Damping Device Fixing Member Hardness for Torque Transmission
Solution Overview
Problem
Existing damping devices for motor vehicle transmission chains, such as double mass flywheels, face issues with fixing rivets deforming under extreme stress, leading to potential damage and reduced reliability due to uneven force distribution during torque transmission.
Innovation Solution
A damping device with a first fixing member of high Rockwell hardness (greater than 30 HRC) to absorb the greatest forces, ensuring reliable fixation, and a second fixing member of lower hardness for axial retention, allowing for efficient torque transmission with vibration damping between elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rivet is used to fix the torque transmission element to the flywheel, then the assembly is simple and easy to manufacture, but the rivet deforms under extreme centrifugal stresses leading to play and potential damage
Solution Approach 1:
The patent changes the material parameter of the fixing member by specifying a Rockwell hardness greater than 30 HRC. This parameter change enables the fixing member to withstand extreme centrifugal stresses without deformation, resolving the reliability issue while maintaining the simplicity of the riveting process
Solution Approach 2:
The patent employs a fixing member with composite properties - it combines the ease of installation characteristic of soft materials with the stress resistance of hard materials by specifying a particular hardness range (Rockwell > 30 HRC). This creates an optimized material that satisfies both manufacturing ease and reliability requirements
2Reliability
If the fixing member is made very hard to prevent deformation, then reliability improves, but the manufacturing process becomes more difficult
Solution Approach 1:
The patent identifies and specifies a critical parameter range for the fixing member material - Rockwell hardness greater than 30 HRC. This parameter specification balances the competing requirements of reliability (needing high hardness) and manufacturability (needing reasonable hardness for installation), resolving the technical contradiction
3Reliability
If the first fixing member absorbs the greatest forces, then the attachment reliability improves, but the force distribution becomes uneven creating stress concentration
Solution Approach 1:
The patent applies local quality by making the first fixing member (located at the critical position nearest the flexible blade) have superior hardness properties (Rockwell > 30 HRC) compared to other fixing members. This localized enhancement of material quality allows the first fixing member to absorb the greatest forces without deforming, while other fixing members handle lesser loads, thus improving attachment reliability at the critical location
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 provides enhanced reliability and durability by ensuring the hardest fixing member takes the majority of forces, preventing deformation and maintaining the integrity of the damping device under stress, thus improving the overall performance and longevity of the transmission system.
Implementation Method 1
the first fixing member being mounted by a tight fit, i.e. without play, in the respective orifice of the torque transmission element and having a Rockwell hardness greater than 30 HRC
Implementation Method 2
at least one elastic damping element capable of coupling the first element to the torque transmission element so as to allow torque transmission with vibration damping
Implementation Method 3
The flexing of the flexible blades dampens vibrations and rotational irregularities between the primary and secondary flywheels while ensuring torque transmission
Data Source
Figure 1
Figure 2~3
Figure 4~7
AI summary
The invention relates to a damping device for a motor vehicle transmission chain comprising: - a first element and a second element (3) movable in rotation relative to each other about an axis of rotation X; - at least one torque transmission element (14) fixed to the second element (3); and - at least one elastic damping element (12) suitable for coupling the first element to the torque transmission element (14) so as to allow torque transmission with vibration damping between the first element and the second element (3); - the torque transmission element (14) being fixed to the second element (3) by means of at least one first and one second fixing members (22; 23); the first fixing member (22) being mounted by an interference fit in a respective orifice of the torque transmission element (14) and having a Rockwell hardness greater than 30 HRC.