Filters and related domestic and international sit -

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0 Introduction
hydraulic filter is used to control the hydraulic system an important component of oil pollution, its role is to filter the oil in the solid particulate pollutants, so that the oil pollution control in key hydraulic components that can withstand the limit, to ensure that the work of the hydraulic system reliability and extend component life. General, it is considered to filter the hydraulic system is safe, is not the case, which often result in failure to determine the hydraulic system of a misunderstanding, can not ignore the quality of the filter itself on the system. In the hydraulic system the correct choice of pollution control devices to achieve the target cleanliness of the system can directly improve system performance, extend component and oil life and reduce maintenance, and more than 80% to avoid the failure of hydraulic system.
With the improvement in the level of industrial automation, people as indispensable components of hydraulic system contamination control - the performance requirements of the filter - are increasingly high. Therefore, the International Organization for Standardization has been the introduction of new products, technical standards and product testing standards to meet the needs of the filter manufacturers and users of manufacturing demand.
1 standard and status of hydraulic filtration products
hydraulic filtration products are filters and filter . Filter by installation location, the filter can be divided into: oil filter, oil return filter, pressure line filter. ① oil filter: oil pipeline installed in the filter. ② back to the oil filter: Install the tank back to the oil port and pipeline on the way back to the filter. ③ pressure line filter: Install the pressure piping in the filter.
filter according to the installation location, the filter can be divided into: oil filter, oil return filter, pressure line filter . ① oil filter: suction port installed in the fuel tank or oil filters in the filter. ② back to the oil filter: back to the oil tank installed in the mouth or back to the oil filter in the filter. ③ pressure pipe filter: Install the pressure line filter in the filter.
by selected filter, the filter can be divided into: inorganic fiber filter, paper filter, metal mesh filter. ① inorganic fiber composite filter: filter material for the inorganic fiber composite filter. ② paper filter: filter material for the plant fiber filter paper. ③ metal mesh filter: filter material for the metal wire cloth.
present, the technical requirements of hydraulic filtration products and their standards are three, as shown in Table 1.

Since the 20th century, since the early 80s, with the introduction of hydraulic pollution control technology, production of hydraulic filtration products is increasing. In recent years, the quality of filtration products exposed to a more serious problem, especially filter elements, and industrial products, lagging far behind the developed countries, and thus the technical requirements of the problem of filtration products to our customers and caused factory attention.
can be seen from Table 1, China's aviation industry in 1996 worked out by an industry standard HB 5825 - 1996, The plant may also have their own corporate standards, and our filter requirements of the national standard GB / T 20079 - 2006 and GB / T 20080 - 2006 is was formulated in 2006.
1.1 GB / T 20079 - 2006 \ 2006, mainly from the technical requirements, test requirements, test requirements, labeling, packaging, storage, etc. to the filter requirements:
(1) of the filter is mainly from the basic parameters, materials , performance, design and manufacturing aspects of proposed technical requirements, including:
1) basic parameters are: filtering accuracy, rated flow, the nominal pressure, dirt holding capacity, the sender pressure drop, pressure drop of the bypass valve open, bypass valve sealing performance, close the bypass valve pressure drop, flow bypass valve pressure drop, filter initial pressure drop, filter pressure drop flow curve.
2) performance requirements are: low-pressure sealing, high pressure seal, burst pressure, flow characteristics.
(2) test requirements are 12 trials: Experimental filtration, nano scale capacity test, the sender drop test, the bypass valve opening pressure drop test, drop test bypass valve is closed, by-pass flow test valve pressure drop, filter the initial pressure drop test, compatibility test, filters, low pressure sealing test, filters, high pressure sealing test, burst pressure test filter, filters, flow characteristics test.
1.2 GB/T20080- 2006 \ technical requirements, test requirements, test requirements, labeling, packaging, storage and other aspects of the filter make such a request:
(1) from the basic parameters of the filter material, performance, design and manufacturing aspects of the technical requirements, including:
1) of the basic parameters of hydraulic filter requirements are: filtering accuracy, nano scale capacity, rated flow filter, clean filter pressure drop, filter pressure drop limit, open the bypass valve pressure drop, bypass valve sealing performance, the bypass valve is closed pressure drop bypass valve pressure drop flow, structural integrity.
2) performance requirements are: structural strength filter: (axial strength, crushing strength), flow characteristics,; flow fatigue.
(2) testing requirements
are 11 trials: Experimental filtration, nano scale capacity test, flow characteristics test, test the structural integrity, structural strength test, flow fatigue test, compatibility test, the bypass valve opening pressure drop test, drop test bypass valve closed, the bypass valve pressure drop flow test, Clean filter pressure drop test.
1.3 HB 5825 - 1996 \ proposed general technical requirements, test methods and inspection rules are proposed in 1996 by aviation industry an industry standard. Content from the standard point of view , the standard is not only a product standard, but also a test method standards. Particularity of the aviation system, the standard of aviation hydraulic filters and filter also makes provision for a more rigorous technical requirements and test methods.
(1) technical requirements
technical requirements from the material, surface treatment, marking, design and structure, reliability, maintainability, performance, environmental requirements, etc. for the detailed provisions.
which, in the performance of the filter, 11 demands : structural integrity, the maximum aperture, the initial filtration, the average specific filtration, pollutant carrying capacity, compared compatibility, cold start, flow fatigue cycle, media migration, axial strength, crush strength.
the filter has 28 requirements: appearance , bypass valve air tight, opening pressure, closing pressure, pressure drop and life, self-styled device leakage and life, pressure indicator indicates pressure, temperature, life, pressure pulse,[link widoczny dla zalogowanych], mechanical shock, filters, low pressure seal, high pressure tightness, pressure, pollution, high temperature pressure impact, limit pressure, NW, environmental requirements are high and low temperature, temperature shock, vibration, shock, humidity, salt spray, mold.
(2) Test methods
test methods are based on technical requirements, performance requirements of each work out each of the corresponding entry procedures and methods of test, a total of 39 trials.
2 test of hydraulic filtration products and the status of
hydraulic filter should have high filtration efficiency, pressure loss and dirt holding capacity, etc. characteristics, and these properties need some test methods to evaluate. Sixties and seventies of the 20th century, some developed countries, proposed the assessment of the performance of hydraulic filter test methods and to develop appropriate national or industry standards, was gradually being adopted by the International Organization for Standardization and into international standard, widely used by countries around the world test of hydraulic filtration products used.
present, the domestic use of hydraulic filtration products in the testing standards in Table 2, Table 3.
2.1 ISO 2941 and GB / T 14041.3 hydraulic filter test method for resistance to cracking

