A balanced gap coating valve and coating device

Abstract

This invention discloses a balanced gap coating valve and a coating device. The balanced gap coating valve includes a balancing valve, an accumulator assembly, a coating valve, a reflux valve, a first inlet, and a first outlet. The coating valve is connected to a coating die head through the first outlet. The first inlet is connected to an inlet tee. The reflux valve has a second inlet and a second outlet. The balancing valve has a third inlet and a third outlet. The other two ports of the inlet tee are connected to the second and third inlets, respectively. The coating valve and the third outlet are connected through the accumulator assembly. The second outlet serves as a reflux port and is connected to a feed tank along with the first inlet. The coating device includes the balanced gap coating valve. This invention can solve problems such as uneven coating thickness and tailing during coating, and improve the stability of the coating process.

Description

Technical Field

[0001] This invention relates to the field of lithium battery production equipment technology, and in particular to a balanced gap coating valve and coating device. Background Technology

[0002] In the manufacturing process of lithium battery electrodes and separators, the coating machine plays a crucial role. The coating valve is a key component of the coating machine. In existing intermittent coating valves, the reflux valve is located in front of the coating valve. The reflux valve stem blocks the middle of the coating valve's inlet, which increases pipeline resistance and pressure difference. Furthermore, the pressure fluctuations caused by the opening and closing of the reflux valve and the coating valve during intermittent coating can affect each other. This can easily lead to uneven coating thickness, tailing, and other defects during use, and the stability needs to be improved. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides a balanced gap coating valve and coating device. The layout adopts a branch system, which can reduce the pressure difference of the coating valve. The addition of a balance valve and accumulator assembly can stabilize the pressure and flow rate at the outlet, so that the device can solve the problems of uneven thickness and tailing of the slurry during coating, and improve the stability of the coating operation.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] A balanced gap coating valve includes a balancing valve, an accumulator assembly, a coating valve, a reflux valve, a first inlet, and a first outlet. The coating valve is connected to a coating die head through the first outlet. The first inlet is connected to an inlet tee. The reflux valve has a second inlet and a second outlet. The balancing valve has a third inlet and a third outlet. The other two ports of the inlet tee are respectively connected to the second inlet and the third inlet. The coating valve is connected to the third outlet through the accumulator assembly. The second outlet serves as a reflux port and is connected to a feed tank along with the first inlet.

[0006] Furthermore, the first feed inlet is equipped with a first pressure sensor, and the first discharge outlet is equipped with a second pressure sensor.

[0007] Furthermore, the reflux valve is connected to a third pressure sensor.

[0008] Furthermore, the balancing valve includes a valve body with an internal cavity. The third inlet is located at the bottom of the valve body, and the third outlet is located on the side of the valve body. The valve body has a top opening. The third inlet, the third outlet, and the top opening are all connected to the internal cavity of the valve body. A sleeve is sealed to the opening end. A valve stem is located inside the sleeve. A spring is located between the valve stem and the sleeve. An adjusting nut is located at the top of the sleeve. A valve sleeve is located in the internal cavity of the valve body. A valve core is located inside the valve sleeve. The valve core divides the internal cavity of the valve body into two parts. The valve core has several balancing holes that penetrate the valve core and connect the two parts of the internal cavity of the valve body divided by the valve core. One end of the valve stem is inserted into the internal cavity of the valve body and fixedly connected to the valve core.

[0009] Furthermore, a sealing ring is provided between the valve sleeve and the valve core, a star-shaped sealing ring is provided on the outer periphery of the upper end of the valve sleeve, and an O-ring is provided on the outer periphery of the lower end of the valve sleeve.

[0010] Furthermore, the valve sleeve is provided with a number of discharge holes, which can transport the material conveyed by the third inlet to the third outlet.

[0011] Furthermore, the accumulator assembly includes a constant pressure gas chamber, a lower base, and an energy storage tee fitting. The lower base is provided with a through liquid passage interface, which is threaded and sealed to the energy storage tee fitting. The gas chamber is located at the top of the lower base, and the gas chamber is provided with a gas pipe connector that communicates with the gas chamber. The gas pipe connector is used to connect the gas circuit.

