Air-driven pump system

1. An air-driven pump comprising:

a source of pressurized air;

a first pump unit including a first pump chamber, a first air chamber and a first pump piston therebetween;

a second pump unit including a second pump chamber, a second air chamber and a second pump piston therebetween,

a directional control valve in communication with the source of pressurized air and the first and second air chambers, the directional control valve shifting responsive to end of stroke positions of the pump pistons to selectively control process air communication between the source of pressurized air and the first and second air chambers;

an efficiency valve pneumatically between the source of pressurized air and the directional control valve and responsive to selected positions of the pump pistons to restrict process air communication between the efficiency valve and the directional control valve, the selected positions of the pump pistons being as the pump pistons move toward the end of stroke positions of the pump pistons, respectively, and before the directional control valve has shifted;

a first air passage communicating from the efficiency valve to the first air chamber through the directional control valve;

a second air passage communicating from the efficiency valve and to the second air chamber through the directional control valve, the efficiency valve including a first valve position having unrestricted process air communication with the first air passage and maximally restricted process air communication with the second air passage and a second valve position having unrestricted process air communication with the second air passage and maximally restricted process air communication with the first air passage, wherein the process air communication from the first and second air passages to the first and second air chambers, respectively, is controlled by the shifting of the directional control valve.

2. The air-driven pump of claim 1 , the first and second valve positions switching at each of the selected positions of the pump pistons.

3. The air-driven pump of claim 1 , the source of pressurized air being in continuous process air communication with the directional control valve across the efficiency valve and through the first and second air passages.

4. The air-driven pump of claim 1 , the efficiency valve further including efficiency valve shifting elements extending into the first and second air chambers to selectively engage the pump pistons.

5. The air-driven pump of 4 , the first and second valve positions switching at each of the selected positions of the pump pistons.

6. The air-driven pump of claim 1 further comprising:

a pilot valve system shifting the directional control valve to selectively control the directional control valve responsive to the end of stroke positions of the pump pistons.

7. An air-driven pump comprising:

a source of pressurized air;

a first pump unit including a first pump chamber, a first air chamber and a first pump piston therebetween;

a second pump unit including a second pump chamber, a second air chamber and a second pump piston therebetween,

a directional control valve in communication with the source of pressurized air and the first and second air chambers, the directional control valve shifting responsive to end of stroke positions of the pump pistons to selectively control process air communication between the source of pressurized air and the first and second air chambers;

an efficiency valve pneumatically between the source of pressurized air and the directional control valve and responsive to two selected positions of the pump pistons to maximally restrict process air communication from the source of pressurized air to the first and second air chambers, respectively, through the directional control valve, the two selected positions of the pump pistons being as the pump pistons move toward the end of stroke positions of the pump pistons, respectively, and before the directional control valve has shifted, the efficiency valve including efficiency valve shifting elements extending into the first and second air chambers to selectively engage the pump pistons, wherein the process air communication from the efficiency valve at the two selected positions of the efficiency valve to the first and second air chambers, respectively, is controlled by the shifting of the directional control valve.

8. The air-driven pump of claim 7 , process air communication without restriction and restricted process air communication between the source of pressurized air and the directional control valve being separate and concurrently open through the efficiency valve.

9. The air-driven pump of claim 8 , the source of pressurized air being in continuous process air communication with the directional control valve through the efficiency valve.

10. The air-driven pump of claim 7 further comprising:

a pilot valve system shifting the directional control valve to selectively control the directional control valve responsive to the end of stroke positions of the pump pistons.

11. An air-driven pump comprising:

a source of pressurized air;

a first pump unit including a first pump chamber, a first air chamber and a first pump piston therebetween;

a second pump unit including a second pump chamber, a second air chamber and a second pump piston therebetween,

a directional control valve in communication with the source of pressurized air and the first and second air chambers, the directional control valve shifting responsive to end of stroke positions of the pump pistons to selectively control process air communication between the source of pressurized air and the first and second air chambers;

an efficiency valve system pneumatically between the source of pressurized air and the directional control valve and responsive to two selected positions of the pump pistons to maximally restrict process air communication from the source of pressurized air to the first and second air chambers, respectively, through the efficiency valve system and the directional control valve, the two selected positions of the pump pistons being as the pump pistons move toward the end of stroke positions of the pump pistons, respectively, and before the directional control valve has shifted, process air communication without restriction and restricted process air communication between the source of pressurized air and the directional control valve being separate and concurrently open through the efficiency valve system, wherein the process air communication from the efficiency valve at the two selected positions of the efficiency valve to the first and second air chambers, respectively, is controlled by the shifting of the directional control valve.

12. The air-driven pump of claim 11 , the source of pressurized air being in continuous process air communication with the directional control valve through the efficiency valve system.

13. The air-driven pump of claim 11 further comprising:

a pilot valve system shifting the directional control valve at the end of stroke positions of the pump pistons to selectively control the directional control valve.

14. The air-driven pump of claim 13 , the efficiency valve system including two efficiency valves, each efficiency valve having an efficiency valve piston in an efficiency valve cylinder and a shaft extending into one of the air chambers to selectively engage the pump piston therein.

15. The air-driven pump of claim 14 , each efficiency valve having an unrestricted process air communication position and a restricted process air communication position.

16. The air-driven pump of claim 14 , the pilot valve system including a pilot valve having pilot valve shifting elements extending into the air chambers to selectively engage the pump pistons therein.

17. The air-driven pump of claim 14 , the pilot valve system including pilot passages through the valve pistons in each of the two efficiency valves.