A life test device and method for a spherical plain bearing using pneumatic loading

Abstract

The present invention discloses a life test device and method for a spherical plain bearing using air pressure loading, which relates to the technical field of life testing. The device includes a vacuum chamber, with an irradiation device installed at the top of the vacuum chamber. A test body is arranged inside the vacuum chamber. One end of the test body is connected to a power transmission device, and a loading device is provided below the other end. The test body includes a test shaft for installing the spherical plain bearing. The loading device includes a cylinder body with a preset medium inside. The cylinder body is connected to a pressurizing component through a piston. When the pressure inside the vacuum chamber decreases, the piston drives the pressurizing component to apply pressure to the test shaft. The present invention makes full use of the imbalance of the internal and external pressure differences during the vacuum test. And because the pressure change range of the vacuum chamber is small, the loading force fluctuation is small. At the same time, an irradiation device is set up to realize the life test of the thin spherical plain bearing under the simulated space environment.

Description

Technical Field

[0001] The present invention relates to the technical field of bearing life test, and particularly relates to a spherical plain bearing life test device and method using air pressure loading. Background Art

[0002] Thin-film self-lubricating spherical plain bearings are commonly used in space environment working conditions. The service performance of self-lubricating spherical plain bearings is closely related to their material properties. With the rapid development of self-lubricating materials, it is particularly important to evaluate the service performance of thin-film self-lubricating spherical plain bearings, especially their service life in space environment. Using a spherical plain bearing testing machine that simulates the space environment to conduct bearing life tests is the most direct way to obtain the life of thin-film self-lubricating spherical plain bearings.

[0003] Currently, there are various spherical plain bearing test devices used in the atmospheric environment. For example, CN 109029998A discloses a spherical plain bearing test device, CN 205981688U discloses a spherical plain bearing life testing machine, and CN105527102B discloses a spherical plain bearing swing life testing machine. In addition, there are also spherical plain bearing testing machines considered for use in extreme environments, such as CN 110617963A discloses a wide temperature range four-dimensional drive spherical plain bearing testing machine, and CN 110793772B discloses a low temperature large temperature change spherical plain bearing test platform and a measuring method for spherical plain bearings, etc.

[0004] Due to the high cleanliness required in the space environment, the current loading in the space environment mainly uses weight loading, supplemented by spring loading and hydraulic loading. Weight loading has a simple structure and stable force value, but the loading force is small. Spring loading has large force value fluctuations without feedback and a complex structure with feedback. Hydraulic loading has a large loading force, but a complex structure, and inevitably there is hydraulic medium leakage, which is not conducive to maintaining a low-pressure environment. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a spherical plain bearing life test device and method using air pressure loading, which makes full use of the imbalance of the internal and external pressure differences during the vacuum test. And because the pressure change range of the vacuum chamber is small, the loading force fluctuation is small. At the same time, an irradiation device is set to realize the life test of thin-film spherical plain bearings under simulated space environment.

[0006] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0007] In the first aspect, an embodiment of the present invention provides a spherical plain bearing life test device using air pressure loading, including a vacuum chamber, an irradiation device is installed on the top of the vacuum chamber, a test body is arranged in the vacuum chamber, one end of the test body is connected to a power transmission device, and a loading device is arranged below the other end;

[0008] The test body includes a test shaft for installing a spherical plain bearing. The loading device includes a cylinder body with a preset medium inside. The cylinder body is connected to a pressurizing component through a piston. When the pressure in the vacuum chamber decreases, the piston drives the pressurizing component to apply pressure to the test shaft.

[0009] As a further implementation, the power transmission device includes a driving source, a magneto - fluid sealing shaft, a torque sensor, and a cooling shaft connected in sequence. A rotary valve is installed on the cooling shaft, and the rotary valve is connected to a temperature control device through a cooling pipeline.

[0010] As a further implementation, an inner ring fixture and an outer ring temperature control fixture of the bearing are installed at the position corresponding to the spherical plain bearing on the test shaft. The outer ring temperature control fixture of the bearing is connected to a temperature control device through a temperature control pipeline.

[0011] As a further implementation, a plurality of compression nuts for clamping the inner ring fixture are also provided on the test shaft; a spherical roller bearing is installed at one end of the test shaft away from the loading device.