[0012] Furthermore, the endotracheal connector is connected to a two-position three-way single-electro-controlled solenoid valve, and the two-position three-way single-electro-controlled solenoid valve is connected to a pressure regulating valve.

[0013] Furthermore, the air chamber is a diaphragm-type air chamber, including an upper end cover and a diaphragm. The air pipe connector is located at the top of the upper end cover. The bottom outer edge of the upper end cover is fixedly connected to the top outer edge of the lower base to form a sealed structure. The diaphragm is disposed between the upper end cover and the lower base.

[0014] Furthermore, the pre-charge pressure P of the accumulator assembly 充 Satisfy the following formula:

[0015]

[0016] Among them, P 管道 The pressure of the feed pipe is r, the inner diameter of the lower base is r, and Q is Q. 泵 ρ is the theoretical flow rate of the material pump, t is the time from when the coating valve is fully closed to when it is fully open, which depends on the blank size and coating speed, ρ is the fluid density of the slurry, and g is the acceleration due to gravity.

[0017] The present invention also provides a coating device, including the balanced gap coating valve described above, and further including a coating machine die head and a feeding barrel. The coating machine die head is connected to the first discharge port. The coating machine die head is provided with a die head return pipe. The second discharge port is connected to a return tee assembly. The other two connectors of the return tee assembly are connected to the die head return pipe and the feeding barrel.

[0018] Furthermore, the dynamic response time of the balancing valve is less than the ratio of the coating blank length to the maximum coating line speed, and the dynamic response time of the balancing valve is less than the dynamic response time of the coating valve and the return valve.

[0019] The beneficial effects of this invention are:

[0020] This invention provides a balanced gap coating valve and coating device. The slurry flow layout adopts a branch system, which can reduce the pressure difference of the coating valve. The addition of a balance valve and accumulator assembly can stabilize the pressure and flow rate at the outlet. Using this invention can avoid uneven slurry thickness, tailing and other defects during coating, and improve the stability of the coating operation. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Figure 1 This is an assembly diagram of the coating valve in this invention;

[0023] Figure 2 This is a schematic diagram of the structure of the balance valve in this invention;

[0024] Figure 3 It is along Figure 2 Sectional view of AA;

[0025] Figure 4 This is an assembly diagram of the energy storage component in this invention;

[0026] Figure 5 It is along Figure 4 Sectional view of AA;

[0027] Figure 6 This is a schematic diagram of the connection relationship of the energy storage components in this invention;

[0028] Figure 7 This is a coating device in the present invention. Detailed Implementation

[0029] The following will clearly and completely describe the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Furthermore, all connections / linkages involved in the patent do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this invention can be combined interactively without contradicting each other.

[0030] Reference Figures 1 to 6 A balanced gap coating valve includes a balance valve 21, an accumulator assembly 22, a coating valve 23, a return valve 26, a first inlet 11, and a first outlet 12.

[0031] The coating valve 23 is connected to a coating die head via the first outlet 12. The first inlet 11 is connected to one interface of the inlet tee pipe 112. A short 90° bend 111 is provided between the first inlet 11 and the inlet tee pipe 112. The reflux valve 26 has a second inlet and a second outlet. The balance valve 21 has a third inlet and a third outlet. The other two interfaces of the inlet tee pipe 112 are respectively connected to the third inlet and the second inlet. The coating valve 23 is connected to the third outlet via an accumulator assembly 22. The second outlet serves as a reflux port and is connected to the feeding tank along with the first inlet 11. The connections between the components are made using quick-release clamps and sealing gaskets.

[0032] The balance valve 21 includes a valve body 210, which has an inner cavity. The third inlet 212 is located at the bottom of the valve body 210, and the third outlet 211 is located on the side of the valve body 210. The valve body 210 has a top opening, and the third inlet 212, the third outlet 211, and the top opening are all connected to the inner cavity of the valve body.

[0033] The top open end is sealed with a sleeve 214. A valve stem 2141 is provided inside the sleeve 214. A spring 2140 is provided between the valve stem 2141 and the sleeve 214. The spring 2140 is a rectangular spring. A spring retainer ring 21401 is provided at the end of the spring 2140. The spring retainer ring 21401 is fixedly connected to the valve stem 2141 by a pin 2142, so that the valve stem 2141 can drive the spring 2140 to move together when it moves.

