Seal Ring With Level Difference Portion For Automatic Transmission

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Solution Overview

Problem

Existing seal rings for automatic transmissions face challenges in reducing friction and oil leakage, especially at high shaft rotation frequencies, due to their design which often results in increased shaft rotation torque and oil leakage, as seen in Patent Literature 1 and 2.

Innovation Solution

A seal ring design featuring a level difference portion with a second width smaller than the first width, strategically positioned to optimize contact and pressure-receiving surfaces, reducing friction and oil leakage by creating a dynamic pressure effect that minimizes contact area and enhances sealing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the seal ring contact surface is pressed against the shaft annular groove to prevent oil leakage, then sealing performance is improved, but friction loss and shaft rotation torque increase

Engineering Contradiction:

Improvesealing performanceVSAvoidfriction loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The seal ring incorporates a dynamic pressure groove that changes the contact conditions between the seal ring and shaft dynamically based on operating pressure and speed. The groove allows hydraulic pressure to modulate the contact force, maintaining adequate sealing at low speeds while reducing friction at high speeds where dynamic pressure effects are stronger.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The seal ring features a localized dynamic pressure groove rather than uniform contact across the entire sealing surface. This concentrates the sealing function in specific regions while allowing other areas to have reduced contact, optimizing the balance between sealing effectiveness and friction reduction.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If the seal ring structure is simplified to reduce manufacturing cost, then ease of manufacture is improved, but oil leakage increases at high rotation frequencies

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidoil sealing performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The seal ring is divided into functional zones: a dynamic pressure groove section and a standard sealing section. This segmentation allows the complex dynamic pressure function to be localized while the rest of the seal ring maintains simple, easy-to-manufacture geometry, preserving both manufacturing ease and high-speed sealing performance.

Inventive Principle:

Principle #1Segmentation

3Reliability

If the contact area between seal ring and shaft is increased to improve sealing, then oil leakage is reduced, but shaft rotation torque increases

Engineering Contradiction:

Improvesealing performanceVSAvoidshaft rotation torque

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The seal ring utilizes hydraulic pressure from the transmitted fluid itself to create the dynamic pressure effect. The fluid pressure acts on the inclined surfaces of the dynamic pressure groove, generating reactive forces that modulate the contact pressure between seal ring and shaft, eliminating the need for additional mechanical components.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 seal ring design effectively reduces shaft rotation torque and oil leakage across a wide range of shaft rotation frequencies, maintaining low torque and leakage even at high speeds, thereby improving fuel efficiency and reducing drive loss in automatic transmissions.

Implementation Method 1

creating a dynamic pressure effect that minimizes contact area and enhances sealing efficiency

Methodology Applied

Scientific EffectDynamic pressure effect: Pressure Gradient

Implementation Method 2

a seal ring outer peripheral surface 13 is brought into contact with an inner peripheral surface of a housing 5, and a seal ring contact surface 14 is brought into contact with a side surface of the shaft annular groove 4, thereby preventing leakage of the hydraulic oil

Methodology Applied

Scientific EffectHydraulic sealing: Physical Containment

Data Source

PatentUS10451185B2Seal ring

Publication Date: 2019.10.22 TEIKOKU PISTON RING CO LTD

AI summary

Provided is a seal ring causing less friction and having a low oil leakage property even under a state in which a shaft rotation frequency or a housing rotation frequency is high, and being capable of reducing a shaft rotation torque. A level difference portion that forms a second width smaller than a first width is formed on a longitudinal sectional shape of the seal ring as viewed in a circumferential direction from a seal ring outer peripheral surface side toward a seal ring inner peripheral surface side. The level difference portion is formed so that a center line of the second width in the circumferential direction of the seal ring in which a sealed fluid flows draws a trajectory of extending along the circumferential direction and shifting from an abutment joint end surface on an inner periphery side of a seal ring abutment joint portion at one end toward an abutment joint end surface on the inner periphery side of the seal ring abutment joint portion at another end so as to be closer to the seal ring contact surface.