This test is to assess the ability of the filter structure of pressure difference. When the hydraulic system in the cold start or filter completely blocked by pollutants, and traffic impact occurs when both ends of the filter will have a lot of pressure, will be destroyed on the structure of the filter,; therefore, to carry out this project inspection.
in the testing process, the system flow to maintain the rated flow in the filter,[link widoczny dla zalogowanych], then add the pollutants in the system, so that both ends of the pressure filter increased gradually until the resistance to rupture under pressure value; Remove the filter, through the ISO2942 test the structural integrity of the filter, the filter pass.
2.2 ISO 2942 and GB / T 14041.1 hydraulic filter test method for structural integrity

The main purpose of this standard test is to test the filter in the process of defects and damage to storage and transportation, such as rupture of the filter media, end cap bonding defects and cracks.
test method is to clean the filter installed in the test apparatus, immersed in isopropyl alcohol under the 12.5mm at the surface to filter through into to the set pressure of the compressed air, 360 ° rotation around the axis, the filter surface should be no obvious bubbles appear continuous, that is that the structural integrity of the filter pass.
2.3 ISO 2943 and GB / T 14041.2 hydraulic filter body material and fluid compatibility testing methods

This test is used to assess the work of a certain temperature, the influence of liquid on the filter material, filter material is brittle occurred , swollen softens and decomposition performance changes.
provided in this experiment to test temperature higher than the maximum filter manufacturers working temperature 15 ℃, but to pay attention to safety,[link widoczny dla zalogowanych], not to exceed the working fluid of the flash point. 72h test, you must filter through the ISO 2941 test of anti-fracture, to be qualified.
2.4 ISO 3723 and GB / T 14041.4 hydraulic filters rated load test method
axial
; in use, the filter end of the installation of hydraulic pressure and the role of applied force, and thus need to test under examination at the end of the filter is to load permanent deformation or damage occurs.
The trial is in the filter after the compatibility test, and finally need to break through the ISO 2941 anti-test.
2.5 ISO 3724 and GB / T 17488 hydraulic filter flow fatigue characteristics of the validation

