Rotary Shaft Seal Lip Structure for Foreign Matter Control
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Solution Overview
Problem
Conventional sealing apparatuses allow foreign matter to deposit between screw projections and circumferential projections, leading to leakage and maintenance issues due to interference with the rotating shaft.
Innovation Solution
A sealing apparatus with an annular reinforcing ring and elastic body part featuring a lip tip portion with a circumferential projection and screw portions, where the non-sealed object side screw projections have a greater pitch and do not overlap, forming a passage to prevent foreign matter deposition and maintain the sealing effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If screw projections are provided on the atmospheric side surface to maintain pumping action, then the sealing performance is improved, but foreign matter can deposit between the screw projections and circumferential projection causing leakage
Solution Approach 1:
The screw projections are segmented into two distinct groups: first screw projections extending from the lip tip toward the circumferential projection, and second screw projections extending from the circumferential projection away from the lip tip. This segmentation creates separate functional zones that prevent foreign matter accumulation while maintaining pumping action on both sides of the circumferential projection.
Solution Approach 2:
The circumferential projection serves as an intermediary element between the first and second screw projections. It acts as a barrier that prevents foreign matter carried by the airflow from reaching the lip tip, while still allowing the pumping action to function effectively on both sides of the projection.
2Object-affected harmful factors
If the circumferential projection is added to suppress foreign matter, then foreign matter suppression is improved, but the complexity of the structure increases
Solution Approach 1:
The circumferential projection is merged with the screw projections to form an integrated structure. The first screw projections extend from the lip tip to the circumferential projection, while the second screw projections extend from the circumferential projection, creating a unified design that performs multiple functions without requiring separate components.
3Object-affected harmful factors
If the pitch of non-sealed object side screw projections is increased, then foreign matter deposition is reduced, but the pumping action efficiency may be affected
Solution Approach 1:
Different pitch values are assigned to different groups of screw projections based on their local functional requirements. The first screw projections have a first pitch optimized for pumping action near the lip tip, while the second screw projections have a second pitch optimized for preventing foreign matter deposition further from the lip tip. This local differentiation allows each zone to perform its specific function effectively.
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 effectively suppresses foreign matter deposition between screw projections, reducing the need for frequent maintenance and ensuring the sealing apparatus maintains its sealing functionality.
Implementation Method 1
a sealing apparatus having a plurality of screw projections arranged at equal intervals to form an airflow from the atmospheric side to the sealed object side and exert a pumping action of pushing back a sealed object such as oil to the sealed object side
Implementation Method 2
a garter spring 108 is attached to a surface on an outer periphery side facing the lip tip portion 105. The garter spring 108 urges the lip tip portion 105 against the inner periphery side to apply a tension force on the rotating shaft
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
There is provided a sealing apparatus capable of suppressing foreign matter from depositing between screw projections further on a non-sealed object side than a circumferential projection. In a sealing apparatus (1), a lip tip portion (24) of a seal lip (21) of an elastic body part (20) is defined by a sealing side surface (26) and an atmospheric side surface (27), connected through a lip tip (25) with each other. The lip tip portion (24) includes a circumferential projection (31) and a screw portion (32) on the atmospheric side surface (27). The circumferential projection (31) extends parallel to the lip tip (25). The screw portion (32) includes a plurality of parallel screw projections (33) and a plurality of bilge screw projections (34). The parallel screw projections (33) are arranged at equal pitch intervals in parallel with each other between the lip tip (25) and the circumferential projection (31). The bilge screw projections (34) are arranged at equal pitch intervals in parallel with each other from the circumferential projection (31) toward the atmospheric side. The bilge screw projections (34) do not overlap the adjacent bilge screw projections (34) in a direction of axis (x) with each other.