Viscosity measurement system and viscosity measurement method

Abstract

This invention provides a viscosity measuring system and a viscosity measuring method. The viscosity measuring system (10) includes a tank (12), a flow path (14), an external force application unit (16), and a pump (18). The viscosity measuring system (10) includes a first pressure detection unit (56) and a second pressure detection unit (58), wherein the first pressure detection unit (56) detects the pressure of the electrode ink; and the second pressure detection unit (58) detects the pressure of the electrode ink at a position downstream of the first pressure detection unit (56). A detection processing unit (72) calculates the viscosity of the electrode ink based on the pressures detected by the first pressure detection unit (56) and the second pressure detection unit (58). Accordingly, the viscosity of the total amount of circulating electrode ink can be measured.

Description

TECHNICAL FIELD

[0001] The present application relates to a viscosity measurement system for measuring viscosity of electrode ink and a viscosity measurement method. BACKGROUND

[0002] An electrode (anode electrode, cathode electrode) constituting a fuel cell is configured by laminating a catalyst layer and a gas diffusion layer. The catalyst layer is manufactured by applying electrode ink (catalyst ink) to a substrate. The viscosity of the electrode ink has an influence on the yield at the time of manufacture and the like. Therefore, for the manufacture of the electrode, it is important to identify the viscosity of the electrode ink. For example, a technique is disclosed in International Publication No. 2016 / 098446, which measures the viscoelasticity of conductive ink printed on a separator of a fuel cell by a rotational rheometer. SUMMARY

[0003] However, the viscosity of the electrode ink also changes due to an external force at the time of flow of the electrode ink at the time of manufacture. Even if a small amount of electrode ink is sampled and the viscosity is measured by a rotational rheometer, the state of the electrode ink flowing at the time of manufacture cannot be grasped. That is, in the related art, the viscosity of the total amount of the electrode ink flowing at the time of manufacture cannot be grasped.

[0004] An object of the present application is to solve the above-described technical problem.

[0005] A viscosity measurement system according to a first aspect of the present application includes a tank, a flow path, an external force application unit, a pump, a first pressure detection unit, a second pressure detection unit, and a detection processing unit. The tank stores electrode ink. The flow path is connected to the tank, and the electrode ink can flow in the flow path. The external force application unit is provided in the flow path, and applies an external force to the electrode ink. The pump is provided in the flow path, and controls the flow rate or flow volume of the electrode ink. The first pressure detection unit is provided in the flow path, and detects the pressure of the electrode ink flowing in the flow path. The second pressure detection unit is provided in the flow path at a position downstream of the first pressure detection unit, and detects the pressure of the electrode ink flowing in the flow path. The detection processing unit calculates the viscosity of the electrode ink based on the pressure detected by the first pressure detection unit and the pressure detected by the second pressure detection unit.

[0006] A second aspect of the present application is a viscosity measurement method for measuring viscosity of electrode ink, including the steps of: storing the electrode ink in a tank, circulating the electrode ink in a flow path connected to the tank by a pump provided in the flow path, applying an external force to the electrode ink by an external force applying section provided in the flow path, detecting a pressure of the electrode ink circulating in the flow path by a first pressure detecting section provided in the flow path, detecting a pressure of the electrode ink circulating in the flow path by a second pressure detecting section provided in the flow path at a position downstream of the first pressure detecting section, and calculating the viscosity of the electrode ink based on the pressures detected by the first and second pressure detecting sections.

[0007] According to the above viscosity measurement system and viscosity measurement method, it is possible to measure the viscosity of the total amount of the electrode ink circulating.

[0008] The above objects, features and advantages will be more apparent from the following description of embodiments taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a diagram schematically showing the overall structure of a viscosity measurement system according to a first embodiment of the present application.

[0010] Figure 2A is a sectional view showing a shearing force adjusting mechanism of an external force applying section. Figure 2B is a sectional view showing a temperature adjusting mechanism of an external force applying section.

[0011] Figure 3 is a side view showing the structure of a state detecting section.

[0012] Figure 4 is a diagram explaining the principle of measuring the viscosity of electrode ink based on pressure loss.

[0013] Figure 5 is a flowchart showing a viscosity measurement method performed by the viscosity measurement system of Figure 1

[0014] Figure 6 is a graph showing the change in viscosity of electrode ink with time when an external force is applied.

[0015] Figure 7 is a diagram schematically showing the overall structure of a viscosity measurement system according to a second embodiment of the present application.

[0016] Figure 8 is a diagram schematically showing the overall structure of a viscosity measurement system according to a third embodiment of the present application. ​Detailed Implementation

[0017] [First Embodiment]

[0018] like Figure 1 As shown, the viscosity measuring system 10 according to the first embodiment of the present invention is configured as an independent device, separate from the electrode manufacturing apparatus for manufacturing electrodes for fuel cells. The viscosity measuring system 10 is in an off-line state relative to the electrode manufacturing apparatus. The viscosity measuring system 10 has a closed-loop structure independent of the electrode manufacturing apparatus. This viscosity measuring system 10 measures the viscosity of the electrode ink flowing within the system by reproducing the external force generated in the electrode manufacturing apparatus, thereby simulating the state of the electrode ink when actually applied to the electrode manufacturing apparatus.

[0019] Electrode inks, for example, are catalyst inks for fuel cell electrodes. Fuel cell electrode catalyst inks typically comprise a catalyst support carrying the catalyst, a proton-conductive ionomer, and a dispersion solvent that disperses the catalyst support and the ionomer. The catalyst support can be conductive carbon (including carbon fibers) or ceramics supporting platinum (Pt) particles. The ionomer is a substance in which a portion of a hydrophobic backbone is replaced by hydrophilic ionic groups (salts of carboxylic acids, sulfonic acids, etc.), and can be a fluorinated electrolytic polymer such as a perfluorosulfonic acid polymer, or a non-fluorinated electrolytic polymer. The ionomer is an electrolytic polymer or an electrolyte solution. The dispersion solvent can be water or ethanol.

[0020] In manufacturing electrode ink, a catalyst support, ionomer, and dispersion solvent are mixed in appropriate proportions to obtain a mixture. For example, the mixture is crushed, kneaded, and stirred using a crushing mechanism such as a bead mill or agitator. Based on this, an electrode ink is prepared by dispersing the catalyst support and ionomer in the dispersion solvent. The prepared electrode ink becomes a paste. Hereinafter, the manufacturing process for preparing this electrode ink will be referred to as the kneading process.

