Working fluid circulating system with backwashing function

Abstract

The present application relates to a kind of working fluid circulation systems with backwash function, including sewage tank, backwash filter core, clean water tank, booster pump and water module connected in turn circulation waterway, backwash filter core includes: shell, filter screen, first valve and second valve being arranged in the shell inside, water inlet, water outlet and blowdown are provided on the shell;Filter screen, first valve and second valve will the space inside shell be divided into three parts, when backwash filter core is in filtration mode, second valve and blowdown are closed, water flow enters from water inlet, after flowing through first valve and filter screen, from water outlet discharge;When backwash filter core is in backwash mode, first valve and water outlet are closed, water flow enters from water inlet, after flowing through second valve and filter screen, from blowdown discharge, the water flow direction flowing through filter screen is opposite to filtration mode, can be efficiently stripped by water flow the adherend on the surface of filter screen, finally through the blowdown that opens, completely discharge system, complete the cleaning of filter screen.

Description

Technical Field

[0001] This invention relates to the field of working fluid circulation technology, and more specifically to a working fluid circulation system with backwashing function. Background Technology

[0002] Taking electrical discharge machining (EDM) technology as an example, the working fluid circulation system is a core component that ensures the smooth operation of the machining process. This system not only undertakes the crucial task of establishing a stable discharge channel during machining to ensure the continuity and efficiency of EDM, but also bears the important function of cooling and heat dissipation. Its performance directly affects machining accuracy, equipment lifespan, and production efficiency.

[0003] However, the working fluid circulation system equipped in current EDM machine tools faces a pressing technical bottleneck in practical applications. Filter clogging is a common problem during system operation. Traditional solutions mainly rely on periodic filter replacement or manual backwashing, but this leads to significant resource waste, low system efficiency, and a substantial increase in maintenance costs. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a working fluid circulation system with backwashing function, so as to solve the problems in the prior art to a certain extent.

[0005] According to a first aspect of the present invention, a working fluid circulation system with a backwashing function is provided, characterized in that it comprises:

[0006] The system consists of a wastewater tank, a backwash filter element, a cleaning water tank, a booster pump, and a water-using module connected in sequence via water channels. The outlet of the water-using module is connected to the inlet of the wastewater tank.

[0007] The outlet of the wastewater tank is connected to the inlet of the backwash filter element; the inlet of the clean water tank is connected to the outlet of the backwash filter element.

[0008] The backwash filter element includes: a housing, a filter screen disposed inside the housing, a first valve, and a second valve. The housing is provided with an inlet, an outlet, and a drain outlet. The filter screen, the first valve, and the second valve divide the space inside the housing into three parts. When the backwash filter element is in filtration mode, the inlet is open, the outlet is open, the drain outlet is closed, the first valve is open, and the second valve is closed. Water flows in from the inlet, passes through the first valve and the filter screen, and then exits from the outlet. When the backwash filter element is in backwashing mode, the inlet is open, the outlet is closed, the drain outlet is open, the first valve is closed, and the second valve is open. Water flows in from the inlet, passes through the second valve and the filter screen, and then exits from the drain outlet.

[0009] Preferably, the working fluid circulation system with backwashing function further includes:

[0010] A liquid level sensor installed inside the wastewater tank, a liquid level sensor installed inside the clean water tank, and a valve controller;

[0011] The outlet of the wastewater tank is installed near the bottom of the tank and connected to the inlet of the backwash filter element; the inlet of the clean water tank is installed near the bottom of the tank and connected to the outlet of the backwash filter element.

[0012] The valve controller is used to control the opening and closing status of the first valve and the second valve based on the data collected by the liquid level sensor.

[0013] Preferably, the valve controller controls the opening and closing states of the first valve and the second valve based on data collected by the liquid level sensor, including:

[0014] The liquid level heights of the wastewater tank and the clean water tank are smoothed using a sliding window smoothing formula, as follows:

[0015]

[0016] in This indicates the liquid level in the clean water tank after smoothing. The level of the return water tank after smoothing is represented by N, the size of the sliding window is N, i represents the current window number, t is the current time, h1(i) is the level of the clean water tank at time i, and h2(i) is the level of the return water tank at time i.

[0017] The pressure difference is calculated based on the liquid level in the smoothed wastewater tank and the liquid level in the clean water tank, using the following formula:

[0018]

[0019] Where ΔP is the pressure difference, ρ1 is the density of the liquid in the clean water tank, ρ2 is the density of the liquid in the return water tank, and g is the acceleration due to gravity.

