| 摘要 |
An expander is provided in which spherical projections ( 61 a) formed at the forward end of pistons ( 42 ) of an axial piston cylinder group abut against spherical depressions ( 31 a) formed in a swash plate ( 31 ), and an elliptical contact point locus (T) of contact points (p) between the spherical depressions ( 31 a) and the spherical projections ( 61 a) is offset toward the expansion stroke side of the axial piston cylinder group. As a result, in a middle region of the expansion stroke where the speed of the piston ( 42 ) is high and the surface pressure of the contact point (p) is high, the position of the contact point (p) can be made as close as possible to an axis (L 3 ) of the spherical depression ( 31 a) and an axis (L 2 ) of the piston ( 42 ), thus reducing a bending moment and a radially biased load exerted on the piston ( 42 ) and minimizing any increase in sliding resistance and any occurrence of abnormal wear.
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