Heavy Duty Tyre Sipe Geometry for Life-Cycle Handling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Heavy duty vehicle tires face challenges in maintaining optimal handling and low rolling resistance throughout their life cycle due to the deformation and stiffening of elastomeric materials, which affects traction and fuel efficiency, especially on wet or snow-covered roads.
Innovation Solution
A tread pattern with deep circumferential sipes of varying width, where the maximum width is positioned roughly at the halfway point of the sipe's depth, allowing for optimal smoothness and handling by maintaining the sipe open during the tire's life cycle, reducing rolling resistance, and compensating for the rigidity caused by aging and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the elastomeric material is used in the tread band, then the tyre provides good initial handling and low rolling resistance, but the material deforms and stiffens during the life cycle, worsening handling and increasing rolling resistance
Solution Approach 1:
The sipe width varies dynamically along the radial depth, creating zones that adapt to different operational conditions. The first zone (narrow width) maintains low rolling resistance when the tyre is new, while the second zone (maximum width) opens up during wear to compensate for material stiffening, and the third zone (converging width) provides structural stability. This dynamic geometric variation compensates for the static material degradation.
Solution Approach 2:
The invention changes the geometric parameters of the sipe (width, depth, position) to compensate for material parameter changes (stiffening, deformation). By positioning the maximum width at approximately half the total depth and creating specific width ratios between zones, the design offsets the elastomeric material's tendency to stiffen over time, maintaining consistent handling characteristics throughout the tyre's life cycle.
2Reliability
If deep circumferential sipes are made with constant width, then the manufacturing is simple, but the tyre cannot maintain optimal performance throughout its life cycle due to material deformation and stiffening
Solution Approach 1:
The sipe is segmented into three distinct zones along its radial depth, each with different width characteristics and functions. The first zone (near the outer surface) has narrow width for low rolling resistance, the second zone (middle depth) has maximum width for handling performance, and the third zone (deeper section) has converging width for structural stability. This segmentation allows each zone to optimize for its specific function while collectively solving the life-cycle performance problem.
Solution Approach 2:
Different portions of the sipe cross-section have different widths tailored to their specific functional requirements. The local quality varies through the radial depth, with the narrowest width at the outer surface, maximum width at intermediate depth, and converging width toward the bottom. This local differentiation enables the single sipe structure to perform multiple functions and compensate for material degradation over time.
3Loss of energy
If the sipe width is reduced to lower rolling resistance, then fuel efficiency improves, but the handling performance on wet or snow-covered roads deteriorates
Solution Approach 1:
The sipe structure dynamically adapts its effective width based on wear state. When new, the narrow first zone dominates to minimize rolling resistance. As the tyre wears and material stiffens, the second zone with maximum width opens up to provide the necessary grip on wet or snow-covered roads. This dynamic adaptation maintains the optimal balance between rolling resistance and traction throughout the tyre's life cycle.
Solution Approach 2:
The invention transitions from considering only the surface width of the sipe to incorporating the radial depth dimension. By creating a three-dimensional sipe structure with varying width through its depth, the design achieves low rolling resistance at the surface level while maintaining traction capability through the deeper zones. This dimensional approach allows simultaneous optimization of both conflicting requirements.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A tyre has a tread pattern comprising at least one circumferential sipe (10), having, in radial section, a profile comprising: a first zone (Z1) close to the radially outer surface (S), having side walls (11) mutually spaced apart according to a minimum width W1; a second zone (Z2), having a portion (Pt) in which the side walls (11) diverge from one another, and a portion of maximum width (Pmax) having a maximum section width W2; and a third zone (Z3) having a maximum width W3, less than W2, radially inner with respect to the second zone (Z2). In the third zone (Z3) the side walls (11) join with a bottom portion (Pf) defining a total depth (H10) of the sipe (10). The ratio between W2 and W1 is greater than 1 and equal to or less than 2. A geometric centre (G2) of the portion of maximum width (Pmax) lies at a depth (PG) comprised between 40% and 60% of the total depth (H10).