< / P > < p > 2.2 design of flameproof enclosure structure [6-8] < / P > < p > the motor adopts explosion-proof structure. The frame shell is made of 12 steel plate Q235A, and the two end plates are 50 steel plate Q235A. Eight reinforcing ribs are welded in the frame. Cooling pipes are distributed around the engine base, and the cooling pipes are fixed on the end plate of the engine base by stretching process. < / P > < p > the end cover and the engine base are matched with the flame-proof surface of the stop, the junction box and the frame are of plane flameproof surface, and the push cover type flame-proof structure is adopted at the shaft through position. The explosion-proof principle is that there is a diameter difference of 0.15-0.2mm between the push cover and the shaft, which can not only ensure the sliding cover to move freely on the shaft, but also greatly reduce the axial explosion-proof gap, improve the safety, and push the cover through The key on the shaft rotates with the shaft, and there is no relative friction, which avoids the possibility of easily holding the shaft due to the small clearance. When the explosion occurs in the inner cavity of the engine base, the explosion pressure pushes the cover to move outward and collide with the bearing sleeve, blocking the propagation path of the explosion flame and playing the role of explosion-proof. At the same time, since the sliding cover can adjust the radial friction through free movement on the shaft, the wear of the push cover is very slight. According to the provisions of the explosion-proof standard, anti rust measures are required for the flame-proof surface. The flame-proof surface matched with the sliding cover is made of stainless steel, including stainless steel shaft sleeve (interference fit with shaft), inner sleeve and baffle plate. The sliding cover is made of wear-resistant material silicon brass. Silicon brass and stainless steel are not easy to produce sparks, which improves the safety of motor operation. The specific structure is shown in Figure 2.
2.3 Measures to reduce the heat generation of bearing bush < / P > < p > as the motor speed is fixed, in order to reduce the heat output of the bearing bush, only by reducing the journal to reduce the linear speed and improving the oil film quality can reduce the friction loss. Therefore, the high-quality alloy forging steel 42CrMo  is selected for the shaft material of the motor, and the quenching and tempering treatment is carried out. The strength and hardness of the alloy steel after quenching and tempering are strengthened The sample can reduce the journal as much as possible in the range of strength. Through the strength calculation, the diameter of the bearing pad of the motor can be reduced from the normal & phi; 140mm to & phi; 110mm, and the linear speed can be effectively reduced and the calorific value can be reduced. < / P > < p > in order to improve the quality of oil film, the lubricating oil grade is determined according to the motor speed and the load on the bearing bush, and the double oil ring structure is selected in the bearing shell structure. During assembly, the bearing bush is scraped and grinded to ensure the formation of convergence wedge-shaped gap between the shaft and the bearing bush, which is more conducive to the formation of oil film during operation.
2.4 Reduce the heat transfer to the bearing bush < / P > < p > when the motor is running, the temperature rise generated by the rotor will be directly transmitted to the bearing bush through the shaft. In the inner cavity of the motor, the high temperature air generated by the stator temperature rise is directly blown to the bearing Bush, which will also cause the temperature rise of the bearing bush. Therefore, the motor temperature rise is strictly controlled in the design of the motor. At the same time, a push cover assembly is added in the frame to connect the bearing bush with the frame The inner cavity is separated to prevent the high temperature air from the inner chamber of the engine base from blowing directly to the bearing bush. < / P > < p > 2.5 improve the bearing bush structure < / P > < p > the motor adopts the self-lubricating oil ring of the end cover sliding bearing. According to the requirements of the technical agreement, the bearing temperature does not exceed 95 ℃ and the oil temperature does not exceed 65 ℃. After the calculation of the bearing temperature rise, the model of the motor bearing is determined as dqz12-110b / BJ, and the specific structure size of the bearing is shown in Fig. 3 .
< / P > < p > in the design of bearing pedestal, this series of bearings have larger heat dissipation area, and increase the oil storage capacity in the oil chamber, which increases the heat dissipation area of the bearing. After installation, the whole tile ball is located outside the motor cavity, which is more conducive to heat dissipation. At the same time, the bearing is equipped with two oil rings, which increases the oil carrying capacity of the oil ring, which can meet the requirements of full film lubrication, accelerate the lubricating oil circulation speed and promote the hot intersection Change. The results are as follows. < / P > < p > through the improvement, the temperature rise of the bearing under the rated condition is calculated under the existing conditions. < p > < p > motor speed: 2985r / min < / P > < p > radial load of each bearing: 12205n < / P > < p > bearing relative clearance: 1.9 & permil; < / P > < p > minimum oil film thickness: 25 & mu; M < / P > < p > lubrication mode: self lubrication < / P > < p > lubricating oil grade: isovg32 < / P > < p > bearing temperature rise: 32K < / P > < p > 2.6 strengthen the cooling of bearing bush < / P > < p > combined with the previous test results of our company, the bearing shell temperature at the motor tail end is 8 ℃ ~ 13 ℃ lower than that at the shaft extension end due to the indirect cooling of the external fan, which shows that the cooling effect of the fan on the bearing shell is very considerable. Therefore, in the design of the motor, an axial fan is added at the shaft extension end of the motor, which can effectively take away the heat generated by the bearing bush at the extension end in time, and reduce the temperature of the bearing bush at the shaft extension end.
2.7 Avoid direct sunlight < / P > < p > since the motor is used in unattended outdoor places, when the sun directly shines on the bearing bush, the temperature of the bearing bush will also rise. Therefore, a protective cover is added at the shaft extension end of the motor, which can not only make the wind path of the axial fan at the shaft extension end more smooth, but also avoid direct sunlight. By taking the above measures, the motor has passed the type test at one time. The stator temperature of the motor rises 63.5k, and the temperature of the bearing bush does not exceed 85 ℃ when the maximum ring temperature is 40 ℃. In addition, the on-line test with the pump has been carried out, and all performance tests have been passed.  Fu Fengli, Tang Xiaohao. AC motor design manual [M]. Hunan: Hunan people's publishing house, 1978. < / P > < p >  Chen Xingwei, Yu Zhaosheng. Optimization design of high efficiency flameproof motor [J]. Explosion proof motor, 2009,44 (1): 15-18. < / P > < p >  Yang Wanqing, Liu Jianzhong. Design, installation and maintenance of practical asynchronous motor [M]. Beijing: Machinery Industry Press, 1996. < / P > < p >  Chen Shikun. Motor design [M]. Beijing: China Machine Press, 2000. < / P > < p >  Tang yunqu. Electrical engineering [M]. Beijing: China Machine Press, 2000. < / P > < p >  gb3836.1-2010, explosive environment Part 1: General requirements for equipment [S]. < / P > < p >  gb3836.2-20