| 摘要 |
PURPOSE:To always keep the inside and outside of a tank at the same pressure to hold a closed condition, and assuredly prevent an oil mist from diffusing to the outside of the tank by providing a valve mechanism which functions in such a manner that the valve is opened only when there is a pressure difference between the inside and outside of the tank, and communicates the inside and outside of the tank. CONSTITUTION:A tank cap 21 is fitted on a tank 1 in such a manner that a stopper 28 of a gripping part 24 in a cap main body 22 is engaged with a flange part 13 of the tank 12, and a packing part 29 of an inner cap 23 may be pressed. Also, a groove group 31 absorbs the deformation of the packing part 29 when the packing is fitted on the flange part 13. In addition, a level gauge 27 is inserted in a strainer 38. Then, when the temperature of a hydraulic oil in the tank 12 ascends, and a pressure in the tank 12 becomes higher than a pressure in a space 37, the internal end edge 30a of a valve body 30 gets on a tapered part 33 of a valve mechanism 25. Then, when the internal end edge 30a reaches a communicating groove 35, an oil mist of a high pressure in the tank 12 is discharged to the outside by passing through the communicating groove 35, section 37 and groove group 31 in this order. |
