Gearbox housing flanges typically require a gearbox design life of 20 years when operating, and reliability requirements are extremely demanding. The overall design stage should meet the requirements of reliability and working life, and compare and optimize the transmission scheme with small volume and small weight as the target. The structural design should meet the requirements of transmission power and space limitation. It is reliable in operation and convenient in maintenance. It should ensure the quality of the product at every stage of the manufacturing process. In the operation, the gearbox running status (bearing temperature, vibration, oil temperature and quality change, etc.) should be monitored in real time and routinely maintained according to the specifications.
Since the gear box flange is not too high, the rated input speed of the gearbox is gradually reduced as the capacity of the single unit increases, and the rated speed of the unit above MW is generally not more than 20r/min. On the other hand, the rated speed of the generator is generally 1500 or 1800r/min, so the speed ratio of the large wind power increasing gearbox is generally around 75~100.
In order to reduce the volume of the gearbox, the wind power transmission box above 500kw usually adopts the power split planetary transmission; the common structure of 500kw~1000kw has two levels of parallel axis + 1 planet and 1 parallel shaft + 2 planetary transmission. The megawatt gearbox adopts the structure of 2-stage parallel axis + 1 planetary transmission. Due to the relatively complicated planetary transmission structure and the difficulty in processing large internal ring gears, the cost is high. Even with the 2-stage planetary transmission, the NW transmission is common.