Two-Bolt Fastening Means for Jammed Heavy Transmission Parts

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Solution Overview

Problem

Existing fixing agents for large gearboxes, such as wind turbine gearboxes, risk deformation during assembly and disassembly, leading to jamming and inability to be removed once deformed, especially in high-mass components.

Innovation Solution

A fixing means comprising a base body with external and internal threads, and two bolts where the second bolt's external thread screws into the internal thread of the base body, allowing the first bolt to be displaced and fixed, and a screw can be used to release the first bolt if it jams due to plastic deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a single fixing device is used to secure heavy transmission components, then the fixing strength is sufficient, but the device deforms and jams under high mass loads

Engineering Contradiction:
Improvefixing strengthVSAvoidremovability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The fixing device is divided into two separate bolts instead of one single fixing element. The first bolt provides the primary clamping force, while the second bolt acts as a release mechanism. This segmentation allows the system to maintain sufficient fixing strength while enabling reliable removal even after plastic deformation occurs in the first bolt.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The second bolt serves as an intermediary release mechanism. When the first bolt jams due to plastic deformation, the second bolt can be screwed into the threaded hole to push the first bolt out, acting as a mediator that enables removal without damaging the fixing device or the workpiece.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the fixing device is designed to be removable, then it can be taken out after use, but it jams and cannot be removed under high mass conditions

Engineering Contradiction:
ImproveremovabilityVSAvoidjamming risk
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The threaded hole is pre-formed in the base body, allowing the second bolt to be screwed in as a preliminary action before attempting to remove the first bolt. This preliminary positioning of the second bolt enables the release mechanism to function reliably even when the first bolt is severely deformed and jammed.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If a through-hole is provided for bolt insertion, then the bolt can be positioned, but plastic deformation causes the bolt to jam in the hole

Engineering Contradiction:
Improvebolt positioningVSAvoidrelease mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The base body integrates both the through-hole for the first bolt and the threaded hole for the second bolt into a single structural element. This merging allows the positioning function (through-hole) and the release function (threaded hole) to coexist in one component, enabling bolt positioning while providing a built-in release mechanism without adding separate positioning devices.

Inventive Principle:
Principle #5Merging (Combining)

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

Enables secure fixing and subsequent release of gear parts without permanent deformation, ensuring the fixing agents can be removed even after plastic deformation occurs, facilitating easy assembly and disassembly of gearbox components.

Implementation Method 1

The screw then forms a support for the head of the screw, with the chin of the head resting on the edge of the opening of the through-hole. When the screw is now screwed into the internal thread, it becomes wedged between the first bolt and the second bolt, or between the internal thread and the edge of the opening.

Methodology Applied
Scientific EffectWedge: Wedge

Implementation Method 2

Due to the force that the screw exerts on the first bolt as a result of this wedged tension, the first bolt can still be moved even if it has become jammed in the first part of the through-hole by plastic deformation.

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4031765B1Fastening means for heavy transmission parts
Publication Date: 2023.09.13 ZF FRIEDRICHSHAFEN AG
  • EP4031765B1 patent drawingFigure 1
  • EP4031765B1 patent drawingFigure 2

AI summary

The invention relates to a fastening means (101) for a transmission part, comprising a main body (103), the main body (103) having at least one external screw thread (105) and at least one through-hole (109). The fastening means has a first pin (117), which can be slid in a first region (115) of the through-hole (109), and a second pin (121) having an external screw thread, a second region (119) of the through-hole (109) having at least one internal screw thread, which can be screwed to the external screw thread of the second pin (121), and the second pin (121) having a through-hole and the first pin (117) having an internal screw thread (125) aligned with the through-hole.