[0021] Furthermore, in the manufacture of fuel cell electrodes, during the substrate transport process, electrode ink prepared through a mixing process is applied to the substrate to a certain thickness using a die head or similar tool. This forms the catalyst layer of the fuel cell electrode (anode or cathode). The substrate can be, for example, a polymer slurry or an electrolyte membrane. Hereinafter, the manufacturing process for forming this catalyst layer will be referred to as the coating process.

[0022] The viscosity measurement system 10 simulates the apparatus used in the manufacture of electrode ink or in the manufacture of fuel cells (when using electrode ink). Specifically, the viscosity measurement system 10 includes: a tank 12 for storing electrode ink; a flow path 14 connected to the tank 12; an external force application unit 16 for applying external force to the electrode ink; a pump 18 for controlling the flow rate or volume of the electrode ink; and a state detection unit 20 for detecting the state of the electrode ink flowing in the flow path 14. The flow path 14 allows the electrode ink to flow. The external force application unit 16 and the pump 18 are disposed in the flow path 14. The viscosity measurement system 10 also includes an information processing unit 22. The information processing unit 22 controls the operation of the external force application unit 16 and the pump 18, and processes the signals from the state detection unit 20.

[0023] The container 12 is formed as a cylinder having a storage space 12a capable of storing electrode ink. An opening is provided at the upper end of the container 12. Electrode ink is added into the storage space 12a through this opening. Electrode materials, such as electrode ink before or during the preparation process, can also be added into the container 12. The electrode materials are, for example, catalyst supports, ionomers, or dispersion solvents.

[0024] The flow path 14 forms a circulation loop that circulates the electrode ink within a closed loop including the tank 12, pump 18, external force application unit 16, and status detection unit 20. Hereinafter, the path from the tank 12 to the status detection unit 20 in the flow path 14 will also be referred to as the supply path 24. The path from the status detection unit 20 to the tank 12 in the flow path 14 will also be referred to as the return path 26. On the supply path 24, the external force application unit 16, pump 18, and status detection unit 20 are sequentially arranged downstream of the tank 12 in the flow direction of the electrode ink. The return path 26 extends from the status detection unit 20 and connects to the upper end of the tank 12. Alternatively, the flow path 14 may also have a structure that does not have a return path 26 and thus does not circulate the electrode ink.

[0025] The flow path 14 has an internal flow channel 14a in which electrode ink can flow. The flow path 14 is composed of a plurality of pipes 28 made of metal or resin. Preferably, a suitable coating is applied to the inner surface of the pipes 28 constituting the flow channel 14a to suppress the electrical effect caused by friction.

[0026] External force application unit 16 applies force to the electrode ink during the above-mentioned mixing process (see also...). Figure 7 ) or coating process (see also) Figure 8 A device that applies an external force approximately the same as the external force experienced in the mixing or coating process. Examples of external forces experienced in the mixing or coating process include shear force and heat. By appropriately adjusting the external force application unit 16 before simulation, it is possible to apply an external force to the electrode ink similar to that experienced in the mixing process, including the piping 28 and the crushing unit 102 (see reference). Figure 7The shear force and heat in the entire process, including piping 28 and coating section 202, are the same. By appropriately adjusting the external force application unit 16 before simulation, the electrode ink can be subjected to the same shear force and heat as the coating process. Figure 8 The shear force and heat are the same throughout the entire process, including the shear force and heat. However, the external force applied to the electrode ink in the external force application unit 16 is set to be the value obtained by subtracting the external force applied to the electrode ink by the flow path 14 of the viscosity measuring system 10 and the external force applied to the electrode ink by the pump 18 from the external force applied to the electrode ink in the mixing process or coating process.

[0027] Specifically, such as Figure 2A and Figure 2B As shown, the external force application section 16 has a shear force adjustment mechanism 30 (shear force application section) and a temperature adjustment mechanism 40 (temperature adjustment section) sequentially arranged downstream of the electrode ink flow direction. Furthermore, in the external force application section 16, the temperature adjustment mechanism 40 may also be positioned upstream of the shear force adjustment mechanism 30. The external force application section 16 may also have a structure that integrates the shear force adjustment mechanism 30 and the temperature adjustment mechanism 40.

[0028] The shear force adjustment mechanism 30 has a container 32 capable of temporarily storing electrode ink, a rotating body 34 disposed within the container 32, and a rotation mechanism 36 for rotating the rotating body 34.

[0029] The container 32 is formed as a cylindrical body 32a connected to a conical lower part 32b. A pipe 28a is connected to the side near the upper end of the cylindrical body 32a, connecting the tank 12 and the external force application part 16. A pipe 28b is connected to the center of the lower end of the conical lower part 32b, connecting the shear force adjustment mechanism 30 and the temperature adjustment mechanism 40. That is, the electrode ink flowing from the tank 12 flows into the upper part of the container 32 through the pipe 28a. The electrode ink flows downwards within the container 32 and exits from the lower end of the conical lower part 32b.

[0030] The rotating body 34 is formed in a disc shape or a cylindrical shape having a prescribed axial length. An axial portion 36a extending from the rotating mechanism 36 is connected to the center portion of the rotating body 34. The rotating body 34 is disposed at a position lower than the connection portion of the pipe 28a in the cylindrical main body portion 32a of the container 32 in a state of being disposed in the container 32. A prescribed gap X is formed between the outer peripheral surface of the rotating body 34 and the inner peripheral surface of the container 32. The rotating body 34 is rotated relative to the container 32 by the rotating mechanism 36, and a shearing force is applied to the electrode ink flowing downward between the outer peripheral surface of the rotating body 34 and the inner peripheral surface of the container 32. In the shearing force adjusting mechanism 30, a plurality of rotating bodies 34 having different outer diameters from each other can be attached to the axial portion 36a. By selecting the rotating body 34 according to the desired gap X and attaching it to the axial portion 36a, the gap X between the rotating body 34 and the container 32 can be adjusted.

