Electric Motor Dual-Circuit Cooling for Stator Heat Removal
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Solution Overview
Problem
Current electric motor cooling solutions either inadequately cool the stator by only addressing surface contact or require costly and complex structural modifications to circulate cooling fluid through the rotor shaft and stator body.
Innovation Solution
An electric motor design featuring a dual cooling system, where a first cooling fluid circulates between the front and rear bearings, and a second cooling fluid circulates within the stator sheets and phase windings, facilitated by a ribbed separator in the front bearing to prevent fluid mixing and allow additional fluid inlet channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooling circuit is provided inside the bearing with which the stator is shrink-fitted, then the stator can be cooled at the surfaces of the lamination pack in contact with the cooled bearing, but this solution does not allow for optimal cooling of the motor as it only cools surface contact areas
Solution Approach 1:
The cooling system is segmented into two independent circuits: a first cooling circuit within the bearing for external stator surface cooling, and a second cooling circuit through the stator core for internal cooling. This segmentation allows each circuit to target specific heat generation zones, achieving comprehensive cooling coverage without requiring a single complex system.
Solution Approach 2:
The cooling approach transitions from two-dimensional surface cooling (first circuit in bearing) to three-dimensional internal cooling (second circuit through stator core laminations). By adding the radial dimension of cooling through the stator core, the system achieves volumetric heat removal capability that surface cooling alone cannot provide.
2Temperature
If oil is circulated through the rotor shaft and then along the stator body to contact the phase winding coils, then cooling coverage is improved, but numerous modifications to the motor structure are required making it difficult to implement and relatively expensive
Solution Approach 1:
The front bearing is designed to serve multiple functions: it provides mechanical support for the rotor shaft, houses the first cooling circuit for bearing cooling, incorporates the rib separator structure, and provides the inlet channel for the second cooling circuit. This multi-functionality eliminates the need for separate cooling components and reduces overall structural complexity.
Solution Approach 2:
The stator core itself serves as the cooling channel structure for the second cooling circuit. The laminations and their arrangement naturally form pathways for coolant flow, eliminating the need for separately manufactured cooling channels or complex internal structures. The stator structure serves both its electromagnetic function and its cooling function.
3Temperature
If a dual cooling system is implemented with independent circuits for bearing and stator cooling, then cooling efficiency is improved, but the device complexity increases
Solution Approach 1:
The front bearing structure merges multiple cooling functions into a single component: it houses the first cooling circuit for bearing cooling, provides the rib separator, and incorporates the inlet channel for the second cooling circuit. This merging reduces the number of separate components and simplifies the overall system architecture while maintaining dual-circuit cooling functionality.
Solution Approach 2:
The rib structure acts as an intermediary element that serves multiple purposes: it separates the first cooling circuit inlet and outlet channels, provides structural support, and serves as the wall through which the second cooling circuit inlet channel is formed. This intermediary structure enables the dual cooling system without requiring separate complex components for each function.
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 configuration enables enhanced heat dissipation by utilizing two independent cooling circuits, improving cooling efficiency without the need for extensive structural modifications.
Implementation Method 1
a first cooling fluid circulates between the front and rear bearings
Implementation Method 2
the front bearing has a projecting rib extending radially towards an inner face of the rear bearing
Implementation Method 3
a second cooling fluid circulating in the stator lamination pack and on the stator coils
Implementation Method 4
said second cooling fluid being supplied via at least one second fluid inlet channel
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The invention relates to an electric motor (10) comprising a rotor (11) mounted on a shaft (12), a stator (13) positioned around the rotor (11), the stator (13) comprising a body formed by a stack of laminations (2) and winding overhangs (19) projecting axially from each side of the stator body, a front bearing (14) and a rear bearing (15) which are connected to one another, the front and rear bearings (14, 15) forming an internal cavity in which the rotor (11) and the stator (13) are housed, wherein the rear bearing (15) is bell-shaped and covers a cylindrical part (142) of the front bearing (14) extending axially from an end wall (141) of the front bearing (14), the rear bearing (15) forming, with the front bearing (14), an internal duct (9) for the circulation of a first cooling fluid inside which duct a first cooling fluid circulates, the first cooling circuit entering the internal duct (9) via a first fluid-inlet duct (26) formed radially through the rear bearing (15) and exiting the internal duct (9) via a first fluid-outlet duct (27) formed radially through the rear bearing (15), characterized in that the front bearing (14) has a projecting rib (28) extending radially towards an internal face (152) of the rear bearing (15), said rib (28) acting as a separator for the internal duct (9), the first fluid-inlet and fluid outlet ducts (26, 27) opening respectively on each side of the rib (28), and in that the electric motor (10) is additionally cooled by a second cooling fluid circulating through the stack of laminations (2) of the stator (13) and over the winding overhangs (19) of the stator (13), the second cooling fluid being supplied via at least a second fluid-inlet duct (31), the at least one second fluid-inlet duct (31) being at least partially formed through the rib (28) of the front bearing (14).