A reverse osmosis water purifier

Abstract

The application discloses a reverse osmosis type water purifier and relates to the technical field of water purifiers. The water purifier can solve the problem that the prior art is difficult to cope with raw water quality fluctuation and cannot balance filtering efficiency and membrane body service life. The water purifier comprises a machine shell, a pumping assembly arranged in the machine shell and used for pressurizing water inlet, a plurality of reverse osmosis membrane bodies fixedly arranged in the machine shell, a shunt pipeline, a distribution module and the like. The plurality of reverse osmosis membrane bodies comprise one main membrane body and two auxiliary membrane bodies, the main membrane body and the two auxiliary membrane bodies are connected in parallel, the shunt pipeline is used for fluidly connecting the outlet of the pumping assembly to the water inlet interfaces of the plurality of reverse osmosis membrane bodies, and the distribution module comprises a plurality of electric proportional regulating valves. The water purifier can realize independent flow pressure regulation through parallel arrangement of the plurality of reverse osmosis membrane bodies and cooperation of the electric proportional regulating valves, can dynamically distribute processing load according to raw water quality and use demand, can significantly improve water purification efficiency, prolong membrane body service life and reduce operation energy consumption.

Description

Technical Field

[0001] This invention relates to the field of water purifier technology, and in particular to a reverse osmosis water purifier. Background Technology

[0002] Reverse osmosis water purifiers, with their high-efficiency filtration performance, have been widely used in water purification in homes, businesses, and industries. Traditional reverse osmosis water purifiers typically use a single-stage reverse osmosis membrane structure, where the incoming water is pumped and pressurized before directly entering the reverse osmosis membrane for filtration.

[0003] Currently, fluctuations in raw water quality are common in practical applications. Water sources in different regions vary significantly in hardness, turbidity, and TDS values. Even within the same region, water quality can change with the seasons. Faced with these fluctuations, traditional single-membrane reverse osmosis structures struggle to balance filtration efficiency and membrane lifespan. Specifically, when the raw water quality is poor, a single membrane bears an excessive load, easily leading to membrane fouling and clogging, resulting in reduced permeate production and increased energy consumption. Conversely, when the raw water quality is good, the membrane's processing capacity cannot be fully utilized, resulting in resource waste.

[0004] In summary, existing technologies have limitations in addressing fluctuations in raw water quality and in balancing filtration efficiency with membrane lifespan. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of traditional reverse osmosis water purifiers, which are unable to cope with fluctuations in raw water quality and cannot balance filtration efficiency and membrane lifespan, and to propose a reverse osmosis water purifier.

[0006] To achieve the above objectives, the present invention employs the following technology: a reverse osmosis water purifier, including a casing; A pumping assembly, located inside the housing, is used to pressurize the incoming water; Also includes: Multiple reverse osmosis membranes are fixedly installed inside the housing. The multiple reverse osmosis membranes include one main membrane and two auxiliary membranes, and the main membrane and the two auxiliary membranes are connected in parallel. A diversion pipeline is used to connect the outlet fluid of the pumping assembly to the inlet water interface of multiple reverse osmosis membranes; The distribution module includes multiple electrically operated proportional control valves, each of which is installed on the feed water passage of a reverse osmosis membrane. These valves are used to independently control the flow rate and pressure of the liquid entering the main membrane and the two auxiliary membranes, enabling the main membrane and the auxiliary membranes to dynamically allocate the treatment load of each membrane according to the feed water quality and usage requirements under the control of the distribution module.

[0007] As a type of reverse osmosis water purifier using the aforementioned technology: The diversion line includes a multi-port connector; The multi-port connector is connected to each reverse osmosis membrane via multiple connecting pipes. The inlet end of the multi-port connector is connected to the water supply pipeline of the pumping assembly. Each electric proportional regulating valve is respectively installed on each outlet end of the multi-port connector. One end of each connecting pipe is fixed to each electric proportional regulating valve, and the other end is respectively connected to the water inlet of the main membrane and the two auxiliary membranes.

