Gear Reducer Seal Lip Structure for Low-Speed Grease Return
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Solution Overview
Problem
Gear reducers in articulated robots face challenges in minimizing grease leakage due to low rotational speeds and exposure to foreign matter, which complicates the sealing process and leads to increased wear and leakage.
Innovation Solution
A sealing device with a composite structure featuring a main seal lip and an auxiliary seal lip, both with spiral structures, is designed to prevent foreign matter ingress and promote a pumping effect by using first and second spiral structures to return leaked grease to the internal space, even at low rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional seal lip is used in a gear reducer with low rotational speed, then the structure is simple, but the pumping effect is insufficient and grease leakage occurs
Solution Approach 1:
The seal lip is divided into multiple segments: a main seal lip for primary sealing and multiple auxiliary seal lips for enhanced sealing and foreign matter prevention. Each segment has specific functions, with the auxiliary seal lips featuring spiral structures to actively pump grease back into the internal space, thereby improving overall sealing reliability without excessive complexity
Solution Approach 2:
The seal lip structure incorporates spiral grooves that create a dynamic pumping effect during rotation. The spiral structures on the auxiliary seal lips actively move grease from the external environment back into the internal space, transforming the static seal into a dynamic grease-returning system that effectively combats leakage even at low rotational speeds
2Reliability
If the seal lip is exposed to gear wear particles and sludge, then foreign matter ingress is possible, but the seal must maintain grease containment
Solution Approach 1:
The auxiliary seal lips act as intermediary elements between the main seal lip and the external environment. These intermediate structures feature spiral grooves that actively pump grease back into the internal space, creating a protective barrier that prevents foreign matter from reaching the main seal lip while maintaining grease containment
Solution Approach 2:
The auxiliary seal lips are positioned to prevent foreign matter from reaching the main seal lip in advance. By creating a preliminary sealing barrier with grease-returning capability, the structure prevents the harmful action of foreign matter ingress before it can affect the primary sealing function
3Use of energy by moving object
If the rotational speed is very low, then energy consumption is reduced, but the pumping effect of the seal lip cannot be obtained
Solution Approach 1:
The spiral grooves on the auxiliary seal lips create a tangential component of grease flow in addition to the radial sealing function. This dimensional change in flow pattern allows the structure to generate pumping action through the spiral geometry itself, rather than relying solely on rotational speed, thereby maintaining grease return capability at low speeds without increasing energy consumption
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 sealing device effectively minimizes grease leakage and reduces wear by restraining foreign matter and utilizing spiral structures to enhance the pumping effect, ensuring reliable sealing in environments with high foreign matter presence.
Implementation Method 1
the seal lip, which is disposed between parts that rotate relative to each other, has an effect of returning a liquid that leaked from a predetermined space back to the predetermined space (pumping effect)
Implementation Method 2
the main seal lip being in slidable contact with an outer peripheral surface of the rotational shaft
Data Source
AI summary
A sealing device acts to seal a gap between a housing of a gear reducer and a rotational shaft that bi-directionally rotates, and separates an internal space of the housing in which a grease is stored from an atmosphere side. The sealing device includes a main seal lip protruding radially inward from an inner peripheral surface of an inner cylindrical portion. The main seal lip has an internal-side inclined surface disposed on a side of the internal space and an atmosphere-side inclined surface disposed on the atmosphere side. An auxiliary seal lip protrudes radially inward and toward the internal space from the internal-side inclined surface of the main seal lip. Multiple first spiral structures and multiple second spiral structures are formed on at least one of the atmosphere-side inclined surface of the main seal lip and an inner peripheral surface of the auxiliary seal lip.