Non-Contact Sealing Geometry for Mobile Tool Drive Units
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Solution Overview
Problem
Mobile machine tools, particularly hand-held power tools, face significant friction and thermal stress issues due to high-performance operations, leading to reduced service life, increased maintenance costs, and safety risks from temperature increases.
Innovation Solution
A non-contact sealing geometry is implemented, which reduces friction and thermal loads by detaching from the counter surface during operation, utilizing a water-based lubricant with additives and a design that includes a V-shaped sealing lip and vortex structures to enhance sealing effectiveness, thereby reducing contact pressure and maintaining a permanent seal when stationary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contact seal is used to seal the lubricant-containing interior, then sealing effectiveness is improved, but friction and thermal stress increase leading to reduced service life
Solution Approach 1:
The harmful contact between sealing elements is extracted/removed by implementing a non-contact seal. The seal is spaced away from the counter surface during operation, eliminating friction and thermal stress while maintaining sealing effectiveness through the spacing itself that prevents lubricant leakage.
Solution Approach 2:
The mechanical contact-based sealing system is replaced with a non-contact sealing system. Instead of relying on physical contact between sealing elements, the invention uses spacing and fluid dynamic effects to achieve sealing, thereby eliminating the mechanical friction that limited service life.
2Duration of action of moving object
If a non-contact seal is used to reduce friction, then service life is improved, but sealing effectiveness may deteriorate due to spacing
Solution Approach 1:
The invention uses fluid dynamic principles where the lubricant itself becomes part of the sealing mechanism. The spacing between seal elements creates fluid dynamic conditions that prevent lubricant leakage, using the lubricant's presence and motion to maintain sealing effectiveness without contact.
Solution Approach 2:
The seal transitions between different states: during operation, it maintains spacing for non-contact sealing; when stationary, the sealing lip contacts the counter surface. This parameter change in contact state allows the seal to optimize for service life during operation while maintaining sealing effectiveness when needed.
3Productivity
If high-performance operations are conducted in mobile machine tools, then productivity is improved, but friction and temperature increases lead to reduced service life and safety risks
Solution Approach 1:
The invention converts the harmful effects of high-performance operation (friction, heat) into beneficial outcomes. By using non-contact sealing, the friction that would normally reduce service life is eliminated, and the thermal stress is reduced, allowing high-performance operations to continue without the usual degradation.
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 solution extends the service life of the sealing geometry, reduces maintenance needs, lowers temperatures, and enhances the performance and battery life of mobile machine tools by minimizing friction and thermal stress, allowing for smaller or omitted lubricant cooling devices.
Implementation Method 1
the sealing geometry can be configured so that the detachment or the reduction of the contact force is caused by a centripetal force generated by the operation of the drive unit
Implementation Method 2
a design that includes a V-shaped sealing lip and vortex structures to enhance sealing effectiveness
Implementation Method 3
utilizing a water-based lubricant with additives
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a sealing geometry (22) for a mobile machine tool, for example a hand-held machine tool (10), in particular for processing natural or artificial, especially cementitious, rocks, wherein the mobile machine tool has a drive unit (20), wherein the sealing geometry (22) is configured to seal an inner region (IB) of the drive unit (20) containing a lubricant (26) against an outer region (AB) outside the drive unit (20). It is characterized in that the sealing geometry (22) has a non-contact seal, at least during operation of the drive unit (20). A mobile machine tool equipped with such a sealing geometry (22) has a particularly long service life.