[0031] The rotating mechanism 36 is disposed at the upper end of the container 32 (cylindrical main body portion 32a) to hold the rotating body 34 in a manner of suspending the rotating body 34. The rotating mechanism 36 has an attachment 38 attachable to the container 32, a motor not shown, and a drive force transmission portion not shown disposed between the motor and the axial portion 36a. The rotating mechanism 36 is electrically connected to the information processing apparatus 22 of the viscosity measuring system 10. The rotation speed of the motor of the rotating mechanism 36 is controlled under the electric power adjustment of the information processing apparatus 22. Accordingly, the axial portion 36a and the rotating body 34 are rotated at the rotation speed set by the information processing apparatus 22 by the rotating mechanism 36.

[0032] The temperature adjusting mechanism 40 has a container 42 capable of temporarily storing the electrode ink and a heater 44 for heating the electrode ink flowing into the container 42. Like the shearing force adjusting mechanism 30, the container 42 is formed in a cylindrical shape in which a cylindrical main body portion 42a and a conical lower portion 42b are connected. A pipe 28b is connected to the upper portion of the container 42. A pipe 28c connected to the pump 18 is connected to the lower portion of the container 42.

[0033] The heater 44 can employ various structures capable of heating under the control of the information processing apparatus 22. Specifically, the heater 44 includes a temperature-raising heater 46 disposed on the outer peripheral surface of the cylindrical main body portion 42a and a temperature-maintaining heater 48 inserted into the container 42. The temperature-raising heater 46 is used to raise the temperature of the electrode ink. The temperature-maintaining heater 48 is used to maintain the temperature of the electrode ink after temperature-raising. For example, the temperature of the temperature-raising heater 46 is set to be about 5 to 10 times higher than the temperature of the temperature-maintaining heater 48 when the external force applying portion 16 is operated.

[0034] The temperature-increasing heater 46 can be a cylindrical belt heater that covers the outer circumferential surface of the container 42 over the entire circumference. The upper end of the temperature-increasing heater 46 is disposed slightly above the upper end of the temperature-holding heater 48. The lower portion of the temperature-increasing heater 46 and the upper portion of the temperature-holding heater 48 are disposed in a vertically overlapping relationship. As the temperature-holding heater 48, for example, a sheath heater formed in a spiral shape can be used. In addition, the temperature adjustment mechanism 40 can have a cooling member (refrigerant flow path, heat sink, or the like) that cools the electrode ink in addition to the heater 44.

[0035] Returning to Figure 1 , the pump 18 has a mechanism that can control the flow rate or flow velocity of the electrode ink flowing in the flow path 14. In order to flow the electrode ink having a high viscosity, as the pump 18, for example, a single-shaft eccentric screw pump can be used. The single-shaft eccentric screw pump has, for example, a twisted rotor (not shown) that rotates by a motor (not shown) and a stator (not shown) that houses the rotor. In this case, in the pump 18, as the rotor rotates, an eccentric cavity is formed between the rotor and the stator. The pump 18 moves the electrode ink from the inlet to the outlet of the cavity while generating a suction force that suctions the electrode ink.

[0036] The state detection portion 20 is disposed at a position downstream of the external force application portion 16. The state detection portion 20 detects (measures) a parameter used to calculate the viscosity of the electrode ink to which an appropriate external force is applied by the external force application portion 16. As the parameter used to calculate the viscosity of the electrode ink, the pressure loss and the temperature of the electrode ink in flow are exemplified. Therefore, the state detection portion 20 is configured to acquire the temperature and two pressures related to the electrode ink in flow.

[0037] As shown in Figure 3 , the state detection portion 20 has a measurement pipe 50, an inlet side support 52 that supports the inlet side of the measurement pipe 50, and an outlet side support 54 that supports the outlet side of the measurement pipe 50. The state detection portion 20 further has a first pressure detection portion 56 provided to the inlet side support 52, a second pressure detection portion 58 provided to the outlet side support 54, and a temperature detection portion 60 provided to the outlet side support 54. The measurement pipe 50, the inlet side support 52, and the outlet side support 54 constitute a part of the flow path 14. A flow path 50a (flow path 14a of the flow path 14) through which the electrode ink flows is provided inside the measurement pipe 50.

[0038] The measurement-use pipe 50 is formed in a straight line and is supported by an inlet-side support 52 and an outlet-side support 54 so as to extend in the horizontal direction. One end of the measurement-use pipe 50 is fixed in the inlet-side support 52. One end of the flow path 50a communicates with a flow path 52a in the inlet-side support 52. The other end of the measurement-use pipe 50 is fixed in the outlet-side support 54. The other end of the flow path 50a communicates with a flow path 54a in the outlet-side support 54.

[0039] The measurement-use pipe 50 is formed in a cylindrical shape that is thinner than the pipe 28 that constitutes the portion of the flow passage 14 other than the state detection section 20. That is, the inner diameter of the measurement-use pipe 50 is set to be smaller than the inner diameter of the portion of the flow passage 14 other than the state detection section 20. It is preferable that the inner diameter of the measurement-use pipe 50 be set to an appropriate value in such a manner that an excessive external force is not applied to the electrode ink. In addition, a coating layer that reduces the frictional resistance of the electrode ink as much as possible and suppresses an electric effect caused by friction is applied to the inner surface of the measurement-use pipe 50 that constitutes the flow path 50a. Thereby, the measurement-use pipe 50 can cause the electrode ink that flows inside the measurement-use pipe 50 to be laminar flow.

[0040] The inlet-side support 52 is fixed to a base 62 of the state detection section 20. A pipe 28d connected to the pump 18 is connected to the lower end of the inlet-side support 52. The upper portion of the inlet-side support 52 holds the measurement-use pipe 50. A flow path 52a is formed in the inlet-side support 52 so as to extend in the vertical direction.

[0041] The inlet-side support 52 has a space 52b for pressure detection at an intermediate position of the flow path 52a (in the vicinity of the measurement-use pipe 50). A first pressure detection section 56 is provided in the space 52b. The first pressure detection section 56 is a pressure sensor that can detect the internal pressure of the space 52b of the inlet-side support 52. The first pressure detection section 56 periodically detects the pressure of the electrode ink and transmits the detected pressure (first pressure information) to the information processing device 22. In addition, the first pressure detection section 56 can be provided in one end (inlet) of the measurement-use pipe 50.

[0042] The outlet-side support 54 is fixed to the base 62 of the state detection section 20. A pipe 28e connected to the tank 12 is connected to the upper end of the outlet-side support 54. The lower portion of the outlet-side support 54 holds the measurement-use pipe 50. A flow path 54a of the electrode ink is formed in the outlet-side support 54 so as to extend in the vertical direction.

