Patent ID: 7252474
Filing Date: 2007-08-07
Classification: F01D,F02C,F04D

Abstract:
1. A compressor for compressing air and gaseous fuel, comprising: a rotatable shaft; a compressor wheel mounted on the shaft, the wheel having a plurality of blades affixed thereto; a bearing casing defining an interior space; a bearing mounted in the bearing casing and rotatably supporting the shaft; a compressor housing surrounding the wheel, the compressor housing defining an inlet duct through which air is led into the compressor, and a main gas flow path, the compressor housing having a fixed wall immediately adjacent to and spaced from a surface of the compressor wheel, said surface extending from a location adjacent the main gas flow path generally radially inwardly toward the bearing casing; a fuel supply duct arranged for supplying fuel into the inlet duct of the compressor, such that the compressor wheel compresses a mixture of air and fuel; the compressor housing and bearing casing defining a leakage pathway from the main gas flow path of the compressor into the interior of the bearing casing, at least part of the leakage pathway being defined between the surface of the compressor wheel and the fixed wall of the compressor housing; and a sealing arrangement located in the leakage pathway, the sealing arrangement comprising a hydraulic resistance element disposed between the surface of the compressor wheel and the fixed wall of the compressor housing, and a pressurized air supply duct leading through the compressor housing into the leakage pathway at a location between the bearing casing and the hydraulic resistance element, and wherein the leakage pathway includes a portion that extends from the hydraulic resistance element to the bearing casing and that is free of any further hydraulic resistance elements; wherein the sealing arrangement is structured and arranged to prevent fuel from leaking via the leakage pathway into the bearing casing and thereby escaping into the atmosphere, by virtue of the sealing arrangement including a source of pressurized air that is free of fuel and that has a pressure exceeding that in the main gas flow path, said source being arranged to feed the pressurized fuel-free air through the pressurized air supply duct into the leakage pathway such that the pressurized fuel-free air prevents fuel from flowing from the main gas flow path past the hydraulic resistance element and into the bearing casing.