Main development trend of hydraulic transmission technology
Main development trend of hydraulic transmission technology
1. Reduce energy consumption and make full use of energy
(1) Reduce the loss of pressure energy. Reduce the internal pressure loss of components and systems to reduce power loss. The use of integrated circuit and cast runner can reduce pipeline loss and oil leakage loss.
(2) Reduce throttling loss and minimize the use of throttling system to regulate flow and pressure.
(3) Static pressure technology and new sealing materials are adopted to reduce friction loss.
(4) Improve hydraulic system performance.
2. Leakage control
Leakage control is an important subject to improve the competitiveness of hydraulic transmission and electrical and mechanical transmission. It mainly includes two aspects: one is to prevent the leakage of liquid to the outside and cause environmental pollution; The second is to prevent the infringement of the external environment on the system.
Develop leak free components and systems; Develop integrated and composite components and systems, realize pipe free connection, and develop new sealed and leak free pipe joints and combined devices of motor and pump (pump is installed in the middle of motor rotor to reduce oil leakage of pump shaft seal).
Pay attention to solve the sealing problems of the system, such as isolated oil tank, design of new piston rod protection device, etc.
3. Pollution control
(1) Develop closed sealing system. Prevent dust, dirt, air and chemicals from invading the system. Establish technical specifications to ensure component cleanliness and study economic and effective cleaning methods.
(2) Improve the component design to make the component have greater pollution resistance and allow the component and system to withstand the erosion of various pollutants.
(3) Develop high-efficiency filter materials and filters with strong pollution resistance.
(4) Develop oil-water separation and purification device, dehumidification device and device for removing bubbles in oil to remove gas and water contained in oil.
(5) Develop new pollution detection methods to measure pollution online.
4. Active maintenance
In case of any sign of failure, carry out maintenance in advance to eliminate the hidden trouble and avoid the occurrence of malignant accidents. To modernize the fault diagnosis of hydraulic system, strengthen the research of expert system, and develop the general tool software of hydraulic system fault diagnosis expert system. The development of hydraulic system self compensation system, including self adjustment, self lubrication and self correction, and self compensation before failure, is the direction of the hydraulic industry.
(1) The application of will continue to expand. Pressure, flow, position, temperature, speed, acceleration and other sensors shall be standardized. Computer interfaces shall also be unified and compatible.
(2) The flow, pressure, temperature, oil pollution and other values of the hydraulic system will be measured and diagnosed automatically. Due to the reduction of the price of the computer, the monitoring system, including centralized monitoring and automatic adjustment system, will be developed.
(3) Computer simulation standardization, especially for high-precision and advanced systems.
(4) The electronic direct control hydraulic pump adopts the general standardized regulation mechanism and changes the program of the electronic controller to realize various regulation modes of the pump.
(5) Improve the performance of hydraulic components to meet the needs of mechatronics. Develop embedded sensors and intelligent hydraulic components with computer and self-management function (fault diagnosis and troubleshooting).
6. Application of computer technology
(1) To enrich the existing hydraulic CAD design software and carry out secondary development, we should concentrate the experience and wisdom of hydraulic experts to establish a knowledge base information system to form a closed cycle of design, manufacturing, sales and use.
(2) By combining computer simulation with real-time control and putting the model into the hardware system, the characteristic parameters can be modified in the software before the actual prototype is built, so as to achieve the best design result.
(3) Long term goal: fully develop hydraulic products by using CAD technology, from conceptual design, appearance design, performance design, reliability design to detailed design of parts, and integrate computer-aided design (CAD), computer-aided analysis (CAE), computer-aided process planning (CAPP), computer-aided inspection (CAD) and computer-aided testing (CAT) Integrated with modern management system to establish computer integrated manufacturing system (CIMS), which makes a breakthrough in hydraulic design and manufacturing technology.
(4) Closely combined with high and new technology, especially microelectronic technology, computer technology, sensor technology, etc.
7. Reliability and performance stability continue to improve
(1) With the continuous introduction of new materials, new processes and new structures, a new generation of materials such as engineering plastics, composites, fine ceramics, low resistance and wear-resistant materials, high-strength light alloys and memory alloys will gradually enter the practical stage. Generally reduce the damage caused by adhesion, scratch and cavitation.
(2) The system reliability design theory will be mature and popularized. Reasonable selection and matching of components, comprehensive analysis of predictable factors as far as possible, and elimination of potential factors inducing faults to the greatest extent have become an essential content of reliability design in system design.
(3) Strengthen and improve the filtration technology of system media. The research shows that the entry of particles larger than the gap is the root cause of wear. Continuously strengthening and improving the filtration technology is the fundamental measure to prolong the service life of components and ensure the reliability and stability of the system.
High precision filters (1-3ym) and filters with new materials and structures such as glass fiber can effectively improve the scale carrying capacity, reduce the degree of sedimentation and enhance the filtration efficiency.
8. Enhance adaptability to the working environment
(1) Attach great importance to energy consumption control technology. With the increase of pressure, energy consumption control is more important. This problem involves the development prospect of hydraulic technology.
(2) Further reduce the working noise. The fully enclosed power combination of pump motor with noise reduction and noise isolation structure is expected to achieve excellent noise reduction effect. The key to system noise reduction is to improve the design level and introduce a dynamic design concept. Of course, it is also necessary to study the electromagnetic switching with impact reduction, no impact and adjustable action time.
(3) Research on improving the performance and adaptability of alternative media.
