Cushioning system for shoe sole and method for making the sole

A cushioned shoe sole comprising:

• an outer sole layer for contacting a ground surface;
• an unitary midsole layer disposed above said outer sole layer having a top surface and a bottom surface, said midsole layer being formed of a resilient elastomeric material and including an opening formed vertically through at least a portion of the midsole layer including its top surface;
• a bladder element sealingly containing a fluid medium and having a top surface, a bottom surface, and a perimeter area, said bladder element having an unobstructed interior cavity within said perimeter area, said bladder element being encapsulated in said elastomeric material of said midsole layer along its perimeter area such that at least said top surface of said bladder element is exposed through a top portion of said opening in said midsole layer to thereby allow close contact between a wearer's foot and said bladder element;
• wherein said opening in said midsole layer has a first dimension along a given direction in the interior of said midsole layer and a second dimension along said given direction in the top surface of said midsole layer, said first dimension being greater than said second dimension and said first dimension being approximately the same as the dimension of said perimeter area of said bladder element inserted into said opening such that said resilient elastomeric material forms a securing surface for holding said bladder element within said opening, said securing surface being defined between the interior of said midsole layer having the first dimension and the top surface of said midsole layer.

A method of forming a cushioned shoe sole comprising the steps of:

• forming a bladder element from an elastomeric material having a perimeter, a hollow interior chamber within the perimeter, and a fluid medium sealingly contained in the chamber;
• molding a unitary midsole from a foam elastomeric material, the midsole extending in longitudinal, transverse and vertical directions, and having opposing upper and lower major surfaces;
• forming an opening in the midsole, the formed opening vertically extending through and from at least one of the upper and lower major surfaces into the interior of the midsole, said formed opening including an integral peripheral cavity within the midsole having a first dimension along a given direction in the interior of the midsole and a second dimension along the given direction in said at least one of the upper and lower major surfaces of the midsole, the first dimension being greater than the second dimension and the first dimension being approximately the same as the dimension of the perimeter of the bladder element to be inserted into the opening such that the elastomeric material of the midsole forms a securing surface for holding the bladder element within the opening, the securing surface being defined between the interior of the midsole having the first dimension and said at least one of the upper and lower major surfaces of the midsole having the second dimension securing surface, the securing surface curving in a vertical direction around at least a major portion of the perimeter of the opening;
• inserting the bladder element into the opening to releasably secure the bladder element to the midsole and within the opening in the midsole by positioning the perimeter of the bladder element within the peripheral cavity securing surface around the perimeter of the bladder element.