Pumps – Motor driven – Electric or magnetic motor
Patent
1986-05-27
1989-01-24
Croyle, Carlton R.
Pumps
Motor driven
Electric or magnetic motor
604155, 222333, 222390, F04B 1300
Patent
active
047998660
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a motor-driven spray pump.
Spray pumps are used in the clinical field and in medical research to administer fairly small amounts of liquid to the patient over a fairly long period of time.
U.S. Pat. No. 4,191,187 discloses a motor-driven spray pump.
This publication acquaints us with a spray pump for metered delivery of a liquid from a spray cylinder by means of a spray piston with at least one interchangeable spray.
This familiar spray pump has a housing with a mounting support for the spray and a motor drive with a screwed-shaft gear unit for transmission of the driving power of the motor from the drive unit to the spray. At the same time, the screwed-shaft gear unit has an axially movable drive element, one end of which can be made to engage the movable spray piston outside the housing, in order to move the spray part translationally. Furthermore, a translationally movable coupling is arranged in a bearing block and has a stop link with a threaded section, to make it possible to establish drive linkage between the drive element and the spray part. Moreover, the bearing block supports an elongated guide piece arranged in the sliding seat on the threaded shaft, the stop link of the coupling being movably supported on the guide piece and/or on the bearing block, and the stop link also being a coupling pin movably supported diagonally to the threaded shaft, with an essentially U-shaped recess running at right angles to its longitudinal axis, through,, which at least part of the circumference of the threaded shaft extends. And the threaded section is located on one side of the U-shaped recess.
The main disadvantage of a spray pump of this type, however, is that the whole length of the threaded shaft is arranged outside the housing. This causes a problem in that the threaded shaft becomes contaminated very easily in operation, thereby involving the risk that the smooth running of the guide piece or the drive element connected to it, so necessary for precise metering, will be impaired, there even being a danger that if heavy contamination builds up, movement will be totally impossible. This in turn leads to the problem of a spray pump of this type, especially in continuous operation having to be checked frequently with regard to functional efficiency, which greatly limits its usefulness in practical operation.
The problem facing the invention, therefore, is to produce a motor-driven spray pump in which smooth running of the gearing and a margin of functional safety are always guaranteed, even in continuous operation.
This problem is solved as described briefly below, and as described in more detail in the Detailed Description of the Preferred Embodiment.
What is first achieved, is that the whole length of the threaded shaft can be accommodated and supported in the housing, so that there is no risk of the threaded shaft being contaminated in any way, which might otherwise lead to the problems previously explained, given the state of the art in this area.
By arranging the drive element and its pivoting in the housing, it also becomes possible to operate a coupling from outside while retaining its simple design, so that making or breaking the drive connection is possible just as easily as with the state of the art in this area.
The drive element of the spray pump according to the invention is indeed drawn outside the housing partially at times when the spray piston is retracted, yet no contamination problems comparable to the state of the art in this area occur at this time, since, for one thing, the surface of the drive element can be designed very smooth, and, for another, only part of it has to be accommodated outside the housing. If the spray pump according to the invention is not being operated, the drive element, over and above that, can be accommodated wholly in the housing, which is not possible given the state of the art in this area as far as its threaded shaft is concerned, since the whole length of the latter is permanently located outside the housing.
From WO No. 82/0
REFERENCES:
patent: 2702547 (1955-02-01), Glass
patent: 4191187 (1980-03-01), Wright
patent: 4255096 (1981-03-01), Coker, Jr. et al.
patent: 4424720 (1984-01-01), Bucchianeri
Faeser Ulrich
Mahn Dieter
Croyle Carlton R.
Fresenius AG
Szczecina Jr. Eugene L.
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