[0043] The status detection unit 20 has a pressure detection space 54b located midway along the flow path 54a (near the measuring pipe 50). A second pressure detection unit 58 is provided in the space 54b. The second pressure detection unit 58 is a pressure sensor capable of detecting the internal pressure of the space 54b of the outlet-side support 54. The second pressure detection unit 58 periodically detects the pressure of the electrode ink and sends the detected pressure (second pressure information) to the information processing device 22. Alternatively, the second pressure detection unit 58 may also be provided at the other end (outlet) of the measuring pipe 50.

[0044] The temperature detection unit 60 of the status detection unit 20 is provided at the upper end of the outlet-side support 54. The upper end of the outlet-side support 54 is a connector 55, which is connected to the piping 28e connected to the tank 12. The temperature detection unit 60 periodically detects the temperature of the electrode ink flowing in the flow path 14a and sends the detected temperature (temperature information) to the information processing device 22. Furthermore, the location of the temperature detection unit 60 is not particularly limited. For example, the temperature detection unit 60 may be provided on the measuring piping 50 or the inlet-side support 52. The temperature detection unit 60 may also be provided in the flow path 14, outside the status detection unit 20, at a position downstream of the external force application unit 16.

[0045] Preferably, the status detection unit 20 has a vent part (not shown) for discharging gas from the flow path 14a of the flow path 14 to prevent changes in internal pressure caused by chemical changes in the electrode ink. For example, the vent part may be provided at the upper end of the inlet-side support 52 or the upper end of the outlet-side support 54.

[0046] The status detection unit 20 may also include an ECU (Electronic Control Unit) (not shown) that includes a processor, memory, and input / output interfaces. The ECU may be configured to calculate pressure loss (or viscosity) based on the pressure of the first pressure detection unit 56 and the pressure of the second pressure detection unit 58, and send the calculated pressure loss (or viscosity) to the information processing device 22.

[0047] exist Figure 1 In this system, the viscosity measuring system 10 allows the electrode ink to flow within a closed flow path 14. The entire viscosity measuring system 10 is housed in a temperature-adjustable chamber (constant temperature chamber). Therefore, the viscosity measuring system 10 eliminates factors other than the external force application part 16 that could alter the temperature of the electrode ink. The viscosity measuring system 10 may also include a heat preservation mechanism (not shown) for maintaining a uniform temperature of the electrode ink within the flow path 14. As a heat preservation mechanism, a temperature controller installed around the flow path 14, or an air conditioner installed indoors, may be suitable.

[0048] The information processor 22 of the viscosity measurement system 10 has one or more processors, memories, input and output interfaces, and electronic circuits (none of which is shown). By the one or more processors executing a program not shown stored in the memories, a plurality of functional modules for controlling respective structures of the viscosity measurement system 10 are formed in the information processing device 22. Further, at least a part of each functional module can also be constituted by an integrated circuit such as an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or an electronic circuit including discrete devices. The memories can be attached to the processors or the integrated circuits, and the like.

[0049] Specifically, the information processing device 22 forms, as functional modules, a system controller 70 that controls the operation of the viscosity measurement system 10, and a detection processing section 72 that stores and processes the detection results of the state detection section 20, inside.

[0050] For example, the system controller 70 controls the operation of the pump 18 to draw the electrode ink from the tank 12 to the pump 18. The system controller 70 controls the operation of the pump 18 to send the electrode ink from the pump 18 to the state detection section 20 and the tank 12. That is, the system controller 70 circulates the electrode ink of the tank 12 at an appropriate flow rate or flow volume via the flow passage 14. The system controller 70 controls the operation of the external force application section 16 to apply an appropriate external force (shear force and heat) to the electrode ink flowing into the external force application section 16, and causes the electrode ink to which the external force is applied to flow to the downstream side.

[0051] The detection processing section 72 calculates the viscosity of the electrode ink from the two pressures and the temperature of the electrode ink. Hereinafter, the principle of calculating the viscosity from the two pressures will be described with reference to Figure 4 The principle of calculating the viscosity from the two pressures will be described.

[0052] In a case where the length of the measurement pipe 50 is set to L, the inner diameter (diameter) of the measurement pipe 50 is set to d, the flow rate of the fluid is set to u, and the viscosity of the fluid is set to μ, the pressure loss ΔP of the fluid flowing in the cylindrical measurement pipe 50 can be expressed by the following equation (1). Further, when the pump 18 is controlled by the system controller 70, the detection processing section 72 can acquire the flow rate u of the electrode ink from the system controller 70. The flow rate u of the electrode ink is expressed by (flow volume of the electrode ink) / (cross-sectional area of the measurement pipe 50). Therefore, the detection processing section 72 can also acquire the flow volume of the electrode ink.

[0053] ΔP = (32 x L x u x μ) / d 2 (1)

[0054] The pressure loss ΔP of the electrode ink circulating in the flow passage 14 of the viscosity measurement system 10 can be calculated using the actual pressure detected by the state detection section 20. That is, the pressure loss ΔP of the electrode ink is calculated by subtracting the second pressure value p2 (second pressure information) on the outlet side from the first pressure value pi (first pressure information) on the inlet side, as shown in the following equation (2).

[0055] ΔP = pi - p2... (2)

[0056] Therefore, based on the above equations (1) and (2), the viscosity μ of the electrode ink circulating in the flow passage 14 can be represented by the following equation (3). The length L of the measurement pipe 50 and the inner diameter d of the measurement pipe 50 in equation (3) are predetermined. The flow rate u of the electrode ink is maintained constant by the pump 18. Therefore, when the inner diameter d is replaced with a proportional coefficient K, equation (4) is obtained. 2 / 32 x L x u.

[0057] μ = ((pi - p2) x d 2 ) / (32 x L x u)... (3)

[0058] μ = K x (pi - p2)... (4)

[0059] That is, the viscosity μ of the electrode ink is proportional to the pressure loss ΔP. The greater the pressure loss ΔP, the greater the viscosity μ. Therefore, the viscosity measurement system 10 can use the pressure loss ΔP calculated from the first pressure information and the second pressure information as a substitute value for the viscosity μ as a parameter for identifying the state of the electrode ink.

[0060] The viscosity μ of the electrode ink can be calculated from the temperature of the electrode ink detected by the temperature detection section 60 of the state detection section 20 using the following equation (5) as the Reynolds equation.

