Segmented Rim Rubber for Tyre Electrostatic Discharge and Low Rolling Resistance
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Solution Overview
Problem
Pneumatic vehicle tires with non-conductive rubber mixtures, particularly those containing silica, face challenges in preventing electrostatic charging and maintaining a reliable conductive connection while trying to reduce rolling resistance.
Innovation Solution
The tire design incorporates a rim rubber part made of a low hysteresis, electrically non-conductive mixture that extends beyond the rim flange and contacts it, combined with an electrically conductive rim rubber part forming the bead toe and seat surface, ensuring effective electrostatic discharge and reduced deformation-induced energy losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electrically conductive rubber mixture is used in the rim rubber part, then electrostatic discharge is ensured, but rolling resistance increases due to high hysteresis
Solution Approach 1:
The rim rubber is divided into two distinct parts: an electrically conductive rim rubber part (7b) that ensures electrostatic discharge, and an electrically non-conductive rim rubber part (7a) with low hysteresis that contacts the rim flange and reduces rolling resistance. This segmentation allows each part to optimize its specific function without compromise.
Solution Approach 2:
Different electrical conductivity properties are assigned to different regions of the rim rubber. The electrically non-conductive part (7a) is positioned where it contacts the rim flange to minimize energy loss, while the electrically conductive part (7b) is positioned to ensure electrostatic discharge functionality. Each region has locally optimized properties for its specific role.
2Loss of energy
If a soft rubber mixture is used to reduce deformation losses, then rolling resistance decreases, but mechanical strength and resistance to mounting damage decrease
Solution Approach 1:
The electrically conductive rim rubber part (7b) is formulated with high Shore hardness (≥60, particularly ≥65) to provide the mechanical strength needed to prevent damage during mounting and to form a durable bead toe. This local strengthening occurs precisely where structural integrity is most critical.
3Loss of energy
If the electrically non-conductive rim rubber part is positioned to contact the rim flange, then rolling resistance is reduced, but the conductive connection path may be interrupted
Solution Approach 1:
The rim rubber is segmented into electrically non-conductive part (7a) for low rolling resistance and electrically conductive part (7b) for electrostatic discharge. The conductive part is specifically positioned to maintain the electrical connection path while the non-conductive part contacts the rim flange.
Solution Approach 2:
The electrically conductive rim rubber part (7b) acts as an intermediary that bridges the electrical connection between the carcass threads and the rim, ensuring continuous conductive path despite the presence of the non-conductive part (7a) in contact with the rim flange.
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 design effectively maintains a reliable conductive connection, reduces rolling resistance, and enhances mechanical strength, preventing damage during mounting by using a rim rubber part with specific rebound resilience and Shore hardness, effectively addressing electrostatic charging and energy loss issues.
Implementation Method 1
A rubber compound with low hysteresis generates less deformation-induced energy losses in the rim rubber part subjected to the rim flange than a rubber compound with high hysteresis and contributes to a reduction in rolling resistance
Implementation Method 2
the electrically conductive rim rubber part also forming the bead toe and with the bead seat surface comes into contact with the rim... creates the electrically conductive connection between the tread strips that come into contact with the road and the rim
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a radial pneumatic vehicle tyre having at least one component made of at least one electrically non-conductive rubber mixture, comprising bead regions having bead cores (3), a carcass ply (4), which extends around the bead cores (3) and has turn-ups (4a), which extend in the direction of side walls (5), and a rim rubber (7, 7'), which forms the outer surface of the bead region and extends along the carcass turn-up (4a) and comprises a rim rubber part (7a, 7'a) made of an electrically non-conductive rubber mixture and a rim rubber part (7b, 7'b) made of an electrically conductive rubber mixture, which rim rubber part made of an electrically conductive rubber mixture connects at least one electrically conductive component to the rim (1), which electrically conductive component extends in the tyre and forms or contributes to the formation of an electrically conductive connection to the outside of the tyre. The electrically non-conductive rim rubber part (7a, 7'a) extends beyond the rim flange (1a) in the direction of a side wall (5) and is in contact with the rim flange and is composed of a rubber mixture having low hysteresis.