[0020] The current permeability k of the filter element is calculated based on the pressure difference, using the following formula:

[0021]

[0022] Where μ is the dynamic viscosity of the fluid, L is the length of the filter element, and ΔP filter It equals ΔP, where A is the cross-sectional area of ​​the filter element, and v represents the average flow velocity of the fluid flowing in the filter element;

[0023] The permeability k is smoothed using a sliding window using the following formula:

[0024]

[0025] The permeability is the smoothed permeability, where N is the size of the sliding window, i represents the current window number, and k(i) is the permeability at window i.

[0026] If the permeability of the filter cartridge after the current smoothing treatment is lower than the first permeability threshold, the backwash filter cartridge is controlled to switch from filtration mode to backwash mode for a preset time.

[0027] Preferably, the working fluid circulation system with backwashing function further includes:

[0028] The volume of water in the cleaning water tank is calculated based on the water level and cross-sectional area of ​​the tank. The formula is as follows:

[0029] V(t)=B*h1(t)

[0030] V(t) is the amount of water in the clean water tank at time t, B is the cross-sectional area of ​​the clean water tank, and h1(t) is the liquid level height of the clean water tank at time t.

[0031] If the current permeability of the filter element is higher than the first permeability threshold, but the water volume in the cleaning tank is less than the sum of the water volume required for the preset backwash time and the constant water volume, then the backwash filter element is controlled to switch from filtration mode to backwash mode for a preset time.

[0032] Preferably, the working fluid circulation system with backwashing function further includes: calculating the rate of change of permeability per unit time.

[0033] If the rate of change of permeability per unit time is greater than the preset rate, then the first permeability threshold is changed to the second permeability threshold, and the second permeability threshold is lower than the first permeability threshold.

[0034] Preferably, the working fluid circulation system with backwashing function further includes:

[0035] Heat exchangers and cooling units;

[0036] The water circuit of the heat exchanger is connected to the cleaning water tank through two water pipes;

[0037] The heat-conducting structure inside the heat exchanger is connected to the cooling unit so that the cooling unit can process the heat transferred from the heat exchanger.

[0038] Preferably, the working fluid circulation system with backwashing function further includes:

[0039] The sterilization module has its inlet connected to the outlet of the booster pump and its outlet connected to the cleaning water tank.

[0040] Preferably, the working fluid circulation system with backwashing function further includes:

[0041] The second filter module is located between the booster pump and the water-using module; the inlet of the second filter module is connected to the outlet of the booster pump, and the outlet of the second filter module is connected to the inlet of the water-using module.

[0042] Preferably, the second filtration module is a magnetic filter or a deionized resin.

[0043] Preferably, the working fluid circulation system with backwashing function further includes:

[0044] A flow regulating valve is installed between the booster pump and the second filter module. The inlet of the flow regulating valve is connected to the outlet of the booster pump, and the outlet of the flow regulating valve is connected to the inlet of the second filter module.

[0045] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects:

[0046] It is understood that the technical solution shown in this invention relates to a working fluid circulation system with backwashing function, including a sewage tank, a backwash filter element, a cleaning water tank, a booster pump, and a water module connected in sequence by a circulating water path. The backwash filter element includes: a housing, a filter screen, a first valve, and a second valve disposed inside the housing. The housing is provided with an inlet, an outlet, and a drain outlet. The filter screen, the first valve, and the second valve divide the space inside the housing into three parts. When the backwash filter element is in filtration mode, the second valve and the drain outlet are closed, and water flows in from the inlet, flows through the first valve and the filter screen, and then exits from the outlet. When the backwash filter element is in backwashing mode, the first valve and the outlet are closed, and water flows in from the inlet, flows through the second valve and the filter screen, and then exits from the drain outlet. The direction of water flow through the filter screen is opposite to that in the filtration mode, which can efficiently remove the adhering substances on the surface of the filter screen through water flow, and finally completely discharge them from the system through the open drain outlet, completing the cleaning of the filter screen. There is no need for manual disassembly and cleaning of the filter screen, and the system has high operating efficiency.

[0047] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0048] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0049] Figure 1 This is a schematic block diagram illustrating a working fluid circulation system with backwashing function according to an exemplary embodiment;

[0050] Figure 2 This is a schematic cross-sectional view of a backwash filter element according to an exemplary embodiment;

[0051] Figure 3 This is a backwashing process diagram illustrated according to an exemplary embodiment;

[0052] Figure 4 This is a schematic diagram of a working fluid circulation system with backwashing function for rough processing, according to an exemplary embodiment.