[0061] μ = μ0exp(-bT)... (5)

[0062] (μ0: viscosity at a reference temperature, b: coefficient, T: absolute temperature)

[0063] The state detection section 20 periodically calculates the viscosity μ of the electrode ink (hereinafter referred to as pressure-dependent viscosity) using the first pressure information, the second pressure information, and the above equation (4), and stores the calculated pressure-dependent viscosity in the memory. At the same time as the pressure-dependent viscosity is calculated, the state detection section 20 periodically calculates the viscosity μ of the electrode ink (hereinafter referred to as temperature-dependent viscosity) using the temperature information and the above equation (5), and stores the calculated temperature-dependent viscosity in the memory.

[0064] Accordingly, the viscosity measurement system 10 can analyze changes in electrode ink using both pressure-dependent viscosity and temperature-dependent viscosity. For example, the user uses the viscosity measurement system 10 to measure the viscosity μ of the electrode ink before the start of the mixing process, the electrode ink at each specified time during the mixing process, and the electrode ink after the end of the mixing process, taking into account the extraction pressure and temperature. Based on this, the user can identify changes in the viscosity μ of the electrode ink during the mixing process. Similarly, the user uses the viscosity measurement system 10 to measure the viscosity μ of the electrode ink at each specified time during the coating process, taking into account the extraction pressure and temperature. Based on this, the user can identify changes in the viscosity μ of the electrode ink during the coating process.

[0065] The operation of the viscosity measuring system 10 of this embodiment will be described below.

[0066] Viscosity measuring system 10 according to Figure 5 The viscosity measurement method shown determines the viscosity μ of the electrode ink. Specifically, the user stores (adds) the electrode ink to be measured into the tank 12 of the viscosity measurement system 10 (step S1). After this, the user starts the viscosity measurement system 10 and inputs the amount of electrode ink added and the simulated external force of the process into the information processing device 22 (step S2). The system control unit 70 calculates the circulation time of the electrode ink based on the input amount of electrode ink (step S3). The circulation time of the electrode ink includes the time for the external force to be applied by the external force application unit 16.

[0067] After the above preparations are completed, the information processing device 22 (system control unit 70) activates the pump 18 (step S4). Accordingly, the electrode ink stored in the tank 12 circulates through the supply path 24 in the external force application unit 16, the pump 18, and the status detection unit 20, and returns to the tank 12 via the return path 26. Through the flow of the electrode ink, gases such as air are discharged from the flow path 14a of the flow path 14, and then the flow path 14a (flow path 50a of the measuring pipe 50) in the status detection unit 20 is filled with electrode ink (step S5).

[0068] The system control unit 70 activates the external force application unit 16 to apply a set external force to the electrode ink flowing in the flow path 14 (step S6). The state detection unit 20 periodically detects the state (first pressure, second pressure, and temperature) of the electrode ink to which the external force has been applied and sends the detection results to the information processing device 22 (step S7). Accordingly, the information processing device 22 stores the received first pressure information, second pressure information, and temperature information in a time-dependent manner in its memory.

[0069] The information processing device 22 determines whether the calculated cycle time has elapsed (step S8). If the cycle time has not elapsed (step S8: No), it returns to step S7 to continue detecting the state of the electrode ink. On the other hand, if the cycle time has elapsed (step S8: Yes), the system control unit 70 stops the operation of the external force application unit 16 and the pump 18 (step S9). After this, the user discharges the electrode ink from the tank 12 and the flow path 14, and cleans each structure of the viscosity measurement system 10.

[0070] The detection processing unit 72 of the viscosity measurement system 10 reads the first pressure information and the second pressure information stored in the memory for each time period, calculates the pressure-dependent viscosity for each time period, and stores the calculated pressure-dependent viscosity in the memory (step S10). Furthermore, the detection processing unit 72 reads the temperature information stored in the memory for each time period, calculates the temperature-dependent viscosity for each time period, and stores the calculated temperature-dependent viscosity in the memory (step S11). Accordingly, the viscosity measurement system 10 can analyze the viscosity change of the electrode ink when a specified external force (simulating the external force of the mixing process and the coating process) is applied, and provide the analysis results to the user.

[0071] For example, according to Figure 6 The graph shown allows users to capture the gradual decrease in the viscosity μ (or pressure loss ΔP) of the electrode ink over time. Additionally, according to... Figure 6 The graph shown allows the user to observe the sharp decrease in viscosity μ at time t, suggesting ink jab. Thus, under the application of external force, the user can monitor the unexpected or expected changes in the viscosity μ of the electrode ink during the process simulated by the viscosity measurement system 10. For example, if the viscosity μ of the electrode ink changes beyond a predetermined value over time, the user can recognize the need to adjust the external force (piping structure, etc.) in that process.

[0072] This invention is not limited to the embodiments described above, and various modifications can be made according to the spirit of the invention. For example, the viscosity measuring system 10 can also change the external force applied to the electrode ink in the external force application unit 16 during the measurement process performed by the state detection unit 20. Accordingly, it is possible to analyze the state changes of the electrode ink when the external force changes due to various reasons such as abnormalities in the actual manufacturing process. Similarly, the viscosity measuring system 10 can also change the flow rate u of the electrode ink by changing the rotation speed of the pump 18. In this case, by sending the changed flow rate u and time to the detection processing unit 72, the detection processing unit 72 can ensure the accuracy of the calculated pressure-related viscosity of the electrode ink.

[0073] exist Figure 1In the viscosity measurement system 10 shown, an external force application unit 16, a pump 18, and a state detection unit 20 are arranged sequentially from the upstream side to the downstream side of the electrode ink flow direction. However, the arrangement of the external force application unit 16, the pump 18, and the state detection unit 20 is not limited to the above. For example, the pump 18, the external force application unit 16, and the state detection unit 20 may also be arranged sequentially from the upstream side to the downstream side of the electrode ink flow direction.

[0074] The viscosity measurement system 10 may also have a sensor for detecting the flow rate u or flow rate of the electrode ink at or near the state detection unit 20 (e.g., between the pump 18 and the state detection unit 20). Accordingly, the detection processing unit 72 can use the real-time flow rate u or flow rate detected by the sensor to obtain the viscosity μ of the electrode ink with higher accuracy.

