Shoulder Rib Arch Shape for Uniform Tire Pressure
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Solution Overview
Problem
Pneumatic tires with main grooves and parallel ribs face issues with non-uniform ground contact pressure in the shoulder rib area, leading to inadequate braking performance and uneven inflation, as the inner ends of slits in the tire width direction are terminated within the shoulder rib or closed during ground contact.
Innovation Solution
The design includes plural main grooves extending in the tire circumferential direction, a shoulder rib between the outermost main groove and ground contact end, with slits extending in the tire width direction and inner ends terminated within the shoulder rib, allowing the shoulder rib to protrude outside the tire reference profile line, creating a uniform ground contact pressure by forming an arch shape that includes a protrusion peak.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If slits are provided in the shoulder rib with inner ends terminated within the shoulder rib or closed during ground contact, then the shoulder rib structure is simplified, but the ground contact pressure becomes non-uniform
Solution Approach 1:
The patent applies local quality by creating a protrusion peak at a specific location within the shoulder rib (in the rib region) rather than uniform modification throughout. This localized protrusion structure ensures that the inner portion of the shoulder rib makes contact with the ground first, distributing pressure uniformly across the shoulder rib width while maintaining the simplified slit structure.
2Stress or pressure
If the entire shoulder rib protrudes uniformly outside the tire reference profile line, then the shoulder rib and center rib contact the ground under substantially the same ground contact pressure, but the non-inflated portion of the shoulder rib is hardly brought into contact with the ground
Solution Approach 1:
The patent applies asymmetry by creating a non-uniform protrusion shape with a distinct protrusion peak located in the rib region rather than uniform protrusion across the entire shoulder rib. This asymmetric configuration ensures that the inner portion (rib region) protrudes more than the outer portion (slit region), guaranteeing reliable ground contact of the inner portion while maintaining appropriate pressure relationship with the center rib.
3Ease of manufacture
If the inner ends of slits are terminated within the shoulder rib or closed during ground contact, then manufacturing is simplified, but the inner portion of the shoulder rib is hardly inflated and ground contact pressure becomes non-uniform
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the shoulder rib, specifically creating a protrusion peak with controlled height and position in the rib region. This parameter modification ensures proper inflation distribution and uniform ground contact pressure while maintaining the simple slit configuration that is easy to manufacture.
Data Source
AI summary
An inner end (27a) of a slit (27) provided in a shoulder rib (25) in a tire width direction is terminated within the shoulder rib (25). The shoulder rib (25) includes a slit region (30) that has the slit (27) and a rib region (31) that has not the slit (27). The shoulder rib (25) protrudes to the outside of a tire reference profile line L on a cross-section in the tire width direction and has a protrusion peak (33) in the rib region (31). A ground contact surface of the shoulder rib (25) draw, on a cross-section in the tire width direction, an arch (M) passing through a ground contact end (22), the protrusion peak (33), and a point (34) on an inner sidewall of a shoulder-side main groove (21) in the tire width direction. The arch (M) passes through a point (35) on the tire reference profile line (L) or outside the tire reference profile line (L) in a normal direction of the tire reference profile line (L) at an inner end of the shoulder rib (25) in the tire width direction.