The main compressors currently used in the field of small-scale refrigeration and air-conditioning are: reciprocating piston type, rolling rotor type, scroll type, oscillating rotor type and high installation precision, high cost, high pressure differential working condition, refrigerator circulation and small displacement air conditioner. The leakage is large, the efficiency is low, and the manufacturing is difficult. Therefore, it is mainly used for air conditioners of 3HP or more, and the annual output of the world is close to 20 million units. (Rolling piston type deformation), these models each have their own characteristics. The rotary rotor compressor is a rolling piston type deformation, which is suitable for different applications. 61. Force and sealing performance is better than rolling piston type However, the sealing performance does not have the advantage of reciprocating piston type, which is reliable in sealing, and has accumulated mature experience after long-term development and production, mainly used in small refrigeration fields such as household refrigerators. Due to the relatively low refrigeration temperature in the refrigerator, the working pressure difference is large, and the working fluid flow is small. It has a fundamental change in the conventional process, and the manufacturing difficulty is higher than that of the rolling piston type 41. Currently, it is mainly used for air conditioners and water heaters. 17191. For more than ten years Although it is recognized that the HHFHC working fluid has reduced the ozone layer damage than the CFCCFC type working fluid, the pressure ratio is usually greater than 1021 when circulating with the HHFCC working fluid. Under such conditions, the reciprocating compressor has good sealing performance. The advantages are fully utilized to make it more comprehensive than other models, with more than 80 million such compressors produced worldwide each year. The main disadvantages of reciprocating compressors are the large number of valves, the large number of parts, the large vibration caused by the reciprocating parts, and the poor resistance to liquid hammer. These shortcomings limit the scope of application.
The advantage of the rolling rotor compressor is that it has fewer parts and saves one intake valve compared with the reciprocating type. The vibration is small and the high-speed frequency conversion performance is better than that of the reciprocating piston type, but its sealing performance is poor, when it is used for high-pressure ratio refrigeration conditions. Large leakage and low efficiency. This type of compressor is currently mainly used for air conditioners below 3HP, and its comprehensive performance index is relatively high. At present, the annual output of the world exceeds 50 million units.
The advantages of the scroll compressor are that there are few parts, no inlet and exhaust valves, small pressure fluctuations, good resistance to liquid hammer, small torque fluctuations, and high-speed frequency conversion performance. The scroll compressor has high efficiency in a certain displacement range and a certain pressure ratio. The disadvantage of this type of compressor is that it creates many hazards in the atmosphere, such as aggravating the room temperature effect. The research on natural working fluids has been carried out globally, especially with C02 as the research focus. Transcritical multi-stage or single-stage compression and the use of an expander instead of a throttle valve to recover part of the expansion work cycle is considered to be the best C02 cycle solution, which is more efficient than conventional cycles and has excellent application prospects 7~161. The ensuing problem is that the pressure difference of the C2 transcritical cycle is 5-10 times that of the traditional working fluid. A large number of research experiments have shown that the rolling piston type, scroll type, and oscillating rotor type compressors have poor sealing performance and large leakage when used for CO2 transcritical cycles, and cannot be effectively used. 117181. Currently, only reciprocating compressors can be used well, but reciprocating The inherent disadvantages of piston compressors limit their range of applications, and more importantly, if used for multi-stage (or single-stage) compression with an expander cycle, whether reciprocating or rolling rotor, vortex Both the oscillating and rotary compressors require multiple working cylinders, which inevitably doubles the valve, moving parts and auxiliary parts, resulting in reduced reliability and efficiency, increased space and manufacturing costs. This problem has become a problem in the development of C02 transcritical cycle applications. Therefore, the high-efficiency, high-reliability 7-body expansion compression mgHouse.Allngntsreserved.:Ir i.nei machine has become a worldwide frontier subject in the field of compressor research.
