Electric Motor Cooling via End Winding Spaces
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Solution Overview
Problem
Existing electric motor designs for wheel drives in construction and mining machines face contamination issues due to oil leaks and increased weight and size requirements for effective cooling, limiting their use in smaller machines.
Innovation Solution
The electric motor design features a peripheral coolant inlet for cooling the stator and rotor, with coolant flowing through the end winding spaces and exiting via one bearing plate, while the other bearing plate is closed, avoiding oil contamination and optimizing spatial use for a compact and lightweight structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cooling air is fed from the outer circumference through the housing, then the electric motor is protected from oil contamination, but the outer diameter and weight of the electric motor increase
Solution Approach 1:
The invention extracts the housing function for air distribution from the electric motor structure. Instead of using the motor housing as the air distribution channel, the cooling air is fed directly into the end winding spaces through the end shields, eliminating the need for a specialized housing and reducing the motor's outer diameter and weight.
Solution Approach 2:
The invention changes the spatial arrangement of the cooling air flow from a radial path through the housing to a direct axial entry into the end winding spaces. The cooling air enters through the end shields and flows directly through the end winding spaces, bypassing the need for radial distribution through the housing structure.
2Temperature
If the wheel-side end shield is open for cooling, then cooling efficiency is improved, but oil contamination of the electric motor increases
Solution Approach 1:
The invention segments the cooling function by providing separate cooling paths for the stator and rotor. The stator is cooled through the end winding spaces via the end shields, while the rotor is cooled through its own cooling channels in the rotor shaft. This segmentation allows the wheel-side end shield to remain open for cooling while preventing oil contamination of the stator.
Solution Approach 2:
The invention introduces the end winding spaces as an intermediary cooling chamber between the external environment and the stator. Cooling air enters through the open wheel-side end shield, flows through the end winding spaces to cool the stator, and then exits through the transmission-side end shield, preventing direct oil contamination while maintaining cooling efficiency.
3Reliability
If a housing is used for air distribution, then cooling protection is achieved, but the spatial compactness and lightweight design are reduced
Solution Approach 1:
The invention makes the end shields multi-functional by using them both as structural components and as cooling air distribution channels. The end shields directly guide cooling air into the end winding spaces, eliminating the need for a separate housing for air distribution and achieving spatial compactness while maintaining cooling protection.
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 ensures effective cooling without contamination, allowing the electric motor to be used in smaller dump trucks and similar machines by utilizing available space for radial installation and reducing unsprung masses.
Implementation Method 1
a cooling device for cooling the stator and rotor comprises at least one coolant path through the end winding spaces
Implementation Method 2
The coolant introduced into the interior of the motor can flow out again via only one bearing plate on one end face of the electric motor
Data Source
Figure 1
AI summary
The invention relates to a driving device for a wheel of a work machine, comprising an electric motor, which has a rotor rotatably accommodated in a stator, which rotor is supported on end shields arranged at end faces, between which end shields winding-head spaces for accommodating winding heads are provided, wherein a cooling device for cooling the stator and the rotor has at least one coolant path through the winding-head spaces, which at least one coolant path can be supplied with coolant by means of a preferably circumference-side coolant inlet from a circumference side. According to an advantageous design of the invention, the stator and a stator winding of the stator are cooled from an outer circumference side of the stator and for this purpose a space around the electric motor or the stator of the electric motor present as the installation environment of the electric motor is used, such that the cooling air flow can flow from the outer circumference side of the stator. The coolant introduced into the motor interior can flow away again via only one end shield at an end face of the electric motor, while the other end shield preferably facing a gearing can be designed closed.