Planet Carrier Flex-Pin Structure for Helical Load Balancing

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Solution Overview

Problem

Helical planetary stages with flex pins face challenges in load balancing due to tilting moments caused by axial forces, leading to undesired deformations and increased noise emissions, while straight-toothed gears result in higher noise levels.

Innovation Solution

A planetary carrier arrangement with a stiffening element and support ring is used to counter tilting moments, incorporating a pin and bushing with a resilient gap filled with a medium, allowing for axial movement and deformation, while maintaining stiffness against tilting, thus enabling load balancing without increasing noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If flex pins are used in helical planetary stages, then load balancing is achieved, but tilting moments cause undesired deformations

Engineering Contradiction:
Improveload balancingVSAvoiddeformation of pin
Core Design Contradiction:
Stability of the object's compositionVSShape

Solution Approach 1:

The pin is divided into a rigid first end fixed in the cheek, a resilient intermediate piece, and a second end in the socket. This segmentation allows different parts to have different mechanical properties, with the intermediate piece providing resilience to tilting moments while the ends maintain structural integrity for load balancing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different parts of the pin have different mechanical properties: the first end is rigid for stable mounting, the intermediate piece is resilient to absorb tilting moments, and the second end is fixed for socket connection. This local differentiation resolves the contradiction by providing both load balancing stability and deformation resistance where needed.

Inventive Principle:
Principle #3Local quality

2Stability of the object's composition

If helical gearing is used, then load balancing is achieved, but axial forces cause tilting moments

Engineering Contradiction:
Improveload balancingVSAvoidtilting moment
Core Design Contradiction:
Stability of the object's compositionVSForce

Solution Approach 1:

The pin's intermediate piece is designed with specific resilience parameters to counteract the tilting moments generated by helical gearing. By adjusting the resilience characteristics of this section, the system can accommodate axial forces while maintaining load balancing capability.

Inventive Principle:
Principle #35Parameter changes

3Object-generated harmful factors

If straight-toothed gears are used, then noise emissions are reduced, but load balancing capability is lost

Engineering Contradiction:
Improvenoise emissionsVSAvoidload balancing
Core Design Contradiction:
Object-generated harmful factorsVSStability of the object's composition

Solution Approach 1:

The segmented pin structure with resilient intermediate piece enables load balancing functionality that allows the use of quieter straight-toothed gears, thereby reducing noise emissions while maintaining load balancing capability through the resilient deformation of the intermediate piece.

Inventive Principle:
Principle #1Segmentation

4Stability of the object's composition

If the pin is made resilient to allow deformation, then load balancing is achieved, but flexural strength is reduced

Engineering Contradiction:
Improveload balancingVSAvoidflexural strength of pin
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The pin is segmented into rigid ends and a resilient intermediate piece, concentrating the deformation capability in a controlled section while maintaining high flexural strength in the critical end regions that require structural integrity for load balancing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The resilient properties are localized to the intermediate piece where controlled deformation aids load balancing, while the first and second ends maintain high strength characteristics for reliable connection to the cheek and socket respectively.

Inventive Principle:
Principle #3Local quality

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

This solution allows for effective load balancing in planetary stages using helical gearing, reducing noise emissions and enhancing flexural strength along the circumference, while maintaining resilience to circumferential forces.

Implementation Method 1

A gap is arranged between the pin and the socket. The gap is preferably filled with a resilient medium.

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

A stiffening element, in particular a stiffening rib, extends between the cap and the support ring in order to stiffen the socket.

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentEP3969782B1Planet carrier with flexible bolts and stiffening rib
Publication Date: 2023.06.07 ZF FRIEDRICHSHAFEN AG
  • EP3969782B1 patent drawingFigure 1~2

AI summary

The invention relates to an arrangement comprising a planet carrier (101) with at least one web (201), comprising a journal (205) and comprising a bushing (207); wherein a first end of the journal (205) is fixed in the web (201); wherein at least a part of the journal (205) projects into the bushing (207); and wherein a second end of the journal (205) is fixed in the bushing (207). The arrangement furthermore comprises at least a stiffening element (111) and a support ring (103); wherein the stiffening element (111) is fixed in the bushing (207) and in the support ring (103); and wherein the bushing (207) and the stiffening element (111) are connected to one another as two pieces.