Diaphragm pump

In an air diaphragm pump comprising a lower housing mounted on a stationary structure for forming a lubrication oil chamber therein;

• an upper housing coupled with said lower housing for forming an air pumping chamber therein and provided thereon with an inlet port and an outlet port;
• a spring-loaded diaphragm piston assembly including a flexible diaphragm interposed and hermetically clamped at the outer periphery thereof between said housings to define said air pumping chamber and an operation rod for reciprocating said diaphragm assembly within said oil chamber;
• valve means assembled within said upper housing and including a first check valve to suck the air into said air pumping chamber through said inlet port and a second check valve to discharge the sucked air though said outlet port;
• and a driving mechanism assembled within said lower housing for operating said operation rod;
• the improvement comprising:
• upper and lower protector plates located respectively within said air chamber and said lubrication oil chamber for fluid-tightly connecting said flexible diaphragm at the center thereof to said operation rod, said plates having substantially planar portions;
• a flexible disc sealing member integral with said flexible diaphragm on the side thereof facing said lubrication oil chamber and clamped between said diaphragm and said lower protector plate;
• the outer periphery of said flexible disc sealing member being interposed and fluid-tightly clamped with the outer periphery of said diaphragm between said housings;
• said flexible disc sealing member being interposed and fluid-tightly clamped between said lower protector plate and said diaphragm throughout the entire planar portion of said lower protector plate;
• and
• a buffer member secured to said upper protector plate to protect said valve means.