Metal working – Method of mechanical manufacture – Prime mover or fluid pump making
Patent
1991-01-29
1992-08-25
Smith, Leonard E.
Metal working
Method of mechanical manufacture
Prime mover or fluid pump making
417429, 417475, F04B 4312
Patent
active
051407477
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to pumps, and is principally concerned with pumps for the metered dosing of one of a plurality of liquids.
In many devices there is a need to dispense liquids from reservoirs to a point of use. In industrial dishwashing equipment, for example, peristaltic pumps are conventionally used to dispense firstly detergent and then rinse additives to the wash compartment. Since these dispensing operations call for precisely measured amounts of liquid to be delivered to the wash compartment, separate peristaltic pumps are used for the respective liquids, individually controlled by a timer device.
The object of the present invention is to effect a cost and equipment saving by the provision of a single pump unit capable of selectively dispensing one of two fluids from respective reservoirs to a delivery point, and to facilitate the assembly and maintenance of such a pump.
According to a first aspect of the present invention a dispensing pump for the selective delivery of a fluid from a reservoir comprises a motor having a first housing from which a driveshaft projects, a pumping arrangement contained in a second housing and having an inlet, an outlet, and a rotor, the rotors being mounted on the driveshaft by means of a coupling capable of transmitting torque in one direction only, the first and second housings being detachably connected together to allow separation of the housings in the axial direction of the driveshaft.
The preferred pumping arrangement is a peristaltic pump, but other positive displacement or rotary vane pumps may be used, depending on the fluid to be pumped and the necessity of fine control over amounts pumped. Two rotors may be provided in the second housing their couplings being so configured that when the driveshaft is rotated in a first sense, a first one of the pumping arrangements is activated while the other remains at rest, and when the driveshaft is rotated in the other sense, the other pumping arrangement is activated and the first remains at rest.
In the preferred embodiment, the second housing contains a pair of rotors, two peristaltic tubes extending along arcuate paths in the housing and being occluded at two or more points by pressure between rollers mounted on the rotors and the housing, each rotor being coupled to the driveshaft by means of a respective helical spring wound round the shaft and having one end part extending radially from the shaft to bear on a torque-transmitting surface of the rotor, the helical springs being wound in opposite senses about the driveshaft.
According to another aspect of the invention, a dispensing pump comprising a first housing having a driveshaft extending therefrom and a second housing containing a pumping arrangement including a rotor and wherein the first and second housings are detachably connectable together to allow separation in the direction of the driveshaft axis is assembled by providing a stub shaft extending through the second housing and carrying the rotor, positioning the first and second housings so as to align axially the stub shaft and the driveshaft, and moving the second housing towards the first in the axial direction of the driveshaft so that the driveshaft enters the second housing and engages the rotor while the stub shaft is urged axially out of the second housing. By attaching the rotor to the driveshaft via a unidirectional coupling, the pump may only transport fluid in one direction. Preventing the possibility of the pump operating to transfer fluid in the wrong direction may have important safety aspects, such as when the pump is used in medical applications, for example in dialysis. The two part construction of the pump allows easy and rapid replacement of a faulty or contaminated pump unit, and in the medical application may provide a disposable pump unit to avoid sterilization problems.
Other applications for the `unidirectional` pump and for the selective dosing pump will become apparent from the following description of a preferred embodiment of the selective dosing pump, in which:
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REFERENCES:
patent: 3951570 (1976-04-01), De Biaggi
patent: 4441867 (1984-10-01), Berelson
Barnett David G.
Skinner Ronald
Brightwell Dispensers Limited
Smith Leonard E.
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