On the other hand, the currently widely used refrigerator refrigeration cycle has serious drawbacks. The pressure ratio of this single-stage compression refrigeration cycle when using HFC working fluid is usually greater than 10 in the actual operation of the refrigerator compressor due to motor heating and the like. The intake air temperature in front of the cylinder is generally higher than that of a piston pin seat; the cylinder head is provided with a shaft hole matched with the piston shaft, and the piston can freely rotate around the piston shaft in the shaft hole, and the spherical top surface of the piston has the same ball as the spherical inner cavity The heart forms a sealed dynamic fit; the center of the lower end surface of the turntable protrudes from a turntable shaft, and the outer peripheral surface between the upper portion and the lower end surface of the turntable is a spherical surface of the turntable. The spherical surface of the turntable and the spherical inner cavity have the same spherical center and are formed close to the spherical cavity. Sealing dynamic fit; corresponding to a piston pin seat on the upper part of the turntable; the center pin is inserted into the piston pin seat and the turntable pin seat, and the spindle bracket is connected with the cylinder body to provide support for the rotation of the main shaft, and one end of the main shaft is an eccentric crank. The eccentric crank is located in the cylinder body and connected to the turntable shaft, and the other end is connected to the power mechanism to provide power for the compressor to change the capacity; the piston shaft and the turntable shaft and the shaft of the main shaft Both pass through the center of the spherical cavity, and the axis of the piston shaft and the rotary shaft form the same angle with the axis of the main shaft. a. In this structure: Vi and V2 are primary compression, V3 and V4 are secondary compression, V5 and V6. For the expansion level.
2.1.3 Introduction to the working process The working process is as follows: the piston and the rotary table are driven when the spindle rotates (the steering of the main shaft is rotated clockwise from the cylinder head). The movement of the piston is the only rotation around its own axis. There are two kinds of motion synthesis: one is the rotation around its own axis, the other is that its axis always passes through the center of the spherical cylinder, and is centered on the center of the spherical cylinder, the cone angle is 2a axis coincides with the axis of the spindle. The circumferential movement of the cone surface (i.e., the axis of the turntable sweeps over the tapered surface of the cone) is synchronized with the period of spindle rotation.
The motion of the above space mechanism is a motion of rotation, so there is no high-vibration moving part. The result of this spatial motion is that the piston and the turntable have a periodic relative swing, and the period of the swing is twice the period of the spindle rotation, and the swing The amplitude of 4a uses this relative oscillation as the basic motion element of volume change, and utilizes the rotation of the piston and the cooperation of the spherical surface on the piston body with the inner surface of the spherical cylinder as an essential element for opening and closing of all intake and exhaust ports.
2.2 Advantages of spherical compressors 2.2.1 Reliable seals Any dynamic seals that need to prevent leakage of working fluids can be designed with a face-to-face dynamic seal with a considerable width to achieve a reliable sealing effect and a good lubrication surface. Reduce the leakage of working fluids.
2.2.2 No inlet and exhaust valves The compression and expansion processes of each stage do not need to be equipped with inlet and exhaust valves to reduce energy consumption and reduce noise, low cost and good reliability.
2.2.3 Two-phase flow is good, the hydraulic resistance is strong. Because each working chamber rotates around the axis of the piston, its mechanism structure is beneficial to the rotation of the liquid in the cylinder through the design of the airway position and local structure. Smooth discharge under the action of centrifugal force to avoid liquid shock and improve two-phase flow.
2.2.4 Compact structure and few parts There are still only 3 moving parts in the realization of multi-stage compression expansion, and the space occupation is small.
2.2.5 Smooth operation, high-speed frequency conversion performance is good. Because there are no air valves, parts are well lubricated, no reciprocating parts and moving parts that can cause high vibration, the operation is stable and the high-speed frequency conversion performance is good.
2.2.6 Low energy consumption Because of no air valve, reliable sealing, less moving parts, good lubrication of parts, etc., it has high efficiency and low energy consumption.
2.2.7 Low Manufacturing Cost Since the parts are basically spherical, cylindrical, flat, and small in number, they are easy to manufacture and low in manufacturing cost.
2.3 Motion and dynamic analysis - the angle of the piston around its axis 转 the angle of rotation of the turntable around its axis - the speed of the piston about its axis = -1 - the angular acceleration of the piston dt - the speed of the turntable around its axis - the angular acceleration of the turntable dt a - The angle between the piston axis and the axis of the turntable and the axis of the spindle V-working volume (two working chambers symmetrically per stage, the phase difference of 720° of the volume change period is 360.) is determined by the motion and dynamic analysis of the space mechanism.
Less 3 = 10 ° 20 today's graph.
2.4 Key Issues Tips From the above motion analysis, it can be seen that the rotation of the piston and the turntable about its own axis in the spherical compressor is not uniform, which is the only factor that causes the vibration of the spherical compressor. However, it can be seen from the analysis of dynamic characteristics that when the angle a is less than 20°, the value caused by the uneven velocity is very small, so by optimizing the design, selecting the appropriate angle a can make the vibration of the spherical compressor non-trend at the beginning. The end of the intake or exhaust is very slow. This feature facilitates the use of the in-cylinder clearance volume so that the inlet and outlet ports on the inner surface of the spherical cylinder are spaced apart in the circumferential direction by a sufficient distance to prevent simmering between the high and low pressure chambers. gas.
