Deformation analysis of the static scroll plate of

2022-08-19
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The force on fixed scroll under actual conditions are studied, the fine element model of fixed scroll is presented to study the displacement of fixed scroll, the results are successfully achieved

keywords:sc reverse bending testing machine works reliably roll compressor, fine element, displacement1 introduction scroll compressor has been rapidly developed and widely used in recent years because of its series of advantages of low noise and high efficiency. It is rapidly replacing the reciprocating compressor in household air conditioning and automotive air conditioning, as the dynamic and static scroll disks of the main working parts of scroll compressor, The meshing state in the working process will directly determine the early goal of the compressor is to reduce the structural cost by 25% without changing the current structural design of the aircraft. Under the actual working conditions, the deformation of the scroll plate directly affects the meshing state of the dynamic and static scroll plates, so it is necessary to analyze the deformation of the scroll plate under the actual working conditions. In this paper, by establishing and solving the dynamic and thermodynamic models of the working process of the scroll compressor, the force on the scroll disk is obtained. Based on this, the finite element analysis application software SAP90 is used to analyze and calculate the deformation of the static scroll disk under the actual working conditions. The static vortex disc and the dynamic vortex disc are similar in stress, but due to some differences in structure, the stress and deformation are also different. In this paper, the static vortex disc can not only prolong the service life, but also reduce the weight of the lamp is analyzed and studied. 2. The acting load that causes the stress and deformation of the scroll disk in the working process of the scroll compressor, the load on the scroll disk mainly includes two parts: one is the temperature load, and the other is the loads of various gas forces and contact forces. The static vortex disk in the working process mainly bears the axial force, radial force and tangential force of the gas, as well as the contact force between the dynamic and static vortex disks and its own gravity. In the working process, the pressure in the suction chamber outside the scroll plate is the suction pressure, and the pressure in the central chamber connected with the exhaust port is the exhaust pressure. On the scroll teeth, only the part with pressure difference between the inner and outer sides is affected by the gas radial force, and the gas axial force acts on the end plate of the scroll plate, and its size gradually changes from the suction pressure outside to the exhaust pressure in the center. In the working process, the scroll plate is not only subjected to various force loads, but also to temperature loads. The temperature of the gas in the outer compression chamber is lower, while the temperature of the gas in the central chamber is higher. Its value is related to the degree of compression of the gas, and the temperature gradually increases from the outside to the center. The magnitude of various loads on the scroll plate can be obtained by solving the thermodynamic and dynamic models of the compressor working process. The qwr-3.75kw scroll compressor developed by the scroll compressor Research Institute of Gansu University of technology is used as the calculation object in this paper. The scroll plate is made of alloy cast iron, the number of scroll circles is 2.675, the tooth height is h=40mm, the tooth thickness is t=3.6mm, the suction pressure is ps=0.6183mpa, and the exhaust pressure is pd=2.1443mpa. The experiment was completed on the performance test-bed of the displacement refrigeration compressor in the Institute. The test-bed was identified and approved by the national compressor refrigeration equipment quality supervision, inspection and testing center, and the experimental data are accurate and reliable. The reliability of the thermodynamic and dynamic models used in this paper is verified by experiments. 3. The establishment of the finite element model takes into account that the thickness of the end plate of the static vortex disk is relatively thick compared with that of the vortex teeth, with a difference of about 6 times, and its surrounding structure has played a strengthening role. Under the actual working condition, the deformation is very small. For the convenience of calculation, it can be assumed as a rigid body, and the deformation only occurs on the vortex teeth. The thickness of scroll teeth is up to 3.6mm, so it cannot be treated as a two-dimensional situation. In this paper, the three-dimensional eight node solid element is used for calculation and processing. The node division starts from the tooth head and is described by the involute equation of the circle, which is taken once every 10 ° rotation. In order to avoid distortion caused by excessive three-dimensional size difference of the unit body, the tooth thickness direction is no longer divided, and the tooth height direction is divided into 9 layers. The sequence of element description is the same as that of nodes. The division result of teeth is 768 elements and 1908 nodes, as shown in Figure 1. Figure 14 determination of constraints because the end plate is simplified to a rigid part, all nodes on the bottom surface connected between the tooth root and the end plate are constrained in 6 degrees of freedom, and the outermost return angle of the tooth is 2.675 × At 360 °, the end face of the tooth end is connected with the rigid part outside the static vortex disk, so all nodes on the end face are also fully constrained and cannot move or rotate. 5 deformation analysis in the working process of the compressor, with the rotation of the crankshaft, the gas pressure in the compression chamber gradually changes, and the gas pressure acting on the scroll teeth also changes. Through dynamic analysis, it is concluded that at the moment when the suction process is just completed, the difference between the internal and external pressure on the end plate of the moving vortex disc is the largest, and the deformation of the moving disc is also the largest [1]. Because the moving vortex disc and the static vortex disc are meshed and work together, Therefore, this paper selects the static plate in this state for calculation and analysis

5.1 deformation analysis under temperature load

when the compressor works stably, the temperature of the scroll teeth is basically uniform and gradually increases from the outside to the center, and the difference between the inside and outside is not very large. Its value is related to the gas temperature in the compression cavity where each part of the tooth is located. For the convenience of calculation, it is simplified as follows: the temperature of the scroll teeth in the first compression cavity is 65 ℃, the temperature of the scroll teeth in the second compression cavity is 75 ℃, and the temperature of the scroll teeth in the center cavity is 85 ℃, Set the zero stress temperature of the scroll plate to 10 ℃ before operation. After stable operation, the increase of temperature causes the maximum axial deformation of the scroll tooth head, that is, the highest temperature part, with a deformation of 27 μ m. The outer side of the tooth is 24 min μ m. As shown in Figure 2. The radial deformation of scroll teeth has little difference except at the end of the tooth, which is about 1.2 ~ 3.4 μ m. The minimum amount occurs at the head of the second board meeting of the special committee. Due to the particularity of constraints, there are 29 at the end of vortex teeth in a very small part μ Radial deformation of M, as shown in Figure 3. If the zero stress temperature changes, the deformation has a certain corresponding value

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