Internal Shaft Liquid Cooling for Electric Motor Gearbox
Solution Overview
Problem
Current cooling systems for electric motors are inefficient in dissipating heat generated by the rotor shaft and the first-stage shaft of the gearbox, leading to increased liquid pressure drop and incomplete heat removal from the gearbox and coupling junction.
Innovation Solution
The design incorporates a coolant path within the motor and first-stage shaft with a sealing element to prevent leakage and fins to enhance heat dissipation, allowing the coolant to travel the shortest distance through internal passageways from the motor shaft to the sump, where it collects and is recirculated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If liquid cooling is directed into the rotor from one side and returns at the same side, then the cooling path length is doubled, but this configuration is simpler to implement
Solution Approach 1:
Instead of having the coolant enter from one side and return to the same side (conventional approach), the invention inverts the cooling path by having the coolant enter at one end of the rotor and exit at the opposite end through the shaft. This single-pass configuration reduces the cooling path length and minimizes pressure drop while still effectively removing heat from the rotor and shaft.
Solution Approach 2:
The invention extends the cooling path into the longitudinal dimension of the shaft by creating internal passageways that traverse the entire length of the shaft from one end to the other. This dimensional approach allows the coolant to efficiently remove heat from both the rotor and the shaft in a single pass, rather than requiring a return path in the radial direction.
2Device complexity
If conventional cooling through motor and gearbox enclosures is used, then the system structure is simpler, but heat removal from the rotor shaft and first-stage shaft is insufficient
Solution Approach 1:
The invention employs liquid hydraulic cooling by routing coolant through internal passageways in both the rotor and the first-stage shaft. This liquid cooling system directly contacts the heated components, efficiently removing heat from the rotor shaft and first-stage shaft bearings, which cannot be achieved through conventional air convection cooling of the enclosures alone.
Solution Approach 2:
The cooling system is nested within the existing motor and gearbox structure by incorporating internal passageways through the rotor and shaft components. The coolant path is embedded within the rotor and shaft themselves, allowing direct heat removal without adding external cooling equipment or complex enclosure cooling systems.
3Device complexity
If the coolant path does not include the first-stage shaft, then the cooling system is simpler, but heat generation from the first-stage shaft and coupling junction is not removed
Solution Approach 1:
The liquid cooling system performs multiple functions simultaneously: it cools the rotor, cools the first-stage shaft through internal passageways, and removes heat from the coupling junction between the motor and gearbox. This multi-functional approach ensures complete heat removal from all critical components without requiring separate cooling systems for each component.
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 improves cooling efficiency by reducing pressure drop and increasing heat dissipation, effectively addressing the limitations of existing cooling systems by providing high-efficiency cooling for the motor, gearbox, and their junctions with minimal pressure loss.
Implementation Method 1
Certain rotor cooling directs liquid into rotor of electric motor from one side of the rotor and have the liquid returning at the same side of the rotor
Implementation Method 2
the gearbox housing includes one or more fins positioned along the coolant path after the second end of the internal passageway of the first-stage shaft. The one or more fins increase the surface area over which the liquid coolant moves so as to increase heat dissipation
Implementation Method 3
at least one sealing element is provided between the motor shaft and the first-stage shaft at the location where the motor shaft and the first-stage shaft are coupled, the at least one sealing element sealing against liquid coolant leakage
Data Source
AI summary
An electric motor comprising a gearbox housing containing a gearbox, a sump, a first-stage shaft rotatably mounted in the gearbox housing, and a rotatably-mounted motor shaft coupled to the first-stage shaft of the gearbox. The first-stage shaft has an internal passageway defined along the longitudinal axis of the first-stage shaft and extending between opposite first and second ends thereof. At the second end the internal passageway communicates with the sump. The rotatably-mounted motor shaft is coupled to the first end of the first-stage shaft. The motor shaft has an internal passageway defined along the longitudinal axis of the motor shaft and extending between opposite first and second ends thereof. At the second end thereof, the internal passageway of the motor shaft communicates with the internal passageway of the first-stage shaft at the first end thereof. The internal passageways of the motor shaft and first-stage gearbox shaft define a coolant path for liquid coolant, the coolant path beginning at the first end of the motor shaft and proceeding entirely through the internal passageways of the motor shaft and the first-stage shaft, and the coolant path terminating at the sump, where coolant exiting the internal passageway of the first-stage shaft at the second end thereof collects.