| 摘要 |
A proportioning pump has a first piston and cylinder, a second piston and cylinder, a shaft connecting the first and second pistons, a spring for biasing the first and second pistons in a first position, a shuttle valve for controlling flow through the first cylinder, and two check valves for controlling flow through the second cylinder. The proportioning pump is used to dispense a predetermined ratio of two fluids. A pressurized first fluid fills the first cylinder and forces the first piston to move to a second position. The motion of the first piston is communicated to the second piston via the shaft. Movement of the second piston draws the second fluid through a check valve into the second cylinder. When both the first and second cylinders are full the shuttle valve closes the inlet to the first cylinder and opens the outlet. The spring then urges the first and second pistons back to their first positions, thus forcing the two fluids from their respective cylinders. The two check valves prevent reverse flow through the second cylinder. The ratio of the volume of the two fluids being pumped can be varied by changing the second cylinder and piston. An accumulator is used to provide even flow of the carbonated water. The arrangement of the carbonated water and syrup nozzles prevents the buildup of syrup at the nozzle openings, thus insuring that proper flow of both fluids is maintained.
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