[0012] As a further implementation, slide rail assemblies are symmetrically installed on both sides of the pressurizing component.

[0013] As a further implementation, the pressurizing component includes a pressurizing bracket and a pair of pressurizing bearings installed on the pressurizing bracket.

[0014] As a further implementation, a valve is installed on the side of the cylinder body, and a cylinder body hole is provided.

[0015] As a further implementation, the vacuum chamber is connected to a vacuum device through a vacuum pipeline.

[0016] As a further implementation, the irradiation device includes an atomic oxygen irradiation device, an ultraviolet irradiation device, and a proton irradiation device, and the foci of the irradiation devices are located at the same point.

[0017] In a second aspect, an embodiment of the present invention further provides a method for testing the life of a spherical plain bearing using air pressure loading, including:

[0018] Install the spherical plain bearing at a set position on the test shaft, and clamp and fix it through the inner ring fixture and the outer ring temperature control fixture of the bearing;

[0019] Adjust the irradiation device, the temperature control device, and the vacuum device according to the space environment parameters;

[0020] As the pressure in the vacuum chamber decreases, based on the internal and external pressure difference, the preset medium in the cylinder starts to do work, pushing the piston to move, so that the pressurizing component applies a load to the test shaft;

[0021] Wait until the pressure in the vacuum chamber reaches the set value to complete the loading process.

[0022] The beneficial effects of the present invention are as follows:

[0023] (1) The present invention provides a vacuum chamber, and a cylinder body is arranged inside the vacuum chamber. By utilizing the low-pressure environment of the vacuum chamber, a medium (gas or liquid) with a certain pressure is prefabricated inside the cylinder body. When the gas pressure inside the vacuum chamber decreases, due to the pressure difference between the inside and the outside, the gas / liquid inside the cylinder body does work, thereby providing the load required for the joint bearing test; the imbalance of the pressure difference between the inside and the outside during the vacuum test is fully utilized, and since the pressure change range of the vacuum chamber is small, the loading force fluctuation is small, and compared with the traditional hydraulic loading, its structure is simpler.

[0024] (2) The present invention installs relevant irradiation equipment outside the vacuum chamber, such as ultraviolet irradiation equipment, atomic oxygen irradiation equipment, etc., which can realize the life test of the joint bearing under the simulated space environment; the test device is also provided with sensors such as torque, which can realize the online monitoring of the life of the joint bearing.

[0025] (3) The test shaft of the present invention is connected to a cooling shaft, and a rotary valve connected to a temperature control device is installed on the cooling shaft; the joint bearing is connected to the temperature control device through a temperature control fixture for the bearing outer ring, and the temperature control device provides the high and low temperature environments required for the joint bearing test and is used to offset the influence of the high and low temperature environments on the heat of other parts.

[0026] (4) The loading device of the present invention includes a cylinder body, a piston, a pressurizing bracket and a pressurizing bearing. Liquid or gas can be pre-introduced into the cylinder body, and the cylinder body is provided with a cylinder body hole for communicating with the vacuum chamber, so as to form a pressure difference inside and outside the cylinder body, and the piston drives the pressurizing bracket and the pressurizing bearing to load the test shaft; and guide rail components are connected to both sides of the pressurizing bracket to ensure the stability of the pressurizing component during the lifting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0028] Figure 1 is a schematic structural diagram of the present invention according to one or more embodiments;

[0029] Figure 2 is a front view of the internal structure of the vacuum chamber of the present invention according to one or more embodiments;

[0030] Figure 3 is a top view of the internal structure of the vacuum chamber of the present invention according to one or more embodiments;

[0031] Figure 4is a partial cross-sectional view of the test part according to one or more embodiments of the present invention;

[0032] Figure 5 is a schematic structural diagram of the loading device according to one or more embodiments of the present invention;

[0033] Figure 6 is a cross-sectional view of the loading device according to one or more embodiments of the present invention;

[0034] Figure 7 is a partially enlarged view of the inner ring clamping according to one or more embodiments of the present invention;

[0035] Figure 8 is a schematic diagram of the outer ring clamping according to one or more embodiments of the present invention.