[0034] The valve cover 213 is provided with several vent holes. The vent holes can be sealed by inserting a plug. In actual use, the air in the valve body cavity is first balanced through the vent holes to prevent poor coating of the slurry due to the presence of air bubbles. Then, the plug is used to seal the valve.

[0035] The valve body cavity is provided with a valve sleeve 216, which has several discharge holes. These discharge holes transport the material conveyed by the third inlet 212 to the third outlet 211, ensuring a minimum flow area even at the lowest system pressure. The upper end of the valve sleeve 216 has a positioning boss, on which a star-shaped sealing ring 2162 is provided. The star-shaped sealing ring 2162 ensures the seal between the valve cover 213 and the valve sleeve 216. The lower outer circumference of the valve sleeve 216 has an O-ring 2160, which seals the valve sleeve 216 and the valve body 210.

[0036] The valve sleeve 216 houses a valve core 217, with a gap between the valve core 217 and the valve sleeve 216. A sealing ring 2161 is fitted around the outer periphery of the valve core 217 to achieve a sliding seal between the valve core 217 and the valve sleeve 216. The valve core 217 has several balance holes 2171 penetrating the valve core 217 for slurry passage. One end of the valve stem 2141 is inserted into the inner cavity and fixedly connected to the valve core 217. The valve stem 2141 and the valve core 217 are connected by a valve stem pressure sleeve 61. The valve sleeve 216 is positioned within a range of 10mm to 27mm from the bottom of the valve cover 213. The valve core 217 can float up and down during operation. If the system exceeds the designed maximum working pressure due to pressure blockage or other reasons, the valve core 217 will be in a malfunctioning state.

[0037] The top of the sleeve 214 is provided with an adjusting nut 215, which is used to adjust the initial sealing force when the valve core 217 is reset, and to facilitate operation when installing or replacing the spring 2140. The sleeve 214 and the top opening are sealed together by the valve cover 213. During installation, the valve cover 213 and the valve body 210 can be precisely positioned and connected. The valve cover 213 is provided with a sealing ring 2130 to further strengthen the sealing effect. A gap is reserved between the valve stem 2141, the valve cover 213, and the sealing ring 2130 to reduce sliding resistance while achieving sealing.

[0038] Because there is a certain pressure loss between the feed pump inlet and the feed inlet 11, a first pressure sensor 113 is installed near the first feed inlet 11, and a second pressure sensor 121 is installed near the first discharge outlet 12 to detect the pressure value. In addition, the return valve 26 is connected to a third pressure sensor 262. When the valve core 217 in the balance valve wears down, causing increased pressure leakage, the third pressure sensor 262 can detect and report the situation, allowing for timely replacement of the valve core 217.

[0039] During normal coating, the valve core 217 floats within a range of 4mm. By improving the internal sealing structure of the balance valve 21, a stable unidirectional pressure and flow rate are achieved from the third inlet 212 to the third outlet 211 when the slurry flows. The balance valve 21 is isolated from the slurry by placing a rectangular spring 2140 inside the sealed sleeve 214. Its service life is approximately 500,000 cycles, and the maximum designed system pressure is 0.8MPa. The sleeve 214 is designed for easy disassembly and replacement, and its stiffness coefficient remains relatively stable throughout its service life, exhibiting sensitive dynamic response. When the valve cavity needs cleaning during shutdown or under special circumstances, the portion above the valve cover 213 can be removed.

[0040] The main structural parameters of the balancing valve 21 include the valve core weight, the spring type inside the sleeve 214, the back pressure of the balancing chamber, the number and size of the balancing holes, and the friction between the sealing ring and the hole wall. The pressure at the third inlet 212, the spring force of the rectangular spring 2140, and the back pressure of the balancing chamber can achieve dynamic balance. The valve core weight and the friction between the sealing ring and the hole wall are inherent structural parameters, while the number and size of the balancing holes must be determined by calculating the response time of the balancing valve to ensure the rationality of the balancing hole design.

