Experimental device and method for testing pre-tightening pressure distribution of fuel cell stack

Abstract

The invention relates to an experimental device and method for a fuel cell stack pre-tightening pressure distribution test. The experimental device comprises an experimental table base, a fuel cell lower support, a guide rod, a fuel cell guide rod, an array type flexible pressure sensor module, a secondary pressing module, a primary pressing module, an upper supporting plate, a stepping motor, a fuel cell stack and a piston control loop. The first-stage pressing module is driven by a stepping motor to press the second-stage pressing module. And the secondary pressing module presses the fuel cell stack through the floating piston while pressing the fuel cell stack through the secondary pressing module support. And meanwhile, an array type film pressure sensor is adopted to obtain the contact pressure between fuel cell stack components in real time. Compared with the prior art, the method has the advantages that the complicated experiment process in the design process of a traditional fuel cell assembly scheme is avoided, the experiment process is greatly simplified, experiments on fuel cell stacks of different specifications are realized, and the method is simple and effective to operate and the like.

Description

Technical Field

[0001] The invention relates to the field of fuel cell detection, and in particular to an experimental device and method for testing the preload pressure distribution of a fuel cell stack. Background Art

[0002] A fuel cell is an energy conversion device that converts the chemical energy in fuel directly into electrical energy. It has the characteristics of high energy conversion efficiency, green and pollution-free, and low operating noise. Against the backdrop of increasingly serious problems such as environmental pollution and energy depletion, it is considered to be one of the ideal energy sources in the future.

[0003] In order to meet the demand for output power in heavy-load application scenarios such as heavy trucks and locomotives, increasing the effective area of ​​a single cell or increasing the number of cells to increase the single stack power of a fuel cell stack is one of the future development directions. However, the large-scale fuel cell stack will increase the difficulty of its assembly, cause uneven pressure distribution in the surface, aggravate the difference in the distribution of internal electron and gas transmission states, and lead to a decrease in fuel cell output performance. This phenomenon of uneven pressure distribution is closely related to the pre-stressing and tensioning process during assembly. The occurrence of this problem can be effectively alleviated by optimizing the clamping structure of the fuel cell stack and adjusting the pre-tightening force distribution. Therefore, it is crucial for the structural design and assembly process design of the fuel cell stack to realize the controllable simulation of the pre-stressing and tensioning process in the assembly of the fuel cell stack and obtain the in-plane pressure distribution state.

[0004] Research on fuel cell stack assembly can be divided into two categories: one is to obtain the stress distribution within the stack surface through static simulation using numerical methods, and the other is to measure the pressure distribution within the stack surface after assembly through pressure-sensitive paper and other means. The former is limited by computing power, and there are problems such as long calculation time, low calculation accuracy and complex adjustment for the simulation of the assembly process of large-scale stacks, which is somewhat different from the actual situation. The latter currently lacks a simulation test plan for the entire process, and it is rather cumbersome to test different tightening schemes; and if the pressure-sensitive paper test plan is used, it is impossible to achieve online quantitative measurement of pressure, and it is difficult to form a quantitative regulation of the stack pre-tightening strategy. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide an experimental device and method for fuel cell stack preload pressure distribution testing which can obtain real-time pressure distribution parameters, realize batch testing of in-plane distribution of the stack, and is easy to operate and flexible to use.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] According to one aspect of the present invention, there is provided an experimental device for testing the preload pressure distribution of a fuel cell stack, comprising a fuel cell stack, a primary clamping module, a secondary clamping module and an array-type flexible pressure sensor module; the primary clamping module comprises a driving platen, the secondary clamping module comprises a secondary clamping module support and a floating piston, the driving platen is fixedly connected to the secondary clamping module support, a plurality of circular holes are provided on the lower surface of the secondary clamping module support and an oil chamber is formed with the floating piston, a plurality of floating pistons are provided and are pressed on top of the fuel cell stack; the array-type flexible pressure sensor module is located in the fuel cell stack.

[0008] Furthermore, the fuel cell stack includes a fuel cell upper end plate, an upper current collecting plate, a bipolar plate, a lower current collecting plate and a fuel cell lower end plate arranged in sequence from top to bottom; the lower surface of the secondary clamping module support is connected to the outer surface of the fuel cell upper end plate, and the outer surface of the fuel cell upper end plate corresponds to the position of the floating piston and has a mounting platform for installing a nut or a metal belt, and the end of the floating piston connected to the nut or the metal belt is provided with a metal platform.

