CN111397562A - Device and method for testing thickness of membrane electrode assembly with high precision - Google Patents
Device and method for testing thickness of membrane electrode assembly with high precision Download PDFInfo
- Publication number
- CN111397562A CN111397562A CN202010331812.XA CN202010331812A CN111397562A CN 111397562 A CN111397562 A CN 111397562A CN 202010331812 A CN202010331812 A CN 202010331812A CN 111397562 A CN111397562 A CN 111397562A
- Authority
- CN
- China
- Prior art keywords
- pressure
- electrode assembly
- membrane electrode
- displacement
- head
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
- G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
- G01B21/08—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness for measuring thickness
Abstract
The invention relates to a device and a method for testing the thickness of a membrane electrode assembly with high precision, wherein the device comprises an upper end head, a lower end head, a pressure sensor, a displacement sensor, a cylinder and the like, wherein the lower end head is embedded in a table top but is not contacted with the table top, the upper surface of the lower end head is used as a lower contact surface with the membrane electrode assembly, the lower surface of the lower end head is fixed on the pressure sensor, the upper end head is connected with the displacement sensor, a probe of the displacement sensor is in contact connection with the upper surface of the upper end head, a probe rod of the displacement sensor is fixed on a base through a bracket, the upper end of the upper end head is connected with a guide rod, the other end of the guide rod is connected with a piston end of the cylinder, an air inlet and an air outlet of the cylinder are; the invention has high measurement precision and high measurement speed, greatly improves the control precision and consistency of the pressure and reduces the error caused by the pressure.
Description
[ technical field ]
The invention belongs to the field of hydrogen fuel cells, and particularly relates to a device and a method for testing the thickness of a membrane electrode assembly with high precision.
[ background art ]
The Membrane Electrode Assembly (MEA) is the core assembly of the electrochemical reaction of the fuel cell, consists of a proton exchange membrane, a catalyst layer, a diffusion layer and a frame, and is the core component of the fuel cell. The thickness of the MEA is an important parameter, and the difference in thickness changes the volume and pressure of the stack, which in turn affects the assembly. More importantly, it also has certain elasticity, and after assembly, it can affect the openness of the cathode and anode flow channels and the contact resistance with the polar plate.
At present, the traditional method for measuring the thickness of the membrane is mainly used for detecting the thickness of the MEA. However, this conventional approach has certain limitations, the most important of which are: (1) the pressure control cannot be satisfied. The thickness of the MEA is strongly related to the pressure and the existing methods do not control or do not control the pressure precisely enough, which can lead to very large errors. (2) The parallelism of the upper and lower tips often requires calibration. Because the area of the probe is large, if the parallelism is not good, the error becomes large, and even the MEA is damaged. Therefore, the parallelism needs to be calibrated before each measurement, which brings trouble to the operation, has higher requirement on operators and reduces the measurement speed.
[ summary of the invention ]
The invention aims to solve the defects and provide a device and a method for testing the thickness of a membrane electrode assembly with high precision, which can be used for measuring the thickness of the membrane electrode assembly, have high measurement precision and high measurement speed, greatly improve the control precision and consistency of pressure and reduce errors caused by the pressure.
