Thrust bearing device for supercharger

A thrust bearing device for a supercharger comprising:

• a turbine wheel and a compressor wheel that are fixed to a rotary shaft;
• a turbine-side thrust collar and a compressor-side thrust collar that are fixed to the rotary shaft;
• a thrust bearing that is fixed to a bearing housing, has the two thrust collars coming into sliding contact therewith from both sides in a thrust direction, and receives a thrust load applied to the rotary shaft,
• an oil passage that is formed in the two thrust collars or the thrust bearing so that lubricating oil is supplied between sliding-contact surfaces in a radial direction, which is an axis-orthogonal direction, formed between the two thrust collars and the thrust bearing;
• and
• a gap that forms a lubricating oil film between the sliding-contact surfaces in the radial direction, which is the axis-orthogonal direction, wherein the gap where the lubricating oil film is formed is formed so that the lubricating oil outflow resistance of a radial outer region becomes larger than that of a radial inner region, and
• wherein at least one surface constituting the sliding-contact surfaces is inclinedly configured so as to approach a facing surface as the sliding-contact surface goes outward in the radial direction, and the gap between the sliding-contact surfaces decreases gradually outward in the radial direction.

A thrust bearing device for a supercharger comprising:

• a turbine wheel and a compressor wheel that are fixed to a rotary shaft;
• a turbine-side thrust collar and a compressor-side thrust collar that are fixed to the rotary shaft;
• a thrust bearing that is fixed to a bearing housing, has the two thrust collars coming into sliding contact therewith from both sides in a thrust direction, and receives a thrust load applied to the rotary shaft,
• an oil passage that is formed in the two thrust collars or the thrust bearing so that lubricating oil is supplied between sliding-contact surfaces in a radial direction, which is an orthogonal direction, formed between the two thrust collars and the thrust bearing;
• and
• a gap that forms a lubricating oil film between the sliding-contact surfaces in the radial direction, which is the axis-orthogonal direction,
• wherein, in order to make the lubricating oil outflow resistance of the radial outer regions in the gap where the lubricating oil film is formed become larger than that of the radial inner regions, steps are formed on both outer peripheral surfaces of the thrust bearing and radial inner regions are formed to have a larger thickness than radial outer regions with the steps as boundaries, radial outer regions of confronting surfaces of the two thrust collars that confront the radial outer regions of the thrust bearing are formed to have a larger thickness than the radial inner regions of the confronting surfaces of the two thrust collars that confront the radial inner regions of the thrust bearing, and the gap formed between the sliding-contact surfaces forms a curved structure.