[0053] Figure 5 This is a schematic diagram of a finely processed working fluid circulation system with backwashing function, according to an exemplary embodiment. Detailed Implementation

[0054] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0055] In one embodiment, Figure 1 This is a schematic block diagram illustrating a working fluid circulation system with backwashing function according to an exemplary embodiment. See also: Figure 1 A working fluid circulation system with backwashing function is provided, comprising:

[0056] The system consists of a wastewater tank, a backwash filter element, a cleaning water tank, a booster pump, and a water-using module connected in sequence via water channels. The outlet of the water-using module is connected to the inlet of the wastewater tank.

[0057] The outlet of the wastewater tank is connected to the inlet of the backwash filter element; the inlet of the clean water tank is connected to the outlet of the backwash filter element.

[0058] The backwash filter element includes: a housing, a filter screen disposed inside the housing, a first valve, and a second valve. The housing is provided with an inlet, an outlet, and a drain outlet. The filter screen, the first valve, and the second valve divide the space inside the housing into three parts. When the backwash filter element is in filtration mode, the inlet is open, the outlet is open, the drain outlet is closed, the first valve is open, and the second valve is closed. Water flows in from the inlet, passes through the first valve and the filter screen, and then exits from the outlet. When the backwash filter element is in backwashing mode, the inlet is open, the outlet is closed, the drain outlet is open, the first valve is closed, and the second valve is open. Water flows in from the inlet, passes through the second valve and the filter screen, and then exits from the drain outlet.

[0059] In practice, Figure 2 A cross-sectional schematic diagram of a backwash filter element is shown. See [link / reference] Figure 2 The backwash filter element is cylindrical, with a cylindrical filter screen inside. There are three valves on the inside of the housing near the water inlet. Valve No. 1 corresponds to the first valve, and valves No. 2 and No. 3 together form the second valve, dividing the space inside the housing into three parts: the space between the water inlet and the valve is the first part, the inside of the filter screen is the second part, and the space between the housing and the filter screen is the third part.

[0060] In filtration mode, valve 1 (first valve) is open, and valves 2 and 3 (second valves) are closed. The water flow direction is as follows: Figure 2 The solid arrow indicates that the water flows through the first valve and enters the second space from the first space. Since the drain outlet is closed, the water flows through the filter screen into the third space and flows out from the outlet. When passing through the filter screen, impurities in the water flow are retained on the inside of the filter screen, thus achieving the filtering effect.

[0061] When backwashing the filter is required, valve 1 (first valve) is closed, and valves 2 and 3 (second valves) are opened. At this time, the water flow direction is... Figure 2 As indicated by the dotted arrow, the water flows through valves 2 and 3, entering the third space from the first space. Since the outlet is closed, the water flows through the filter screen into the second space. As it passes through the filter screen, the water washes away the impurities inside the screen and removes surface deposits. Finally, the water flows through the filter screen and is discharged from the drain outlet.

[0062] Figure 2 The valves are designed as electric directional valves, and valves 1, 2 and 3 are designed as deflectors. When in filtration mode, deflector 1 is open and deflectors 2 and 3 are closed. When the electric directional valve is pressed, the three deflectors rotate 90° simultaneously, deflectors 2 and 3 are open and deflector 1 is closed.

[0063] It is understood that the technical solution shown in this invention relates to a working fluid circulation system with backwashing function, including a sewage tank, a backwash filter element, a cleaning water tank, a booster pump, and a water module connected in sequence by a circulating water path. The backwash filter element includes: a housing, a filter screen, a first valve, and a second valve disposed inside the housing. The housing is provided with an inlet, an outlet, and a drain outlet. The filter screen, the first valve, and the second valve divide the space inside the housing into three parts. When the backwash filter element is in filtration mode, the second valve and the drain outlet are closed, and water flows in from the inlet, flows through the first valve and the filter screen, and then exits from the outlet. When the backwash filter element is in backwashing mode, the first valve and the outlet are closed, and water flows in from the inlet, flows through the second valve and the filter screen, and then exits from the drain outlet. The direction of water flow through the filter screen is opposite to that in the filtration mode, which can efficiently remove the adhering substances on the surface of the filter screen through water flow, and finally completely discharge them from the system through the open drain outlet, completing the cleaning of the filter screen. There is no need for manual disassembly and cleaning of the filter screen, and the system has high operating efficiency.

