Universal Joint Spider Temperature Sensing for Early Wear Detection

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Solution Overview

Problem

Existing methods for detecting impending wear in universal joints of cardan shafts, such as those used between tractors and agricultural machines, are not reliable or compact, and often rely on ultrasonic sensors or temperature monitoring within the spider, which may not effectively indicate wear due to misalignments or friction issues.

Innovation Solution

A spider with integrated temperature sensors, preferably located on the base and extending into the pins, measures the temperature of the spider or lubricant to detect increased friction and power loss, with multiple sensor elements connected to a central logic for signal processing and evaluation, allowing for early wear detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If ultrasonic sensors are used to monitor radial gap for wear detection, then wear detection capability is improved, but device complexity and reliability are worsened due to mounting issues and fixed spatial relationship requirements

Engineering Contradiction:
Improvewear detection capabilityVSAvoidsensor mounting reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces ultrasonic sensors with temperature sensors to detect wear. Instead of mechanically measuring radial gap with ultrasonic sensors, the invention uses thermal field measurement through temperature sensors that directly contact the journal cross, substituting a mechanical measurement system with a thermal field-based system that is more reliable and easier to implement.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If temperature sensors are placed in the cross member, then wear detection is improved, but device complexity is worsened

Engineering Contradiction:
Improvewear detection capabilityVSAvoidsensor integration complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the temperature sensor directly with the journal cross structure. The sensor is integrated into the base of the journal cross, combining the sensing function with the structural component, thereby simplifying the overall device by eliminating separate sensor mounting structures and reducing system complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The journal cross structure itself serves as the mounting platform for the temperature sensor. The base of the journal cross provides the integration point for the sensor, allowing the structure to serve both its mechanical function and as a sensor mounting platform, eliminating the need for additional mounting structures.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If multiple sensor elements are assigned to each journal for individual monitoring, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improveindividual journal monitoring precisionVSAvoidsensor element quantity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the monitoring function by assigning at least one temperature sensor to each journal of the journal cross. This segmentation allows individual monitoring of each journal's temperature, enabling precise detection of wear in specific journals while maintaining a relatively simple overall structure compared to more comprehensive sensor arrays.

Inventive Principle:
Principle #1Segmentation

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 provides a reliable and compact method for detecting impending wear in universal joints by monitoring temperature changes, enabling early identification of wear through friction and power loss indicators, independent of external temperature variations.

Implementation Method 1

Wearing bearings typically have increased friction coefficients. Misalignment of individual components of the journal cross that move relative to each other can also lead to increased power loss in the journal cross, which increases the temperature.

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

The temperature sensor directly detects the temperature of the journal cross. Typically, the temperature sensor detects the current temperature of the material forming the journal cross or of a lubricant (usually grease) contained in the base of the journal cross.

Methodology Applied
Scientific EffectViscous Heating: Viscous Heating

Data Source

PatentEP3971433B1Universal joint spider with a temperature sensor and universal joint with such a spider
Publication Date: 2024.09.18 OFF HIGHWAY POWERTRAIN SERVICES GERMANY GMBH
  • EP3971433B1 patent drawingFigure 1~3

AI summary

The present invention relates to a pivot cross (8) of a universal joint with four pins (6) projecting from a base (14), with at least one temperature sensor attached to the pivot cross. To detect incipient wear, the present invention proposes that the temperature sensor has at least one sensor element arranged on the outer circumference of one of the pins (6).