[0009] Furthermore, the experimental device also includes a test bench base and a fuel cell lower support. The test bench base is provided with an installation site, and the fuel cell lower support is installed on the test bench base through the installation site; the outer surface of the lower end plate of the fuel cell corresponds to the position of the floating piston and has an installation platform for installing nuts or metal belts, and the position of the fuel cell lower support corresponding to the installation platform is provided with a support platform.

[0010] Furthermore, the experimental device also includes guide rods and fuel cell guide rods. The guide rods connect the experimental bench base and the upper support plate. The fuel cell guide rods are located on the outside of the lower support of the fuel cell to constrain the lateral movement of various components of the fuel cell stack. The number of guide rods and fuel cell guide rods are both multiple.

[0011] Furthermore, a plurality of through holes are provided at the edge of the driving pressure plate, the number of the through holes being consistent with the number of the guide rods, and metal polymer sliding bearings are installed in the through holes, and the metal polymer sliding bearings are matched with the guide rods.

[0012] Furthermore, the experimental device also includes an upper support plate and a stepper motor, which is installed on the upper support plate and drives the first-level clamping module to move longitudinally; the first-level clamping module also includes a driving column, one end of which is connected to the stepper motor and the other end is fixedly connected to the driving pressure plate.

[0013] Furthermore, the experimental device also includes a piston control circuit, which connects both ends of all floating pistons and is used to control the bidirectional movement of the floating pistons.

[0014] Furthermore, the piston control circuit controls each floating piston in a manner including synchronous motion control and asynchronous motion control, and can achieve individual regulation and maintenance of the output pressure, and the control between different floating pistons is independent of each other.

[0015] According to another aspect of the present invention, an experimental method for testing the preload pressure distribution of a fuel cell stack is provided, comprising an experimental preparation stage, a data acquisition stage and a data sorting stage, wherein the data acquisition stage comprises the following steps:

[0016] Start the fuel cell compression and tightening procedure;

[0017] The stepper motor is driven to drive the primary pressing module and the secondary pressing module to move downward, so that the lower surface of the secondary pressing module contacts the fuel cell stack, simulating the pre-pressing stage in the assembly process of the fuel cell stack;

[0018] Control the floating piston to press down the upper end plate of the fuel cell according to the pre-calculated pressure in a certain order to simulate the tensioning stage during the assembly of the fuel cell stack;

[0019] During the experiment, the readings of the pressure sensor are read and recorded at a certain sampling rate.

[0020] Further, the steps in the experimental preparation stage include placing the fuel cell stack and the array flexible pressure sensor module, setting the compression and tightening program, and manually adjusting the primary and secondary compression modules to above the fuel cell stack;

[0021] The steps in the data collation stage are to relieve the pressure of the first-level clamping module and the second-level clamping module to restore them to their initial state, record the test data, and obtain test data such as the in-plane pressure distribution through data post-processing.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. The present invention designs an experimental device for testing the pre-tightening pressure distribution of a fuel cell stack, and designs a structure of a two-stage clamping module. Among them, the first-stage clamping module is driven by a stepper motor to clamp the second-stage clamping module. While the second-stage clamping module presses the fuel cell stack through the second-stage clamping module support to simulate the pre-tightening stage in the assembly process of the fuel cell stack, it presses down the fuel cell stack through the floating piston to simulate the tensioning stage in the assembly process of the fuel cell stack. At the same time, an array-type thin film pressure sensor is used to obtain the contact pressure between the components of the fuel cell stack in real time, avoiding the complex experimental process in the design process of the traditional fuel cell assembly scheme, and greatly simplifying the experimental process.

[0024] 2. The present invention realizes the experiment of fuel cell stacks of different specifications by utilizing compression modules and bases of different areas and shapes, and the operation is simple and effective.

[0025] 3. The present invention proposes an experimental method for simulating the pre-stressing and tensioning process of a fuel cell stack by applying a controllable load, and realizing online measurement of the pressure distribution in the stack, thereby providing a way for experimental research on the pressure distribution of fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the overall schematic diagram of the experimental device of the present invention;

[0027] Figure 2 It is a schematic diagram of the experimental method of the present invention;

[0028] Figure 3 The pressure distribution cloud diagram of the MEA area in the experiment according to the present invention.