[0008] As a type of reverse osmosis water purifier using the aforementioned technology: A partition plate is fixedly installed inside the housing, which divides the housing into a primary water purification zone and a secondary water purification zone. The main membrane and the two auxiliary membranes are all fixedly installed in the primary water purification zone.

[0009] As a type of reverse osmosis water purifier using the aforementioned technology: It also includes a sub-membrane fixedly installed in the secondary water purification zone. The sub-membrane serves as the second-stage reverse osmosis membrane, and the main membrane and the auxiliary membrane together serve as the first-stage reverse osmosis membrane assembly.

[0010] As a type of reverse osmosis water purifier using the aforementioned technology: It also includes a pressure exchange device, which includes a first pressure exchange tank and a second pressure exchange tank fixed in the secondary water purification zone. The first and second pressure exchange tanks are equipped with elastic diaphragms that separate the first and second pressure exchange tanks into a high-pressure chamber and a low-pressure chamber.

[0011] As a type of reverse osmosis water purifier using the aforementioned technology: The elastic diaphragms in the first and second pressure exchange tanks have a corrugated structure.

[0012] As a type of reverse osmosis water purifier using the aforementioned technology: The inlet of each high-pressure chamber is connected to the concentrate outlet of the first-stage reverse osmosis membrane unit via a pipeline, the outlet of each high-pressure chamber is connected to a drainage pipeline, the inlet of each low-pressure chamber is connected to the pure water outlet of the first-stage reverse osmosis membrane unit via a pipeline, and the outlet of each low-pressure chamber is connected to the inlet of the sub-membrane via a pipeline.

[0013] As a type of reverse osmosis water purifier using the aforementioned technology: It also includes the controller; And a plurality of reversing valves are installed on the pipeline between the first-stage reverse osmosis membrane module and the first pressure exchange tank and the second pressure exchange tank. Each of the reversing valves is electrically connected to the controller and is used to control the switching of the reversing valve.

[0014] As a type of reverse osmosis water purifier using the aforementioned technology: An observation window is provided on the outer wall of the casing, and an explosion-proof glass is fixedly installed inside the observation window.

[0015] As a type of reverse osmosis water purifier using the aforementioned technology: An observation window is provided on the outer wall of the casing, and an explosion-proof glass is fixedly installed inside the observation window.

[0016] In summary, due to the adoption of the above-mentioned technology in this reverse osmosis water purifier, the beneficial effects of this invention are: (1) The present invention, by setting one main membrane and two auxiliary membranes in parallel and cooperating with the electric proportional regulating valve in the distribution module, can independently and precisely adjust the influent flow rate and pressure of each reverse osmosis membrane in real time according to the influent water quality and usage requirements. This effectively avoids overload or idleness of a single membrane due to water quality fluctuations, realizes dynamic optimization distribution of treatment load, significantly improves the overall water purification efficiency, balances the wear of each membrane, and greatly extends the overall service life of the membrane group.

[0017] (2) The solution of the present invention distributes the pumping component outlet fluid evenly or differently to each membrane through the multi-port joint and connecting pipe structure in the diversion pipeline, and combined with the precise adjustment of the electric proportional regulating valve, effectively reduces the local contamination or premature aging of the membrane caused by uneven flow, and extends the overall service life of the reverse osmosis membrane.

[0018] (3) The present invention divides the casing into a primary water purification zone and a secondary water purification zone by setting a partition plate, and uses the main membrane and auxiliary membrane as the first-stage reverse osmosis membrane group, and sets the auxiliary membrane as the second-stage reverse osmosis membrane in the secondary water purification zone, forming a two-stage filtration structure, which further improves the purity of the produced water, and is especially suitable for the deep treatment of raw water with high hardness or high salinity.

