Rotor Core Eccentricity Prevention Using Plate Spring in Water Turbine Generator
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Solution Overview
Problem
In rotating electrical machines, the rotor core becomes eccentric to the spider arms during load cut-off or emergency stop, leading to increased axial runout and potential machine damage due to the reduction in torque from a water turbine and application of reverse torque.
Innovation Solution
A plate spring is mounted to the spider arm, engaging with both the rotor core and the spider arm, providing a constant pushing force to prevent eccentricity by maintaining contact between the T key and key way, even when circumferential gaps are produced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If T key and cotters are used to join rotor core and spider arms, then the rotor core is securely fixed during normal operation, but circumferential gaps are produced between T key and key way during load cut-off or emergency stop, leading to rotor core eccentricity
Solution Approach 1:
The plate spring applies a preliminary pushing force in the rotational direction to the rotor core component through the T key, creating a pre-compression that prevents the rotor core from moving eccentrically during load cut-off or emergency stop when reverse torque is applied. This preliminary anti-action counteracts the potential harmful movement before it occurs.
Solution Approach 2:
The plate spring is designed as a flexible component that can dynamically adjust its pushing force based on operational conditions. During normal operation, the spring maintains contact pressure; during load cut-off or emergency stop, the spring's elasticity allows it to sustain the pushing force that prevents eccentricity, adapting to changing torque conditions.
2Strength
If the rotor core is allowed to expand circumferentially under centrifugal force during operation, then the rotor can withstand rotational stress, but gaps are produced between T key and key way, reducing connection stability
Solution Approach 1:
The plate spring applies a preliminary pushing force in the rotational direction to the rotor core component through the T key, creating a pre-compression that prevents the rotor core from moving eccentrically during load cut-off or emergency stop when reverse torque is applied. This preliminary anti-action counteracts the potential harmful movement before it occurs.
Solution Approach 2:
The plate spring changes the force parameter by applying a continuous pushing force that compensates for the gap formation. The spring's elastic properties allow it to maintain contact pressure despite the circumferential expansion of the rotor core under centrifugal force, ensuring continuous stabilizing force is applied.
3Adaptability or versatility
If reverse torque is applied during load cut-off or emergency stop, then the rotor core experiences destabilizing force, but without additional restraining mechanism, the rotor core becomes eccentric and causes axial runout
Solution Approach 1:
The plate spring applies a preliminary pushing force in the rotational direction to the rotor core component through the T key, creating a pre-compression that prevents the rotor core from moving eccentrically during load cut-off or emergency stop when reverse torque is applied. This preliminary anti-action counteracts the potential harmful movement before it occurs.
Solution Approach 2:
The plate spring acts as an intermediary component between the spider arm and the rotor core component. It transmits the stabilizing pushing force from the spider arm structure to the rotor core, mediating the interaction and ensuring continuous alignment stability even when reverse torque is applied during load cut-off or emergency stop.
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
The constant pushing force from the plate spring ensures the rotor core remains aligned with the spider arms, preventing eccentricity and axial runout, thus stabilizing the machine's operation and reducing the risk of damage.
Implementation Method 1
a plate spring (9) mounted to a spider arm (6), the plate spring (9) having one side engaging the spider arm (6), the other side engaging the rotor core component (7), and a middle portion fastened to the spider arm (6)
Implementation Method 2
the rotor rotates when the rotating electrical machine operates to apply a stress to the rotor core 7 due to centrifugal force. Then, the rotor core 7 displaces to widen circumferentially and radially
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A rotating electrical machine is provided in which, even when torque from a water turbine is reduced and reverse torque is applied due to load cut off, a rotor core is not eccentric to spider arms. The rotor of a rotating machine includes a vertical rotating shaft, spider arms extending radially from the vertical rotating shaft, and a rotor core component provided to the outer circumference of the spider arms. A T key and cotters are inserted into and secured to a key way provided to an abutment surface of the inner circumference of the rotor core component and the top end of the spider arm. A plate spring is mounted to a surface of the spider arm, the surface facing a rotational direction for electrical generation. The plate spring has one side engaging the spider arm, the other side engaging the rotor core component, and a middle portion bolted from an opposite surface of the spider arm.