[0036] Wherein, 1. Servo motor; 2. Flange; 3. Atomic oxygen irradiation equipment; 4. Flange; 5. Ultraviolet irradiation equipment; 6. Proton irradiation equipment; 7. Handle; 8. Vacuum chamber; 9. Vacuum pipeline; 10. Vacuum equipment; 11. Temperature control pipeline; 12. Cooling pipeline; 13. Temperature control equipment; 14. Control device; 15. Control line; 16. Magnetic fluid sealing shaft; 17. Coupling; 18. Torque sensor; 19. First support; 20. Cooling shaft; 21. Rotary valve; 22. Second support; 23. Third support; 24. Self-aligning ball bearing; 25. First inner ring fixture; 26. Second inner ring fixture; 27. Compression nut; 28. Loading device; 28-1. Slide rail support; 28-2. Slide rail; 28-3. Slide block; 28-4. Pressing shaft; 28-5. Pressing bearing; 28-6. Piston; 28-7. Guide block; 28-8. Cylinder hole; 28-9. Valve; 28-10. Seal; 28-11. Sliding bearing; 28-12. Retaining ring; 28-13. Cylinder block; 28-14. Pressing support; 29. Test shaft; 30. Spherical plain bearing; 31. Temperature control fixture for bearing outer ring; 32. Fixture bolt. Detailed implementation manners

[0037] Embodiment 1:

[0038] This embodiment provides a spherical plain bearing life test device using pneumatic loading, especially for the life test of thin-film self-lubricating spherical plain bearings, as Figure 1 shown, including a space environment simulation part, a test part and a control part. The space environment simulation part is used to simulate the space environment during the test, such as simulating high and low temperatures, atomic oxygen irradiation, ultraviolet irradiation, proton irradiation, etc.; the control part is mainly composed of a control device 14 and a control line 15, and is used for the operating conditions of the test device, collecting the signals of sensors and displaying the change rules of data.

[0039] The specific structure of the life test device is as follows:

[0040] As Figure 1 and Figure 2 shown, the space environment simulation part includes a vacuum chamber 8, a vacuum device 10, a temperature control device 13 and an irradiation device. The vacuum chamber 8 is connected to the vacuum device 10 through a vacuum pipeline 9, and is connected to the temperature control device 13 through a temperature control pipeline 11 and a cooling pipeline 12. An irradiation device is installed outside the vacuum chamber 8. In order to facilitate changing the opening of the vacuum cavity, a handle 7 is installed on the vacuum chamber 8.

[0041] The temperature control device 13 is used to provide the high and low temperature environments required for the testing of the articulated bearing 30 and to offset the influence of the high and low temperature environments on the heat of other parts; the temperature control pipeline 11 is used to supply the liquid for the high and low temperature environments required for the testing of the articulated bearing 30; the cooling pipeline 12 is used to supply the cooling medium for the high temperature environment and the heating medium for the low temperature environment required for the testing of the articulated bearing 30.

[0042] The irradiation device in this embodiment includes an atomic oxygen irradiation device 3, an ultraviolet irradiation device 5 and a proton irradiation device 6. The atomic oxygen irradiation device 3, the ultraviolet irradiation device 5 and the proton irradiation device 6 are all installed on the top of the vacuum chamber 8 and are connected to the vacuum chamber 8 through a flange 4, and the foci of the irradiation devices should be located at the same point; it can meet the working conditions required for the vacuum environment testing, temperature testing and irradiation testing of the thin-film self-lubricating radial spherical plain bearing.

[0043] The testing part includes a power transmission device, a testing main body and a loading device 28. The power transmission device is connected to the testing main body and is used to provide rotational power for the testing main body; the loading device 28 is used to apply pressure to the testing main body.

[0044] As Figure 3 and Figure 4 shown, the power transmission device includes a drive source, a magneto-fluid seal shaft 16, a torque sensor 18, a rotary valve 21, a cooling shaft 20, and a self-aligning ball bearing 24. In this embodiment, the drive source is a servo motor 1. The servo motor 1 is installed outside the vacuum chamber 8 through a flange 2. The output end of the servo motor 1 is connected to the magneto-fluid seal shaft 16. The magneto-fluid seal shaft 16, the torque sensor 18 and the cooling shaft 20 are connected in sequence, and the torque sensor 18 is connected to both the magneto-fluid seal shaft 16 and the cooling shaft 20 through a coupling 17.

