Resin Seal Ring with Elastic Push for Low Torque Sealing
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Solution Overview
Problem
Conventional seal rings fail to maintain a sealing function effectively when fluid pressure is low or absent, leading to oil leakage and poor responsiveness in automotive transmissions, such as AT and CVT systems, due to their design which does not allow for sealing without oil pressure.
Innovation Solution
A sealing device comprising an outer peripheral ring made of resin and an inner peripheral ring made of a rubber-like elastic body, where the outer peripheral ring has a concave portion extending from the high pressure side to the low pressure side, allowing it to maintain contact with the shaft hole even without fluid pressure and reducing sliding torque by introducing fluid into the concave portion as pressure increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the peripheral length of the outer peripheral surface is made shorter than the inner peripheral surface of the shaft hole to reduce sliding torque, then sliding torque is reduced, but the seal ring cannot maintain sealing function when fluid pressure is low or absent
Solution Approach 1:
The seal ring transitions from a static design to a dynamic one where the outer peripheral surface length changes with fluid pressure. At low pressure, it maintains a shorter effective length for low sliding torque; at high pressure, it expands to provide sufficient sealing contact length. This dynamic adaptation resolves the contradiction between low sliding torque and reliable sealing across all pressure conditions.
Solution Approach 2:
The invention changes the physical parameter of the outer peripheral surface length based on fluid pressure conditions. The seal ring is designed to expand radially when subjected to high fluid pressure, increasing the contact length with the shaft hole inner peripheral surface. This parameter change allows the seal to provide sufficient sealing length only when needed (under pressure) while maintaining short sliding contact at low pressure for reduced torque.
2Force
If the seal ring is designed without tightening margin to reduce sliding torque, then sliding torque is reduced, but the seal ring separates from the shaft hole when oil pressure is not applied
Solution Approach 1:
The seal ring utilizes dynamic expansion under fluid pressure to achieve sealing contact only when needed. During idle stop or low-pressure conditions, the seal ring remains retracted with minimal contact, reducing sliding torque. When fluid pressure is applied, the seal ring expands dynamically to make intimate contact with the shaft hole, ensuring reliable sealing without requiring permanent tightening margin.
Solution Approach 2:
The invention extracts the tightening margin function from the seal ring's static design and replaces it with a pressure-activated expansion mechanism. The seal ring body itself serves as the expanding element, eliminating the need for separate tightening features while achieving the same sealing effect only when fluid pressure is present.
3Reliability
If the seal ring expands in diameter under high oil pressure to make intimate contact, then sealing function is improved, but sliding torque increases due to increased contact length
Solution Approach 1:
The seal ring design applies local quality by concentrating the sealing contact function at the outer peripheral surface while minimizing the sliding contact length at the inner peripheral surface. The expansion under pressure increases sealing contact locally at the outer diameter, while the inner diameter contact length remains relatively short, thus achieving good sealing without proportionally increasing sliding torque.
Solution Approach 2:
The dynamic expansion mechanism allows the seal ring to increase its outer diameter contact length for sealing purposes while maintaining a controlled increase in inner diameter sliding contact. The differential expansion characteristics ensure that sealing improvement is prioritized over sliding torque reduction, resolving the contradiction between these two opposing requirements.
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 ensures a consistent sealing function across varying fluid pressures, preventing oil leakage and maintaining responsiveness in automotive transmissions by maintaining contact with the shaft hole and reducing sliding torque, even when fluid pressure is low or absent.
Implementation Method 1
an inner peripheral ring made of a rubber-like elastic body that is in intimate contact with an inner peripheral surface of the outer peripheral ring and a groove bottom surface of the annular groove, respectively, thereby to push the outer peripheral ring toward an outer peripheral surface side
Implementation Method 2
the outer peripheral ring has a concave portion formed on its outer peripheral surface to extend from an end of a high pressure side to a position which does not arrive at an end of a low pressure side, so as to introduce fluid thereinto from the high pressure side
Implementation Method 3
an outer peripheral ring made of resin that is in intimate contact with a side wall surface of the annular groove at a low pressure side, and slides with respect to an inner peripheral surface of a shaft hole in the housing
Data Source
Figure 1~3
Figure 4~5
Figure 6
AI summary
A sealing device which is fitted into an annular groove formed in an outer periphery of a shaft so as to seal an annular gap between said shaft and a housing which rotate relative to each other, thereby to hold a fluid pressure in a region to be sealed which is constructed such that the fluid pressure therein changes, characterized by comprising: an outer peripheral ring made of resin that is in intimate contact with a side wall surface of said annular groove at a low pressure side thereof, and slides with respect to an inner peripheral surface of a shaft hole in said housing through which said shaft is inserted; and an inner peripheral ring made of a rubber-like elastic body that is in intimate contact with an inner peripheral surface of said outer peripheral ring and a groove bottom surface of said annular groove, respectively, thereby to push said outer peripheral ring toward an outer peripheral surface side thereof; wherein said outer peripheral ring is formed on its outer peripheral surface with a plurality of concave portions which are spaced from one another in a circumferential direction and which each extend from an end of a high pressure side to a position which does not arrive at an end of a low pressure side, so as to introduce fluid thereinto from the high pressure side; and wherein convex portions each formed between adjacent concave portions are formed so as to extend from the low pressure side toward the high pressure side as they go in the sliding direction of said outer peripheral ring with respect to said housing.