[0019] (4) The present invention provides a pressure exchange device, including a first pressure exchange tank and a second pressure exchange tank, and a corrugated elastic diaphragm inside it, which can recover the concentrated water pressure generated by the first-stage reverse osmosis membrane group and use it to assist in driving the feed water of the sub-membrane, thereby greatly reducing the overall energy consumption of the system and improving the energy utilization efficiency.

[0020] (5) The solution of the present invention effectively solves the adaptability problem caused by water quality fluctuations by adopting a multi-membrane dynamic load distribution technology solution with pressure exchange device, reversing valve and distribution module working together, and realizes the equalization of membrane life; wherein, the distribution module focuses on the optimization of system energy consumption, and the pressure exchange device and distribution module are functionally independent and structurally separable. Compared with the traditional single structure water purifier, this design can be used in combination to achieve the best comprehensive performance in practical applications, and can also be deployed independently according to the cost and performance requirements of different application scenarios, which is more flexible. Attached Figure Description

[0021] Figure 1 A schematic diagram of the overall structure (with side panels removed) according to the present invention is shown; Figure 2 A schematic diagram of the overall structure according to the present invention is shown; Figure 3 A schematic cross-sectional view of the structure according to the present invention is shown; Figure 4 A schematic diagram of the primary and secondary water purification zones inside the housing according to the present invention is shown. Figure 5 A top view of the cross-sectional structure of the secondary water purification zone according to the present invention is shown; Figure 6 A top view of the cross-sectional structure of the primary water purification zone according to the present invention is shown; Figure 7 A schematic diagram of the structure of the second pressure exchange tank according to the present invention is shown; Figure 8 A schematic diagram of the structure of the first pressure exchange tank according to the present invention is shown.

[0022] Legend: 1. Housing; 11. Divider plate; 12. Pumping assembly; 13. Observation window; 131. Explosion-proof glass; 101. Primary water purification zone; 102. Secondary water purification zone; 2. Auxiliary membrane; 3. Main membrane; 4. Diversion pipeline; 41. Multi-port connector; 42. Connecting pipe; 5. Distribution module; 51. Electric proportional regulating valve; 52. Reversing valve; 6. Secondary membrane; 7. Pressure exchange device; 71. First pressure exchange tank; 72. Second pressure exchange tank; 73. Elastic diaphragm; 701. High-pressure chamber; 702. Low-pressure chamber. Detailed Implementation

