Cardan Joint Stiffness Measurement Using Gravitational Torque
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Solution Overview
Problem
Current methods for measuring cardan joint tightness are inefficient, costly, and impractical for serial production, as they require specialized equipment and lengthy inspection processes, leading to issues like wear, noise, vibration, and corrosion, and do not allow for 100% inspection.
Innovation Solution
A portable, low-cost tightness measurement apparatus with a bidirectional weight mechanism that applies varying torque to cardan joints, allowing for rapid and direct measurement of joint stiffness within specified ranges, comprising a housing, extension, and weight, enabling easy operation by any personnel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a torquemeter and inspection bench are used to measure joint stiffness, then measurement accuracy is achieved, but inspection duration increases and productivity decreases
Solution Approach 1:
The patent replaces the complex mechanical torquemeter system with a gravitational force system. Weights are attached to the cardan shaft, and their gravitational force directly applies torque to the joint. The angular displacement is measured visually or with simple sensors, eliminating the need for complex torque application and measurement mechanisms, thus reducing inspection time while maintaining measurement capability
Solution Approach 2:
The patent creates a simplified measurement model where the cardan shaft is positioned at a specific angle (e.g., 45 degrees) and weights are attached at known positions. This creates a reproducible gravitational torque scenario that copies the essential measurement function of the torquemeter but with much simpler apparatus, enabling rapid repeated measurements
2Measurement precision
If a torquemeter and inspection bench are used to measure joint stiffness, then measurement capability is achieved, but device complexity and operational difficulty increase
Solution Approach 1:
The complex torquemeter device is replaced with simple gravitational weights and basic angular position indicators. The measurement capability is maintained by using the known gravitational force (mass × gravity) and the lever arm distance to calculate torque, combined with visual or simple electronic angular displacement measurement, eliminating the need for complex mechanical torque sensors
Solution Approach 2:
The cardan shaft itself serves as part of the measurement apparatus. By positioning it at a specific angle and attaching weights, the system uses its own geometry and the universal gravitational field to generate the measurement conditions, eliminating the need for external complex measurement equipment and reducing operational complexity
3Measurement precision
If a torquemeter and inspection bench are used to measure joint stiffness, then tightness assessment is achieved, but inspection cost increases
Solution Approach 1:
The patent uses inexpensive weights and simple angular indicators instead of expensive torquemeters. The measurement apparatus can be easily manufactured or acquired at low cost, and while individual components like weights may be consumed or worn, their low cost allows for replacement without significant expense, making the system economically viable for high-volume inspection
Solution Approach 2:
The expensive mechanical torquemeter system is replaced with a gravitational measurement system using simple weights and angular position indicators. This substitution dramatically reduces equipment cost while maintaining the ability to assess joint tightness through the relationship between applied gravitational torque and measured angular displacement
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 quick, cost-effective, and 100% inspection of cardan joint tightness, reducing inspection time and equipment costs, while ensuring proper tightness levels are maintained, thus preventing wear, noise, and corrosion, and facilitating balanced shaft operation.
Implementation Method 1
allow application of varying and increasing amount of torque by means of a weight which is able to carry out bidirectional motion on an extension connected with the cardan joint
Data Source
Figure 1~2
Figure 3
Figure 4~5.1
AI summary
The tightness measurement apparatus (20) intended to be used to measure the tightness of cardan joints (12) which are attached between the end connector yokes (11') of cardan shafts (10), in a low-cost, practical and rapid way, comprising; at least one housing (21) which is fixed to the said end connector yoke (11'), at least one extension (22) which is connected to the said housing (21), and at least one weight (23) which engages to the extension (22) and is able to perform bidirectional motion thereon. In the tightness measurement method (A) where the tightness measurement apparatus (20) is used, the torque value at which the cardan joint (12) starts moving in vertical direction and thereby the tightness level is determined.