Exhaust gas is obtained for a longer period of time, thereby reducing flow losses and facilitating airway design.
From the structural analysis, it can be known that the increase of the a angle when the inner diameter of the spherical cylinder is constant is beneficial to the increase of the working volume V. V is proportional to 4a but the excessive angle a will cause the width of the sealing surface to decrease and the uneven rotation of the piston and the turntable to increase. Therefore, the application should be fully optimized according to different conditions of use.
The average speed of the turntable and its own axis is equal to and not fluctuating. Therefore, the friction speed between the outer surface of the piston and the turntable and the inner surface of the spherical cylinder is roughly proportional to today's = 1 V = K Deng Dingguo, Shu Pengcheng. Rotary compressor. Beijing: Mechanical Industry Press, Wu Yezheng. Design guide for small refrigeration units. Beijing: Mechanical Industry Press, 1998. Li Liansheng. Scroll compressor. Beijing: Mechanical Industry Press, 1998 Yu Yongzhang. Volumetric compressor technical manual. Beijing: Mechanical Industry Press, 2000 Zhao Yuanyang, Li Liansheng, Shu Pengcheng. The technical status and development trend of compressors. General Machinery, 2005 Zhao Yuanyang, Li Liansheng, Xiong Chunjie, Shu Pengcheng. Overview of scroll compressors. Liu Defeng Yu Bingfeng. Research progress in carbon dioxide transcritical compressors. Refrigeration Guo Wei, Peng College, Xing Ziwen. Development status of carbon dioxide heat pump water heater systems and compressors. Journal of Refrigeration, 2002 (1).
Wang Jinggang, Ma Yitai, Wei Dong, Wang Yihong. Research on refrigeration cycle of carbon dioxide transcritical two-stage compression belt expander. Journal of Refrigeration, 2001 (2).
Ma Yitai, Wei Dong, Wang Jinggang. The status quo and development trend of natural working fluid research at home and abroad. HVAC, 2003 (Li Minxia, ​​Ma Yitai, Li Lixin, Su Weicheng. Research progress in CO2 transcritical cycle refrigeration compressors. Compressor Technology, 2004 (5).
Guan Haiqing, Ma Yitai, Li Minxia, ​​Yang Junlan. Design and parameter calculation of CO2 swing piston expansion compressor for refrigeration and air conditioning. Mechanical design, parametric design of piston compressor parts developed by computer application in 2004 Bai Liangliang, Tang Liangbao (Guilin University of Electronic Technology, Guilin, Guangxi 541004, China) illustrates the specific design method to shorten the design cycle of piston compressors. Comparing the parametric design method based on PioE secondary development, it is easier to operate Solilworks with visualbasic6.0.
Introduction Piston compressors are general-purpose machines and have a wide range of applications in the fields of chemical engineering and refrigeration. In the series design process of the piston compressor, some parts with the same structure or similar and different sizes, such as pistons, connecting rods, connecting rod bolts, etc., are often repeated. The traditional design method is to design each part separately, which takes up most of the designer's time and energy, which seriously affects the development cycle of new products, thus restricting the technological progress and sustainable development of the enterprise. With the continuous application of CAD technology in enterprises, various CAD design software has been widely used. Soldworks software is the world's first 3D CAD software specifically designed for mechanical design in Windows environment by Solid woiks. Soldworks Soft: 2007 Serenity Red, Ma Yitai, Li Minxia. Thermodynamic analysis of carbon dioxide low temperature refrigeration cycle. Refrigeration and Air Conditioning, 2005 (6).
Chen Jiangping, Mu Jingyang, Chen Zhijiu. Research progress in the application of carbon dioxide automotive air conditioning systems. Refrigeration air conditioner and electric machine Shen Yongnian. Thermal process analysis and experimental study of scroll expander. Low temperature workers Li Lixin, Ji Jiangang, Le Weikang, Wang Rende. Environmentally friendly carbon dioxide transcritical refrigeration system. Journal of Southeast University, 2001 (4).
Zhou Zicheng. Carbon dioxide heat pump water heater. Refrigeration and air conditioning, 2005 (Wang Luyi. A variable-capacity mechanism for compressors. Chinese patent: ZL03114505. Wang Luyi. Ball compressor and expansion compressor capable of multi-stage compression. Zhong Wang Lu Yi. Carbon dioxide spherical expansion compressor Chinese patent: ZL20062 (1) 79799 cylinder and cylinder head connected to form a spherical cavity, the piston has a spherical top surface, a piston shaft from the center of the spherical top surface, the lower part of the piston
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