; filter in the hydraulic system pressure and flow fluctuations often in the role, which filter material prone to damage and rupture caused by fatigue. This fatigue failure generally occurs in the folded filter cartridge line roots, by the pressure and flow fluctuations, folding root fatigue damage caused by repeated bending. The test is to simulate filter
work pressure changes that occur periodically, filter medium resistance to bending fatigue testing capabilities. Test, to maintain maximum pressure control pressure in the filter within 10% of the limit is zero and the maximum test flow loop between the cyclical changes to the required number of cycles, the requirements Bursting through the ISO 2941 test of the filter, the filter pass.
2.6 ISO 11170 Hydraulic fluid power - Filter elements - procedures for verifying performance characteristics of the filter is
The main function of the hydraulic filter element, and its performance is measured through a series of tests, and the standard was subject to a rational and effective use of the existing standard test methods for testing the performance characteristics of the filter process steps, and the use of at least the filter, the minimum number of tests, the best completion of eight permutations and combinations fully reflect the structural performance of the filter, filter performance test will be content.
2.7 ISO 3968 and GB / T 17486 hydraulic filter pressure drop versus flow characteristics of the evaluation

; oil flow through the filter, because the resistance of filter media on the oil pressure loss arising from certain, and therefore out of the oil in the filter between the mouth of a certain pressure. According to principles of fluid mechanics, fluid flows through the filter media and the pressure loss generated when the flow through, fluid viscosity, and the physical structure of filter media and other factors. Therefore, to select the correct filter, the filter in the hydraulic system under the nominal flow of least resistance, to be conducted on the filter pressure drop flow characteristics.
filter the test is to simulate the actual use of the state, in the test medium viscosity of certain preconditions, the test flow rate from zero to 10% of rated flow 10 points between the selected pressure measurements, and to find the best work area.
2.8 ISO 16889, ISO 4572 and GB / T 18853, GJB
3820 Hydraulic fluid power filters Filtration performance of a test system by way many times through the oil is circular, straight from the upstream pilot study entry Dust system, not pilot test the filter dust filter back to test the fuel tank in the test system, and many times through the loop filter, which is the pollutant concentration in the upstream changes.
many times through the test filter in the hydraulic system simulation of the actual working conditions, pollutants continuously immersed in from outside and within, the filter continuously filters In addition to some pollutants, but not filter out part of the cycle in the system and repeatedly through the filter. So many times through the law closer to the actual condition of filters, which were adopted by the International Organization for Standardization.
many times through the test include: assessment of different filter than the filter particle size, pressure characteristics, and the dirt holding capacity. Test, test system to maintain a certain flow, a continuous injection of pollutants to the test tank, with a differential manometer monitors the pressure difference across the filter, while the upstream and downstream from the filter to take oil samples, using online liquid automatic particle counters for particle count analysis of oil samples, the statistics of the allotted time, the number of particles when the pressure provided to calculate the filtration,[link widoczny dla zalogowanych], filtration, pollutant carrying capacity, assess the filtration performance of filter.
3 filter test the relationship between projects and standards for application of hydraulic filtration products
for the assessment of performance and product quality control, need to filtration products for a series of experiments, shown in Figure 1, reference the new national standards and GB/T20080 GB/T20079 required inspection items, the corresponding The method chosen criteria shown in Table 4. HB5825 has more severe because the technical requirements and test conditions, the standard is mainly used in aviation hydraulic filtration products. If necessary, other industries can also be implemented by reference.