[0023] The following will describe, with reference to the accompanying drawings of the embodiments of the present invention, a reverse osmosis water purifier according to the present invention in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figures 1-8 As shown, a reverse osmosis water purifier includes a casing 1, a pumping assembly 12, multiple reverse osmosis membranes, and a distribution pipeline 4. Specifically, an observation window 13 is provided on the outer wall of the casing 1, and an explosion-proof glass 131 is fixedly installed inside the observation window 13 to facilitate real-time viewing of the internal operating status; The pumping assembly 12 is installed inside the housing 1, specifically fixed to the bottom or side wall of the primary water purification zone 101, and is used to pressurize the incoming water to meet the pressure requirements of the reverse osmosis membrane. It should be noted that the pumping assembly 12 includes a variable frequency pump, a water supply pipeline and other auxiliary components. The water inlet of the pump body is connected to the diversion pipeline 4. Multiple reverse osmosis membranes are fixedly installed inside the casing 1. The multiple reverse osmosis membranes include a main membrane 3 and two auxiliary membranes 2. A partition plate 11 is fixedly installed inside the casing 1, which divides the casing 1 into a primary water purification zone 101 and a secondary water purification zone 102. The main membrane 3 and the two auxiliary membranes 2 are fixedly installed in parallel in the primary water purification zone 101. The main membrane 3 and the auxiliary membranes 2 together serve as the first-stage reverse osmosis membrane group to perform preliminary filtration of the raw water. The diversion line 4 is used to connect the outlet fluid of the pumping assembly 12 to the inlet water interface of multiple reverse osmosis membranes; the diversion line 4 includes a multi-port connector 41 and multiple connecting pipes 42 connecting the multi-port connector 41 to each reverse osmosis membrane, and the inlet end of the multi-port connector 41 is connected to the outlet of the pumping assembly 12. Combination Figures 1-8 In order to solve the problem that traditional reverse osmosis water purifiers cannot cope with fluctuations in raw water quality and cannot balance filtration efficiency and membrane life, the following design is provided: Distribution module 5; Specifically, the distribution module 5 includes multiple electric proportional control valves 51. Each electric proportional control valve 51 is correspondingly set on the water inlet passage of a reverse osmosis membrane, and is used to independently control the liquid flow rate and pressure entering the main membrane 3 and the two auxiliary membranes 2. Each electric proportional control valve 51 is respectively set on each outlet end of the multi-port connector 41. One end of each connecting pipe 42 is fixed to each electric proportional control valve 51, and the other end is respectively connected to the water inlet interface of the main membrane 3 and the two auxiliary membranes 2. It also includes a controller, with each electric proportional regulating valve 51 electrically connected to the controller for controlling the switching of the electric proportional regulating valve 51; It should be noted that the electric proportional regulating valve 51 adopts a high-pressure resistant and fouling-resistant structure. Its valve core opening can be automatically adjusted according to the instructions issued by the controller (not shown). The controller can adjust the opening of each electric proportional regulating valve 51 according to the preset program or the real-time detected water quality parameters (such as TDS value, turbidity, hardness, etc.), thereby independently controlling the water flow and pressure entering the main membrane 3 and the two auxiliary membranes 2. The control principle of this part is existing technology and the working principle has been disclosed. In this way, according to actual needs, such as giving priority to the use of the main membrane 3 or evenly distributing the load, flexible regulation can be achieved. Under the regulation of the distribution module 5, the main membrane 3 and the auxiliary membranes 2 can dynamically distribute the treatment load of each membrane according to the influent water quality and usage requirements, avoiding overload or idleness of a single membrane, significantly improving the overall water purification efficiency and extending the membrane life. To enable independent control of each electric proportional regulating valve 51 based on the influent water quality and usage requirements, the controller has multiple preset control modes, including but not limited to the following: Form 1: Priority Main Membrane Mode When the TDS value of the influent is lower than the first preset threshold (e.g., 200 ppm), the controller determines that the raw water quality is good. At this time, the main membrane 3 is used for filtration first, and the electric proportional regulating valves 51 corresponding to the two auxiliary membranes 2 are kept closed or only maintained at the minimum flow opening (e.g., opening ≤ 5%) to reduce system energy consumption. When the cumulative treated water volume of the main membrane 3 reaches the preset value or its product water flow rate is detected to decrease by more than 10%, the controller gradually opens one auxiliary membrane 2 to share the load, realizing a smooth switching between the main and auxiliary membranes. Form 2: Balanced Distribution Model When the TDS value of the influent is between the first preset threshold and the second preset threshold (e.g., 200~500ppm), the controller determines that the raw water quality is moderate. At this time, it controls the opening of the three electric proportional regulating valves 51 to be equal or to distribute the flow according to a preset ratio (e.g., 4:3:3) so that the main membrane 3 and the two auxiliary membranes 2 can bear the treatment load equally and avoid overloading of a single membrane. Form 3: Peak Load Mode When the TDS value of the influent is higher than the second preset threshold (e.g., 500 ppm) or the user-set water production demand exceeds the maximum water production capacity of a single membrane, the controller determines that it has entered the peak load state. At this time, the opening of the three electric proportional regulating valves 51 is adjusted to the maximum, so that the main membrane 3 and the two auxiliary membranes 2 are all running at full load to ensure that the water production flow and water quality meet the standards. Form 4: Membrane Rotation and Maintenance Mode The controller records the cumulative runtime and cumulative treated water volume of each membrane. When the cumulative runtime of an auxiliary membrane 2 reaches a preset rest threshold (e.g., 200 hours), the controller closes its corresponding electric proportional regulating valve 51 to put it into a "rest" state, while another auxiliary membrane 2 is activated to take over the work. During the rest period, the membrane can be backwashed or naturally restored, which helps to delay membrane fouling and aging. Form 5: Adaptive Adjustment Mode The controller monitors the pressure difference (ΔP) between the inlet and outlet of each membrane in real time. When the ΔP of a certain membrane exceeds the preset alarm threshold (e.g., 0.3MPa), it is determined that the membrane is showing signs of fouling or blockage. At this time, the controller reduces the opening of the electric proportional regulating valve 51 corresponding to that membrane, while increasing the opening of the electric proportional regulating valve 51 corresponding to other membranes. This achieves automatic load transfer, prevents the fouled membrane from continuing to operate under overload, and thus protects the membrane and maintains the overall water production efficiency.