[0045] A first support 19 is installed at the bottom of the torque sensor 18. The torque sensor 18 is used to collect the torque value of the articulated bearing 30 during the testing process. A rotary valve 21 is detachably connected to the cooling shaft 20, for example, through a bolt connection; the bottom of the rotary valve 21 is supported by a second support 22.

[0046] Inside the rotary valve 21, there is a vertical through-hole. The through-hole coaxial with the servo motor 1 is used to install the cooling shaft 20, and the other through-hole is used to connect the cooling pipeline 12. The rotary valve 21 is connected to the temperature control device 13 through the cooling pipeline 12, and provides power for the test of the joint bearing 30 through the cooling shaft 20 and the rotary valve 21, offsetting the heat generated during the test of the joint bearing 30 and monitoring its operating state at the same time.

[0047] As Figure 4 shown, the test body includes a test shaft 29, an inner ring fixture, and an outer ring temperature control fixture 31 for the bearing. The joint bearing 30 is installed at a specific position on the test shaft 29, and this position should be at the focal point of the atomic oxygen irradiation device 3, the ultraviolet irradiation device 5, and the proton irradiation device 6.

[0048] One end of the test shaft 29 is connected to the cooling shaft 20 through a coupling, and a self-aligning ball bearing 24 is installed at the end close to the cooling shaft 20. The self-aligning ball bearing 24 is supported by the third support 23. The self-aligning ball bearing 24 is used to adjust the shaft eccentricity during the test and improve the test accuracy.

[0049] As Figure 7 shown, a first inner ring fixture 25 is installed on one side of the joint bearing 30, and a second inner ring fixture 26 is installed on the other side. On the side of the joint bearing 30 opposite to the self-aligning ball bearing 24, there is a compression nut 27. The compression nut 27 clamps the inner ring of the joint bearing 30 and the inner ring fixture through the thread on the test shaft 29, making the inner ring of the joint bearing 30 relatively fixed to the test shaft 29. At least two compression nuts 27 are provided to ensure that they do not loosen during the reciprocating motion.

[0050] The outer ring temperature control fixture 31 for the bearing is installed on the outside of the joint bearing 30, and the outer ring of the joint bearing 30 is clamped by adjusting the fixture bolt 32 at the top of the outer ring temperature control fixture 31 for the bearing. As Figure 8 shown, the outer ring temperature control fixture 31 for the bearing is provided with a through-hole, and the through-hole is connected to the temperature control pipeline 11 to provide the required ambient temperature for testing the joint bearing 30.

[0051] In this embodiment, the outer ring temperature control fixture 31 for the bearing can be installed with vibration sensors, temperature sensors, etc. to monitor vibrations, temperature rises, etc. during the test.

[0052] As Figure 5 and Figure 6 shown, the loading device 28 includes a cylinder block 28-13, a piston 28-6, a pressurizing component, and a slide rail component. The piston 28-6 is connected to the cylinder block 28-13 through a seal 28-10. The seal 28-10 can be selected from magnetic fluid, liquid metal, sealing rings, etc.

[0053] The extended end of the piston 28-6 is connected to the pressurizing assembly. Slide rail assemblies are symmetrically installed on both sides of the pressurizing assembly. Introducing gas or liquid into the cylinder block 28-13 can cause the cylinder block 28-13 to drive the pressurizing assembly to rise. A valve 28-9 is installed on one side of the cylinder block 28-13 for introducing gas or liquid with a certain pressure into the cylinder block 28-13. A cylinder block hole 28-8 is also provided on the side of the cylinder block 28-13. The cylinder block hole 28-8 is located above the valve 28-9 and is used to communicate with the environment inside the vacuum chamber 8.

[0054] A guide block 28-7 is installed on the top of the cylinder block 28-13. A hole for the piston 28-6 to pass through is provided at the center of the guide block 28-7. A sliding bearing 28-11 is sleeved on the piston 28-6, and the outer side of the sliding bearing 28-11 is in contact with the hole wall of the guide block 28-7. A retaining ring 28-12 is installed on the upper side of the sliding bearing 28-11. Through components such as the guide block 28-7, sliding bearing 28-11, and retaining ring 28-12 inside the cylinder block 28-13, the vertical movement of the piston 28-6 is ensured.

