In the volumetric compressor, the screw compressor has more and more applications due to its advantages of simple structure, reliable operation and convenient maintenance. Especially in power compressors, it has become an inevitable trend to replace conventional piston compressors with screw compressors. In order to meet the market demand of urban rail vehicle applications, our factory has undertaken the development of a series of screw compressors for urban rail vehicles. This paper introduces the development process of the 16 m 3 screw air compressor main engine. 1 Technical parameters The main technical parameters and requirements of the LFK-1 6/10 fuel injection screw air compressor are as follows: exhaust pressure: 1 0MPa (gauge pressure); anode rotor speed: 2940 r / min; displacement: 1 6m 3 / min; shaft power: 11 5 kW; drive mode: motor direct connection; cooling method: air cooling. The 2 type line design has developed a new rotor line for the requirements of urban rail conditions. The profile is characterized by bilateral asymmetry, and all of the constituent tooth curves are arc or arc envelopes. The rotor profile can completely complete the surface-to-surface sealing between the rotors, help to form a fluid dynamic lubricating oil film, reduce lateral leakage through the contact line, and improve compressor efficiency. In addition, the processing properties of the rotor are improved and it is easy to process by grinding. The end face pattern and the number of teeth of the designed line are as shown. 3 Theoretical calculations (1) Volumetric flow The actual volumetric flow of a screw compressor refers to the actual volumetric flow that is converted to the inhalation state. Considering volumetric efficiency, qv = v C n1 CD 1 2 Ln 1 where qv is the volumetric flow rate, m 3 /min; v is the volumetric efficiency, usually 0 75 0 95; C n1 is the area utilization factor; C is the twist angle Coefficient; D 1 is the outer diameter of the male rotor, m; L is the length of the rotor, m; n 1 is the rotational speed, r / min. According to the simulation results of the working process of SCCAD software, the volumetric efficiency is v = 88%. Considering the anode rotor speed n 1 = 2 940 r/min, the volumetric flow rate of the designed compressor is obtained: qv = 0 88 0 46634 0 975 0 1 2 0 136 2940= 1 6 m 3 / min( 2) The theoretical isentropic adiabatic power of the design condition of the shaft power is: N ad = nn - 1 psqvpdps n- 1 n - 1 / 60 Is the isentropic adiabatic power of the compressor, kW; n is the isentropic index of the compressed gas; ps is the suction pressure of the compressor, Pa; pd is the discharge pressure of the compressor, Pa. By introducing the relevant parameters into the formula, the isentropic adiabatic power of the designed condition can be obtained. N ad = 1 4 1 4- 1 10 5 1 6/ 60 11 1 4- 1 1 4 - 1 = 9 2 kW According to the working process simulation results of the SCCAD software, take the heat indicating efficiency i = 85%, and take the machine Efficiency m = 95%, compressor shaft power: N s = N ad im = 9 2 0 85 0 95 = 11 4 kW (3) Oil cooler heat load 1) The fuel injection amount is 5 times the gas mass flow rate, then: G 0 = qv 1 15 5 = 9 2kg/ min 2) The exhaust gas temperature can be calculated by the heat balance type The gas temperature T d is N s = G g C pg(T d - T sg) + G o C po(T d - T so) where N s is the compressor shaft power, kW, taking 11 4 kW; G g For gas mass flow, kg / s; G o is the mass flow rate of injection, kg / s; C pg is the specific pressure heat capacity of the gas, kJ / kg K; C po is the specific pressure heat capacity of the oil, kJ / kg K; T sg is the inhalation temperature of the gas, the standard condition is 20; T so is the injection temperature, and T d is the exhaust temperature. Take T sg = 20 , T s 0 = 50 , and bring in the relevant parameters, then: 11 4 = 1 6 1 15 60 1 02(T d - 20) + 9 2 60 2 05 (T d - 50), so T d = 80 2 3) Oil cooler heat load Q = G 0 C po(T d - T s0) = 9 2/ 60 2 05(80 2- 50) = 9 5 kW ( 4) Cooling air volume Q g = Q/ (C pg t) takes t = 10, then: Q g = 9 5 60/ (1 02 10 1 15) = 48 5 m 3 / min 4 Host structure design (1) The determination of the gaps of each part is described in the literature 1, The selection of the clearance of the screw compressor needs to consider many factors, such as manufacturing precision, assembly error, thermal deformation, and normal clearance of the bearing. The rotor is machined with high precision grinding machine, and the body and cover are machined by machining center, which has high processing precision. At the same time, the rotor, the body and the end cover are all aged, which can eliminate the residual internal stress during the processing of the blank, so the matching clearance of each part is smaller. In addition to the use of a reasonable gap value in the design, the processing technology must also start with high-precision machining, using advanced special processing equipment and advanced technology to achieve design requirements. Only in this way can the leakage of the conjugate tooth profile engagement gap of the rotor be reduced, so that the influence on the compressor volumetric efficiency v is not obvious. At the same time, high-precision machining and assembly can avoid the biting and seizing of the rotor mating surface during the working process, making the operation smooth and reducing mechanical noise and vibration. (2) Determination of fuel injection amount According to the recommendation in Document 3, the screw injection capacity is controlled at 1% 2% of the volume flow rate, and the screw compressor has better performance. When the pressure is low, the value is small, and when the pressure is high, the larger value is taken. . In the LFK- 1 6/ 10 air compressor, the injection volume is designed to take 12% of the volume flow, ie 19 2 dm 3 / min. The volume of the storage tank is designed to be 20 dm 3 , which can meet the requirements. (3) Bearing selection instructions The main bearing of this machine adopts SKF bearing, a total of 6 bearings, which bear the axial and radial forces of the male and female rotors. At the suction end, both the male and female rotors use cylindrical roller bearings to withstand radial forces. According to the calculation result of the force of the rotor, the radial force of the cathode rotor at the suction end is small, and a smaller bearing can be used. There is a certain thermal expansion during the working process of the rotor, and the suction end face has a large gap, which allows the rotor to have a certain degree of axial movement. For the above reasons, the suction end uses a cylindrical roller bearing that can move axially to withstand the radial force, and the 4-point contact ball bearing is used to withstand the pure axial force. This arrangement allows the bearings to exert their respective advantages without affecting each other. . (4) Structure and performance of shaft seal This machine adopts HN2390 shaft seal made in Germany. The shaft seal is PTFE line contact shaft seal. It has the advantages of self-lubrication, high sealing line speed, high pressure and simple structure. It is a kind of shaft seal widely used in medium and small screw compressors at home and abroad. 5 Conclusion The host is completely self-designed from the line to the structure and developed independently. The main components of the mainframe are cast, machined and the assembly of the complete machine is completely autonomous. After the completion of the development of the host, all performance tests were carried out. The test data proves that the host meets the design technical requirements, and the index parameters of the machine performance such as volumetric efficiency and specific power are close to the level of international similar products. 80GSM Fast Dry Sublimation Paper 80Gsm Fast Dry Sublimation Paper,Fast Dry Sublimation Paper,Heat Transfer Printing Paper,Transfer Paper Roll Suzhou Hummberg Paper CO.,LTD , https://www.humpaper.com