The device and the method for testing the thickness of the membrane electrode assembly with high precision are designed to achieve the purpose, and comprise an upper end 1, a lower end 2, a pressure sensor 3, a displacement sensor 4, a table top 5, a cylinder 6, a guide rod 7, an electromagnetic valve 8 and a control circuit board 9, wherein the lower end 2 is embedded in the table top 5 but is not contacted with the table top 5, the upper surface of the lower end 2 and the upper surface of the table top 5 are positioned on the same horizontal plane, the upper surface of the lower end 2 is used as the lower contact surface with the membrane electrode assembly, the pressure sensor 3 is arranged below the lower end 2, the lower surface of the lower end 2 is fixed on the pressure sensor 3, the pressure sensor 3 is fixed on a base 10, the upper end 1 is arranged above the lower end 2, the upper end 1 and the lower end 2 are oppositely arranged, and the pressure sensor 3 is used for measuring the pressure born by the membrane electrode assembly between the upper end 1 and the, the device comprises an upper end 1, and is characterized in that a displacement sensor 4 is connected to the upper end 1, a probe of the displacement sensor 4 is in contact connection with the upper surface of the upper end 1, a probe rod of the displacement sensor 4 is fixed on a base 10 through a support 14, the displacement sensor 4 is used for measuring the thickness of a membrane electrode assembly, the upper end of the upper end 1 is connected with a guide rod 7, the other end of the guide rod 7 is connected with a piston end of a cylinder 6, the cylinder 6 is used for driving the upper end 1 to move up and down and applying pressure to the membrane electrode assembly through the upper end 1, an air inlet and an air outlet of the cylinder 6 are respectively connected with an electromagnetic valve 8, the other end of the electromagnetic valve 8 is connected with atmosphere and compressed air, a circuit control end of the electromagnetic valve 8 is connected with a control circuit.
Furthermore, a spherical groove 11 is formed in the middle of the top of the upper end head 1, a spherical raised head 12 is arranged at the lower end of the guide rod 7, the spherical raised head 12 is in contact connection with the spherical groove 11, symmetrically arranged springs 13 are connected to the left side and the right side of the guide rod 7, and the other end of each spring 13 is connected to the edge of the upper surface of the upper end head 1.
Furthermore, a display screen is further arranged, the display screen is connected with the control circuit board 9 through a line, and the control circuit board 9 displays the measured pressure data and displacement data through the display screen.
Further, the bottom of the table-board 5 is provided with a column, and the table-board 5 is fixed on the base 10 through the column.
The invention also provides a measuring method of the device for testing the thickness of the membrane electrode assembly with high precision, which comprises the following steps:
1) before testing, firstly, carrying out pressure calibration and displacement calibration, then placing the membrane electrode assembly on a table board, and moving the membrane electrode assembly to enable the measuring point to be positioned between the upper end head and the lower end head;
2) the control circuit board sends a control signal to enable an air inlet of the electromagnetic valve to be conducted to inflate the air cylinder, the air cylinder pushes the guide rod and the upper end head to move downwards, and meanwhile data of the pressure sensor are monitored in real time;
3) when the pressure value gradually rises to a set value, controlling the air inlet of the electromagnetic valve to be closed, and keeping the pressure between the upper end head and the lower end head; and reading the data of the displacement sensor to calculate the thickness of the membrane electrode assembly.
Further, the pressure calibration comprises the steps of: and under the condition that the upper end head is lifted, reading the value of the pressure sensor as a zero value, and subtracting the zero value from the value read in the test process to obtain a pressure value.
Further, the displacement calibration comprises the steps of: and under the state that the membrane electrode assembly is not placed, the control circuit board sends a control signal to enable the air inlet of the electromagnetic valve to be communicated and inflate the air cylinder, the air cylinder pushes the guide rod and the upper end head to move downwards, meanwhile, the data of the pressure sensor is monitored in real time, when the pressure data gradually rises to a set value, the air inlet of the electromagnetic valve is controlled to be closed, the pressure between the upper end head and the lower end head is kept, the value of the displacement sensor is read at the moment and is used as a displacement zero point, and then the displacement zero point value is subtracted from the displacement value read in the testing process to be used.
Compared with the prior art, the invention has the following advantages:
(1) the invention adopts automatic control, greatly improves the control precision and consistency of the pressure and reduces the error caused by the pressure;
(2) the invention adopts the high-precision displacement sensor to directly fix the displacement sensor on the base, thereby avoiding the distortion of the rack caused by pressure, improving the precision and enabling the resolution to reach 0.1 mu m after calibration;
(3) according to the invention, the guide rod and the upper end head adopt a self-parallel connection mode of the special groove and the spring, so that the parallelism of the upper end head and the lower end head is not required to be calibrated during testing, and the spring is deformed and automatically adjusted to be parallel to the surface of the lower end head under the action of pressure even if the upper end head is slightly unparallel;
(4) the invention can improve the measuring speed while automatically measuring, reduce the labor cost, realize automatic recording, facilitate data export and greatly improve the efficiency;
(5) the invention overcomes the problems that the existing method has no control on the pressure or the control is not accurate enough to cause very large errors, and the parallelism needs to be calibrated before each measurement to bring trouble to the operation, the requirement on operators is high, and the like.