1) At present, environmental protection media have been proved to be available under certain conditions, including natural fat or synthetic ester and vegetable oil. Vegetable oil represented by vegetable oil is ideal and is a promising environmental protection medium.
2) Water-based medium is a very promising anti combustion medium, including water glycol, water oil emulsion, high water-based medium (HWBF) and so on. It is necessary to improve the stability and important quality indexes of water-based media, and gradually promote its application. Other high-quality flame-retardant media continue to be developed internationally, such as chlorotrichloroethylene (CTFE) with excellent flame resistance, which has been applied in military equipment.
3) "Electrorheological" liquid is a two-phase suspension in which solid particles are mixed in the base liquid. Under the action of electric field, it has the electrorheological effect of rapid conversion between liquid and solid, which can be sensitively controlled. If the control with ER fluid as the medium can be realized, the flow impedance can directly feel the electric field signal and adjust the change. Once this unique liquid is successfully studied, it will cause a major change in hydraulic technology.
4) The research on material adaptability is an unavoidable technical problem in the use of alternative media and emerging media. The first is the sealing material and the most suitable friction pair material. A lot of time-consuming tests need to be carried out. Choose materials with good compatibility and abandon materials that can not be used.
(4) Develop horizontal derivative products. The standardization of connection dimensions, the generalization of core parts and the development of horizontal derivative series products are the most economical and effective ways to meet the diversified needs of different levels of the market in various environments. For example, like the standard solenoid valve, in addition to the basic type, it can also derive a series of varieties such as high pressure, high speed, low energy consumption, low noise, no impact and suitable for water-based media, which can be selected by users.
9. Highly integrated to improve the functional density of components
(1) The combination of single functional components is developing to multi-functional components. The integrated multi-functional components which only change the shape of the separated component valve body and are combined according to the functional needs are the primary form of integration. From the working principle, it is still similar to the separation elements, such as superimposed valve blocks, and its combination degree and structural compactness are greatly limited.
The multi-function valve focuses on the thorough transformation of the valve core of the function, and uses the changes of pressure, differential pressure and flow signals to realize different functions through the relative movement of different parts. The shape is similar to that of single function components, so the structure can be highly compact. For example, a multifunctional valve used in the closed pump motor system of construction machinery can complete four functions: one-way oil supplement, high-pressure overflow, bypass and pressure release.
(2) Integrated device subsystem. This is an integrated device composed of representative functions, or a pump or cylinder with certain functional flexibility, even including energy conversion elements, which has strong universality. Users only need to connect with the actuator or power source to form a system with excellent performance, which greatly facilitates users. This modular subsystem integrated device makes the boundary between the system and components increasingly blurred, and is also conducive to improving the technical level of users.
For example, the development of cartridge valve in the form of integrated control block and function expansion block is an example. The core component of cartridge valve composed of valve core, valve sleeve and spring is a highly simplified and versatile structural form. Various hydraulic systems can be formed only by equipped with appropriate pilot control elements, valve body and valve sleeve. Obviously, there are more technical problems involved in the integrated device subsystem when the system is connected with a very mature single function conventional element. Manufacturers must undertake the parts with high technical content and develop relatively independent and flexible function blocks. Users can put forward ordering requirements and use them when they buy them, which is conducive to promoting the development of cartridge valve technology.
Another example is the power source integrated subsystem with the pump as the core, the integrated subsystem with the hydraulic motor or cylinder as the core, and even the compact integral hydraulic power unit including the motor, pump and cylinder.
(3) Strengthen the electronic part and develop intelligent integrated devices. With the development of integrated circuit, the weak current control part is gradually removed from the control cabinet, including a / D, D / a conversion, rectification, amplification circuit, etc. it is directly integrated into the hydraulic components to form an integrated device with high function density, which is convenient for direct interface with the computer. Even small microprocessors are integrated into the pump control circuit, and intelligent electronic devices are added between the control command and the proportional valve, which can not only realize various flexible adjustment modes, but also enable them to correct the artificial control signal, realize the reasonable distribution of power and automatically maintain the best working state; Realize additional intelligent functions such as soft start and braking.
10. Develop light and small devices and micro hydraulic technology
The demand for hydraulic technology in special application departments such as aerospace, aviation, submarine, car, robot and medical equipment is increasing. Their common characteristics are narrow installation space, low additional quality, high power density, response frequency bandwidth and fast speed. Only by vigorously developing light, small and micro hydraulic technology can we meet the challenges and demands of hydraulic technology.
(1) Improve the power density of light and small devices. For example, small superimposed valves and threaded cartridge valves with small diameter (6mm, 10mm) have been published successively. Cartridge valve was only a kind of valve used for large flow. Now it has broken through the diameter boundary of no less than 16mm, and the pressure level has been continuously improved, which is expected to reach more than 50MPa. Various light, small and high power density oil circuit blocks with compact structure and high reliability can be formed with a few parts, which is very convenient to use.
(2) Development of micro hydraulic technology. The problems in the field of micro hydraulic technology can not be solved by using conventional structures and methods. It will face a series of new topics to be studied and solved, such as structural materials, technology, assembly, inspection and so on.
Based on the above, in order to meet the development needs of mechanical products in the direction of high performance, high precision and automation, the main development directions of hydraulic products are: saving energy consumption and improving efficiency; Improve the control performance to adapt to the development of mechatronics; Improve reliability, service life, safety and maintainability; Adapt to environmental protection (reduce noise and vibration, no leakage).