[0041] Correspondingly, the response time is related to the flow rate out of the balance orifice, the inner and outer diameters of the valve core 217, and its sensitivity. Let ΔP be the pressure change at the third inlet 212, Δh be the spring compression caused by the pressure change, S1 be the pressure-bearing area at the bottom of the valve core 217, S be the pressure-bearing area at the top of the valve core 217, and K be the spring constant. The relationship is as follows:

[0042]

[0043] Let Q V The volumetric flow rate of the balance orifice of the balance valve 21 is calculated according to the following formula:

[0044]

[0045] In the formula, C is the outflow coefficient of the balance orifice of the balance valve 21, and d s Let β be the equivalent diameter of the balancing orifice, and β be the throttling ratio of the balancing orifice. The formula for calculating β is: β = d s / D, where D is the outer diameter of valve core 217, ΔP is the pressure difference, and ρ is the fluid density of the slurry.

[0046] Let t 响 The dynamic response time of valve core 217 is the time required for valve core 217 to return to equilibrium after a pressure fluctuation caused by the opening and closing of the gap coating valve once. The dynamic response time of the balancing valve 21 is less than the ratio of the coating blank length to the maximum coating line speed, and the dynamic response time of the balancing valve 21 is less than the dynamic response time of the coating valve 23 and the return valve 26. 响 The calculation formula is as follows:

[0047]

[0048] Generally, the maximum pressure fluctuation at the third feed inlet 212 should not exceed 0.1 MPa. When the pressure fluctuation at the third feed inlet 212 is 0.1 MPa, the dynamic response time of the balance valve 21 needs to be much shorter than the theoretical coating time for the gap coating blank size. The spring constant in the sensitivity definition formula is determined based on the following balance formula:

[0049] Where h is the height of the valve body cavity at a certain moment, that is, the distance from valve core 217 to valve cover 213 at a certain moment, and F 静 The static friction force between valve core 217 and valve sleeve 216 is K. The determination of the K value requires continuous verification of the above values ​​to ensure that the height of the back pressure chamber fluctuates within the range of 10–27 mm, satisfying the requirements of a compact and reasonable structure. The corresponding maximum pressure fluctuation is 0.4 MPa. The balancing valve 21 plays a role in stabilizing the outlet pressure and flow rate in the balanced gap coating valve. Simultaneously, when the return valve 26 is closed, it isolates the return valve 26 and the coating valve 23, eliminating the pressure impact of the return valve 26's closure on the first outlet 12.

[0050] The accumulator assembly 22 includes a constant pressure gas chamber, a lower base 223, and an energy storage three-way pipe. The lower base 223 is provided with a through liquid circuit interface. The energy storage three-way pipe includes a first connection port 222 at the top, a second connection port 221 at the bottom, and a third connection port 220 at the bottom. The lower base 223 is threadedly sealed to the first connection port 222 at the top of the energy storage three-way pipe. The first connection port 222 is connected to a coating valve 23, and the second connection port 221 is connected to a balance valve 21.

[0051] The air chamber is located at the top of the lower base 223. The air chamber is a diaphragm-type air chamber, including an upper cover 214 and a diaphragm 2232. The outer edge of the top of the lower base 223 is fixedly connected to the outer edge of the upper cover 224, and the connection is formed by several fasteners 2231, which can be screws. The top of the upper cover 224 is provided with an air pipe connector 225 that connects to the air chamber. The air pipe connector 225 is used to connect to an external air circuit. The diaphragm 2232 is located between the upper cover 224 and the lower base 223.

[0052] The lower base 223 has a circular concave structure at its top center, within which a diaphragm 2232 is provided. The diaphragm 2232 is made of EPDM (ethylene propylene diene monomer) material. The upper end cap 224 has an annular protruding structure at its bottom. The outer circumference of the protruding structure matches the inner circumference of the concave structure. When the upper end cap 224 is connected to the lower base 223, the protruding structure engages with the concave structure. The outer circumference of the diaphragm 2232 is less than or equal to the inner circumference of the protruding structure, allowing the protruding structure to press the diaphragm 2232 firmly into the concave structure of the lower base 223.