[0075] [Second Implementation]

[0076] like Figure 7 As shown, the viscosity measuring system 10A according to the second embodiment differs from the viscosity measuring system 10 according to the first embodiment in that it measures the viscosity μ of the electrode ink in the actual mixing process. Furthermore, in the following description, structural elements having the same structure or function as those in the above embodiments will be labeled with the same reference numerals, and detailed descriptions thereof will be omitted.

[0077] Specifically, the manufacturing system 100 (viscosity measuring system 10A) for the mixing process includes a tank 12, a flow path 14, a pump 18, a crushing unit 102, a state detection unit 20, and an information processing device 22. The tank 12 stores electrode ink or electrode material for the electrode ink. The electrode material is a mixture of a catalyst carrier, an ionomer, and a dispersing solvent. The flow path 14 forms a circulation loop that circulates the electrode ink around the tank 12. The pump 18 is installed on the flow path 14 and configured to control the flow rate u or flow rate of the electrode ink.

[0078] The crushing section 102 is positioned downstream of the pump 18 in the flow path 14 to crush, mix, and agitate the electrode material of the electrode ink. The crushing section 102 is one type of external force application unit in this invention. The crushing section 102 in this embodiment includes: a crushing chamber 104 into which the electrode material flows; and an agitator (not shown) disposed within the crushing chamber 104. The crushing section 102 is a bead mill that crushes the electrode material by rotating the agitator. The rotational speed of the agitator in the crushing section 102 (bead mill) is controlled by an information processing device 22. The mixing time or number of mixing cycles for the electrode material is adjusted by the information processing device 22. The viscosity μ of the electrode ink changes depending on the crushing, mixing, and agitation of the electrode material in the crushing section 102. The viscosity μ of the electrode ink may decrease or increase. Furthermore, the structure of the crushing section 102 is not particularly limited.

[0079] A state detection unit 20 is disposed in the flow path 14 between the pump 18 and the crushing section 102. Because the state detection unit 20 is located upstream of the crushing section 102, it can continuously measure the viscosity μ of the total amount of electrode ink flowing into the crushing section 102 from the flow path 14. The state detection unit 20 can be configured similarly to the state detection unit 20 described in the first embodiment. That is, the state detection unit 20 includes: a measuring pipe 50; a first pressure detection unit 56 disposed at the inlet side of the measuring pipe 50; a second pressure detection unit 58 disposed at the outlet side of the measuring pipe 50; and a temperature detection unit 60 disposed at the outlet side of the measuring pipe 50. The first pressure detection unit 56 and the second pressure detection unit 58 detect the pressure of the electrode ink flowing in the flow path 14 and send the detection results to the information processing device 22. The temperature detection unit 60 detects the temperature of the electrode ink flowing in the flow path 14 and sends the detection results to the information processing device 22.

[0080] The information processing device 22 has one or more processors, a memory, an input / output interface, and electronic circuitry. By executing a program (not shown) stored in the memory by one or more processors, a crushing control unit 106 and a detection processing unit 72 are formed within the information processing device 22.

[0081] The crushing control unit 106 controls the operation of the pump 18 and the crushing unit 102 according to user settings, etc. That is, the pump 18 controlled by the crushing control unit 106 causes the electrode ink to flow at an appropriate flow rate u or flow rate. In addition, the crushing unit 102 controlled by the crushing control unit 106 causes the agitator to rotate at an appropriate rotation speed to crush, mix, and stir the electrode ink.

[0082] Preferably, the crushing control unit 106 automatically controls (feedback control) the mixing time or number of mixing cycles of the crushing unit 102 based on the viscosity μ of the electrode ink calculated by the detection and processing unit 72. For example, if the calculated viscosity μ of the electrode ink is greater than the upper limit value, the crushing control unit 106 controls the mixing time or the number of mixing cycles to be reduced. Conversely, if the calculated viscosity μ of the electrode ink is less than the lower limit value, the crushing control unit 106 controls the mixing time or the number of mixing cycles to be increased.

[0083] The detection processing unit 72 calculates the viscosity μ of the total amount of electrode ink (electrode material) flowing to the crushing unit 102 during the mixing process based on the detection results (first pressure information, second pressure information, and temperature information) received from the status detection unit 20, and stores the calculated viscosity μ in a memory. The detection processing unit 72 can also predict the yield rate (product yield) of the electrode ink prepared during the mixing process based on the viscosity μ of the electrode ink accumulated in the memory. For example, the detection processing unit 72 has mapping information about the prepared electrode ink, which is information that establishes a correlation between mixing time or number of mixing cycles, viscosity μ, and the yield rate obtained from simulation or past results. Accordingly, for example, under open-loop control, when the predicted yield rate reaches the desired yield rate, the information processing device 22 (crushing control unit 106) can determine the end of the mixing process.

[0084] [Third Implementation]

[0085] like Figure 8 As shown, the viscosity measuring system 10B according to the third embodiment differs from the viscosity measuring systems 10 and 10A according to the first and second embodiments in that it measures the viscosity μ of the electrode ink in the actual coating process.

[0086] Specifically, the manufacturing system 200 (viscosity measuring system 10B) for the coating process includes a tank 12, a flow path 14, a pump 18, a coating section 202, a condition detection section 20, and an information processing device 22. The tank 12 stores the electrode ink prepared through the mixing process. The flow path 14 forms a non-circulating loop that allows the electrode ink to flow from the tank 12 to the coating section 202. The pump 18 is installed on the flow path 14 and is capable of controlling the flow rate u or flow volume of the electrode ink.

[0087] The coating section 202 is one embodiment of the external force application section in this invention. The coating section 202 is positioned downstream of the pump 18 on the flow path 14 and coats the substrate 204 with electrode ink. The coating section 202 includes a die 206 for coating electrode ink and a conveying structure 208, wherein the conveying structure 208 delivers the substrate 204 wound into a roll. The coating section 202 is a coating machine that ejects electrode ink from the die 206 during the delivery of the substrate 204 by the conveying structure 208. In the coating section 202, the ejection pressure and ejection volume of the electrode ink from the die 206 are controlled by the information processing device 22, and the delivery speed of the substrate 204 is also controlled. Furthermore, the structure of the coating section 202 is not particularly limited.