[ description of the drawings ]
FIG. 1 is a schematic structural view of the present invention;
in the figure: 1. the device comprises an upper end 2, a lower end 3, a pressure sensor 4, a displacement sensor 5, a table top 6, a cylinder 7, a guide rod 8, an electromagnetic valve 9, a control circuit board 10, a base 11, a spherical groove 12, a spherical raised head 13, a spring 14 and a support.
[ detailed description of the invention ]
The invention is further described below with reference to the accompanying drawings:
as shown in the attached figure 1, the invention provides a device and a method for testing the thickness of a membrane electrode assembly with high precision, which comprises an upper end 1, a lower end 2, a pressure sensor 3, a displacement sensor 4, a table 5, a cylinder 6, a guide rod 7, an electromagnetic valve 8 and a control circuit board 9, wherein the lower end 2 is embedded in the table 5 but is not contacted with the table 5, the upper surface of the lower end 2 and the upper surface of the table 5 are positioned on the same horizontal plane, the upper surface of the lower end 2 is used as the lower contact surface with the membrane electrode assembly, the pressure sensor 3 is arranged below the lower end 2, the lower surface of the lower end 2 is fixed on the pressure sensor 3, the pressure sensor 3 is fixed on a base 10, the upper end 1 is arranged above the lower end 2, the upper end 1 and the lower end 2 are arranged oppositely, the pressure sensor 3 is used for measuring the pressure born by the membrane electrode assembly between the, go up and be connected with displacement sensor 4 on end 1, displacement sensor 4's probe is connected with the upper surface contact of last end 1, displacement sensor 4's probe rod passes through support 14 to be fixed on base 10, displacement sensor 4 is used for measuring membrane electrode assembly's thickness, the upper end of last end 1 is connected with guide arm 7, the guide arm 7 other end links to each other with the piston end of cylinder 6, cylinder 6 is used for driving last end 1 and reciprocates, and exert pressure for membrane electrode assembly through last end 1, the air inlet of cylinder 6, solenoid valve 8 is connected respectively to the gas vent, atmosphere and compressed air are connected to the solenoid valve 8 other end, control circuit board 9 is connected to solenoid valve 8's circuit control end, pressure sensor 3 is connected to control circuit board 9 electricity respectively, displacement sensor 4.
Wherein, the bottom of the table-board 5 is provided with a column, and the table-board 5 is fixed on the base 10 through the column; and a display screen can be arranged and is connected with the control circuit board 9 through a line, and the control circuit board 9 displays the measured pressure data and displacement data through the display screen. The middle of the top of the upper end head 1 is provided with a spherical groove 11, the lower end of the guide rod 7 is provided with a spherical raised head 12, the spherical raised head 12 is in contact connection with the spherical groove 11, the left side and the right side of the guide rod 7 are connected with symmetrically arranged springs 13, and the other end of each spring 13 is connected with the edge of the upper surface of the upper end head 1. Here, the special recess that guide arm and top end adopted adds the self parallel connection mode of spring, need not the depth of parallelism of end about the calibration during messenger's test, even have slight nonparallel, the top end also can make spring deformation automatic adjustment make it parallel with bottom end surface under the effect of pressure, this kind of mode not only self-adaptation is parallel, and contact surface pressure is even moreover, and measurement accuracy is high, and measuring speed is fast. However, the self-parallel connection mode of the present invention is not limited to this, and can also be realized by using a floating joint.