[0053] The diaphragm 2232 of the accumulator assembly 22 is easy to replace. Simply open the return valve 26 to release pressure, and the balance valve 21 will cut off the slurry to the accumulator assembly 22, which makes it easy to replace the diaphragm 2232 parts, and the constant pressure gas chamber is stable.

[0054] In practical applications, the selection of the diaphragm requires calculation. Assuming the diaphragm is cylindrical and its bottom surface is uniformly compressed, it is known that the shear stress and shear strain of rubber under compression deformation satisfy the following relationship:

[0055]

[0056] In the formula, σ is the stress, and E a E is the static elastic modulus of the material. a The value depends not only on the hardness of the rubber, but also on its shape and size, deformation characteristics, and the consolidation state of the metal support surface. For compression deformation, hot vulcanization, or consolidation where the contact surface maintains a large amount of dry friction, the following conditions must be met:

[0057] E a =iG a

[0058] Among them, G a Let i be the static shear modulus, and i be a coefficient related to the shape factor S and Shore hardness HS of the rubber, satisfying the following expression:

[0059] i = 3 + KS 2

[0060] Wherein, the shape factor S refers to the ratio of the bearing surface area to the surrounding free area of ​​the rubber element under compressive load. For a cylinder, its expression for S is:

[0061]

[0062] Where W is the radial width of the support part, K ​​is the Shore hardness, and d is the diameter of the cylindrical rubber element, which is the outer diameter of the diaphragm.

[0063] In the above text, ξ represents strain, and ξ satisfies the following equation:

[0064]

[0065] Where f is the component deformation and h is the component thickness;

[0066] Given f = 4.45 mm, d = 25 mm, and HS, h, and W are design values, taking h = 2, HS = 45, and W = 8.5, then K = 6.29, S = 0.735, and i = 6.4. Therefore, E a =3.52MPa. When the strain ξ = 2.225, the stress σ = 3.66MPa can be calculated. 4045-EPDM that meets the condition is selected as the diaphragm in this invention.

[0067] The accumulator assembly 22 in this invention is a non-standard design, suitable for use on coating machines. The main parameters of the accumulator assembly 22 are pore size, diaphragm specifications, and the height of the constant pressure gas chamber. The pore size refers to the portion of the slurry acting on the diaphragm, which includes two important parameters: thickness and outer diameter. Pressure changes within the pipeline will cause changes in the static pressure at the gas-liquid equilibrium surface; the gas chamber is generally filled with inert gases such as nitrogen. Regarding the pre-charge pressure P of the accumulator assembly 22... 充 The size reference is as follows:

[0068]

[0069] In the formula, P 管道 Where is the pipe pressure, r is the inner diameter of the lower base, and Q is... 泵Here, ρ is the theoretical flow rate of the material pump, t is the time from when the coating valve 23 is fully closed to when it is fully open, which depends on the blank size and coating speed, ρ is the fluid density of the slurry, and g is the acceleration due to gravity. The fraction on the right side of the above equation represents the magnitude of the dynamic pressure caused by the action of the coating valve 23, and is a characteristic parameter of the pressure difference range of the coating valve 23. The air chamber pressure can be adjusted by the pressure regulating valve. When the equipment is running, it is a constant pressure, so that the change in pipeline dynamic pressure and the resulting static pressure of the slurry are in dynamic balance. After the slurry compresses the diaphragm, it will cause a change in static pressure. The thickness and outer diameter of the diaphragm are also closely related to the height of the static pressure change, and there is a strict selection calculation process, which will not be elaborated here. The main function of the accumulator assembly 22 in operation is to absorb the pressure change caused by the rapid closure of the coating valve 23 when the coating valve 23 is closed and the return valve 26 is open. Note that at this time, the pressure is released to the return valve 26, and the valve core 217 in the balance valve is closed.

[0070] Reference Figure 6 This is the air circuit design of the accumulator assembly 22. The air pipe interface of the accumulator assembly 22 is connected to the two-position three-way single-electro-controlled solenoid valve 25. The two-position three-way single-electro-controlled solenoid valve 25 is connected to the pressure regulating valve 24, which can ensure the stability of the air pressure in the diaphragm cavity. The corresponding parameter values ​​can be read through the pressure gauge of the pressure regulating valve 24. In special circumstances such as shutdown or maintenance, the compressed air can be controlled to flow into the atmosphere through the silencer 251.