[0088] A state detection unit 20 is disposed in the flow path 14 between the pump 18 and the coating section 202. Because the state detection unit 20 is located upstream of the coating section 202, it can continuously measure the viscosity μ of the total amount of electrode ink flowing into the coating section 202 from the flow path 14. The first pressure detection unit 56 and the second pressure detection unit 58 of the state detection unit 20 detect the pressure of the electrode ink flowing in the measuring pipe 50 and send the detection results to the information processing device 22. A temperature detection unit 60 detects the temperature of the electrode ink flowing in the measuring pipe 50 and sends the detection results to the information processing device 22.

[0089] The information processing device 22 has one or more processors, a memory, an input / output interface, and electronic circuitry. A coating control unit 210 and a detection processing unit 72 are formed within the information processing device 22 by executing a program (not shown) stored in the memory by one or more processors.

[0090] The coating control unit 210 controls the operation of the pump 18 and the coating unit 202 according to user settings. Accordingly, electrode ink is continuously coated onto the substrate 204 at an appropriate thickness. Furthermore, it is preferable that the coating control unit 210 automatically controls (feedback control) the coating speed (electrode ink ejection rate, substrate 204 delivery rate) of the coating unit 202 based on the electrode ink viscosity μ calculated by the detection processing unit 72. For example, if the electrode ink viscosity μ is greater than an upper limit value, the coating control unit 210 decreases the coating speed; if the electrode ink viscosity μ is less than a lower limit value, the coating control unit 210 increases the coating speed.

[0091] The coating control unit 210 can estimate the amount of electrode ink based on the pressure information (at least one of the first pressure information and the second pressure information) measured by the state detection unit 20, and urge the replenishment of electrode ink and adjust the coating of the coating unit 202. Accordingly, the yield of electrode ink coated on the substrate 204 is further improved.

[0092] The detection processing unit 72 calculates the viscosity μ of the total amount of electrode ink (electrode material) flowing to the crushing unit 102 during the mixing process based on the detection results (first pressure information, second pressure information, and temperature information) received from the state detection unit 20. The detection processing unit 72 stores the calculated viscosity μ in a memory. During the coating process, the detection processing unit 72 can also predict the yield (quality rate) of the electrode ink coated on the substrate 204 based on the viscosity μ of the electrode ink accumulated in the memory. Accordingly, under open-loop control, when the viscosity μ of the electrode ink falls within a predetermined range, the information processing device 22 can determine that the desired yield rate has been maintained. On the other hand, when the viscosity μ of the electrode ink is outside the predetermined range, the information processing device 22 can determine that the desired quality rate has been lost.

[0093] The following describes the technical ideas and effects that can be grasped from the above implementation methods.

[0094] The first aspect of the present invention is a viscosity measuring system (10, 10A, 10B) comprising a tank (12), a flow path (14), an external force application unit (16), a pump (18), a first pressure detection unit (56), a second pressure detection unit (58), and a detection processing unit (72), wherein the tank (12) is used to store electrode ink; the flow path (14) is connected to the tank, and the electrode ink can flow in the flow path (14); the external force application unit (16) is disposed on the flow path to apply an external force to the electrode ink; and the pump (18) is disposed on the flow path. The flow path is provided, and the flow rate or flow rate of the electrode ink can be controlled; the first pressure detection unit (56) is provided in the flow path to detect the pressure of the electrode ink flowing in the flow path; the second pressure detection unit (58) is provided in the flow path at a downstream side of the first pressure detection unit to detect the pressure of the electrode ink flowing in the flow path; the detection processing unit (72) calculates the viscosity of the electrode ink based on the pressure detected by the first pressure detection unit and the pressure detected by the second pressure detection unit.

[0095] Based on the above structure, the viscosity measurement system can continuously detect the pressure of the electrode ink subjected to external force by the external force application unit through a first pressure detection unit and a second pressure detection unit located at different positions in the flow path. The viscosity measurement system can stably measure the viscosity μ of the total amount of electrode ink based on the two detected pressures. That is, the viscosity measurement system can identify the change in the viscosity μ of the electrode ink caused by the application of an appropriate external force without removing a portion of the electrode ink sample or stopping the flow of the electrode ink.

[0096] The first pressure detection unit is disposed downstream of the external force application unit in the flow path. The external force application unit includes a shear force application unit and a temperature adjustment unit. The shear force application unit applies shear force to the electrode ink, and the temperature adjustment unit heats or cools the electrode ink. Accordingly, the viscosity measurement system can accurately measure the viscosity μ of the electrode ink after the shear force and temperature have been adjusted by the external force application unit 16.

[0097] The flow path includes a cylindrical measuring pipe (50) between the first pressure sensing unit and the second pressure sensing unit. This measuring pipe is thinner than the portion of the flow path other than the measuring pipe itself. The first pressure sensing unit detects the pressure of the electrode ink at or near the inlet of the measuring pipe, and the second pressure sensing unit detects the pressure of the electrode ink at or near the outlet of the measuring pipe. Accordingly, the viscosity measurement system can detect the pressure loss ΔP generated by the electrode ink in the measuring pipe with higher accuracy, thereby improving the accuracy of measuring the viscosity μ of the electrode ink.

[0098] The viscosity measurement system includes a temperature detection unit that detects the temperature of the electrode ink flowing in the flow path downstream of the external force application unit. The detection processing unit calculates the viscosity of the electrode ink based on the temperature detected by the temperature detection unit. Therefore, the viscosity measurement system can also determine the viscosity μ of the electrode ink based on the temperature detected by the temperature detection unit, thereby making it easier to identify the characteristics of the electrode ink.

[0099] The external force application section is a crushing section (102) that breaks down the electrode material of the electrode ink, and the first pressure detection section (56) is located in the flow path between the pump and the crushing section. Accordingly, the viscosity measuring system can measure the viscosity μ of the total amount of electrode ink in a manufacturing process having the crushing section.

[0100] Furthermore, the viscosity measuring system includes a crushing control unit that controls the mixing time or number of mixing cycles in the crushing section based on the viscosity of the electrode ink calculated by the detection and processing unit. Accordingly, the viscosity measuring system can significantly improve the yield of electrode ink during crushing, mixing, and other processes required for preparing electrode ink.

[0101] The external force application unit is a coating unit (202) that applies the electrode ink to a substrate, and the first pressure detection unit is disposed in the flow path between the pump and the coating unit. Accordingly, the viscosity measuring system can measure the viscosity μ of the total amount of electrode ink during the manufacturing process having the coating unit.