[0025] As a further preferred option, the reverse osmosis water purifier also includes a secondary membrane 6 fixedly installed in the secondary water purification zone 102. The secondary membrane 6 serves as a second-stage reverse osmosis membrane and is used to deeply filter the pure water produced by the first-stage reverse osmosis membrane group, further improving the purity of the produced water. It is especially suitable for the deep treatment of raw water with high hardness or high salinity.

[0026] As a further preferred option, the reverse osmosis water purifier also includes a pressure exchange device 7. It should be noted that the pressure exchange device 7 is not a necessary structure for realizing the aforementioned dynamic load distribution function, but rather serves as an additional energy recovery optimization method. In some application scenarios where energy consumption requirements are not high (such as small-flow household water purifiers), the pressure exchange device 7 can be omitted to simplify the structure and reduce costs; the following provides a detailed description of this optional pressure exchange device 7. The pressure exchange device 7 includes a first pressure exchange tank 71 and a second pressure exchange tank 72 fixed in the secondary water purification zone 102. The first pressure exchange tank 71 and the second pressure exchange tank 72 are provided with an elastic diaphragm 73. The elastic diaphragm 73 has a corrugated structure and divides the first pressure exchange tank 71 and the second pressure exchange tank 72 into a high-pressure chamber 701 and a low-pressure chamber 702. The inlet of each high-pressure chamber 701 is connected to the concentrate outlet of the first-stage reverse osmosis membrane group through a pipeline. The concentrate outlet and the pure water outlet of the first-stage reverse osmosis membrane group are both connected to a connecting pipe 42. The outlet of each high-pressure chamber 701 is connected to a drainage pipe. The inlet of each low-pressure chamber 702 is connected to the pure water outlet of the first-stage reverse osmosis membrane group through a pipeline. The outlet of the low-pressure chamber 702 is connected to the inlet of the sub-membrane body 6 through a pipeline, so as to form multiple interconnected and independently controlled passages. More specifically, there are multiple reversing valves 52 on the pipeline between the first-stage reverse osmosis membrane module and the first pressure exchange tank 71 and the second pressure exchange tank 72. Each reversing valve 52 is electrically connected to the controller and is used to control the switching of the reversing valve 52. Pressure sensors are installed on the first pressure exchange tank 71 and the second pressure exchange tank 72, and the probes of the pressure sensors are located in each high-pressure chamber 701. To achieve continuous alternating operation between the first pressure exchange tank 71 and the second pressure exchange tank 72, the controller performs control based on the pressure sensor signal installed in the high-pressure chamber 701, as follows: When the pressure in the high-pressure chamber 701 of the first pressure exchange tank 71 drops to a preset lower limit, such as 3 bar, the controller adjusts the reversing valve 52 at the inlet of the high-pressure chamber 701 of the first pressure exchange tank 71 to close, and at the same time opens the reversing valve 52 at the inlet of the high-pressure chamber 701 of the second pressure exchange tank 72, so that the first-stage concentrate is switched into the second pressure exchange tank 72. Simultaneously, the controller opens the reversing valve 52 at the outlet of the high-pressure chamber 701 of the first pressure exchange tank 71, switching it to the drainage state and completing one pressure exchange cycle. Through this alternating working mode, a continuous pressure exchange process can be achieved, recovering the concentrated water pressure generated by the first-stage reverse osmosis membrane module and using it to assist in driving the feed water of the sub-membrane 6. No additional pumping is required, reducing the extra pumping energy consumption required by the sub-membrane 6, thereby reducing the overall energy consumption of the system and improving energy utilization efficiency.

