Motor Cooling Flow Paths for Balanced Stator and Rotor Oil Supply
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Solution Overview
Problem
In conventional drive devices with branched oil flow paths, an orifice at the oil inlet of the cooling pipe can lead to pressure release, preventing adequate oil supply to the cooling pipe if the cross-sectional area of the flow path inside the rotor shaft is large.
Innovation Solution
The drive device incorporates a motor portion with a rotor and stator, featuring a shaft with a tubular and hollow portion, and a housing with refrigerant flow paths, including a fourth flow path with a smaller cross-sectional area than the third flow path, ensuring efficient oil supply to both the stator and rotor, thereby maintaining pressure and flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an orifice is formed at the oil inlet of the cooling pipe, then the flow rate can be controlled, but the pressure is released and oil cannot be supplied to the cooling pipe if the cross-sectional area of the flow path inside the rotor shaft is large
Solution Approach 1:
The patent applies local quality by creating different flow path configurations in different locations of the system. Specifically, the stator cooling flow path has a smaller cross-sectional area than the rotor shaft flow path, allowing localized pressure control and oil supply regulation without affecting the entire system uniformly. This resolves the contradiction by enabling adequate oil supply to the cooling pipe while maintaining necessary pressure through differentiated local flow path design.
2Productivity
If the cross-sectional area of the flow path inside the rotor shaft is large, then the flow capacity is increased, but the pressure is released making it impossible to supply oil to the cooling pipe
Solution Approach 1:
The patent segments the cooling system into separate flow paths with different cross-sectional areas. The rotor shaft has a larger flow path for high flow capacity, while the stator cooling pipe has a smaller flow path for pressure maintenance. This segmentation allows each component to have optimized flow characteristics, resolving the contradiction between overall flow capacity and localized pressure requirements.
Solution Approach 2:
Different cross-sectional areas are assigned to different locations: the rotor shaft flow path has a larger area for high flow capacity, while the stator cooling flow path has a smaller area for pressure maintenance. This local differentiation resolves the contradiction by allowing high overall flow capacity while maintaining sufficient pressure in the cooling pipe through localized flow path design.
3Quantity of substance
If the minimum flow-path cross-sectional area in the fourth flow path is made smaller than in the third flow path, then oil supply to the hollow portion is ensured, but the device complexity increases
Solution Approach 1:
The patent merges the oil supply function into the existing refrigerant flow paths without adding separate dedicated oil supply systems. The fourth flow path utilizes the refrigerant circulation system already present in the motor housing, combining multiple functions (cooling and lubrication) into a unified flow path configuration. This reduces device complexity while ensuring adequate oil supply to the hollow portion through the smaller cross-sectional area design.
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 ensures consistent oil supply to both the stator and rotor, maintaining pressure and enhancing cooling efficiency without increasing flow pressure, thus addressing the issue of inadequate oil supply due to large cross-sectional areas.
Implementation Method 1
The refrigerant to be supplied to the motor portion flows through the second flow path. The third flow path supplies a part of the refrigerant flowing through the second flow path to the outer surface of the stator. The fourth flow path supplies another part of the refrigerant flowing through the second flow path to the hollow portion of the shaft.
Data Source
AI summary
A housing of a drive device includes a refrigerant flow path through which a refrigerant flows. The refrigerant flow path includes a first flow path, a second flow path, a third flow path, and a fourth flow path. The refrigerant to be sent from a pump flows through the first flow path. The refrigerant to be supplied to the motor portion flows in the second flow path. The third flow path supplies a part of the refrigerant flowing through the second flow path to the outer surface of a stator. The fourth flow path supplies the other part of the refrigerant flowing through the second flow path to a hollow portion of a shaft. A minimum flow-path cross-sectional area in the fourth flow path is smaller than a minimum flow-path cross-sectional area in the third flow path.