Pulsation damping device

A pulsation damping device comprising:

• a sealed device body casing having a liquid chamber which receives liquid to be transported by a reciprocal pump or the like through an inflow passage, which temporarily stores the liquid, and which then allows the liquid to flow out through an outflow passage, and an air chamber which is to be filled with compressed air for suppressing pulsation;
• and a pulsation suppression diaphragm which is disposed in said device body casing to separate said liquid chamber and said air chamber from each other, and which is freely extended and contracted in accordance with a balance between variations in flow quantity and pressure of the transported liquid flowing into said liquid chamber, and an air filling pressure of said air chamber, wherein said pulsation damping device includes:
• a valve casing which is placed in said air chamber to be opposed to a center portion of a closed end face of said pulsation suppression diaphragm, said closed end face facing said air chamber, and which has an air supply port through which, when the air filling pressure of said air chamber is to be raised, the compressed air is introduced into said air chamber, and an air discharge port through which, when the air filling pressure of said air chamber is to be lowered, the compressed air is discharged from said air chamber to an outside;
• an air supply valve which is disposed in said valve casing, and which opens and closes said air supply port, and a spring which always closingly urges said air supply valve;
• an air discharge valve which is disposed in said valve casing to be juxtaposed with said air supply valve, and which opens and closes said air discharge port, and a spring which always closingly urges said air discharge valve;
• an air supply/discharge valve control plate which is placed to abut against the center portion of said closed end face of said pulsation suppression diaphragm;
• an air supply valve rod pressing portion which is disposed on said air supply/discharge valve control plate, and which pushes a rear end portion of a valve rod of said air supply valve to open said air supply valve, in accordance with that the liquid pressure of said liquid chamber is raised to overcome the air pressure of said air chamber and said pulsation suppression diaphragm is extended;
• an air discharge valve rod pulling portion which is juxtaposed with said air supply valve rod pressing portion on said air supply/discharge valve control plate, which is slidably connected to a rear end portion of a valve rod of said air discharge valve, and which pulls said valve rod to open said air discharge valve, in accordance with that the liquid pressure of said liquid chamber is lowered, the air pressure of said air chamber overcomes the liquid pressure of said liquid chamber, and said pulsation suppression diaphragm is contracted;
• and
• springs which are interposed between said valve casing and said air supply/discharge valve control plate to respectively surround outer peripheries of said air supply valve rod and said air discharge valve rod, and which pressingly urge said air supply/discharge valve control plate toward the center portion of said closed end face of said pulsation suppression diaphragm.