[0055] The pressurizing assembly includes a pressurizing bracket 28-14 and a pressurizing bearing 28-5. The pressurizing bracket 28-14 is connected to the top of the piston 28-6, and the pressurizing bearing 28-5 is connected to the pressurizing bracket 28-14 through a pressurizing shaft 28-4; the load is transmitted by contacting the test shaft 29 through the pressurizing bearing 28-5.

[0056] In this embodiment, two pressurizing bearings 28-5 are provided, and the axes of the two are parallel to the axis of the test shaft 29; a pressurizing area is formed between the two pressurizing bearings 28-5.

[0057] Both ends of the pressurizing bracket 28-14 are respectively connected to the slide rail assemblies to ensure that the direction of the applied load is perpendicular to the bottom surface of the vacuum chamber 8. The slide rail assemblies include a slide rail bracket 28-1 and a slide rail 28-2 fixed to one side of the slide rail bracket 28-1. The slide rail 28-2 is arranged vertically; the slide rail 28-2 is slidably connected to a slider 28-3, and the slider 28-3 is connected to the pressurizing bracket 28-14; under the action of the piston 28-6, the pressurizing assembly can move up and down along the slide rail 28-2.

[0058] When this embodiment is in use, first, the cylinder block 28-13 is installed in the vacuum chamber 8. Since the pressure inside the chamber is the same as the atmospheric pressure outside at this time, the piston 28-6 does not do external work and remains stationary. Subsequently, the spherical plain bearing 30 is installed at the set position of the test shaft 29, that is, at the focal point of the atomic oxygen irradiation device 3, ultraviolet irradiation device 5, and proton irradiation device 6. Then, the inner ring fixture and the bearing outer ring temperature control fixture 21 are installed at the determined positions of the spherical plain bearing 30, and the inner ring and the outer ring are fixed through the fixture bolts 32 and the compression nuts 27.

[0059] Then, based on the required space environment test parameters, the control unit adjusts the test speed, irradiation equipment, temperature control device 13, and vacuum equipment 10 accordingly, and collects sensor signals. Once vacuum equipment 10 begins operating, the gas pressure within vacuum chamber 8 decreases. Due to the internal and external pressure differential, the pre-formed gas within cylinder 28-13 begins to perform work, pushing piston 28-6, which in turn pushes pressurized support 28-14, which is then blocked by test shaft 29, applying a load to test shaft 29.

[0060] Once the predetermined gas pressure is reached, the load is applied to the spherical plain bearing 30 under test. The torque sensor signal is then monitored by the control device to enable real-time monitoring of the bearing's condition. After the test is complete, the pressure within the vacuum chamber is restored to atmospheric pressure, at which point the load is reduced. Finally, the relevant fixtures are released, and the spherical plain bearing 30 under test is removed.

[0061] This embodiment utilizes the low pressure within vacuum chamber 8 by pre-filling cylinder 28-13 with a gas or liquid at a predetermined pressure. When the vacuum chamber pressure drops, the pressure differential between the inside and outside of cylinder 28-13 generates a load. Furthermore, a space environment simulation device is designed to simulate high and low temperatures, atomic oxygen irradiation, ultraviolet radiation, and proton irradiation. Furthermore, it can collect real-time status signals during spherical plain bearing testing, effectively analyzing the service characteristics of the spherical plain bearing and providing support for its actual service.

[0062] Example 2:

[0063] This embodiment provides a method for testing the life of a spherical plain bearing using air pressure loading. The test apparatus described in Example 1 is used. A thin-film self-lubricating radial spherical plain bearing is described in detail with an inner diameter of 10 mm, an outer ring width of 8 mm, a cylinder filled with gas at 1 standard atmospheric pressure, an inner diameter of 80 mm, a test vacuum condition of 1 × 10-4 Pa, and a loading load of approximately 502.4 N. The method includes the following steps:

[0064] Step 1: Based on the required load size, the required cylinder diameter is obtained according to the formula F = (P1-P2) × S (F is the load, P1 is the pressure inside the cylinder, P2 is the pressure of the vacuum chamber, and S is the area of the cylinder).

