Spindle Motor Bearing Segmentation for Friction Reduction
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Solution Overview
Problem
Spindle motors with limited lubrication have short service lives, especially with long stroke lengths, requiring frequent relubrication and experiencing high relative speeds and pressure differences that lead to friction and oscillation issues.
Innovation Solution
A spindle motor design featuring a threaded spindle supported on both sides with a bearing system that includes a plastic outer ring with a spring-loaded support, axial ventilation holes, and an oil-air mixture to reduce friction and pressure differences, allowing for continuous operation with oil bath lubrication and improved heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the threaded spindle is supported only at one end with limited grease, then the device complexity is reduced, but the service life is shortened and friction increases
Solution Approach 1:
The support structure is segmented into multiple independent bearing units distributed along the threaded spindle. Each bearing unit can be independently mounted on the piston rod, allowing the system to handle long stroke lengths effectively while maintaining reliable support throughout the spindle's length.
Solution Approach 2:
The bearing units are arranged axially along the piston rod in addition to the radial support function. This axial distribution of bearing units transforms a single-point support problem into a distributed multi-point support system, resolving the contradiction between service life and device complexity.
2Loss of energy
If the piston rod diameter is increased to reduce relative speeds, then the friction is reduced, but the device complexity and space requirements increase
Solution Approach 1:
Instead of increasing the piston rod diameter, the support function is segmented into multiple bearing units distributed along the rod. This maintains the original rod dimensions while reducing friction through improved support distribution and lower relative speeds at each bearing point.
3Reliability
If high pressure seals are used to prevent oil leakage, then the sealing performance is improved, but the pressure differences cause oscillation and reduce reliability
Solution Approach 1:
The sealing system is segmented into multiple sealing zones corresponding to each bearing unit location. This distribution of sealing points along the piston rod reduces pressure differences at any single location, preventing oscillation while maintaining effective sealing performance.
Solution Approach 2:
The distributed bearing units act as intermediaries that support the threaded spindle at multiple points, thereby reducing the pressure differential across any single seal. This mediator function allows seals to operate within optimal pressure ranges, preventing oscillation and improving reliability.
4Object-affected harmful factors
If ventilation holes are added to equalize pressure, then the pressure difference is reduced, but the device complexity increases
Solution Approach 1:
The ventilation function is merged with the existing bearing unit structure. Ventilation holes are integrated into the bearing housings or piston rod surface at strategic locations, combining pressure equalization with the mechanical support function without adding separate ventilation components.
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
The design significantly extends the service life of spindle motors by reducing friction, maintaining preload at high temperatures, and preventing vacuum formation, ensuring reliable operation and heat dissipation across the spindle drive.
Implementation Method 1
the support comprises a spring area, by means of which the support derives support forces on the piston rod
Implementation Method 2
an oil-air mixture is provided in the spatial areas
Implementation Method 3
the spindle nut has ventilation holes... so that no high pressure difference can be built up between the space surrounded by the piston rod and the space between the piston rod and the housing
Implementation Method 4
the bearing absorbs the rotary movement of the threaded spindle and the support absorbs the linear movement. Thus, a low-friction ball bearing can be used
Data Source
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AI summary
The invention relates to a spindle motor, comprising an electric motor (1) having a rotor (2) connected to a threaded spindle (5), the thread thereof engaging with a thread of a spindle nut (6) connected to a piston rod (14), wherein the spindle nut (6) having the piston rod (14) is axially guided in a housing part (15) of the spindle motor (1), wherein a guide part (9) is connected to the spindle nut (6) and the piston rod (14) for axially guiding the same, wherein the threaded spindle (5) is supported by means of bearings at the axial end area thereof facing the electric motor (1) or in a second housing part connected to the first housing part, wherein the threaded spindle (5) is supported on the piston rod (14) by means of a bearing (18) disposed on the threaded spindle (5) at the axial end area thereof facing away from the electric motor (1).