverse osmosis membrane, and at the same time, reducing the TDS value of the first glass of water during the next water production and improving the user experience.

[0037] Embodiment 2.

[0038] Referring to Figure 2 As shown, a reverse osmosis membrane water path switching structure of a water purifier provided in this embodiment is basically the same as that in Embodiment 1, except that a third water inlet valve 14 is provided at the water inlet end of the first reverse osmosis membrane unit 1, and the concentrated water ends of the second reverse osmosis membrane unit 2 and the third reverse osmosis membrane unit 3 flow unidirectionally into the water inlet end of the first reverse osmosis membrane unit 1 through a third one-way pipeline 15, and the water outlet end of the third one-way pipeline 15 is connected to the water outlet side of the first water inlet valve 14; the concentrated water end of the first reverse osmosis membrane unit 1 is connected to the waste water pipe 9 through a corresponding normally closed valve 8.

[0039] In this way, by changing the series-parallel positions of the first reverse osmosis membrane unit 1, the second reverse osmosis membrane unit 2, and the third reverse osmosis membrane unit 3, it is also possible to achieve that the second reverse osmosis membrane unit 2 and the third reverse osmosis membrane unit 3 are connected in parallel first and then in series with the first reverse osmosis membrane unit 1. Compared with Embodiment 1, this embodiment can better evenly consume the service life of each reverse osmosis membrane, achieve long-term use, realize an ultra-long membrane life, and has the advantages of not replacing the filter element for 10 years and a high wastewater ratio. The starting wastewater ratio is 3:1, and the limit can reach 5:1.

[0040] Embodiment 3.

[0041] Refer to Figure 3 As shown, a reverse osmosis membrane water path switching structure of a water purifier provided in this embodiment is basically the same as that in Embodiment 1, except that the first reverse osmosis membrane unit 1, the second reverse osmosis membrane unit 2, and the third reverse osmosis membrane unit 3 are in a series structure. The first reverse osmosis membrane unit 1 enters the second reverse osmosis membrane unit 2, and the concentrated water of the second reverse osmosis membrane unit 2 enters the third reverse osmosis membrane unit 3; two water inlet pipes are respectively connected to the water inlet end of the first reverse osmosis membrane unit 1 and the concentrated water end of the third reverse osmosis membrane unit 3, and corresponding water inlet valves are respectively provided on the two water inlet pipes; the water inlet end of the first reverse osmosis membrane unit 1 and the concentrated water end of the third reverse osmosis membrane unit 3 are respectively connected to the wastewater pipe 9 through corresponding normally closed valves 8, and a wastewater valve 10 is provided on the wastewater pipe 9.

[0042] The reverse osmosis membrane water path switching structure of a water purifier provided in this embodiment can achieve the series connection of the first reverse osmosis membrane unit 1 → the second reverse osmosis membrane unit 2 → the third reverse osmosis membrane unit 3 during operation, and can also achieve the series connection of the third reverse osmosis membrane unit 3 → the second reverse osmosis membrane unit 2 → the first reverse osmosis membrane unit 1, which can make the first reverse osmosis membrane unit 1 and the third reverse osmosis membrane unit 3 be swapped in order, and at the same time, the water inlet and outlet directions of each membrane are also swapped, evenly consuming the service life of each reverse osmosis membrane and achieving long-term effectiveness.

[0043] Embodiment 4.

[0044] Refer to Figure 4 As shown, a reverse osmosis membrane water path switching structure of a water purifier includes a first reverse osmosis membrane unit 1 and a second reverse osmosis membrane unit 2 connected in parallel. The water production ends of the first reverse osmosis membrane unit 1 and the second reverse osmosis membrane unit 2 are connected to the water inlet end of the water inlet pump 16 through a pressure relief pipeline 12, and a pressure relief valve 13 is provided on the pressure relief pipeline 12; the concentrated water ends of the first reverse osmosis membrane unit 1 and the second reverse osmosis membrane unit 2 are connected to the water inlet end of the water inlet pump 16 through a wastewater return pipeline 17, and a wastewater ratio valve 18 is provided on the wastewater return pipeline 17.

[0045] A reverse osmosis membrane water path switching structure of a water purifier provided in this embodiment can, by setting a wastewater return pipeline 17 and a wastewater ratio valve 18, return the wastewater to the front of the reverse osmosis membrane when the TDS is good, that is, the secondary utilization of the concentrated water, reduce the discharge of the concentrated water, and improve the recovery rate of the whole machine. Moreover, when the whole machine is heating, theoretically only 400 ml / min of water volume is required. When the reverse osmosis membrane system is greater than this flow rate, the wastewater can be returned to the front of the water inlet pump through the wastewater ratio valve to increase the flow rate on the membrane surface, reduce the risk of membrane blockage; at the same time, reduce the pressure after the water inlet pump, reduce the load of the water inlet pump, and reduce the noise of the whole machine.