[0029] In the figure, 1. experimental table base, 2. fuel cell lower support, 3. guide rod, 4. fuel cell guide rod, 5. array flexible pressure sensor module, 6. secondary clamping module, 61. secondary clamping module support, 62. floating piston, 7. primary clamping module, 72. drive pressure plate, 71. drive column, 8. upper support plate, 9. stepper motor, 10. fuel cell stack, 101. fuel cell upper end plate, 102. collector plate, 103. bipolar plate, 104. collector plate, 105. fuel cell lower end plate, 11. piston control circuit. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0031] The present invention proposes an experimental device for testing the preload pressure distribution of a fuel cell stack, such as Figure 1 As shown, it includes a test bench base 1, a fuel cell lower support 2, a guide rod 3, a fuel cell guide rod 4, an array-type flexible pressure sensor module 5, a secondary clamping module 6, a primary clamping module 7, an upper support plate 8, a stepper motor 9, a fuel cell stack 10 and a piston control circuit 11.

[0032] The test bench base 1 and the upper support plate 8 are connected and fixed by four guide rods 3, and together they form a test bench frame. The fuel cell lower support 2, the guide rod 3, the array-type flexible pressure sensor module 5, the secondary clamping module 6 and the primary clamping module 7 are arranged and installed on the test bench base 1 from bottom to top, and the stepper motor 9 is located above the upper support plate 8 and fixedly connected to the primary clamping module 7. The fuel cell guide rod 4 is located outside the fuel cell lower support 2, and is used to limit the lateral movement of the fuel cell stack 10.

[0033] The fuel cell stack 10 includes a fuel cell upper end plate 101, an upper current collecting plate 102, a bipolar plate 103, a lower current collecting plate 104 and a fuel cell lower end plate 105 arranged in sequence from top to bottom; the fuel cell lower end plate 105 is mounted on the fuel cell lower support 2, the lower surface of the secondary clamping module support 61 is in contact with the outer surface of the fuel cell upper end plate 101, and there are mounting platforms for mounting tensioning bolts, nuts or metal belts on the fuel cell upper end plate 101 and the fuel cell lower end plate 105. As a preferred embodiment, the mounting platform can be a concave platform or a convex platform.

[0034] In this embodiment, a mounting site is provided on the test bench base 1, and the fuel cell lower support 2 is mounted on the test bench base 1 through the mounting site. As a preferred embodiment, the mounting site is a T-slot, and the test bench base 1 and the fuel cell lower support 2 are connected and fixed by screws and T-nuts. The fuel cell lower support 2 provides fixation for the fuel cell stack 10 through a support platform, and the position of the support platform corresponds to the position of the mounting site on the fuel cell lower end plate 105. As a preferred embodiment, the support platform can be a round table or a square table.

[0035] The upper support plate 8 is provided with a driving stepper motor 9 for driving the primary clamping module 7 to move up and down along the guide rod 3, and realizing the application and maintenance of the primary clamping force of the fuel cell stack 10. The primary clamping module 7 is composed of a driving column 71 and a driving platen 72. One end of the driving column 71 is connected to the driving platen 72 through a flange and screws, and the other end is connected to the stepper motor 9. Four circular holes are opened near the edges of both sides of the driving platen 72, and metal polymer sliding bearings are placed in the circular holes. The bearings are matched with the guide rod 3 to reduce the sliding friction between the guide rod 3 and the driving platen 72.

[0036] The secondary clamping module 6 includes a secondary clamping module support 61 and a floating piston 62. The number and position of the floating piston 62 correspond to the position of the mounting site on the upper end plate 101 of the fuel cell. A circular hole is provided at a position corresponding to the floating piston 62 on the secondary clamping module support 61 to form an oil chamber with the floating piston 62. The oil chamber is connected to the piston control circuit 11 through the inlet and outlet oil channels and the flexible stainless steel pipe. A metal round table or square table is connected to the outer side of the floating piston 62 to contact the nut or metal belt mounting concave table or convex table of the upper end plate 101 of the fuel cell. The floating piston 62 is driven to move by controlling the flow rate of the hydraulic oil and the oil pressure at both ends of the floating piston 62 to simulate the tensioning process of the fuel cell bolts or metal belts.

[0037] As a preferred embodiment, the upper surface of the secondary clamping module support 61 contacts the lower surface of the driving pressure plate 72 and is fixed by screws, and the lower surface contacts the outer surface of the upper end plate 101 of the fuel cell stack, thereby realizing the synchronous movement of the two-stage modules and the transmission of the primary clamping force.

