Vehicle Drive Shaft Alignment to Reduce Bearing Load and Noise
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Solution Overview
Problem
In electrically operated vehicles, the deflection of the gear mechanism drive shaft due to a lever arm length between the rotor shaft rotary bearing and the centering seat leads to excessive loading of the rotor shaft bearing, noise generation, and reduced service life.
Innovation Solution
The centering seat on the gear mechanism drive shaft is arranged without axial offset relative to the rotor shaft rotary bearing, and the rotor shaft bearing is designed as an axially displaceable, resiliently pretensioned floating bearing, forming a three-point bearing with the gear mechanism drive shaft, which reduces bending stress and shaft deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the centering seat is spaced apart from the rotor shaft rotary bearing by a lever arm length, then the gear mechanism drive shaft can be structurally simplified, but shaft deflection occurs leading to excessive bearing loading, noise generation, and reduced service life
Solution Approach 1:
The patent changes the axial position parameter of the centering seat relative to the rotor shaft rotary bearing. By positioning the centering seat axially aligned with the bearing (eliminating the lever arm), the patent transforms the force transmission path to eliminate bending moments, thereby resolving the contradiction between structural simplicity and bearing reliability
Solution Approach 2:
The patent addresses the force transmission issue by moving from a configuration with axial offset (creating a moment arm in the radial plane) to axial alignment (eliminating the moment arm). This dimensional repositioning in the axial direction prevents the generation of bending moments while maintaining structural simplicity
2Ease of manufacture
If the centering seat is spaced apart from the rotor shaft rotary bearing, then manufacturing is easier, but excessive shaft deflection occurs during operation
Solution Approach 1:
By changing the axial position parameter of the centering seat to be aligned with the rotor shaft rotary bearing, the patent eliminates the lever arm that causes shaft deflection. This parameter change maintains manufacturing ease while significantly reducing shaft deflection during operation
3Device complexity
If a lever arm length exists between the centering seat and rotor shaft rotary bearing, then the gear mechanism drive shaft can be designed with simpler structure, but radial forces cause bending stress and noise
Solution Approach 1:
The patent eliminates the lever arm by positioning the centering seat axially aligned with the rotor shaft rotary bearing. This parameter change transforms the force transmission to be purely radial without bending moments, thereby eliminating noise generation while maintaining structural simplicity
Solution Approach 2:
The patent converts the potentially harmful bending moments (caused by lever arm) into beneficial direct radial force transmission. By aligning the centering seat with the bearing, the radial forces from gears are transmitted directly without creating bending stress, thus converting a potential harm into a beneficial direct force path
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 minimizes shaft deflection, reduces noise, and extends the service life of the rotor shaft bearing by directly introducing radial forces without bending stress, while maintaining smooth running and reducing production complexity and costs.
Implementation Method 1
resiliently pretensioned floating bearing
Implementation Method 2
resiliently pretensioned floating bearing
Data Source
AI summary
A drive apparatus for a vehicle having an electric machine whose rotor shaft is constructed as a hollow shaft having an internal tooth arrangement. A gear mechanism drive shaft, which has an external tooth arrangement, is inserted coaxially relative to the hollow shaft into the hollow shaft, to form a torque-transmitting spline. The rotor shaft with a rotor shaft rotary bearing being interposed is guided outward through a bearing opening of an electric machine housing, and the gear mechanism drive shaft has a centering seat which is in abutment with the internal circumference of the rotor shaft with a tight clearance fit. The gear mechanism drive shaft is subjected to bending (D) during travel operation as a result of radially active operating forces (FR). To reduce the bending stress (D), the centering seat of the gear mechanism drive shaft is arranged without an axial offset with respect to the rotor shaft rotary bearing, in axial alignment relative to the rotor shaft rotary bearing.