[0064] In another embodiment, it should be noted that the automatic backwashing function can be achieved by adding a liquid level sensor and a controller. The working fluid circulation system with backwashing function further includes:

[0065] A liquid level sensor is installed inside the wastewater tank, a liquid level sensor is installed inside the clean water tank, and a valve controller is installed.

[0066] The outlet of the wastewater tank is installed near the bottom of the tank and connected to the inlet of the backwash filter element; the inlet of the cleaning water tank is installed near the bottom of the tank and connected to the outlet of the backwash filter element. The wastewater tank, backwash filter element, and cleaning water tank form a U-shaped connecting tube. The valve controller is used to control the opening and closing status of the first and second valves based on data collected by the liquid level sensor.

[0067] Ideally, the liquid levels in the wastewater tank and the clean water tank will remain the same. However, with continuous filtration, the filter cartridge will gradually become clogged, leading to a reduction in the filtered water volume. Furthermore, the difference in liquid level between the return water tank and the clean water tank will increase, necessitating backwashing. The valve controller can automatically control the opening and closing of the first and second valves based on the liquid levels in the wastewater and clean water tanks, enabling the backwash filter cartridge to switch between filtration mode and backwashing mode.

[0068] It should be noted that the valve controller controls the opening and closing states of the first and second valves based on data collected by the liquid level sensor, including:

[0069] The pressure difference is calculated based on the liquid levels in the wastewater tank and the clean water tank, and the current permeability of the filter element is calculated based on this pressure difference. If the current permeability of the filter element is lower than a first permeability threshold, the backwash filter element is switched from filtration mode to backwash mode for a preset time.

[0070] In practical application, see Figure 3 The current pressure difference can be calculated using the formula ΔP = ρgΔh, where ΔP is the pressure difference, ρ is the density of the liquid, g is the acceleration due to gravity, and Δh is the height difference between the liquid levels in the return water tank and the clean water tank.

[0071] To reduce fluctuations in liquid level data, the liquid level data of the return water tank and the cleaning water tank are smoothed: the liquid level data h1(t) (liquid level height of the cleaning water tank) and h2(t) (liquid level height of the return water tank) at corresponding time t are recorded, and the smoothing is calculated according to the sliding window formula:

[0072]

[0073] in and These represent the smoothed water levels in the cleaning tank and return tank, respectively. N is the size of the sliding window, and i represents the current window number. The formula for calculating the smoothed pressure is:

[0074]

[0075] ρ1 is the density of the liquid in the clean water tank, ρ2 is the density of the liquid in the return water tank, h2 is the height of the liquid level in the return water tank, and h1 is the height of the liquid level in the clean water tank.

[0076] According to Darcy's law, the permeability k of the filter element can be expressed as:

[0077]

[0078] Where μ is the dynamic viscosity of the fluid, L is the length of the filter element, and ΔP filter Approximately equal to ΔP, where A is the cross-sectional area of ​​the filter element, and v represents the average flow velocity of the fluid within the filter element. v can be calculated using the flow rate Q measured by the flow meter and the cross-sectional area A of the filter element.

[0079]

[0080] To avoid errors in the calculation of permeability k that could affect backwashing, a sliding window smoothing process is applied to k:

[0081]

[0082] Where N is the size of the sliding window, and i represents the current window number.

[0083] When the smoothed permeability Below the set penetration threshold k threshold At that time, the backwashing process is triggered.

[0084] Due to the complex operating conditions of the working fluid circulation system, the filter element will also start backwashing under the following two special circumstances.

[0085] The first special case is when the water level in the cleaning tank is too low. The working fluid circulation system with backwashing function also includes:

[0086] The amount of water in the cleaning water tank is calculated based on the water level and cross-sectional area of ​​the cleaning water tank. If the current permeability of the filter element is higher than the first permeability threshold, but the amount of water in the cleaning water tank is less than the sum of the water required for the preset backwash time and the constant water volume, the backwash filter element is controlled to switch from filtration mode to backwash mode for a preset time.

[0087] The water volume in the clean water tank, V(t), is calculated as V * h1(t), where B is the cross-sectional area of ​​the clean water tank and L is the constant water volume. Based on the filter element size and backwashing time requirements, estimate the water volume V required for each backwash. m When the water volume in the clean water tank is V(t) <V m When +L is reached, the backwashing process is triggered. Constant water volume L refers to the reserve safety water volume to ensure the water tank does not become empty.

[0088] The second special case involves abnormal changes in permeability. The working fluid circulation system with backwashing function further includes: calculating the rate of change of permeability per unit time.

[0089] The rate of change in permeability per unit time reflects the clogging rate of the filter cartridge:

[0090]

[0091] Where Δt is the time interval.