[0071] In this embodiment, the coating valve 23 is a pneumatic straight-through diaphragm valve. This pneumatic straight-through diaphragm valve is a double-acting, linear flow valve with an electric positioner. Double-acting means that compressed air can be input into both chambers of the diaphragm cylinder, achieving bidirectional action. The valve opens and closes quickly and can be used for large strokes, but requires a stable and reliable air source. The pressure difference across the pneumatic straight-through diaphragm valve 23 is related to the flow rate, slurry density, flow resistance coefficient, and pipe diameter. Compared to a typical weir-type diaphragm valve, its flow coefficient is much smaller when the opening is greater than 60%. When the opening is 20%, the flow rate needs to be reduced due to the increased flow resistance coefficient, thus controlling the pressure difference within a reasonable range at small openings. The pneumatic straight-through diaphragm valve is stable in performance, easy to maintain, and reasonably priced.

[0072] The reflux valve 26 in this embodiment adopts a conventional reflux valve structure. Compared with conventional electric drive debugging and control, the reflux valve 26, driven by a cylinder, has more advantages. In addition, some optimizations have been made to the reflux valve. The first optimization is to change the original stainless steel valve core and seat design to stainless steel valve core and seat, reducing the wear of the valve seat after long-term use while ensuring good sealing performance. The second optimization is to maintain the original 3.5mm opening size, gradually increase the speed of the cylinder rod, reduce the time required for valve opening and closing, and increase the diameter of the valve rod, etc. The principle is the same as the old mechanism. In this balanced gap coating valve, the reflux valve does not have the function of adjusting the balanced coating pressure and reflux pressure; its main function is as a pressure relief valve, while ensuring a reliable sealing effect and preventing leakage during normal coating.

[0073] In this embodiment, the sensitivity of the balance valve 21, calculated according to actual needs, is 4.05 × 10⁻⁶. -5 The pressure per millisecond (mm / Pa) is related to the spring stiffness coefficient K, the planar area S of the valve core 217, and the slurry density ρ. It is a key parameter of the balancing valve, representing the displacement change caused by a unit pressure change per Pa. The dynamic response time is related to this and is calculated to be 0.04–0.06 ms. The action time of the coating valve 23 when fully open and fully closed is 0.02 s, so at a 20% opening, its value becomes 4 ms. After the improvement of the return valve 26, the theoretical action time can be even lower, down to 4.2 ms. The existing electric gap coating valve has an action response time of 12 ms, therefore, the coating speed will be three times the original, at 66 m / min or 150 m / min. The blanking dimensions of the two are different, and the actual production mainly uses 66 m / min.

[0074] Reference Figure 7 The present invention also provides a coating device, including the balanced gap coating valve described above, and further including a die head 4, a ball valve 2, a return pipe 3, and a return tee assembly 263. The return tee assembly 263 connects the return pipe 3 of the die head and the pipe of the return valve 26, and returns the material to the feeding unit through the discharge port 264 for reuse. In operation, the material is first fed to the first inlet 11 of the balanced gap coating valve, and after passing through the balanced gap coating valve, it is transported to the coating port of the die head 4. The base 41 of the die head is usually designed as a sliding structure. A linear guide rail is installed at the bottom of the base, and the feed is pushed by a cylinder. The feed speed and output force can be adjusted. Finally, the die head 4 evenly coats the slurry onto the substrate.

[0075] When using the coating apparatus provided by this invention for coating applications, the main steps include the following:

[0076] Intermittent coating; control the slurry to enter the die head 4 or the return pipe, and close the return pipe of the upper die head 4 to achieve intermittent coating;

[0077] The circulation pipeline; the coating valve 23 in the balanced gap coating valve is open, the return valve 26 is closed, and the return pipeline of the upper die head 4 is open. The slurry passes through the balanced gap coating valve and the die head 4, and then returns to the storage tank through the return pipeline of the upper die head 4 to prevent the slurry in the flow channel from solidifying.