standards in these tests, some reference standard is applied to each other. Such as the structural integrity of the test (GB/T14041. 1, ISO2942) in a number of test methods to be used: in a number of the experiment (GB / T 18853, GJB 3820, ISO 16889, ISO 4572); before and after the compatibility test (GB / T 14041.2, ISO 2943 ), flow of fatigue test (GB/T17488, ISO 3724), structural strength test of the anti-rupture test (GB / T 14041.3, ISO 2941) and the end of the load test (GB / T14041.4, ISO 3723) . Can see the structural integrity test (GB/T14041.1, ISO 2942) standard is the most basic test of the importance of the project.
is reasonable and effective use of these standard test method for testing the filter performance, ISO 11170 specifies the filter test procedures, as shown in Figure 1; below. The standard in determining the need for a comprehensive examination of a number of filter performance characteristics of the request, work out at least 3 filters need to select the whole test procedure can be completed. Therefore, examination of the filter, refer to the program method. Currently, the standards are being translated into national standards.
4 international and domestic standards development
4.1
with the development of international standards science and technology to improve industrial automation, hydraulic drive technology has been widely in the international application, in order to work the hydraulic drive system is more secure, reliable, efficient, and the corresponding key components - Filter production; - products technical requirements and inspection standards are constantly introducing new updates. March 2006, the International Organization for Standardization ISO/TC131/SC6N441 discussed at a meeting in Orlando, 37 standards, of which 12 standards have been established in the future expiration date, there are six for the existing criteria, 6 were under discussion, other proposals did not pass or deleted. Standard drafting schedule shown in Table 5.
4.2
the development of national standards in recent years as pollution control and monitoring of domestic hydraulic technology development, and testing equipment , instruments constantly updated, in the National Standardization Technical Committee of hydraulic and pneumatic organization, widely promoted and made amendments to a number of hydraulic pollution control standards, and related filter material test.
present, the current total of 20 domestic hydraulic pollution standards, of which the national standard of 17 (15 with ISO standards); Industry Standard 3. The six standards are being revised, GB 4, line marked 2. There are 4 standard adoption program, the Chinese standard GB / T 14041.3-1993 \ ISO standard ISO2941 is being revised, so not yet implemented. Proposes to develop the industry standard \ Standards development and adoption of domestic standard conditions shown in Table 6.
5 Summary
in a hydraulic system, the filter is to ensure that the system clean, improve the reliability of the work to extend the equipment a key component of life. And how to properly design, select the hydraulic system filter, you need to work according to their actual status, such as the installation location, role types, the use of appropriate technical standards for product design and manufacture of filtration products appropriate to meet the system requirements. Upon completion of design and manufacturing, product inspection process, also need to select a different type of product the appropriate test standards, a comprehensive and rational evaluation of its performance indicators.
Therefore, in order to promote technological development of filtration products, the need to constantly learn from the advanced science and technology, with reference to international standards, take people long make up our own short , the preparation for China's national conditions, scientific, advanced, operational testing of product technical standards and standards to reach the goal of improving the quality of filtration products, but also with the international Product technical specifications on the filter convergence purposes. Limit alarm.
1.3 function tests
pumping the hydraulic oil by the first attempt to directly drive the way mercury moves, so it is necessary to mercury and hydraulic oil compatibility study to confirm that the two can be well separated; In addition, to ensure the safety of system operation, it is necessary to pump too far and whether mercury into the oil system, the actual assessment.
end, were the static mercury and hydraulic oil compatibility tests, and dynamic security testing, test case in Figure 2 , Figure 3 instructions.

The results show that the static compatibility tests: hydraulic oil, and mercury can be well separated from the mercury in the following proportion, hydraulic oil and a small proportion of the above.
Dynamic Safety Test results show that: when all the mercury in a jar, to continue to pump hydraulic oil, hydraulic oil will take up through the mercury, The hydraulic oil is not to take up with mercury beads, mixed with mercury will not go into the oil system, the system is not security issues. Pumping stopped, the rest of about 2h, the mercury level can be maintained is maintained, proved that the robot pitch attitude stability is maintained after adjusting.
the above experiment, confirmed that sent the mercury-type hydraulic pump control system trim the feasibility and safety of the system can be adjusted to meet the underwater robot pose necessary to meet system performance requirements.
2 Summary and Outlook
the topics, type of hydraulic pump to send the mercury trim control system design and research, and compatibility tests were static and dynamic security testing. The results show that: the use of mercury in the hydraulic pump to send the attitude control system is entirely feasible; according to the weight of a suitable design configuration of the mercury mercury tank volume, the system is to guarantee security.
fact, both the hydraulic oil system or the mercury system, water use and water are not guaranteed to completely cut off from the absolute zero leakage does not exist. Meanwhile, the liquid mercury is difficult to seal, and there are highly toxic and can cause leakage of mercury pollution on the environment and human body injury. In order to eliminate this adverse effect, it has been carrying out a large flow of water directly to the hydraulic system to achieve the attitude adjustment underwater robot research and development work. However, with the depth of work required to increase the pressure on the improvement of sea water pump, to ensure a large flow of sea water pump is still very difficult task.
According to reliable sources, the current maturity of the domestic sea water pump technology has reached 14MPa, 100L/min. The United States is developing the \
of materials science is currently developing very rapidly, a variety of new construction materials (such as engineering ceramics, polymer materials and corrosion resistant alloy, etc.) continue to emerge, precision processing technology advances, and water hydraulic technology has matured, water hydraulic system of underwater robots in the future be more widely used.

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