Electric Machine Closing Devices for Air Gap Sealing
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Solution Overview
Problem
Existing electric machines with liquid cooling systems face design conflicts between minimizing the magnetic air gap for high power density and maintaining mechanical stability, as thin split tubes used for cooling can buckle under pressure and induce electromagnetic losses with conductive materials.
Innovation Solution
The implementation of closing devices, such as intermediate tooth elements, between the stator teeth to seal the air gap, allowing for a reduction in the magnetic air gap and eliminating the need for a thin-walled split tube, thereby enhancing stability and power density by utilizing previously unused space for sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a thin-walled split tube is used to minimize the magnetic air gap, then the power density is improved, but the mechanical stability deteriorates due to buckling under pressure
Solution Approach 1:
The stator is segmented into multiple teeth with intermediate spaces between them. Closing devices are placed in these intermediate spaces to perform the sealing function, allowing the split tube in the air gap to be removed or made thinner without compromising mechanical stability.
Solution Approach 2:
The sealing function is moved from the radial dimension (air gap region) to the axial dimension (intermediate spaces between teeth). By placing closing devices in the intermediate spaces along the axial direction, the patent eliminates the need for a thick-walled split tube in the radial air gap region.
2Strength
If an electrically conductive material is used for the split tube, then the mechanical strength is improved, but electromagnetic losses increase due to induced eddy currents
Solution Approach 1:
The split tube is extracted from the air gap region and replaced by closing devices placed in the intermediate spaces between teeth. This extraction removes the source of eddy current losses from the magnetic air gap while maintaining the cooling function through the closing devices.
Solution Approach 2:
Closing devices made from electrically insulating materials serve as intermediaries to perform the sealing function in the intermediate spaces. These insulating closing devices prevent eddy currents while maintaining structural integrity, and can be connected to electrically conductive components through non-magnetic connectors.
3Stability of the object's composition
If the split tube wall thickness is increased to improve mechanical stability, then the buckling resistance is improved, but the magnetic air gap increases reducing power density
Solution Approach 1:
The stator structure is segmented into teeth with intermediate spaces, allowing the sealing function to be distributed to closing devices in these spaces. This segmentation enables the removal of the thick-walled split tube from the air gap, reducing the magnetic air gap while maintaining stability through the closing devices.
Solution Approach 2:
The mechanical support and sealing function is shifted from the radial dimension (split tube wall thickness) to the axial dimension (closing devices in intermediate spaces). This dimensional shift allows thin-walled or removed split tubes without compromising buckling resistance.
4Length of stationary object
If closing devices are added to seal the intermediate spaces, then the magnetic air gap is reduced improving power density, but the device complexity increases
Solution Approach 1:
The closing devices perform multiple functions: sealing the intermediate spaces, providing mechanical support, and serving as mounting positions for cooling channels. This multi-functionality reduces the need for separate components, offsetting the added complexity with functional integration.
Solution Approach 2:
The closing devices are integrated with the cooling system, combining the sealing function with the cooling channel structure. This merging reduces the number of separate components and simplifies the overall design despite adding closing devices to seal the intermediate spaces.
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 magnetic air gap, improves power density, and stabilizes the electric machine by transferring load absorption from thin-walled split tubes to the closing devices, which are designed to be leak-tight and made from insulating materials, preventing electromagnetic losses.
Implementation Method 1
a plurality of closing devices for closing the respective intermediate spaces in relation to the air gap... respectively seal the air gap
Implementation Method 2
the split tube may be formed from an electrically insulating material. This is because, if electrically conductive materials were used in the magnetic air gap, eddy currents would be induced, leading to additional electromagnetic losses
Implementation Method 3
there is a cooling liquid between the teeth of the stator in the respective intermediate spaces. This cooling liquid serves, in particular, to dissipate from the coils the heat generated during the operation of the electric machine
Data Source
AI summary
The disclosure relates to an electric machine including a stator having a plurality of teeth and on which a winding of the electric machine is arranged, wherein a respective intermediate space is formed between neighboring teeth. The electric machine further includes a rotor that may rotate relative to the stator, wherein an air gap is formed between the stator and the rotor. The electric machine further includes a plurality of closing devices for closing the respective intermediate spaces in relation to the air gap, and wherein a respective closing device of the plurality of closing devices is arranged between neighboring teeth of the stator.