Fluid apparatus

Abstract

A fluid apparatus includes a bellows that is configured to be extendable and contractible in an axial direction in order to suck a fluid from a suction flow passage and eject the fluid to an ejection flow passage. The bellows has peak portions and valley portions, which are alternately formed in the axial direction, and annular side surface portions, which are located between the peak portions and the valley portions and connect the peak and valley portions to each other. A ratio B/A of the thickness B of the axial middle part of each of the peak portions in a direction which is perpendicular to the axial direction, to the thickness A of each of the side surface portions in the axial direction is set within a range of 1.3 to 1.8.

1 . A fluid apparatus including a bellows which is configured to be extendable and contractible in an axial direction in order to suck a fluid from a suction flow passage and eject the fluid to an ejection flow passage, wherein
 the bellows comprises: peak portions and valley portions which are alternately formed in the axial direction; and annular side surface portions which are located between the peak portions and the valley portions, and which connect the both portions to each other, and   a ratio B/A of a thickness B of the axial middle part of each of the peak portions in a direction which is perpendicular to the axial direction, to a thickness A of each of the side surface portions in the axial direction is set within a range of 1.3 to 1.8.   
     
     
         2 . The fluid apparatus according to  claim 1 , wherein the ratio B/A of the thickness B of the axial middle part of each of the peak portions in the direction which is perpendicular to the axial direction, to the thickness A of each of the side surface portions in the axial direction is set within a range of 1.3 to 1.5. 
     
     
         3 . The fluid apparatus according to  claim 1 , wherein, when the bellows is maximally contracted in the axial direction, each of side surface portions is located in a plane which is substantially perpendicular to the axial direction of the bellows. 
     
     
         4 . The fluid apparatus according to  claim 2 , wherein, when the bellows is maximally contracted in the axial direction, each of side surface portions is located in a plane which is substantially perpendicular to the axial direction of the bellows.