[0092] according to The clogging status of filter elements can be categorized as follows: Low-speed clogging: Smaller filter size results in slower clogging. Medium-speed clogging: Medium clogging rate: The filter cartridge clogs at a moderate rate, consistent with normal clogging speeds. High-speed clogging: Larger filter cartridges clog faster.

[0093] If the rate of change of permeability per unit time is greater than the preset rate, it indicates that the current state is a high-speed blockage. In this case, the first permeability threshold is changed to the second permeability threshold, which is lower than the first permeability threshold.

[0094] When the filter element is experiencing high-speed clogging, appropriately reduce the threshold k. threshold Prematurely triggering reverse shuffling.

[0095] It is understandable that this structure has the following three advantages: (1) The connection between the return water tank and the clean water tank adopts a U-shaped tube design. Utilizing the principle of fluid dynamics, the liquid in the return water tank flows naturally into the clean water tank through pressure difference without the need for additional pumping equipment, thereby saving energy consumption. (2) The U-shaped tube structure is based on the principle of communicating vessels, so that under static conditions, the liquid level in the two tanks is automatically adjusted to be equal. When the liquid level is unbalanced, backwashing can be performed to make the liquid levels on both sides reach balance again, realizing automatic balance control of the liquid level and ensuring the stability of the system. (3) The backwash filter element structure, this bidirectional flushing mode can efficiently remove surface deposits and finally completely discharge them from the system through the open drain port, completing a fully automatic cleaning cycle. (4) The system can automatically determine when to perform backwashing. When the liquid level difference continues to increase and exceeds the preset safety range, the system will automatically start the backwashing program without manual intervention. In addition, the system can also predict the clogging trend of the filter element based on the water volume and operating status in the tank, and perform backwashing in advance, thereby further extending the service life of the filter element and reducing maintenance frequency and cost.

[0096] In one specific embodiment, a coarse-processed working fluid circulation system with backwashing function is provided, specifically which can be... Figure 4 For example, this system is designed to achieve a filtration accuracy of less than 100 micrometers. The primary filtration stage uses PP cotton to remove large particulate impurities from the working fluid. The working fluid is circulated via pumps and pipelines, simplifying the system structure. It lacks sterilization and temperature control features, reducing operating costs and meeting the economic and practical needs of coarse processing.

[0097] In this embodiment, the water tank dimensions are 300mm long, 300mm wide, and 1000mm high, and the diameter of the pipe between the two water tanks is 50mm. The backwash filter element has a length L = 0.3m and a cross-sectional area A = 0.05m³. 2 Penetration threshold k threshold =5.0×10 -10 m 2 Initially, the liquid level in both tanks is 500mm, and the system operating flow rate is 6L / min.

[0098] Calculated based on the flow velocity formula: The system operating flow rate Q = 6.0 L / min = 1.0 × 10⁻⁶ -4 m 3 / s, cross-sectional area A=0.05m 2 .

[0099] Let the liquid level difference be Δh(t), and initially Δh(0) = 0. As time progresses, the liquid level h2(t) in the return water tank rises, while the liquid level h1(t) in the clean water tank falls. The rate of change of liquid level caused by the flow rate Q is: Where B is the cross-sectional area of ​​the water tank, which is 0.09m³. 2 .

[0100] The liquid level difference is Δh(t) = h2(t) - h1(t) = 2.222 × t × 10 -3 m, where h2(t) = 0.5 + 1.111 × t × 10 -3 h1(t) = 0.5 - 1.111 × t × 10 -3 .

[0101] The pressure across the filter element is ΔP(t) = ρ2gh2(t) - ρ1gh1(t) = 1100 × 9.81 × (0.5 +

[0102] 1.111×10 -3 ×t)-1000×9.81×(0.5-1.111×10 -3 ×t)=9.81×(50+2.333×10 - 3 t)Pa.

[0103] Calculate filter cartridge permeability based on Darcy's law. Where μ = 0.001 Pa·s is the dynamic viscosity of the fluid, L = 0.3 m is the length of the filter element, and the pressure across the filter element ΔP(t) = 9.81 × (50 + 2.333 × 10⁻⁶) / 2. -3 t)Pa, A=0.05m 2 It is the cross-sectional area of ​​the filter element, v = 2.0 × 10⁻⁶ -3 This represents the average flow rate of the fluid flowing in the filter element.