In the device for testing the thickness of the Membrane Electrode Assembly (MEA) with high precision, the upper surface of the lower end head is used as a contact surface with the MEA, the upper surface of the lower end head and the upper surface of the table top are on the same horizontal plane, and the whole end head is embedded in the middle of the table top but is not contacted with the table top; the lower surface of the lower end is fixed on a pressure sensor, the pressure sensor is fixed on a base, and the table top is also fixed on the base through an upright post. A probe of the displacement sensor is contacted with the upper surface of the upper end head, and a probe rod of the displacement sensor is fixed on the base through a bracket; simultaneously, the upper end is connected with the guide rod in a connecting mode: the middle of the upper end head is provided with a spherical groove, the lower end of the guide rod is provided with a spherical raised head, the raised head is contacted with the spherical groove, and the guide rod is also connected with the edge of the upper end head through a spring; the guide rod is connected with the cylinder; the air inlet and the air outlet of the air cylinder are respectively connected with an electromagnetic valve, and the other end of the electromagnetic valve is connected with the atmosphere and the compressed air. The circuit control end of the electromagnetic valve is connected with the control circuit board, and the control circuit board is also connected with the pressure sensor.
The invention has the functions that the table top is used for placing MEA, the pressure sensor is used for measuring the pressure born by the MEA between the upper end head and the lower end head, the base is used for fixing the table top, the displacement sensor and the lower end head, the guide rod is used for connecting the air cylinder and the upper end head, the air cylinder is used for moving the upper end head up and down and applying pressure to the MEA through the upper end head, the electromagnetic valve is used for controlling the air inlet and the air outlet of the air cylinder so as to move the guide rod of the air cylinder or change the applied pressure, the displacement sensor is used for measuring the thickness of the MEA, the control circuit board is the control center of the whole system and has the following functions of ① controlling the opening and closing of the electromagnetic valve so as to move and press the air cylinder, ② reads the pressure data measured by the pressure sensor.
The specific working process of the invention is as follows: before testing, a pressure calibration and a displacement calibration are required. The pressure calibration process comprises the following steps: and under the condition that the upper end head is lifted, reading the value of the pressure sensor as a zero value, and subtracting the zero value from the value read in the test process to obtain a pressure value. The displacement calibration process comprises the following steps: nothing is put on the table board, the control circuit board sends a control signal to enable an air inlet of the electromagnetic valve to be conducted to inflate the air cylinder, the air cylinder pushes the guide rod and the upper end head to move downwards, and meanwhile data of the pressure sensor are monitored in real time; when the pressure data gradually rises to a set value, controlling the air inlet of the electromagnetic valve to be closed, and keeping the pressure between the upper end and the lower end; and reading the value of the displacement sensor as a displacement zero point, and subtracting the displacement zero point value from the displacement value read in the test process to obtain a displacement value. The MEA is then placed on the table and moved so that the measurement site is located between the upper and lower tips. The measurement process is as follows: firstly, under the state that the membrane electrode assembly is not placed, the control circuit board sends a control signal to enable an air inlet of the electromagnetic valve to be conducted to inflate the air cylinder, the air cylinder pushes the guide rod and the upper end head to move downwards, and meanwhile data of the pressure sensor are monitored in real time. When the pressure value gradually rises to a set value, the air inlet of the electromagnetic valve is controlled to be closed, so that the pressure between the upper end and the lower end is maintained. And reading the data of the displacement sensor, and calculating the thickness of the MEA.
The invention adopts automatic control, greatly improves the control precision and consistency of pressure, reduces errors caused by pressure, improves the measurement speed while automatically measuring, reduces the labor cost, can realize automatic recording, is beneficial to data export and greatly improves the efficiency. In addition, the invention adopts the high-precision displacement sensor to directly fix the displacement sensor on the base, thereby avoiding the distortion and deformation of the rack caused by pressure, improving the precision and enabling the resolution to reach 0.1 mu m after calibration.
The present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents and are included in the scope of the present invention.