[0046] Embodiment 5.

[0047] Refer to Figure 5 As shown, a reverse osmosis membrane water path switching structure of a water purifier provided in this embodiment is basically the same as that in Embodiment 4, except that corresponding water inlet valves are respectively provided at the water inlet ends of the first reverse osmosis membrane unit 1 and the second reverse osmosis membrane unit 2. The concentrated water of the first reverse osmosis membrane unit 1 flows into the water inlet end of the second reverse osmosis membrane unit 2 through a corresponding one-way pipeline, and the concentrated water of the second reverse osmosis membrane unit 2 flows into the water inlet end of the first reverse osmosis membrane unit 1 through a one-way pipeline; the concentrated water ends of the first reverse osmosis membrane unit 1 and the second reverse osmosis membrane unit 2 are respectively connected to a wastewater pipe 9 through corresponding normally closed valves 8, and a wastewater valve 10 is provided on the wastewater pipe 9.

[0048] Compared with Embodiment 4, a reverse osmosis membrane water path switching structure of a water purifier provided in this embodiment can realize the parallel connection of two reverse osmosis membranes and the series connection in both positive and negative directions, thereby balancing the service lives of the two reverse osmosis membranes and making the service lives evenly consumed.

[0049] Embodiment 6.

[0050] Refer to Figure 6As shown in the figure, a reverse osmosis membrane water path switching structure of a water purifier includes a first reverse osmosis membrane unit 1. An inlet water pump 16 and a fourth inlet water valve 21 are connected to the water inlet end of the first reverse osmosis membrane unit 1, and the fourth inlet water valve 21 is connected to the water outlet end of the inlet water pump 16. The water production end of the first reverse osmosis membrane unit 1 is connected to the water inlet end of the inlet water pump 16 through a pressure relief pipeline 12, and a pressure relief valve 13 is provided on the pressure relief pipeline 12. The concentrated water end of the first reverse osmosis membrane unit 1 is connected to the water inlet end of the inlet water pump 16 through a waste water return pipeline 17, and a waste water ratio valve 18 is provided on the waste water return pipeline 17. A first normally closed valve 19 and a water inlet branch 20 are connected to the concentrated water end of the first reverse osmosis membrane unit 1. One end of the water inlet branch 20 is connected between the first normally closed valve 19 and the concentrated water end of the first reverse osmosis membrane unit 1, and the other end is connected between the inlet water pump 16 and the fourth inlet water valve 21. A fifth inlet water valve 22 is provided on the water inlet branch 20. A concentrated water branch 23 is connected to the water inlet end of the first reverse osmosis membrane unit 1. One end of the concentrated water branch is connected between the water inlet end of the first reverse osmosis membrane unit 1 and the fourth inlet water valve 21, and the other end is connected to the side of the first normally closed valve 19 away from the first reverse osmosis membrane unit 1. A second normally closed valve 24 is provided on the concentrated water branch 23.

[0051] The reverse osmosis membrane water path switching structure of the water purifier provided in this embodiment not only has the effects of concentrated water reflux and water production pressure relief, but also realizes forward and reverse water inlet of a single reverse osmosis membrane, so that the front and rear sections of the single reverse osmosis membrane consume evenly in terms of service life, and the service life of the single reverse osmosis membrane is prolonged.

[0052] It should be noted that the normally closed valves in the embodiments of the present utility model can be replaced by other forms of on-off valves known in the art or to be realized in the future; the waste water ratio valve and the pressure relief valve are both existing valve structures, and their specific structures are common technical knowledge mastered by those skilled in the art.

[0053] In addition, it should be noted that in the description of the present utility model, for orientation terms, if there are terms such as "center", "horizontal", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation and position relationship is based on the orientation or position relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of the present utility model.

[0054] In addition, terms such as "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present utility model, the meaning of "at least" is one or more, unless otherwise specifically defined.

[0055] In the present utility model, unless otherwise clearly specified and defined, terms such as "assembled", "connected", and "joined" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may also be a mechanical connection; it may be directly connected, or connected through an intermediate medium, and may be internally connected and communicated between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0056] In the utility model, unless otherwise specified and defined, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "below", and "on top of" the second feature includes the first feature being directly above and diagonally above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "above", "below", and "beneath" the second feature includes the first feature being directly below or diagonally below the second feature, or merely indicating that the horizontal height of the first feature is lower than that of the second feature.

[0057] Through the description of the above structure and principle, those skilled in the art should understand that the present utility model is not limited to the above specific embodiments. Improvements and substitutions using well-known techniques in the art based on the present utility model fall within the protection scope of the present utility model. The protection scope of the present utility model shall be defined by each claim item and its equivalents. Parts not described in the specific embodiments are all prior art or common general knowledge.

