US Patent 11662025 Mechanical seal with sliding surfaces with minimum diameter

A mechanical seal having a first seal ring, which is mounted in a receptacle of a fixed part, and a second seal ring, which is mounted in a sleeve of a rotary part having a fixing portion fixed to a rotary shaft. The second seal ring extends radially inwards relative to the fixing portion of the sleeve, above an upper ending surface of the rotary shaft. The first seal ring is disposed above the second seal ring in such a way that the sliding surfaces of the first seal ring and of the second seal ring are in mutual contact. The sliding surfaces of the first seal ring and of the second seal ring have a mean diameter that is lower than an external diameter of the rotary shaft.