Rotor Hollow Shaft Potential Equalization Without Cooling Flow Loss
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Solution Overview
Problem
Existing electrical machines face challenges in achieving potential equalization between the rotor and housing without adversely affecting the cooling process, as prior methods often disrupt the flow of cooling fluids.
Innovation Solution
An electrical machine design featuring a hollow rotor shaft with a rotationally fixed tube for cooling fluid supply, incorporating a potential equalization device with a rod aligned along the axis of rotation and a contact element electrically connected to the tube, ensuring conductive contact without interfering with the cooling fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a potential equalization device is installed in existing electrical machines, then electrical potential equalization between rotor and housing is achieved, but the flow of cooling fluids is disrupted
Solution Approach 1:
The potential equalization rod is nested inside the hollow rotor shaft, which itself is positioned within the tube that guides cooling fluid. This nested arrangement allows the potential equalization device to occupy the central axial space without interfering with the cooling fluid flow path, resolving the contradiction between achieving potential equalization and maintaining cooling fluid flow.
Solution Approach 2:
The potential equalization rod is positioned in the axial dimension (along the rotation axis) while the cooling fluid flows radially through the tube. By utilizing different spatial dimensions for the two functions, the patent allows potential equalization and cooling fluid flow to coexist without interference.
2Reliability
If a potential equalization device is added to equalize voltage, then unwanted voltage discharges are prevented, but device complexity increases
Solution Approach 1:
The hollow rotor shaft serves multiple functions: it provides structural support for the rotor, acts as a guide for the potential equalization rod, and allows passage of cooling fluid. By making the rotor shaft multi-functional, the patent reduces overall device complexity while achieving potential equalization.
Solution Approach 2:
The potential equalization rod acts as an intermediary element that bridges the electrical potential difference between the rotating rotor and the stationary housing. This simple rod-like intermediary provides the necessary electrical connection without requiring complex mechanisms.
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 design effectively equalizes electrical potential between the rotor and housing while maintaining uninterrupted cooling fluid flow, ensuring efficient operation without leakage or interference.
Implementation Method 1
a cooling fluid can be supplied to the tube... When a cooling fluid is introduced into the tube through the inlet of the hollow rotor shaft, it is directed through the tube's outlet openings into the interior of the hollow rotor shaft
Implementation Method 2
Internal channels for internal rotor cooling can be provided in the rotor laminated core... a cooling fluid can thus be supplied through the inlet of the hollow rotor shaft so that it flows into the tube arranged in a rotationally fixed manner in the hollow rotor shaft
Implementation Method 3
a contact element which is arranged in the tube along the rotation axis and is electrically conductively connected to the tube, and wherein the potential equalization rod is in electrically conductive contact with the contact element
Data Source
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AI summary
To provide an electric machine with which electrical potential equalization between the rotor and the housing of the electric machine can take place without adversely affecting the cooling of the rotor, an electric machine (100) comprising a housing (10), a stator (11) and a rotor (12) is proposed, wherein the rotor (12) comprises a rotor hollow shaft (13) with an interior space (15), wherein a tube (16) is arranged in the interior space (15) and is fixedly connected to the rotor hollow shaft (13), wherein the rotor hollow shaft (13) has an inlet (17) through which a cooling fluid can be supplied to the tube (16), and wherein a potential equalization device (22) is provided, and wherein it is further provided thatthat the equipotential bonding device (22) comprises an equipotential bonding rod (23) fixed to the housing and aligned along an axis of rotation (25) of the rotor hollow shaft (13) and projecting into the tube (16) through the inlet (17), and a contact element (24) arranged along the axis of rotation (25) in the tube (16) and electrically connected to the tube (16), and that the equipotential bonding rod (23) is in electrically conductive contact with the contact element (24).