| 摘要 |
A spool bore ( 4 ) where a spool ( 6 ) slides, a concave portion ( 23 ) opened to the spool bore ( 4 ) and facing a return port 12 opened to the spool bore ( 4 ), and a land portion ( 11 ) disposed in an outer periphery of the spool ( 6 ) are provided. A width of the concave portion ( 23 ) and a width of the return port ( 12 ) each are greater than a width of the land portion ( 11 ) and a groove bottom ( 23 a) of the concave portion ( 23 ) is formed to be a flat plane generally in proportion to an axis line of the spool ( 6 ).
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