[0027] To facilitate understanding of the embodiments of this solution by those skilled in the art, the working principle of this solution will now be briefly explained in conjunction with specific application scenarios: Combination Figures 1-8 The process flow / principle of a reverse osmosis water purifier provided by this invention is as follows: First, the raw water is pressurized by the pumping assembly 12 to reach the pressure required by the reverse osmosis membrane, and then the pressurized water flows from the water delivery pipeline of the pumping assembly 12 into the diversion pipeline 4.

[0028] Subsequently, the multi-port connector 41 in the diversion pipeline 4 guides the pressurized water flow to multiple electrically operated proportional control valves 51. Each electrically operated proportional control valve 51 corresponds to a reverse osmosis membrane, including one main membrane 3 and two auxiliary membranes 2. At this time, the controller adjusts the opening of each electrically operated proportional control valve 51 according to the preset program or the water quality parameters detected in real time, thereby independently controlling the water flow and pressure entering the main membrane 3 and the two auxiliary membranes 2. This allows for flexible control based on actual needs, such as prioritizing the use of the main membrane 3 or simultaneously using the main membrane 3 and one side of the auxiliary membrane 2 to balance the load. The independently regulated water then enters the main membrane 3 and the two auxiliary membranes 2 to operate in parallel, enabling each membrane to perform the first stage of reverse osmosis filtration on the raw water, producing first-stage pure water and first-stage concentrated water.

[0029] After the first-stage reverse osmosis filtration, the primary pure water enters the low-pressure chamber 702 of the pressure exchange device 7, while the primary concentrate enters the high-pressure chamber 701. The pressure exchange device 7 contains a corrugated elastic diaphragm 73 in the first pressure exchange tank 71 and the second pressure exchange tank 72, dividing the tank into the high-pressure chamber 701 and the low-pressure chamber 702. The controller, by controlling the opening or closing of the reversing valve 52, controls the primary concentrate to alternately enter the high-pressure chamber 701 of the first and second pressure exchange tanks 71 and 72, causing the elastic diaphragm 73 to deform, thereby pressurizing the primary pure water in the low-pressure chamber 702. This pressurized primary pure water serves as the feed water for the secondary membrane 6. This design effectively recovers the pressure energy from the concentrate, eliminating the need for additional pumps and reducing the extra pumping energy required for the secondary membrane 6.

[0030] The pressurized primary pure water then enters the secondary membrane 6, the second-stage reverse osmosis membrane, for deep filtration, producing secondary pure water and secondary concentrate. The secondary pure water is used as the final product, while the secondary concentrate can be recycled or discharged. The primary concentrate, after pressure exchange, is depressurized and discharged through a drain pipe, completing the entire purification process. During purification, an explosion-proof glass observation window on the outer wall of the casing 1 allows for real-time monitoring of the internal operating status. Through this process, the present invention achieves flexible control and energy recovery of the multi-stage reverse osmosis membranes, significantly improving water purification efficiency, membrane lifespan, and energy utilization.

[0031] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the reverse osmosis water purifier and its inventive concept, should be covered within the scope of protection of the present invention.

