Drive Unit Seal Arrangement for High-Speed Rotating Shafts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drive units with electromotive drives and transmissions face challenges in effectively sealing gaps between rotating parts, leading to lubricating oil penetration and potential coking due to high rotational speeds, which results in seal wear and reduced effectiveness.
Innovation Solution
The introduction of a sealing arrangement where the second input shaft of the sub-transmission is connected in a rotationally fixed manner to the output shaft, reducing the relative rotating speeds and thus the centrifugal forces on the sealing lip, ensuring the seal bridges an annular clearance and is attached to a second input shaft that rotates at lower speeds, preventing lubricating oil penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a radial shaft seal is arranged in the annular clearance between the rotor shaft and transmission output shaft, then the seal can prevent lubricating oil penetration, but the high rotational speeds cause centrifugal forces that lift the sealing lip and reduce sealing effectiveness
Solution Approach 1:
The patent introduces an intermediate shaft (input shaft of the speed reducer) between the rotor shaft and the transmission output shaft. The seal is arranged in the annular clearance between the intermediate shaft and the transmission output shaft instead of directly between the rotor shaft and output shaft. This intermediary shaft rotates at reduced speed due to the speed reducer, thereby reducing centrifugal forces on the sealing lip while maintaining the sealing function.
Solution Approach 2:
The patent changes the rotational speed parameter of the shaft to which the seal is attached. By attaching the seal to the input shaft of the speed reducer instead of the rotor shaft, the rotational speed of the sealed shaft is reduced from the high speed of the rotor shaft to the lower speed of the intermediate shaft, thereby reducing centrifugal forces and improving sealing effectiveness.
2Reliability
If the seal is attached to the rotor shaft rotating at high speeds, then the seal can bridge the annular clearance, but the high rotational speeds cause the sealing lip to wear and reduce seal life
Solution Approach 1:
The patent introduces an intermediate shaft (input shaft of the speed reducer) between the rotor shaft and the transmission output shaft. The seal is arranged in the annular clearance between the intermediate shaft and the transmission output shaft instead of directly between the rotor shaft and output shaft. This intermediary shaft rotates at reduced speed due to the speed reducer, thereby reducing centrifugal forces on the sealing lip while maintaining the sealing function.
Solution Approach 2:
The patent changes the rotational speed parameter of the shaft to which the seal is attached. By attaching the seal to the input shaft of the speed reducer instead of the rotor shaft, the rotational speed of the sealed shaft is reduced from the high speed of the rotor shaft to the lower speed of the intermediate shaft, thereby reducing centrifugal forces and improving sealing effectiveness.
3Reliability
If the seal operates at high rotational speeds, then it can maintain sealing contact, but the centrifugal forces cause the sealing lip to lift from the sealing surface
Solution Approach 1:
The patent introduces an intermediate shaft (input shaft of the speed reducer) between the rotor shaft and the transmission output shaft. The seal is arranged in the annular clearance between the intermediate shaft and the transmission output shaft instead of directly between the rotor shaft and output shaft. This intermediary shaft rotates at reduced speed due to the speed reducer, thereby reducing centrifugal forces on the sealing lip while maintaining the sealing function.
Solution Approach 2:
The patent changes the rotational speed parameter of the shaft to which the seal is attached. By attaching the seal to the input shaft of the speed reducer instead of the rotor shaft, the rotational speed of the sealed shaft is reduced from the high speed of the rotor shaft to the lower speed of the intermediate shaft, thereby reducing centrifugal forces and improving sealing effectiveness.
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 arrangement reduces wear on the sealing lip and maintains an effective sealing contact across all speed ranges, preventing lubricating oil from penetrating the gap between the rotor shaft and transmission output shaft, even at high rotational speeds.
Implementation Method 1
the heat generation of the electromotive drive can have the negative effect that the lubricating oil is coked... the relative rotating speeds between the rotor shaft and the transmission output shaft are extremely high, so that the sealing lip is lifted from the sealing surface with high rotational speeds and the sealing effect of a contact seal is cancelled
Data Source
AI summary
A drive unit includes a housing having first and second chambers. An electromotive drive is disposed in the first chamber and including a hollow rotor shaft. A transmission is disposed in the second chamber and includes an output shaft extending through the rotor shaft such that a gap is formed. The transmission further includes a gearing arrangement that operably couples the output shaft to the rotor shaft and reduces a speed ratio between the rotor shaft and the output shaft so that the output shaft rotates slower than the rotor shaft when operating. The gearing arrangement includes a first element fixed to the rotor shaft and a second element that rotates slower than the first element when operating. An annular clearance is defined between the first and second elements. An annular seal has a first portion engaging with the first element and a second portion engaging with the second element.