[0104] The permeability threshold of the filter element is k threshold =5.0×10 -10 m 2 Backwashing is required when the filter element reaches the threshold. Let k(t) = 5.0 × 10 -10 It can be concluded that Solving for t, we get t ≈ 29000 seconds = 8.06 hours. The calculation shows the system will reach the permeability threshold in approximately 8.06 hours, triggering the backwashing process.

[0105] In another embodiment, see Figure 5 The working fluid circulation system with backwashing function further includes:

[0106] A heat exchanger and a cooling unit; the water circuit of the heat exchanger is connected to a clean water tank via two water pipes; the heat-conducting structure inside the heat exchanger is connected to the cooling unit so that the cooling unit can process the heat transferred from the heat exchanger.

[0107] The heat exchanger and cooling unit utilize the Licheng LC-LTC-5 / 10 cryogenic cooling circulator. It is responsible for regulating the temperature of the working fluid, ensuring its circulation within a suitable temperature range. This module helps maintain temperature balance in the processing area, preventing overheating and improving processing efficiency and quality.

[0108] In another embodiment, see Figure 5 The working fluid circulation system with backwashing function further includes: a sterilization module ( Figure 5 The sterilization module is equipped with UV ultraviolet light, and its inlet is connected to the outlet of the booster pump. The outlet of the sterilization module is connected to the cleaning water tank.

[0109] In another embodiment, see Figure 5 The working fluid circulation system with backwashing function further includes:

[0110] A second filtration module is installed between the booster pump and the water-using module. The inlet of the second filtration module is connected to the outlet of the booster pump, and the outlet of the second filtration module is connected to the inlet of the water-using module. The second filtration module is a magnetic filter or a deionized resin filter.

[0111] The backwash filter element, sterilization module, and second filtration module together constitute the filtration system. Its function is to remove impurities and particles from the working fluid, improving its cleanliness, protecting machine tools, and extending the working fluid's service life. The filtration system adopts a modular design and includes a backwash filter element, allowing for flexible replacement of different filter media such as PP cotton, UF ultrafiltration, deionization resin devices, and magnetic filters to meet varying processing requirements. This design enhances the system's adaptability and flexibility, allowing users to select and configure suitable filter media based on specific processing conditions and quality requirements.

[0112] In the initial filtration stage, the system collects wastewater generated during machine tool processing from the wastewater tank. This wastewater first passes through a backwash filter element, the primary purpose of which is to remove large particulate impurities such as metal shavings and larger dust particles. As the filtration process continues, the filter element may gradually become clogged, causing a difference in liquid level between the left and right sides of the U-tube. Monitors installed in both tanks can monitor the liquid level and density (k) in real time. The current permeability threshold (k) and backwash cycle can be calculated using a backwashing algorithm. When the calculated value is lower than this threshold, it indicates that the filter element may be severely clogged, requiring backwashing. The backwashing operation is performed through the backwash filter element; this step is crucial for improving the accuracy of EDM and extending the machine tool's lifespan. Subsequently, the working fluid after the initial filtration flows into the clean water tank for storage. The working fluid in the clean water tank flows into a heat exchanger under gravity, the heat exchanger's function being to regulate the temperature of the working fluid to meet the precise temperature conditions required for EDM. The heat exchanger and the clean water tank are connected by pipes to form a communicating vessel structure, which ensures that the cooled working fluid automatically flows back to the clean water tank to maintain the continuous operation of the circulation system.

[0113] In the secondary treatment and distribution stage, the booster pump draws working fluid from the clean water tank and distributes it to two paths. One path is the circulation sterilization path, where the working fluid undergoes UV sterilization treatment. This step is to eliminate potential microbial contamination and ensure the hygiene and safety of the working fluid. The treated working fluid is then returned to the clean water tank, ready for the next cycle.

[0114] The other path is the machine tool supply path, where the working fluid undergoes deionization resin treatment to further increase the water's resistivity, remove ions, and ensure that the working fluid's conductivity meets the requirements of EDM. This step plays a crucial role in preventing electric arcs during machining and improving machining quality. The deionized working fluid is finally delivered to the EDM machine tool for cooling and cleaning the machining area, removing heat and debris generated during machining, and ensuring the stability of the machining process and the accuracy of the machined parts.

[0115] The three separate filtration modules not only allow for the selection of the most suitable filter media based on specific filtration needs, avoiding over-investment and resource waste, but also mean that when a filter media needs replacement or upgrade, only that module needs to be operated on, without replacing the entire system, thus reducing long-term operation and maintenance costs. The modular design simplifies the maintenance and upgrade process, allowing for quick and economical repairs or replacements of specific filter media, reducing system downtime. Furthermore, as technology advances, users can easily introduce new technologies or upgrade existing modules, including backwash filter cartridges, to improve system performance, ensuring the system remains at the forefront of technology while protecting the initial investment. The automated cleaning function of the backwash filter cartridges further reduces maintenance workload and improves system reliability and efficiency.