[0038] In this embodiment, the array-type flexible piezoelectric sensor module 5 is placed inside the fuel cell stack 10 to collect the contact pressure distribution between the components in the stack in real time. The placement and quantity of the sensor can be determined according to the actual test requirements, and can be placed between the positive and negative bipolar plates, between the end plate and the current collector, or between the current collector and the bipolar plate. As a preferred embodiment, the stepper motor and floating piston are driven programmatically, the array-type flexible piezoelectric sensor data is read and saved, and the system status is visually monitored through an industrial computer.

[0039] As a preferred embodiment, the array-type flexible piezoelectric sensor module 5 is composed of a plurality of thin film pressure sensors and is packaged on a flexible circuit board. The pressure sensor data is converted into a voltage signal through a sampling resistor and an operational amplifier. The data collection and power supply are interacted with the host computer through a socket. The number of thin film pressure sensors and the area of ​​a single sensor are selected according to the area of ​​the MEA to be measured to match different sizes of stacks and obtain different spatial resolution test accuracies.

[0040] In particular, the cross-sectional size of the secondary clamping module support 61 and the fuel cell lower support 2 is the cross-sectional size of the fuel cell stack 10, and the position of the floating piston 62 and the boss of the fuel cell lower support 2 is the installation position of the tension bolt of the fuel cell stack 10. Therefore, by replacing the secondary clamping module 6 and the fuel cell lower support 2, the purpose of studying fuel cell stacks 10 of different sizes can be achieved.

[0041] In particular, the device is provided with a piston control circuit 11 connecting both ends of all floating pistons 62, which is used to control the bidirectional movement of the floating pistons 62. The control of different pistons in the secondary clamping module 6 should be independent of each other, and can realize synchronous or asynchronous motion control of different pistons, and can realize the individual regulation and maintenance of the output pressure, so as to truly simulate the bolt tensioning sequence and preload size during the assembly process of the fuel cell stack.

[0042] Figure 2 The method flow of the complete experimental process is demonstrated. The experiment includes three stages: experimental preparation, data acquisition and data collation. The experimental preparation mainly completes the placement of the fuel cell stack 10 and the array flexible piezoelectric sensor module 5, sets the compression and tightening program, and manually adjusts the compression module to the top of the fuel cell stack 10. When the data recording starts, the second stage is entered. After the compression and tightening program is started, the driving motor drives the compression module to move downward, so that the lower surface of the secondary compression module 6 contacts the end plate of the fuel cell stack 10, and compresses the fuel cell stack 10 with a certain set primary compression force F1, simulating the pre-compression stage during the assembly of the fuel cell stack 10. Then the floating piston 62 is controlled to press the fuel cell end plate according to the pre-calculated pressure in a certain order to simulate the tensioning stage during the assembly of the fuel cell stack 10. During this period, the reading of the pressure sensor is read and recorded at a certain sampling rate. When the compression and tightening program is completed, the third stage of the experiment is entered. This stage mainly completes the pressure relief of the compression module to restore the initial state, and records the test data, and obtains the test data such as the in-plane pressure distribution through data post-processing.

[0043] As one of the embodiments, a fuel cell single cell experimental sample with a cross-sectional area of ​​100mm*100mm (MEA cross-sectional area of ​​50mm*50mm) is taken as an example, and 8 bolts are used for tightening, and each bolt applies a pre-tightening torque of 6.0N·m. The pressure distribution of the MEA area of ​​the bipolar plate is obtained by using the test method proposed in the present invention, and the results are as follows: Figure 3 as shown.

[0044] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An experimental device for testing the preload pressure distribution of a fuel cell stack, characterized in that: The invention comprises a fuel cell stack (10), a primary clamping module (7), a secondary clamping module (6) and an array-type flexible pressure sensor module (5); the primary clamping module (7) comprises a driving clamping plate (72), the secondary clamping module (6) comprises a secondary clamping module support (61) and a floating piston (62), the driving clamping plate (72) is fixedly connected to the secondary clamping module support (61), a plurality of circular holes are provided on the lower surface of the secondary clamping module support (61) and an oil cavity is formed with the floating piston (62), the floating piston (62) is in plurality and is pressed on top of the fuel cell stack (10); the array-type flexible pressure sensor module (5) is located in the fuel cell stack (10).