Claims (7)
1. The utility model provides a device of high accuracy test membrane electrode assembly thickness, includes upper end (1), lower end (2), pressure sensor (3), displacement sensor (4), mesa (5), cylinder (6), guide arm (7), solenoid valve (8), control circuit board (9), its characterized in that: the lower end (2) is embedded in the table board (5) but is not contacted with the table board (5), the upper surface of the lower end (2) and the upper surface of the table board (5) are positioned on the same horizontal plane, the upper surface of the lower end (2) is used as a lower contact surface with the membrane electrode assembly, a pressure sensor (3) is arranged below the lower end (2), the lower surface of the lower end (2) is fixed on the pressure sensor (3), the pressure sensor (3) is fixed on a base (10), the upper end (1) is arranged above the lower end (2), the upper end (1) and the lower end (2) are oppositely arranged, the pressure sensor (3) is used for measuring the pressure born by the membrane electrode assembly between the upper end (1) and the lower end (2), a displacement sensor (4) is connected on the upper end (1), the probe of the displacement sensor (4) is contacted with the upper surface of the upper end (1), the probe rod of the displacement sensor (4) is fixed on the base (10) through a support (14), the displacement sensor (4) is used for measuring the thickness of a membrane electrode assembly, the upper end of the upper end (1) is connected with a guide rod (7), the other end of the guide rod (7) is connected with the piston end of a cylinder (6), the cylinder (6) is used for driving the upper end (1) to move up and down, pressure is applied to the membrane electrode assembly through the upper end (1), an air inlet and an air outlet of the cylinder (6) are respectively connected with an electromagnetic valve (8), the other end of the electromagnetic valve (8) is connected with atmosphere and compressed air, a circuit control end of the electromagnetic valve (8) is connected with a control circuit board (9), and the control circuit board (9) is respectively and electrically connected with the pressure sensor (3) and the.
2. The apparatus for testing the thickness of a membrane electrode assembly with high precision according to claim 1, wherein: the middle of the top of the upper end (1) is provided with a spherical groove (11), the lower end of the guide rod (7) is provided with a spherical raised head (12), the spherical raised head (12) is in contact connection with the spherical groove (11), the left side and the right side of the guide rod (7) are connected with springs (13) which are symmetrically arranged, and the other end of each spring (13) is connected with the edge of the upper surface of the upper end (1).
3. The apparatus for testing the thickness of a membrane electrode assembly with high precision according to claim 2, wherein: the pressure sensor is further provided with a display screen, the display screen is connected with the control circuit board (9) through a line, and the control circuit board (9) displays the measured pressure data and displacement data through the display screen.
4. The apparatus for testing the thickness of a membrane electrode assembly with high precision according to claim 2, wherein: the table top is characterized in that a stand column is arranged at the bottom of the table top (5), and the table top (5) is fixed on the base (10) through the stand column.
5. A measuring method of an apparatus for testing membrane electrode assembly thickness with high precision according to any one of claims 1 to 4, characterized by comprising the steps of:
1) before testing, firstly, carrying out pressure calibration and displacement calibration, then placing the membrane electrode assembly on a table board, and moving the membrane electrode assembly to enable the measuring point to be positioned between the upper end head and the lower end head;
2) the control circuit board sends a control signal to enable an air inlet of the electromagnetic valve to be conducted to inflate the air cylinder, the air cylinder pushes the guide rod and the upper end head to move downwards, and meanwhile data of the pressure sensor are monitored in real time;
3) when the pressure value gradually rises to a set value, controlling the air inlet of the electromagnetic valve to be closed, and keeping the pressure between the upper end head and the lower end head; and reading the data of the displacement sensor to calculate the thickness of the membrane electrode assembly.
6. The method of claim 5, wherein the pressure calibration comprises the steps of: and under the condition that the upper end head is lifted, reading the value of the pressure sensor as a zero value, and subtracting the zero value from the value read in the test process to obtain a pressure value.
