US Patent 11661989 Hollow tubular center bulging foam spring

A hollow tubular foam spring having a plurality of radially extending holes extending from an outer surface towards a central hollow core. The tubular foam spring is arranged with wall thickness and diameter to height ratios such that center bulging is achieved under compressive loads. In an embodiment, such as in a mattress, seat, cushion or pillow, springs are arranged in an array whereby some impinge upon one another due to central bulging.