[0116] In another embodiment, see Figure 5 The working fluid circulation system with backwashing function further includes: a flow regulating valve, which is disposed between the booster pump and the second filter module. The inlet of the flow regulating valve is connected to the outlet of the booster pump, and the outlet of the flow regulating valve is connected to the inlet of the second filter module.

[0117] In addition, it includes manual control valves, level switches, etc., for adjusting and controlling the flow rate, level, and circulation process of the working fluid. It can automatically or manually adjust the supply and circulation of the working fluid according to processing requirements.

[0118] In one specific embodiment, a finely processed working fluid circulation system with backwashing function is provided, specifically which can be... Figure 5 For example, a sterilization module is added to ensure sterile water quality. A flow control valve is also added to ensure highly stable flow rate and process stability. In this embodiment, the water tank dimensions are 200mm long, 200mm wide, and 800mm high, with a 50mm diameter pipe between the two tanks. The heat exchanger is placed below the clear water tank and connected to it via two 50mm diameter rigid pipes on either side for effective heat exchange. In this system, the primary filtration stage uses a UF ultrafiltration filter. The filter element length L = 0.2m and cross-sectional area A = 0.05m³. 2 Penetration threshold k threshokd =1.0×10 -10 m 2 Initially, the liquid level in both tanks is 400mm, and the system operating flow rate is 5L / min.

[0119] Calculated based on the flow velocity formula: The system operating flow rate is Q = 5 L / min = 8.33 × 10⁻⁶. -5 m 3 / s, cross-sectional area A=0.05m 2 .

[0120] Let the liquid level difference be Δh(t), and initially Δh(0) = 0. As time progresses, the liquid level h2(t) in the return water tank rises, while the liquid level h1(t) in the clean water tank falls. The rate of change of liquid level caused by the flow rate q is:

[0121] Where B is the cross-sectional area of ​​the clean water tank, which is 0.04 m³. 2 .

[0122] The liquid level difference is Δh(t) = h2(t) - h1(t) = 2 × 2.0825 × 10 -3 ×t=4.165×t×10 -3 m.

[0123] The pressure across the filter element is ΔP(t) = ρ2gh2(t) - ρ1gh1(t) = 1050 × 9.81 × (0.4 +

[0124] 2.0825×10 -3 ×t)-1000×9.81×(0.4-2.0825×10 -3 ×t)=9.81×

[0125] (20+4.2691×10 -3 t)Pa, where h2(t)=0.4+2.0825×t×10 -3 h1(t) = 0.4 - 2.0825 × t × 10 -3 .

[0126] Calculate filter cartridge permeability based on Darcy's law. Where μ = 0.001 Pa·s is the dynamic viscosity of the fluid, L = 0.2 m is the length of the filter element, and the pressure across the filter element ΔP(t) = 9.81 × (20 + 4.2691 × 10⁻⁶) / 2. -3 t)Pa, A=0.05m 2 It is the cross-sectional area of ​​the filter element, v = 1.66 × 10⁻⁶. -3 This represents the average flow rate of the fluid flowing in the filter element.

[0127] The permeability threshold of the filter element is k threshold =1.0×10 -10 m 2 Backwashing is required when the filter element reaches the threshold. Let k(t) = 1.0 × 10 -10 It can be concluded that Solving The system is calculated to reach the permeability threshold in approximately 12.5 hours, triggering the backwashing process.

[0128] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0129] It should be noted that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means at least two.

[0130] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0131] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0132] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0133] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0134] The storage media mentioned above can be read-only memory, disk, or optical disk, etc.