[0078] Clean the die head; in the balanced gap coating valve, the coating valve 23 is closed and the return valve 26 is opened to clean the die head 4 and the return pipe.

[0079] In applications, the coating apparatus also includes a pump for pressurizing the slurry through the supply pipeline to the nozzle. The pump's speed is controlled by a motor, and the speed has a linear relationship with the pump's outlet flow rate. The flow rate is determined by the process and is related to the coating thickness, die gap, and coating speed.

[0080] The pump speed is set according to the process flow rate. At this time, the pressure at the pump inlet is slightly lower than 0.8 MPa, the pressure at the die head inlet is 0.3 MPa, and the overall pressure loss is 0.5 MPa. The setting of the gap coating valve can ensure that the outlet pressure of the coating valve is consistent with the process setting parameters.

[0081] The specific workflow is as follows: exhaust air, set reasonable process parameter values, rotate the pump motor, open the exhaust hole on the end cover of the coating valve 23 to discharge the slurry and remove the air; then close the ball valve to allow the air in the pipelines of the accumulator assembly 22 and the coating valve 23 to be discharged through the coating port of the die head 4.

[0082] During normal coating, the reflux valve 26 closes rapidly, and the pneumatic diaphragm valve 23 opens rapidly. The pressure change caused by the closure of the reflux valve 26 is approximately 0.1 MPa, resulting in pressure fluctuations in the material conveyed by the pump. These fluctuations are absorbed by the balancing valve, stabilizing the pressure at the third outlet 212 and preventing additional impact on the opening of the pneumatic diaphragm valve 23. This ensures that during intermittent coating, the thickness of the substrate at the beginning and end (8-10 mm) and the thickness in the middle section meet the production process requirements. The cylinder speed and output of the reflux valve 26 are adjustable. The valve opening of the reflux valve 26 is 3.5 mm, and the opening and closing time is less than 5 ms. A 32mm cylinder diameter is used for output. The reflux valve 26 is equipped with a rapid exhaust valve, a dual-electrically controlled 2-position 5-way solenoid valve, and a separate pressure regulating valve. When the intermittent coating slurry layer is finished, the coating valve 23 closes rapidly, and the reflux valve 26 opens rapidly. The actual valve opening will not be too large, around 20%, which can meet the action time within 5mms.

[0083] The pressure difference across coating valve 23 is related to the flow rate, slurry density, flow resistance coefficient, and pipe diameter. When the flow rate, slurry density, and pipe diameter are fixed, the flow resistance coefficient is highly dependent on the opening degree, and in extreme cases, it will not exceed 0.1 MPa. Return valve 26 is then quickly closed via a 2-position 5-way solenoid valve. During operation, the accumulator assembly on the side of the pneumatic diaphragm valve only needs to maintain its pressure regulating valve value at 0.3 MPa; generally, this assembly does not require separate control during coating.

[0084] At the start of coating, the return valve 26 is closed, and the pressure flow passes through the balance valve 21. The pressure fluctuations caused by the return valve 26 are absorbed by the balance valve 21, and the flow rate at the third outlet 212 of the balance valve is stable. At the end of the coating process, the coating valve 23 closes quickly, and the return valve 26 opens. Because the pressure difference caused by the closure of the coating valve 23 is relatively small, and the resistance loss is slightly large due to the long pipe entering the die head 4, the pressure at the die head 4 is relatively stable. Because the pressure at the first inlet 11 is released to the return valve, and the balance valve 21 is sealed by the pre-pressure of the top rectangular spring 2140, the small pressure fluctuations at this time are absorbed by the accumulator assembly 22.

[0085] In summary, the balancing valve 21 serves to isolate the coating pressure and the backflow pressure, as well as stabilize the coating pressure. Due to the accumulator assembly 22, the pressure between the coating valve 23 and the balancing valve 21 does not experience sudden changes in pressure or flow rate when the coating valve 23 opens rapidly. The balancing valve 21 must maintain a certain flow diameter during normal coating. Pressure fluctuations caused by the opening of the backflow valve 26 are sensitively fed back by a spring. The overall device employs a branched layout, significantly reducing the pressure differential at the coating valve 23.

