Stamped Universal Joint Yoke Reinforcement Appendages

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Solution Overview

Problem

Current stamped universal joint jaws in motor vehicle steering columns face issues with transmitting high rotational and tightening torques, leading to slippage and loosening due to inadequate clamping and reaction forces, while maintaining a similar size and weight.

Innovation Solution

A stamped universal joint jaw with reinforcement appendages made from excess material near high-stress areas, arranged to maintain continuous fibers and provide enhanced clamping and reaction capabilities, utilizing a method that includes cutting, heat treatment, and deformation without fiber breakage, to create a one-piece part with improved clamping and holding functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a stamped universal joint jaw is made from a thick sheet without modifying thickness, then the jaw can transmit high torque, but the clamping system experiences slippage and loosening under high tightening and rotation torques

Engineering Contradiction:
Improvetorque transmission capabilityVSAvoidclamping stability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention transitions from a two-dimensional sheet metal blank to a three-dimensional structure by forming reinforcing appendages that protrude from the clamping surfaces. These appendages add vertical dimension to the clamping interface, creating multiple contact points and increasing friction surface area, which prevents slippage while maintaining torque transmission capability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The clamping surface is segmented into multiple contact zones through the formation of reinforcing appendages. Instead of a single flat clamping surface, the appendages create distributed contact points along the clamping axis, which prevents stress concentration and reduces slippage risk under high torque conditions.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the sheet thickness is increased to prevent slippage, then clamping stability improves, but the jaw size and weight increase

Engineering Contradiction:
Improveclamping stabilityVSAvoidjaw weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

Rather than increasing sheet thickness in the vertical direction, the invention creates reinforcing structures by deforming the sheet material into three-dimensional appendages. This approach increases clamping stability through geometric configuration rather than material quantity, maintaining lightweight characteristics while improving performance.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The invention changes the geometric parameters of the jaw structure by forming appendages with specific dimensions and configurations. These parameter changes optimize the distribution of clamping forces and increase friction without requiring additional material thickness, thereby maintaining weight efficiency.

Inventive Principle:
Principle #35Parameter changes

3Strength

If reinforcement appendages are added after stamping, then high-stress areas are strengthened, but the manufacturing process becomes more complex

Engineering Contradiction:
Improvehigh-stress area resistanceVSAvoidmanufacturing process simplicity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The reinforcing appendages are formed during the stamping process itself, before final assembly. The blank is designed with excess material in strategic locations that is then deformed into appendages during stamping. This preliminary formation of reinforcements eliminates the need for separate manufacturing steps, maintaining manufacturing simplicity while achieving the desired strength enhancement.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention merges the reinforcement formation operation with the main stamping process. Instead of adding reinforcements as a separate post-processing step, the appendages are created during the primary forming operation by strategically positioning and deforming excess material in the blank, thereby combining multiple functions into a single manufacturing step.

Inventive Principle:
Principle #5Merging (Combining)

4Ease of manufacture

If the sheet is folded to create clamps, then the clamping structure is formed, but fiber breakage and material bending occur reducing performance

Engineering Contradiction:
Improveclamp formationVSAvoidmaterial integrity
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

Instead of folding the sheet in-plane to create clamps, the invention forms three-dimensional appendages by deforming excess material vertically from the clamping surfaces. This dimensional approach creates the necessary clamping structure without subjecting the material to severe bending stresses that would cause fiber breakage.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The invention changes the forming parameters from severe folding operations to controlled deformation processes. The appendages are formed by gradually deforming excess material into the desired shape during stamping, avoiding sharp bends and folds that would compromise material integrity, thereby maintaining both manufacturability and strength.

Inventive Principle:
Principle #35Parameter changes

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 solution effectively increases the jaw's performance in transmitting high torques and resisting plastic deformation, ensuring better clamping and reaction forces without increasing size or weight, and simplifies machining and deburring operations.

Implementation Method 1

The deformation by stamping of said sheet takes place without breaking the fibers of the material constituting it

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

cutting of a thick sheet with a surplus of material with shapes for the four appendages, heat treatment adapted to the desired resistance

Methodology Applied
Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentEP2007995B1Pressed joint yoke for a motor vehicle steering column universal joint
Publication Date: 2012.01.18 ZF SYST DE DIRECTION NACAM S
  • EP2007995B1 patent drawingFigure 1
  • EP2007995B1 patent drawingFigure 2
  • EP2007995B1 patent drawingFigure 3~4

AI summary

The joint yoke is made of one piece and comprises: an articulation fork (1) with two articulation arms (11, 12) bearing a hole (13, 14) having a hinge pin (3) for articulating a spider, and a connection element (2) for connecting to the shaft (5) comprising two clamping portions (21, 22) connected by a joining portion (23) and comprising a clamping hole (25, 24) having an axis (4). Four reinforcing appendages (27, 28 - 29, 30) are arranged on the corresponding clamping portion and face one another in pairs to form, together with the portions (21, 22, 23), the housing for the shaft (5); the said joint yoke being pressed in order to give it the desired thickness for the highly and lightly stressed regions.