Gearbox design

Compared with other industrial gearboxes, because the wind turbine gearbox is installed in a small cabin that is several tens of meters or even more than one hundred meters high from the ground, its own volume and weight for the cabin, tower, foundation, unit wind load, installation and maintenance Costs and the like have an important impact, so it is important to reduce the size and weight. At the same time, due to inconvenient maintenance and high maintenance costs, the design life of the gearbox is usually required to be 20 years, and the reliability requirements are extremely demanding. Because size and weight and reliability are often a pair of irreconcilable contradictions, the design and manufacture of wind turbine gearboxes often fall into a dilemma. The overall design stage should meet the requirements of reliability and working life, and compare and optimize the transmission scheme with the minimum volume and minimum weight as the target; the structural design should meet the transmission power and space constraints, and consider the structure as simple as possible. Reliable operation and convenient maintenance; ensure product quality at every stage of the manufacturing process; in the operation, the gearbox operating status (bearing temperature, vibration, oil temperature and quality changes, etc.) should be monitored in real time and routinely maintained according to specifications.

Since the tip line speed cannot be too high, the rated input speed of the gearbox gradually decreases with the increase of the single unit capacity, 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 a 2-stage parallel shaft +1 planetary transmission structure. Due to the relatively complicated planetary transmission structure and the difficulty in processing large internal ring gears, the cost is relatively high. Even with the 2-stage planetary transmission, the NW transmission is the most common.