7. The method of claim 5, wherein the displacement calibration comprises the steps of: and when the pressure data gradually rises to a set value, the electromagnetic valve air inlet is controlled to be closed, so that the pressure between the upper end head and the lower end head is maintained, the numerical value of the displacement sensor is read at the moment and is used as a displacement zero point, and then the numerical value read in the test process is subtracted from the numerical value read to be used as a displacement value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010331812.XA CN111397562A (en) | 2020-04-24 | 2020-04-24 | Device and method for testing thickness of membrane electrode assembly with high precision |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010331812.XA CN111397562A (en) | 2020-04-24 | 2020-04-24 | Device and method for testing thickness of membrane electrode assembly with high precision |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111397562A true CN111397562A (en) | 2020-07-10 |
Family
ID=71437141
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010331812.XA Pending CN111397562A (en) | 2020-04-24 | 2020-04-24 | Device and method for testing thickness of membrane electrode assembly with high precision |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111397562A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112762878A (en) * | 2021-01-07 | 2021-05-07 | 天津大学 | Detection system and detection method for thickness of membrane electrode |
| CN112902902A (en) * | 2021-01-19 | 2021-06-04 | 深圳市金天光学科技有限公司 | Lens thickness detection anchor clamps and have thickness detection device of this anchor clamps |
| CN114964101A (en) * | 2022-07-28 | 2022-08-30 | 新恒汇电子股份有限公司 | Automatic measuring equipment and measuring method for module glue height |
-
2020
- 2020-04-24 CN CN202010331812.XA patent/CN111397562A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112762878A (en) * | 2021-01-07 | 2021-05-07 | 天津大学 | Detection system and detection method for thickness of membrane electrode |
| CN112902902A (en) * | 2021-01-19 | 2021-06-04 | 深圳市金天光学科技有限公司 | Lens thickness detection anchor clamps and have thickness detection device of this anchor clamps |
| CN114964101A (en) * | 2022-07-28 | 2022-08-30 | 新恒汇电子股份有限公司 | Automatic measuring equipment and measuring method for module glue height |
| CN114964101B (en) * | 2022-07-28 | 2023-01-10 | 新恒汇电子股份有限公司 | Automatic measuring equipment and measuring method for module glue height |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111397562A (en) | Device and method for testing thickness of membrane electrode assembly with high precision | |
| CN206725363U (en) | A kind of concrete compression-resistanmodifier detection means | |
| CN112113850A (en) | Soft package battery thickness measuring device and method | |
| CN208818190U (en) | The automatic measuring thickness device for measuring electric resistance of battery | |
| CN211651564U (en) | Device for testing thickness of membrane electrode assembly with high precision | |
| CN219640916U (en) | Core sample size measuring instrument | |
| CN111337749A (en) | Membrane electrode assembly resistance measuring device and method with pressure control function | |
| CN112197895A (en) | Square electricity core bulging force testing arrangement | |
| CN110017313B (en) | Cylinder performance detection method | |
| CN208075819U (en) | Aluminum plastic film seal measurer for thickness | |
| CN106644329A (en) | 120MN bridge support tester for high-precision dynamic measurement | |
| CN212111592U (en) | Membrane electrode assembly resistance measuring device with pressure control function | |
| CN209470684U (en) | Power battery measuring thickness device | |
| CN208952929U (en) | A kind of novel power battery thickness of the shell detection fixture | |
| CN209513176U (en) | Fuel cell bipolar plate tightness detecting tool | |
| CN210719489U (en) | Grid cell clamping force detection device | |
| CN110285857A (en) | A kind of fuel cell detection device | |
| CN214472510U (en) | Calibration device for cupping test machine | |
| CN212779058U (en) | Device for detecting parallel error of opposite end faces of wind power bearing channel | |
| CN219694976U (en) | Nondestructive testing membrane electrode active area expansion device | |
| CN214096960U (en) | Soft-package battery thickness measuring device | |
| CN109974600A (en) | The measuring device and method of soft-package battery thickness | |
| CN218524059U (en) | Automatic calibration platform of length measuring device | |
| CN214472335U (en) | Flexible graphite polar plate compression ratio detection device | |
| CN212458525U (en) | Battery expansion volume measuring instrument |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |