Wind Turbine Lubrication Pump Gearbox for Cold-Start Torque
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Solution Overview
Problem
Wind turbine lubrication systems require larger motors during cold start-ups due to the higher viscosity of lubricants, leading to increased torque requirements and reduced motor efficiency during normal operations, as the motor needs to be oversized to handle cold start-up conditions.
Innovation Solution
A gearbox arrangement is introduced between the motor and the pump, allowing the motor to operate at its rated speed by reversing the direction of rotation, which reduces the motor torque required during cold start-ups and enables the use of a smaller, more efficient motor by varying the pump's speed through an epicyclic gear set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the motor is oversized to handle cold start-up conditions, then the torque requirement during cold start-up is met, but the motor runs outside its optimum load area during normal operation resulting in reduced efficiency
Solution Approach 1:
The patent applies a variable ratio gearbox that dynamically changes the speed ratio between motor and pump based on operating conditions. During cold start-up, the gearbox provides a higher ratio to multiply motor torque for pumping viscous lubricant. During normal operation, it transitions to a lower ratio to maintain motor efficiency while still meeting pump requirements. This dynamic adjustment resolves the contradiction by allowing the motor to operate in its optimal load range across different operating conditions.
Solution Approach 2:
The patent changes the operational parameters of the motor-pump system by introducing a gearbox with variable speed ratio. The gearbox allows the motor speed and pump speed to be decoupled, enabling the motor to operate at optimal speed for efficiency while the pump receives appropriate speed variations based on lubricant viscosity conditions. This parameter change resolves the efficiency loss caused by oversized motor operation.
2Power
If the motor speed is reduced during cold start-up, then the torque requirement is reduced, but the power induced into the oil via the pump is also reduced resulting in reduced flow and heat contribution
Solution Approach 1:
The variable ratio gearbox dynamically adjusts the speed transmission ratio based on system needs. During cold start-up, when high torque is needed, the gearbox maintains a favorable ratio to multiply motor torque even at reduced speeds. When pump flow and heating are prioritized, the gearbox adjusts to transmit more power to the pump. This dynamic control resolves the contradiction between torque requirements and productivity.
3Loss of energy
If a gearbox arrangement is introduced between the motor and pump, then the motor can operate at rated speed with optimized efficiency, but the device complexity increases
Solution Approach 1:
The patent introduces a gearbox as an intermediary mechanism between the motor and pump. This gearbox serves as a mediator that reconciles the conflicting requirements of motor efficiency and pump performance. By placing this intermediate device, the system can optimize motor operation while still meeting pump demands, accepting the trade-off of increased mechanical complexity for improved overall system efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces the motor size and cost while maintaining efficient operation during normal conditions, improving cold start-up times and reducing the risk of lubricant starvation in wind turbine components.
Implementation Method 1
The epicyclic gear set may comprise a sun gear, a plurality of planet gears and a ring gear. The sun gear may be coupled to the input shaft so that rotation of the input shaft drives rotation of the sun gear. The ring gear may be coupled to the output shaft so that rotation of the ring gear drives rotation of the output shaft.
Implementation Method 2
The epicyclic gear set may provide a gear ratio in the range of 2:1 to 4:1 in the second mode of operation, such that the first speed of rotation is in the range of two to four times faster than the second speed of rotation in the second mode of operation.
Implementation Method 3
The unidirectional clutch may be configured to allow rotation of the carrier about the central axis in the first direction and prevent rotation of the carrier about the central axis in the second direction.
Data Source
Figure 1
Figure 2
Figure 3~4a
AI summary
A pump system for supplying lubricant to components of a wind turbine comprises: a pump for pumping lubricant through a fluid circuit of the wind turbine; a drive means for driving the pump; and, a gearbox arrangement arranged to couple the drive means to the pump. The gearbox arrangement comprises a rotatable input shaft configured to be driven by the drive means and a rotatable output shaft configured to drive the pump. The input shaft is rotatable in a first direction of rotation and a second direction of rotation when driven by the drive means. The output shaft is rotatable in the first direction of rotation, and the speed of rotation of the output shaft is determined by an operational mode of the gearbox arrangement. In a first mode of operation, when the input shaft rotates in the first direction of rotation at a first speed of rotation, the gearbox arrangement is configured to drive the output shaft to rotate also in the first direction of rotation at the first speed of rotation. In a second mode of operation, when the input shaft rotates in the second direction of rotation at the first speed of rotation, the gearbox arrangement is configured to drive the output shaft to rotate in the first direction of rotation at a second speed of rotation.