[0086] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A balanced gap coating valve, characterized in that, The device includes a balance valve, an accumulator assembly, a coating valve, a reflux valve, a first inlet, and a first outlet. The coating valve is connected to a coating die head through the first outlet. The first inlet is connected to an inlet tee. The reflux valve has a second inlet and a second outlet. The balance valve has a third inlet and a third outlet. The other two ports of the inlet tee are connected to the second inlet and the third inlet, respectively. The coating valve is connected to the third outlet through the accumulator assembly. The second outlet serves as a reflux port and is connected to the feed tank along with the first inlet. The balancing valve includes a valve body with an internal cavity. A third inlet is located at the bottom of the valve body, and a third outlet is located on the side of the valve body. The valve body has a top opening. The third inlet, the third outlet, and the top opening are all connected to the internal cavity of the valve body. A sleeve is sealed to the opening. A valve stem is located inside the sleeve. A spring is located between the valve stem and the sleeve. An adjusting nut is located at the top of the sleeve. A valve sleeve is located in the internal cavity of the valve body. A valve core is located inside the valve sleeve. The valve core divides the internal cavity of the valve body into two parts. The valve core has several balancing holes that penetrate the valve core and connect the two parts of the internal cavity of the valve body divided by the valve core. One end of the valve stem is inserted into the internal cavity of the valve body and fixedly connected to the valve core. The accumulator assembly includes a constant pressure air chamber, a lower base, and an energy storage tee fitting. The lower base is provided with a through liquid passage interface, which is threaded and sealed to the energy storage tee fitting. The air chamber is located at the top of the lower base and is provided with an air pipe connector that communicates with the air chamber. The air pipe connector is used to connect the air passage circuit.

2. The balanced gap coating valve according to claim 1, characterized in that, The first feed inlet is equipped with a first pressure sensor, and the first discharge outlet is equipped with a second pressure sensor.

3. A balanced gap coating valve according to claim 1, characterized in that, The reflux valve is connected to a third pressure sensor.

4. A balanced gap coating valve according to claim 1, characterized in that, A sealing ring is provided between the valve sleeve and the valve core. A star-shaped sealing ring is provided on the outer periphery of the upper end of the valve sleeve, and an O-ring is provided on the outer periphery of the lower end of the valve sleeve.

5. A balanced gap coating valve according to claim 4, characterized in that, The valve sleeve is provided with a number of discharge holes, which can transport the material conveyed by the third inlet to the third outlet.

6. A balanced gap coating valve according to claim 1, characterized in that, The endotracheal connector is connected to a two-position three-way single-electro-controlled solenoid valve, and the two-position three-way single-electro-controlled solenoid valve is connected to a pressure regulating valve.

7. A balanced gap coating valve according to claim 6, characterized in that, The air chamber is a diaphragm-type air chamber, including an upper cover and a diaphragm. The air pipe connector is located at the top of the upper cover. The bottom outer edge of the upper cover is fixedly connected to the top outer edge of the lower base to form a sealed structure. The diaphragm is located between the upper cover and the lower base.

8. A balanced gap coating valve according to claim 7, characterized in that, The accumulator assembly is pre-charged with an air pressure P. 充 Satisfy the following formula: Among them, P 管道 The pressure of the feed pipe is r, the inner diameter of the lower base is r, and Q is Q. 泵 ρ is the theoretical flow rate of the material pump, t is the time from when the coating valve is fully closed to when it is fully open, which depends on the blank size and coating speed, ρ is the fluid density of the slurry, and g is the acceleration due to gravity.

9. A coating apparatus, characterized in that, The coating includes the balanced gap coating valve according to any one of claims 1 to 8, and further includes a coating machine die head and a feeding hopper. The coating machine die head is connected to the first discharge port. The coating machine die head is provided with a die head return pipe. The second discharge port is connected to a return tee assembly. The other two connectors of the return tee assembly are connected to the die head return pipe and the feeding unit.

10. A coating apparatus according to claim 9, characterized in that, The dynamic response time of the balancing valve is less than the ratio of the coating blank length to the maximum coating line speed, and the dynamic response time of the balancing valve is less than the dynamic response time of the coating valve and the return valve.

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