Claims

1. A reverse osmosis water purifier, comprising a casing (1); A pumping assembly (12) is disposed inside the housing (1) and is used to pressurize the incoming water; Its features are, Also includes: Multiple reverse osmosis membranes are fixedly installed inside the housing (1). The multiple reverse osmosis membranes include a main membrane (3) and two auxiliary membranes (2). The main membrane (3) and the two auxiliary membranes (2) are connected in parallel. The diversion pipeline (4) is used to connect the outlet fluid of the pumping assembly to the inlet water interface of multiple reverse osmosis membranes; The distribution module (5) includes multiple electric proportional control valves (51). Each electric proportional control valve (51) is installed on the inlet water passage of a reverse osmosis membrane and is used to independently control the liquid flow rate and pressure entering the main membrane (3) and the two auxiliary membranes (2). Under the control of the distribution module (5), the main membrane (3) and the auxiliary membranes (2) can dynamically distribute the treatment load of each membrane according to the inlet water quality and usage requirements.

2. The reverse osmosis water purifier according to claim 1, characterized in that, The diversion line (4) includes a multi-port connector (41); And multiple connecting pipes (42) connecting the multi-port connector (41) to each reverse osmosis membrane, the inlet end of the multi-port connector (41) is connected to the water supply pipeline of the pumping assembly (12), each of the electric proportional regulating valves (51) is respectively set on each outlet end of the multi-port connector (41), one end of each connecting pipe (42) is fixed on each electric proportional regulating valve (51), and the other end is respectively connected to the water inlet interface of the main membrane (3) and the two auxiliary membranes (2).

3. A reverse osmosis water purifier according to claim 1, characterized in that, A partition plate (11) is fixedly installed inside the housing (1). The partition plate (11) divides the housing (1) into a primary water purification zone (101) and a secondary water purification zone (102). The main membrane body (3) and the two auxiliary membrane bodies (2) are all fixedly installed in the primary water purification zone (101).

4. A reverse osmosis water purifier according to claim 3, characterized in that, It also includes a sub-membrane (6) fixedly installed in the secondary water purification zone (102), the sub-membrane (6) serving as the second-stage reverse osmosis membrane, and the main membrane (3) and the auxiliary membrane (2) together serving as the first-stage reverse osmosis membrane group.

5. A reverse osmosis water purifier according to claim 4, characterized in that, It also includes a pressure exchange device (7), which includes a first pressure exchange tank (71) and a second pressure exchange tank (72) fixed in the secondary water purification zone (102). The first pressure exchange tank (71) and the second pressure exchange tank (72) are provided with an elastic diaphragm (73), which separates the first pressure exchange tank (71) and the second pressure exchange tank (72) into a high-pressure chamber (701) and a low-pressure chamber (702).

6. A reverse osmosis water purifier according to claim 5, characterized in that, The elastic diaphragm (73) in the first pressure exchange tank (71) and the second pressure exchange tank (72) has a corrugated structure.

7. A reverse osmosis water purifier according to claim 5, characterized in that, The inlet of each high-pressure chamber (701) is connected to the concentrate outlet of the first-stage reverse osmosis membrane unit through a pipeline, the outlet of each high-pressure chamber (701) is connected to a drainage pipeline, the inlet of each low-pressure chamber (702) is connected to the pure water outlet of the first-stage reverse osmosis membrane unit through a pipeline, and the outlet of the low-pressure chamber (702) is connected to the inlet of the sub-membrane (6) through a pipeline.

8. A reverse osmosis water purifier according to claim 5, characterized in that, It also includes the controller; And a plurality of reversing valves (52) are provided on the pipeline between the first-stage reverse osmosis membrane group and the first pressure exchange tank (71) and the second pressure exchange tank (72), each of the reversing valves (52) being electrically connected to the controller for controlling the switching of the reversing valve (52).

9. A reverse osmosis water purifier according to claim 1, characterized in that, An observation window (13) is provided on the outer wall of the housing (1), and an explosion-proof glass (131) is fixedly installed inside the observation window (13).

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