Claims

1. A reverse osmosis membrane water path switching structure, characterized in that, it includes a reverse osmosis membrane unit. When there is one reverse osmosis membrane unit, the raw water in the total water inlet pipeline is connected to the water inlet end and the concentrated water end of the reverse osmosis membrane unit through two water inlet pipes respectively. Corresponding water inlet valves are respectively arranged on the two water inlet pipes. The water inlet end and the concentrated water end of the reverse osmosis membrane unit are respectively connected to the waste water pipe through corresponding concentrated water on-off pipelines; when there are at least two reverse osmosis membrane units, each of the reverse osmosis membrane units forms a series structure, and the water flow passes through each of the reverse osmosis membrane units in sequence. The raw water in the total water inlet pipeline is connected to the water inlet end of the first reverse osmosis membrane unit and the concentrated water end of the last reverse osmosis membrane unit through two water inlet pipes respectively. The water inlet end of the first reverse osmosis membrane unit and the concentrated water end of the last reverse osmosis membrane unit are respectively connected to the waste water pipe through corresponding concentrated water on-off pipelines.

2. The reverse osmosis membrane water path switching structure according to claim 1, characterized in that, when there is one reverse osmosis membrane unit, a fourth water inlet valve is connected to the water inlet end of the reverse osmosis membrane unit, a water inlet branch is connected to the concentrated water end of the reverse osmosis, a fifth water inlet valve is arranged on the water inlet branch, and a concentrated water branch is also connected to the water inlet end of the reverse osmosis membrane unit.

3. The reverse osmosis membrane water path switching structure according to claim 2, characterized in that, the reverse osmosis membrane unit is the first reverse osmosis membrane unit, a water inlet pump is connected to the water inlet end of the reverse osmosis membrane unit, and the fourth water inlet valve is connected to the water outlet end of the water inlet pump.

4. The reverse osmosis membrane water path switching structure according to claim 3, characterized in that, a first normally closed valve is also connected to the concentrated water end of the reverse osmosis membrane unit. One end of the water inlet branch is connected between the first normally closed valve and the concentrated water end of the first reverse osmosis membrane unit, and the other end is connected between the water inlet pump and the fourth water inlet valve.

5. The reverse osmosis membrane water path switching structure according to claim 4, characterized in that, one end of the concentrated water branch is connected between the water inlet end of the first reverse osmosis membrane unit and the fourth water inlet valve, and the other end is connected to the side of the first normally closed valve away from the first reverse osmosis membrane unit. A second normally closed valve is arranged on the concentrated water branch.

6. The reverse osmosis membrane water path switching structure according to claim 3, characterized in that, the water production end of the first reverse osmosis membrane unit is connected to the water inlet end of the water inlet pump through a pressure relief pipeline, and a pressure relief valve is arranged on the pressure relief pipeline.

7. The reverse osmosis membrane water path switching structure according to claim 3, characterized in that, the concentrated water end of the first reverse osmosis membrane unit is connected to the water inlet end of the water inlet pump through a waste water return pipeline, and a waste water ratio valve is arranged on the waste water return pipeline.

8. The reverse osmosis membrane water path switching structure according to claim 1, characterized in that, When there are at least two reverse osmosis membrane units, the reverse osmosis membrane units include a first reverse osmosis membrane unit, a second reverse osmosis membrane unit, and a third reverse osmosis membrane unit. The first reverse osmosis membrane unit, the second reverse osmosis membrane unit, and the third reverse osmosis membrane unit are in a series structure. The first reverse osmosis membrane unit feeds into the second reverse osmosis membrane unit, and the concentrated water of the second reverse osmosis membrane unit feeds into the third reverse osmosis membrane unit. Two water inlet pipes are respectively connected to the water inlet end of the first reverse osmosis membrane unit and the concentrated water end of the third reverse osmosis membrane unit. The water inlet end of the first reverse osmosis membrane unit and the concentrated water end of the third reverse osmosis membrane unit are respectively connected to a waste water pipe through corresponding normally closed valves, and a waste water valve is provided on the waste water pipe.

9. The reverse osmosis membrane water path switching structure according to claim 8, characterized in that a pressure relief pipeline is connected between the water production ends of the first reverse osmosis membrane unit, the second reverse osmosis membrane unit, and the third reverse osmosis membrane unit and the total water inlet pipeline, and a pressure relief valve is provided on the pressure relief pipeline; the concentrated water ends of the second reverse osmosis membrane unit and the third reverse osmosis membrane unit are respectively connected to a waste water pipe through corresponding concentrated water pipelines with normally closed valves, and a waste water valve is provided on the waste water pipe.

10. A water purifier, characterized in that it has a reverse osmosis membrane water path switching structure according to any one of claims 1-9.

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