2. The experimental device for testing the preload pressure distribution of a fuel cell stack according to claim 1, characterized in that: The fuel cell stack (10) comprises a fuel cell upper end plate (101), an upper current collecting plate (102), a bipolar plate (103), a lower current collecting plate (104) and a fuel cell lower end plate (105) arranged in sequence from top to bottom; the lower surface of the secondary clamping module support (61) is connected to the outer surface of the fuel cell upper end plate (101); the outer surface of the fuel cell upper end plate (101) has a mounting platform for mounting a nut or a metal belt at a position corresponding to the floating piston (62); and the end of the floating piston (62) connected to the nut or the metal belt is provided with a metal platform.

3. The experimental device for testing the preload pressure distribution of a fuel cell stack according to claim 2, characterized in that: The experimental device also includes a test bench base (1) and a fuel cell lower support (2); the test bench base (1) is provided with a mounting site, and the fuel cell lower support (2) is mounted on the test bench base (1) via the mounting site; the outer surface of the fuel cell lower end plate (105) has a mounting platform for mounting a nut or a metal belt at a position corresponding to the floating piston (62), and the fuel cell lower support (2) has a supporting platform at a position corresponding to the mounting platform.

4. The experimental device for testing the preload pressure distribution of a fuel cell stack according to claim 3, characterized in that: The experimental device also includes a guide rod (3) and a fuel cell guide rod (4), wherein the guide rod (3) is connected to the experimental table base (1) and the upper support plate (8), and the fuel cell guide rod (4) is located outside the fuel cell lower support (2) to restrict the lateral movement of various components of the fuel cell stack (10), and the number of the guide rod (3) and the number of the fuel cell guide rod (4) are both multiple.

5. The experimental device for testing the preload pressure distribution of a fuel cell stack according to claim 4, characterized in that: A plurality of through holes are provided at the edge of the driving pressure plate (72), the number of the through holes being consistent with the number of the guide rods (3), and metal polymer sliding bearings are installed in the through holes, and the metal polymer sliding bearings are matched with the guide rods (3).

6. The experimental device for testing the preload pressure distribution of a fuel cell stack according to claim 1, characterized in that: The experimental device also includes an upper support plate (8) and a stepper motor (9), wherein the stepper motor (9) is mounted on the upper support plate (8) and drives the primary clamping module (7) to move longitudinally; the primary clamping module (7) also includes a driving column (71), wherein one end of the driving column (71) is connected to the stepper motor (9) and the other end is fixedly connected to the driving plate (72).

7. The experimental device for testing the preload pressure distribution of a fuel cell stack according to claim 6, characterized in that: The experimental device also includes a piston control circuit (11), which connects the two ends of all floating pistons (62) and is used to control the bidirectional movement of the floating pistons (62).

8. The experimental device for testing the preload pressure distribution of a fuel cell stack according to claim 7, characterized in that: The piston control circuit (11) controls each floating piston (62) in a manner including synchronous motion control and asynchronous motion control, and can achieve individual regulation and maintenance of output pressure, and the control between different floating pistons (62) is independent of each other.

9. An experimental method for an experimental device for testing the preload pressure distribution of a fuel cell stack according to claims 1-8, comprising an experimental preparation stage, a data acquisition stage and a data sorting stage, characterized in that: The data acquisition phase includes the following steps: Start the fuel cell compression and tightening procedure; The stepper motor (9) is driven to drive the primary pressing module (7) and the secondary pressing module (6) to move downward, so that the lower surface of the secondary pressing module (6) contacts the fuel cell stack (10), thereby simulating the pre-pressing stage in the assembly process of the fuel cell stack (10); Controlling the floating piston (62) to press down the fuel cell upper end plate (101) in a certain order according to a pre-calculated pressure, simulating a tensioning stage in the assembly process of the fuel cell stack (10); During the experiment, the readings of the pressure sensor are read and recorded at a certain sampling rate.

10. The experimental method according to claim 9, characterized in that: The steps of the experimental preparation stage include placing the fuel cell stack (10) and the array-type flexible pressure sensor module (5), setting the compression and tightening program, and manually adjusting the primary compression module (7) and the secondary compression module (6) to the top of the fuel cell stack (10); The steps of the data sorting stage are to relieve the pressure of the primary clamping module (7) and the secondary clamping module (6) to restore them to their initial state, record the test data, and obtain the test data such as the in-plane pressure distribution through data post-processing.

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