Ultralight Sole and Shoe with Sealed Internal Cavity

The problem

In footwear manufacturing, there is often a trade-off between durability and weight. A thick sole made of solid rubber or EVA foam provides necessary support and wear resistance but adds significant mass, which can hinder performance in running or long-distance walking. Conversely, thin soles reduce weight but may lack the structural rigidity needed to protect the foot and withstand ground impact. Furthermore, if a hollow design is used to save weight, maintaining a clean, dry internal environment is difficult; traditional adhesives or mechanical fasteners can fail over time, allowing dust or moisture to enter the cushioning chamber, degrading its properties.

The solution

The patent describes a sole body composed of an upper sole (3) and a lower sole (4). Between these two layers lies an inner cavity (5). The lower sole is constructed from a material with higher strength, such as hard rubber, allowing the sole to remain thick enough for durability without being excessively heavy due to the hollow center.

To support this cavity, multiple groups of support blocks (6) are fixed on the surface of the lower sole facing the cavity. These blocks have connecting clamping grooves (7) where elastic plates (9) are inserted. The upper ends of these plates connect to bonding plates (8), which contact the inner wall of the upper sole. This arrangement distributes load across the cavity floor.

Sealing the gap between the upper and lower sole is critical. The design uses a connecting sealing structure involving an upper sealing frame (11) and a sealing ring (10). The upper sealing frame is L-shaped and fixed to the inner wall of the cavity. The sealing ring sits on the upper surface of the lower sole. Crucially, a first magnetic suction plate (12) is fixed on the upper sealing frame, and a second magnetic suction plate (13) is fixed inside the sealing ring. These magnets attract each other, pulling the sealing ring tightly against the frame to create a strong seal.

Cushioning is further enhanced by a rubber air bag (16) attached to the upper sole. A middle plate (17) divides the air bag into a first air cavity (18) and a second air cavity (19). Channels allow air to move between these cavities and the main inner cavity, while springs regulate pressure, providing dynamic response to foot movement.

Who it is for

• Running Shoe Brands: Manufacturers seeking to reduce midsole weight while maintaining high rebound and stability for athletic performance.
• Casual Lifestyle Footwear Lines: Companies needing durable, lightweight soles for daily wear shoes that resist water ingress through sealed components.
• Orthopedic Support Specialists: Designers who require adjustable internal structures, such as varying the number of elastic plates, to customize firmness levels for specific foot types.
• Industrial Safety Footwear Makers: Producers who need tough, wear-resistant outsoles that do not compromise comfort or agility for workers on their feet all day.

How it works

The main parts

Operating Steps

1. Assembly: The lower sole is fitted with support blocks. Elastic plates are inserted into the grooves.
2. Sealing: The upper sole is placed over the lower sole. The magnetic plates align and attract, forcing the sealing ring into the groove of the upper sealing frame, closing the inner cavity.
3. Impact Absorption: When the foot strikes the ground, the lower sole flexes slightly. The elastic plates compress, absorbing energy.
4. Air Regulation: Pressure changes in the inner cavity affect the air bag. Air moves between the first and second air cavities via channels, adjusting stiffness dynamically based on the step phase.

Applications

Performance Running Shoes

Runners benefit from the reduced mass of the hollow sole, which improves speed and reduces leg fatigue. The magnetic seal ensures that sweat or rain does not degrade the internal cushioning materials during intense activity.

Lightweight Walking Trainers

For daily walkers, the combination of high-strength rubber and internal elastic plates offers a balance of durability and comfort. The sealed cavity prevents dirt accumulation, extending the life of the shoe’s internal structure.

Customizable Orthotic Inserts

Brands offering customizable fit can vary the number or density of elastic plates in the cavity. This allows users to adjust the firmness of the midsole without changing the external shape of the shoe.

Wet Environment Work Boots

Workers in damp environments need soles that resist water penetration. The magnetic compression seal creates a tight barrier around the cavity, protecting the internal air bag and elastic supports from moisture damage.

Where it is less suitable

• Ultra-minimalist Barefoot Shoes: This design relies on a thick, structured sole with an internal cavity, making it unsuitable for shoes intended to mimic barefoot conditions with minimal material.
• Standard Slip-and-Cast Soles: Traditional injection-molded single-piece soles are cheaper and simpler to produce than this multi-component assembly with magnetic and mechanical locking features.