[0102] The viscosity measurement system includes a coating control unit that controls the operation of the coating unit based on the viscosity of the electrode ink calculated by the detection processing unit, the pressure detected by the first pressure detection unit, or the pressure detected by the second pressure detection unit. Accordingly, the viscosity measurement system can significantly improve the yield of electrode ink during coating.

[0103] Furthermore, a second aspect of the present invention is a viscosity measurement method for measuring the viscosity of electrode ink, comprising the following steps: storing the electrode ink in a tank (12); circulating the electrode ink in a flow path (14) connected to the tank using a pump (18); applying an external force to the electrode ink using an external force application unit (16) provided in the flow path; detecting the pressure of the electrode ink circulating in the flow path using a first pressure detection unit (56) provided in the flow path; detecting the pressure of the electrode ink circulating in the flow path using a second pressure detection unit (58) provided in the flow path at a position downstream of the first pressure detection unit; and calculating the viscosity of the electrode ink based on the pressure detected by the first pressure detection unit and the pressure detected by the second pressure detection unit. Accordingly, the viscosity measurement method can accurately measure the viscosity μ of electrode ink to which an external force has been applied by the external force application unit.

[0104] The first pressure detection unit is located in the flow path at a position downstream of the external force application unit.

[0105] The external force application section is a crushing section (102) that crushes the electrode material of the electrode ink, and the first pressure detection section is located in the flow path between the pump and the crushing section. Accordingly, the viscosity measurement method can effectively measure the viscosity μ of the electrode ink after it has been crushed, mixed, etc. by the crushing section.

[0106] The external force application unit is a coating unit (202) that applies the electrode ink to the substrate (204), and the first pressure detection unit is disposed in the flow path between the pump and the coating unit. Accordingly, the viscosity measurement method can accurately measure the viscosity μ of the electrode ink applied by the coating unit.

Claims

1. A viscosity measurement system (10, 10A, 10B) characterized by comprising: a tank (12), a flow path (14), an external force application section (16), a pump (18), a first pressure detection section (56), a second pressure detection section (58), and a detection processing section (72), wherein the tank (12) is for storing an electrode ink; the flow path (14) is connected to the tank, and the electrode ink is able to flow in the flow path (14); the external force application section (16) is provided to the flow path, and is for applying an external force to the electrode ink; the pump (18) is provided to the flow path, and is able to control a flow rate or flow volume of the electrode ink; the first pressure detection section (56) is provided to the flow path, and is for detecting a pressure of the electrode ink flowing in the flow path; the second pressure detection section (58) is provided to a portion of the flow path that is on a downstream side from the first pressure detection section, and is for detecting a pressure of the electrode ink flowing in the flow path; the detection processing section (72) is for calculating a viscosity of the electrode ink based on the pressure detected by the first pressure detection section and the pressure detected by the second pressure detection section, the flow path has a measurement pipe (50) between the first pressure detection section and the second pressure detection section, the measurement pipe is formed in a cylindrical shape that is thinner than other portions of the flow path, and the measurement pipe passes through a total amount of the electrode ink that flows from the pump, the first pressure detection section detects the pressure of the electrode ink at an inlet of the measurement pipe, and the second pressure detection section detects the pressure of the electrode ink at an outlet of the measurement pipe.

2. The viscosity measurement system according to claim 1, characterized in that the first pressure detection section is provided to a portion of the flow path that is on a downstream side from the external force application section, the external force application section has a shear force application section and a temperature adjustment section, wherein the shear force application section applies a shear force to the electrode ink, and the temperature adjustment section heats or cools the electrode ink.

3. The viscosity measurement system according to claim 1 or 2, characterized by comprising a temperature detection section that detects a temperature of the electrode ink flowing in a portion of the flow path that is on a downstream side from the external force application section, and the detection processing section calculates the viscosity of the electrode ink based on the temperature detected by the temperature detection section.

4. The viscosity measurement system according to claim 1, characterized in that the external force application section is a crushing section (102) that crushes an electrode material of the electrode ink, and the first pressure detection section (56) is provided to a portion of the flow path that is between the pump and the crushing section.

5. The viscosity measurement system according to claim 4, characterized by comprising a crushing control section that controls a mixing time or a mixing number of times of the crushing section based on the viscosity of the electrode ink calculated by the detection processing section. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6. The viscosity measurement system according to claim 1, wherein the external force applying section is an application section (202) that applies the electrode ink to a substrate, the first pressure detecting section is provided in a portion of the flow path between the pump and the application section.

7. The viscosity measurement system according to claim 6, wherein a control section that controls the operation of the application section based on the viscosity of the electrode ink calculated by the detection processing section, the pressure detected by the first pressure detecting section, or the pressure detected by the second pressure detecting section.

8. A viscosity measurement method for measuring the viscosity of electrode ink, comprising: storing the electrode ink in a tank (12), circulating the electrode ink in a flow path (14) by a pump (18) provided in the flow path, applying an external force to the electrode ink by an external force applying section (16) provided in the flow path, detecting the pressure of the electrode ink circulating in the flow path by a first pressure detecting section (56) provided in the flow path, detecting the pressure of the electrode ink circulating in the flow path by a second pressure detecting section (58) provided in a portion of the flow path downstream of the first pressure detecting section, calculating the viscosity of the electrode ink based on the pressure detected by the first pressure detecting section and the pressure detected by the second pressure detecting section, the flow path has a measurement pipe (50) between the first pressure detecting section and the second pressure detecting section, the measurement pipe being formed in a cylindrical shape that is thinner than other portions of the flow path and passing the total amount of the electrode ink flowing from the pump, the first pressure detecting section detects the pressure of the electrode ink at or near the inlet of the measurement pipe, the second pressure detecting section detects the pressure of the electrode ink at or near the outlet of the measurement pipe.

9. The viscosity measurement method according to claim 8, wherein the first pressure detecting section is provided in a portion of the flow path downstream of the external force applying section.

10. The viscosity measurement method according to claim 8, wherein the external force applying section is a crushing section (102) that crushes the electrode material of the electrode ink, the first pressure detecting section is provided in a portion of the flow path between the pump and the crushing section.

11. The viscosity measurement method according to claim 8, wherein the external force applying section is an application section (202) that applies the electrode ink to a substrate (204), the first pressure detecting section is provided in a portion of the flow path between the pump and the application section. ​

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