Pneumatic air booster

A pneumatic air booster (100) which comprises;

• a shaft (160) extending in a axis direction,
• a body (110, 111) surrounding the shaft (160) and including a first body (110) and a second body (111), wherein the second body (111) is coupled to the first body (110) and provided at a higher level than the first body (110) when measured along the axis direction,
• an air inlet (112) extending from a first sidewall surface of the body (110, 111) to between the first body and the second body (110, 111) in a first radius direction, wherein the first radius direction is perpendicular to the axis direction,
• an air outlet (113) extending from a second sidewall surface of the body (110, 111) to between the first body and the second body (110, 111) in a second radius direction, wherein the second radius direction is perpendicular to the axis direction,
• a pressure chamber (114) (i) formed between the first body (110) and the shaft (160) and (ii) communicating the air inlet (112),
• an air control passage (115) (i) formed between a lower part of the second body (111) and the shaft (160) and (ii) communicating the pressure chamber (114),
• a pressure control chamber (116) (i) provided over the shaft (160) and over the second body (111) and (ii) vertically aligned with the shaft (160) in the axis direction,
• a bonnet (190) that is coupled to an upper part of the second body (111) and surrounding the pressure control chamber (116),
• a lower cover (120) that surrounds the pressure chamber (114),
• a valve (140) that (i) is installed between the pressure chamber (114) and the shaft (160) and (ii) opens and closes the air control passage (115) to and from the pressure chamber (114), and
• a valve spring (150) that (i) is vertically aligned under the shaft (160) in the axis direction, (ii) is surrounded by the pressure chamber (114), and (iii) presses the valve (140) upward and downwards in the axis direction,
• wherein a lower end of the shaft (160) is coupled to the valve (140) and lifts and lowers the valve (140) in the axis direction to open and close the air control passage (115) to and from the pressure chamber (114),
• wherein a valve seat (170) is provided between the pressure control chamber (116) and supported on and an upper end of the shaft (160) in a manner of being lifted and lowered, wherein the valve seat (170) is open or closed depending on whether being pressed upwards or downwards in the axis direction,
• wherein a connection passage (102a) is extended between the air outlet (113) and the pressure control chamber (116),
• wherein the air outlet (113) and the pressure control chamber (116) communicate with each other through the connection passage (102a),
• wherein, when air in the air outlet (113) flows into the pressure control chamber (116) through the connection passage (102a), a pressure in the pressure control chamber (116) increases, and the valve seat (170) is pushed downward.