Air motor having ceramic valves

A pump assembly comprising:

• a motive fluid inlet (335) adapted to receive a flow of motive fluid;
• a cylinder (615);
• a piston (620) within the cylinder (615), the piston (620) dividing the cylinder (615) into an upper chamber (635) above the piston (620) and a lower chamber (640) below the piston (620);
• a valve chamber (355) including a pilot chamber portion (515);
• a spool valve (360) shiftable between first and second positions, the spool valve (360) including a reduced diameter section (480) and an enlarged diameter section (485), the enlarged diameter section (485) being exposed to the pilot chamber portion (515);
• a ceramic D-valve plate (375) including a first D-valve port (455) communicating with the upper chamber (635), a second D-valve port (460) communicating with the lower chamber (640), and a D-valve exhaust port (465) communicating with atmosphere;
• a ceramic D-valve (370) having a flat surface surrounding a concave surface (520), the flat surface being in sliding contact with the D-valve plate (375) and the concave surface (520) facing the D-valve plate (375), the D-valve (370) being coupled via a lost motion interconnection (525) to the reduced diameter section (480) of the spool valve (360), the D-valve (370) being shiftable with the spool valve (360) between first and second positions corresponding to the respective first and second positions of the spool valve (360), wherein the D-valve (370) uncovers the first D-valve port (455) when the D-valve (370) is in the first position to introduce motive fluid into the upper chamber (635), the concave surface (520) of the D-valve (370) placing the second D-valve port (460) in communication with the D-valve exhaust port (465) to place the lower chamber (640) in communication with the atmosphere when the D-valve (370) is in the first position, wherein the D-valve (370) uncovers the second D-valve port (460) when the D-valve (370) is in the second position to introduce motive fluid into the lower chamber (640), the concave surface (520) of the D-valve (370) placing the first D-valve port (455) in communication with the D-valve exhaust port (465) to place the upper chamber (635) in communication with the atmosphere when the D-valve (370) is in the second position;
• a ceramic pilot valve plate (385) including a first pilot port (470) communicating with the pilot chamber portion (515) and a second pilot port (475) communicating with atmosphere;
• a ceramic pilot valve (380) having a flat surface surrounding a concave surface (530), the flat surface being in sliding contact with the pilot valve plate (385) and the concave surface (530) facing the pilot valve plate (385), the pilot valve (380) being coupled to the reduced diameter section (480) of the spool valve (360), the pilot valve (380) being shiftable with the spool valve (360) between first and second positions corresponding to the respective first and second positions of the spool valve (360), wherein the pilot valve (380) uncovers the first pilot port (470) when the pilot valve (380) is in the first position to introduce motive fluid into the pilot chamber (515), and wherein the concave surface (530) of the pilot valve (380) places the first and second pilot ports (470, 475) in communication with each other to place the pilot chamber (515) in communication with the atmosphere when the pilot valve (380) is in the second position, wherein introduction of motive fluid into the pilot chamber (515) shifts the spool valve (360) to the first position, wherein exposing the pilot chamber (515) to atmosphere facilitates shifting the spool valve (360) to the second position;
• an actuation rod (625) having a first end (650) and a second end (660) opposite the first end (650), the first end (650) being interconnected by way of a lost motion connection (490, 655) to the spool valve (360), the second end (660) being interconnected by way of a lost motion connection (725, 665) to the piston (620), such that upward movement of the piston (620) assists the spool valve (360) moving from the second position toward the first position, and such that downward movement of the piston (620) assists the spool valve (360) moving from the first position to the second position;
• an output rod (710) interconnected for reciprocal movement with the piston (620);
• and
• a piston pump (120) including a pump cylinder (170), an outlet (175), and a one-way valve supported for reciprocation within the pump cylinder (170) and operable to move fluid from below the one-way valve toward the outlet (175), the one-way valve being interconnected with the output rod (710) to cause reciprocation of the one-way valve to move a fluid to be pumped from within the cylinder (170) out the outlet (175) to a desired destination.