Vacuum apparatus

A vacuum apparatus comprising:

• a cylinder member including a top wall disposed on a top side of an inner space, a bottom wall disposed on a bottom side of the inner space to be spaced apart from the top wall, a side wall interconnecting the top wall and the bottom wall and surrounding a lateral side of the inner space, and a guide shaft extending downward from the top wall to be disposed in a central area of the inner space;
• and
• a piston module including a separating and opening/closing unit fitted in the inside of the cylinder member to be vertically movable and to separate the inner space of the cylinder member into an upper first space and a lower second space, the separating and opening/closing unit being provided with a first O-ring on an outer circumferential surface thereof to be in contact with an inner circumferential surface of the side wall so that the first O-ring opens/closes the first space and the second space in relation to each other while being moved vertically according to a moving direction in relation to the cylinder member, and a hollow rod unit extending downward from a central area of the separating and opening/closing unit in such a manner that a part of the hollow rod unit is exposed to an outside through the bottom wall, the hollow rod unit being formed with a guide bore in the inside thereof to accommodate the guide shaft therein to guide an ascent/descent of the guide shaft,
• wherein the cylinder member is formed with a first vent hole that allows the air in the first space to be discharged to the outside while the first space is being reduced according to the descent of the cylinder member, and the hollow rod unit is formed with a second vent hole to communicate the second space with the outside, and
• wherein the bottom wall of the cylinder member is formed with a through-hole, through which the hollow rod unit passes,
• wherein the hollow rod unit includes:
• a hollow shaft portion extending downward from the central area of the separating and opening/closing unit and being formed with the guide bore in an inside thereof;
• and a tubular body provided with a through-hole at a bottom portion thereof, and fitted on an outer circumferential surface of the hollow shaft portion in such a manner that the second vent hole is formed between the tubular body and the outer circumferential surface of the hollow shaft portion, and
• wherein a catch protrusion is formed on a bottom surface of the hollow shaft portion, a catch step is formed at a center of the lower end of the tubular body such that the catch protrusion is caught by the catch step, and an O-ring is installed between the bottom surface of the hollow shaft portion and the bottom portion of the tubular body to block a gap between the bottom surface of the hollow shaft portion and the bottom portion of the tubular body, and to resiliently support the bottom surface of the hollow shaft portion and the bottom portion of the tubular body therebetween.