Planetary Gear Pin Locking and Thrust Washer Sealing
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Solution Overview
Problem
Existing planetary gear assemblies in vehicles face issues with pin security and thrust washer movement, leading to oil leakage and non-serviceability due to lack of effective sealing and locking mechanisms.
Innovation Solution
Incorporating a pin with a shoulder and pin locking feature, and thrust washers with locking members that engage with the carrier and cover locking features, preventing pin rotation and axial sliding, thus securing the pin and containing it within the assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pins are press-fitted into the planetary carrier, then the pins are secured relative to the carrier, but this creates a leak path for oil and renders parts non-serviceable
Solution Approach 1:
A seal member is introduced as an intermediary component between the pin and the planetary carrier. The seal member includes a body portion positioned in a recess of the carrier and a protruding portion that extends along the pin, creating an oil-tight barrier without interfering with the press-fit connection. This mediator prevents oil from leaking along the pin-carrier interface while maintaining secure pin mounting.
2Object-generated harmful factors
If pins are bolted onto the planetary carrier, then oil leakage is avoided, but the bolts can become loose during operation
Solution Approach 1:
The seal member serves as a mediator that eliminates the need for bolts while preventing oil leakage. By positioning the seal member in a recess and having it protrude along the pin, it creates an oil-tight seal that prevents leakage without requiring additional fastening hardware that could loosen.
3Ease of operation
If thrust washers are free to move during operation, then they can accommodate thrust loads, but they may damage other components of the planetary gear system
Solution Approach 1:
The thrust washer is designed with differentiated local qualities: the face portions are made of a softer material than the pin to provide wear protection, while the outer periphery includes a hardened locking portion for secure engagement. This local quality differentiation allows the washer to accommodate thrust loads through controlled movement while preventing damage to other components through material selection and geometric constraints.
Solution Approach 2:
The thrust washer is pre-configured with a locking portion that engages with a corresponding feature on the pin before operation begins. This preliminary locking action prevents the washer from moving excessively during operation, thereby preventing damage to other components while still allowing sufficient movement to accommodate thrust loads.
4Reliability
If multiple separate components are used for pin securing and thrust washer locking, then reliability is improved, but manufacturing cost and assembly complexity increase
Solution Approach 1:
The seal member and thrust washer are merged into a single integrated component. The seal member portion provides oil sealing and pin securing functions, while the thrust washer portion provides thrust load accommodation and locking functions. This merging eliminates the need for separate seal members and thrust washers, reducing assembly complexity and manufacturing cost while maintaining reliability through the combined functionality of the integrated component.
Data Source
AI summary
A vehicle including a chassis and a planetary gear assembly supported by the chassis. The planetary gear assembly includes a planetary carrier having a carrier locking feature, at least one planetary gear, at least one pin supporting the at least one planetary gear and including at least one pin locking feature, and at least one thrust washer coupled to and supported by the at least one pin. The at least one thrust washer includes a first locking member engaging with the carrier locking feature, which prevents the at least one thrust washer from rotating, and a second locking member engaging with the at least one pin locking feature such that the at least one thrust washer prevents the at least one pin from rotating and axially sliding.