| 主权项 |
1. A liquid pumping system which includes:
(a) a liquid transfer pump arrangement (12) which includes a liquid inlet port (54), a liquid discharge port (66), a first pump chamber (28) with a first maximum volume, a first non-return valve (56) connected to and between the liquid inlet port (54) and the first pump chamber (28), a first control device (30) for pumping liquid from the first pump chamber (28), a second pump chamber (50) with a second maximum volume, wherein the second maximum volume is at least half the size of the first maximum volume, the second pump chamber (57) being connected to the liquid discharge port (66), a second non-return valve (67) connected to, and between, the first pump chamber (28) and the second pump chamber (50) and a second control device (46) for pumping liquid from the second pump chamber (50), (b) a hydraulic fluid constant flow pump (72), and (c) control structure (100) which, responsive to liquid flow rates from each pump chamber (28, 50), directs hydraulic fluid to the first and second control devices (30, 46) at respective controlled rates whereby, upon actuation of the first and second control devices (30, 46), in a cyclical manner:
(1) liquid is expelled from the first pump chamber (28) through the second non-return valve (60):
(1.1) at a controlled delivery rate to the liquid discharge port (66), and(1.2) into the second pump chamber (50), and, thereafter,(2) liquid is directed from the liquid inlet port (54) through the first non-return valve into the first pump chamber (28), and liquid is expelled from the second pump chamber (50) at said controlled delivery rate to the liquid discharge port (66). |