[0135] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0136] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A working fluid circulation system with backwashing function, characterized in that, include: The system consists of a wastewater tank, a backwash filter element, a cleaning water tank, a booster pump, and a water-using module connected in sequence via water channels. The outlet of the water-using module is connected to the inlet of the wastewater tank. The outlet of the wastewater tank is connected to the inlet of the backwash filter element; the inlet of the clean water tank is connected to the outlet of the backwash filter element. The backwash filter element includes: a housing, a filter screen disposed inside the housing, a first valve, and a second valve. The housing is provided with an inlet, an outlet, and a drain outlet. The filter screen, the first valve, and the second valve divide the space inside the housing into three parts. When the backwash filter element is in filtration mode, the inlet is open, the outlet is open, the drain outlet is closed, the first valve is open, and the second valve is closed. Water flows in from the inlet, passes through the first valve and the filter screen, and then exits from the outlet. When the backwash filter element is in backwash mode, the inlet is open, the outlet is closed, the drain outlet is open, the first valve is closed, and the second valve is open. Water flows in from the inlet, passes through the second valve and the filter screen, and then exits from the drain outlet. It also includes: a liquid level sensor installed inside the wastewater tank, a liquid level sensor installed inside the clean water tank, and a valve controller; The outlet of the wastewater tank is installed near the bottom of the tank and connected to the inlet of the backwash filter element; the inlet of the clean water tank is installed near the bottom of the tank and connected to the outlet of the backwash filter element. The valve controller is used to control the opening and closing states of the first valve and the second valve based on data collected by the liquid level sensor, including: The liquid level heights of the wastewater tank and the clean water tank are smoothed using a sliding window smoothing formula, as follows: in This indicates the liquid level in the clean water tank after smoothing. This indicates the level of the wastewater tank after smoothing. N It is the size of the sliding window. i Indicates the current window number. t It is the current moment. yes i The level of the cleaning water tank at the specified window time; yes i The liquid level in the sewage tank at the specified window time; The pressure difference is calculated based on the liquid level in the smoothed wastewater tank and the liquid level in the clean water tank, using the following formula: in It is a pressure difference. It is the density of the liquid in the clean water tank. ρ is the density of the liquid in the sewage tank, and g is the acceleration due to gravity. The current permeability of the filter element is calculated based on the pressure difference. The formula is as follows: in It is the dynamic viscosity of the fluid. L It is the length of the filter element. equal , A It is the cross-sectional area of ​​the filter element. v This represents the average flow rate of the fluid within the filter element; The permeability is calculated using the following formula. Perform smoothing of sliding windows: To smooth the permeability, N It is the size of the sliding window. i Indicates the current window number. yes i Penetration rate at the window of opportunity; If the permeability of the filter cartridge after the current smoothing treatment is lower than the first permeability threshold, the backwash filter cartridge is controlled to switch from filtration mode to backwash mode for a preset time.

2. The working fluid circulation system with backwashing function according to claim 1, characterized in that, Also includes: The volume of water in the cleaning water tank is calculated based on the water level and cross-sectional area of ​​the tank. The formula is as follows: V ( t ) =B* ( t ) V ( t )for t Clean the water level in the tank regularly. B It is the cross-sectional area of ​​the clean water tank. ( t )yes t Clean the water level in the tank regularly; If the current permeability of the filter element is higher than the first permeability threshold, but the water volume in the cleaning tank is less than the sum of the water volume required for the preset backwash time and the constant water volume, then the backwash filter element is controlled to switch from filtration mode to backwash mode for a preset time.

3. The working fluid circulation system with backwashing function according to claim 1, characterized in that, Also includes: Calculate the rate of change of permeability per unit time ; If the rate of change of permeability per unit time is greater than the preset rate, then the first permeability threshold is changed to the second permeability threshold, and the second permeability threshold is lower than the first permeability threshold.

4. The working fluid circulation system with backwashing function according to any one of claims 1 to 3, characterized in that, Also includes: Heat exchangers and cooling units; The water circuit of the heat exchanger is connected to the cleaning water tank through two water pipes; The heat-conducting structure inside the heat exchanger is connected to the cooling unit so that the cooling unit can process the heat transferred from the heat exchanger.

5. The working fluid circulation system with backwashing function according to any one of claims 1 to 3, characterized in that, Also includes: The sterilization module has its inlet connected to the outlet of the booster pump and its outlet connected to the cleaning water tank.

6. The working fluid circulation system with backwashing function according to any one of claims 1 to 3, characterized in that, Also includes: The second filtration module is located between the booster pump and the water supply module; The inlet of the second filter module is connected to the outlet of the booster pump, and the outlet of the second filter module is connected to the inlet of the water-using module.

7. The working fluid circulation system with backwashing function according to claim 6, characterized in that, The second filtration module is a magnetic filter or a deionized resin.

8. The working fluid circulation system with backwashing function according to claim 6, characterized in that, Also includes: A flow regulating valve is installed between the booster pump and the second filter module. The inlet of the flow regulating valve is connected to the outlet of the booster pump, and the outlet of the flow regulating valve is connected to the inlet of the second filter module.

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