| 主权项 |
1. A thrust sliding bearing comprising: an upper casing having an upper annular planar portion; a synthetic resin-made lower casing which is superposed on said upper casing so as to be rotatable about an axis of said upper casing and has a lower annular planar portion opposing the upper annular planar portion of said upper casing, a first and a second annular protrusion formed on the lower annular planar portion concentrically with each other, and a lower annular recess surrounded by the first and the second annular protrusion; and a synthetic resin-made thrust sliding bearing piece disposed in the lower annular recess of the lower casing and having an annular thrust sliding bearing surface which is brought into sliding contact with at least one of the upper annular planar portion and the lower annular planar portion,
wherein said thrust sliding bearing piece has first inner recessed portions which are arranged on the thrust sliding bearing surface along a circumferential direction, second outer recessed portions which are arranged on the thrust sliding bearing surface along a circumferential direction outside first inner recessed portions in a radial direction, and a lubricating oil filled in each of said first of inner recessed portions and said second outer recessed portions, the first inner recessed portions and the second outer recessed portions being arranged with a circumferential phase difference with respect to each other, wherein each of said first inner recessed portions is defined by an inner arcuate wall surface extending arcuately about the axis, an outer arcuate wall surface extending arcuately about the axis on a radially outer side with respect to the inner arcuate wall surface, a pair of partially circular wall surfaces respectively connected to both the inner arcuate wall surface and the outer arcuate wall surface and opposing each other in the circumferential direction, and a bottom surface connected to the inner arcuate wall surface, the outer arcuate wall surface, and the pair of partially circular wall surfaces, wherein each of said second outer recessed portions is defined by an inner arcuate wall surface extending arcuately about the axis, an outer arcuate wall surface extending arcuately about the axis on the radially outer side with respect to the inner arcuate wall surface, a pair of partially circular wall surfaces respectively connected to both the inner arcuate wall surface and the outer arcuate wall surface and opposing each other in the circumferential direction, and a bottom surface connected to the inner arcuate wall surface, the outer arcuate wall surface, and the pair of partially circular wall surfaces, wherein each of said first inner recesses portions and each of said second outer recesses portions corresponding to said each of first inner recesses portions are arranged partially overlapping in the radial direction, respectively. |
