Abstract: Damage is not caused even when oil mist in a gas is trapped, and clogging of a filter paper due to an oil film can be less likely to occur. A filtration member formed by folding a filter paper for trapping oil mist in a gas into a corrugated shape in which mountain folds and valley folds are alternately repeated is provided. The filter paper includes a nanofiber layer formed of polyolefin fibers. In the nanofiber layer, a content of fibers having a fiber diameter of 0.2 ?m to 0.4 ?m is 3% or more, a content of fibers having a fiber diameter of 0.4 ?m to 0.6 ?m is 24% or more, a content of fibers having a fiber diameter of 0.6 ?m to 0.8 ?m is 15% or more, and a content of fibers having a fiber diameter of 0.8 ?m to 1.0 ?m is 9% or more.

Abstract: A leakage of liquid inside a differential pressure detection device is reliably preventable. A diaphragm portion that detects a differential pressure as a pressure difference between a high pressure side and a low pressure side includes an annular member, a strain gauge provided in a hollow portion of the annular member, and a first plate and a second plate provided such that the annular member and the strain gauge are sandwiched. The first plate and the second plate each abut on a first annular packing. A first groove and a second groove (the first annular packing) overlap with the annular member when viewed from a first direction along an axis of the first hole.

Abstract: A leakage of liquid inside a differential pressure detection device is reliably preventable. A diaphragm portion that detects a differential pressure as a pressure difference between a high pressure side and a low pressure side includes an annular member, a strain gauge provided in a hollow portion of the annular member, and a first plate and a second plate provided such that the annular member and the strain gauge are sandwiched. The first plate and the second plate each abut on a first annular packing. A first groove and a second groove (the first annular packing) overlap with the annular member when viewed from a first direction along an axis of the first hole.

Abstract: A tank for storing oil includes a suction strainer with first and second filtration portions. The first filtration portion has a substantially cylindrical shape and formed by bending a thin plate into a pleated shape. The second filtration portion is provided on the outer side of the first filtration portion. The second filtration portion has a substantially cylindrical shape and is formed of a material having a plurality of spaces formed in a surface and interior of the material.

Abstract: When a lid covers an opening portion formed at an upper end of a filter case with a bottomed substantially cylindrical shape inside which a filter element is disposed, the internal space between the lid and the filter case is formed. A bypass flow path connecting the internal space and outside space is formed in the lid, and a relief valve disposed moveably between a position closing the bypass flow path and a position opening the bypass flow path includes an air bleeder formed from a porous material.

Abstract: A return filter is provided in a tank, for removing bubbles from hydraulic oil before returning the hydraulic oil to the tank. A vortex forming portion that includes a spiral-shaped blade member is provided in an outflow portion that has a substantially cylindrical shape and communicates with a hollow portion of a filter element. Thus, a vortex forms in the hydraulic oil flowing through the outflow portion and bubbles contained in the hydraulic oil are collected.

Abstract: When a lid covers an opening portion formed at an upper end of a filter case with a bottomed substantially cylindrical shape inside which a filter element is disposed, the internal space between the lid and the filter case is formed. A bypass flow path connecting the internal space and outside space is formed in the lid, and a relief valve disposed moveably between a position closing the bypass flow path and a position opening the bypass flow path includes an air bleeder formed from a porous material.

Abstract: A first discharge tube having a substantially cylindrical shape with openings at both ends is inserted through an outflow hole of a filter case and provided protruding toward the bottom surface of the tank. A second discharge tube having a substantially cylindrical shape is provided so as to cover the first discharge tube. The second discharge tube includes a first end that comes into contact with a bottom surface of the filter case, and is provided protruding from the bottom surface of the filter case toward the bottom surface of the tank. A tip end of the second discharge tube is covered by a bottom surface cover, and a plurality of discharge holes are formed in a region near an upper end of a side surface.

Abstract: A return filter is provided in a tank, for removing bubbles from hydraulic oil before returning the hydraulic oil to the tank. A vortex forming portion that includes a spiral-shaped blade member is provided in an outflow portion that has a substantially cylindrical shape and communicates with a hollow portion of a filter element. Thus, a vortex forms in the hydraulic oil flowing through the outflow portion and bubbles contained in the hydraulic oil are collected.

Abstract: A tank for storing oil includes a suction strainer with first and second filtration portions. The first filtration portion has a substantially cylindrical shape and formed by bending a thin plate into a pleated shape. The second filtration portion is provided on the outer side of the first filtration portion. The second filtration portion has a substantially cylindrical shape and is formed of a material having a plurality of spaces formed in a surface and interior of the material.