Patent ID: 9127657
Filing Date: 2015-09-08
Classification: F04B

Abstract:
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.