| 摘要 |
PROBLEM TO BE SOLVED: To compact a piston pump furthermore and suppress the cost while the eccentricity of the armature shaft of a piston pump driving part is enlarged. SOLUTION: A shell form outer ring 2 of a shell type needle roller bearing 1 fitted in an eccentric part 14a of the armature shaft 14 as a motor output shaft and supporting a piston 17 is made from a steel plate of middle-high carbon content in which the carbon content is 0.3 mass % or more, and at least the raceway surface of the outer ring 2 formed through press working is subjected to high-frequency quenching. Thereby the strength from the surface to the inside of the outer ring 2 is heightened quickly using a simple heat treatment facility without requiring atmospheric adjustment, and the lifetime of the shell type needle roller bearing 1 depending upon a surface-originating exfoliation or an internally originating exfoliation is secured sufficiently, and compacting the piston pump furthermore and suppressing the cost are accomplished while the eccentricity of the armature shaft 14 is enlarged. COPYRIGHT: (C)2006,JPO&NCIPI
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