[0065] Step 2: Install the cylinder in the vacuum chamber;

[0066] Step 3: Install the thin-film self-lubricating radial spherical plain bearing on the set position of the test shaft, then install the inner ring fixture and the bearing outer ring temperature control fixture at the appropriate position of the spherical plain bearing, and fix the inner ring and outer ring of the radial spherical plain bearing with the fixture bolts and compression nuts.

[0067] Step 4: According to the required space environment parameters, the test speed, irradiation equipment, temperature control equipment, and vacuum equipment are adjusted through the control part, and the sensor signals are collected.

[0068] Step 5: As the gas / liquid pressure in the vacuum chamber decreases, the prefabricated gas / liquid inside the cylinder begins to work due to the internal and external pressure difference, pushing the piston rod to move, and then pushing the pressurized bracket to move, which is hindered by the test shaft, causing the load to be added to the test shaft.

[0069] Step 6: Wait until the pressure inside the vacuum chamber reaches the set value and the test load is applied;

[0070] Step 7: During the test, the torque signal and other state parameters that can characterize the performance of the thin-film self-lubricating spherical plain bearing are collected in real time and displayed graphically.

[0071] Step 8: After the test is completed, the pressure inside the chamber is restored to atmosphere, the load is reduced, and then the relevant fixtures are loosened, and finally the tested spherical plain bearing is removed.

[0072] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for testing the service life of a spherical plain bearing using pneumatic loading, characterized in that, Adopt a joint bearing life test device using pneumatic loading. The test device includes a vacuum chamber, an irradiation device is installed on the top of the vacuum chamber, and a test body is arranged in the vacuum chamber. One end of the test body is connected to a power transmission device, and a loading device is arranged below the other end. The test body includes a test shaft for installing the joint bearing. The loading device includes a cylinder body with a preset medium inside. The cylinder body is connected to a pressurizing component through a piston. When the pressure in the vacuum chamber decreases the piston drives the pressurizing component to apply pressure to the test shaft. A valve is installed on the side of the cylinder body, and a cylinder body hole is provided. The test method includes the following steps: Install the joint bearing at the set position of the test shaft and clamp and fix it through an inner ring fixture and a bearing outer ring temperature control fixture. Adjust the irradiation device, temperature control device, and vacuum device according to the space environment parameters. As the pressure in the vacuum chamber decreases, based on the internal and external pressure difference, the preset medium in the cylinder body starts to do work, pushing the piston to move, so that the pressurizing component applies a load to the test shaft. Wait until the pressure in the vacuum chamber reaches the set value to complete the loading process.

2. The method for testing the service life of a spherical plain bearing using pneumatic loading according to claim 1, characterized in that, The power transmission device includes a driving source, a magneto-fluid sealing shaft, a torque sensor, and a cooling shaft connected in sequence. A rotary valve is installed on the cooling shaft, and the rotary valve is connected to the temperature control device through a cooling pipeline.

3. A method for testing the service life of a spherical plain bearing using air pressure loading according to claim 1 or 2, characterized in that Inner ring fixtures and bearing outer ring temperature control fixtures are installed at the positions corresponding to the joint bearings on the test shaft. The bearing outer ring temperature control fixture is connected to the temperature control device through a temperature control pipeline.

4. A method for testing the service life of a spherical plain bearing using pneumatic loading according to claim 3, characterized in that A plurality of compression nuts for clamping the inner ring fixture are also provided on the test shaft; a self-aligning ball bearing is installed at one end of the test shaft away from the loading device.

5. A method for testing the service life of a spherical plain bearing using air pressure loading according to claim 1, characterized in that Slide rail components are symmetrically installed on both sides of the pressurizing component.

6. A method for testing the service life of a spherical plain bearing using air pressure loading according to claim 1 or 5, characterized in that [[ID= 7. A method for testing the service life of a spherical plain bearing using air pressure loading according to claim 1, characterized in that, ​ 8. A method for testing the service life of a spherical plain bearing using pneumatic loading according to claim 1, characterized in that, ​

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