Imperforate bowl: centrifugal separators – Rotatable bowl – Including means for imparting other movement to bowl in...
Patent
1991-09-17
1993-01-19
Jenkins, Robert W.
Imperforate bowl: centrifugal separators
Rotatable bowl
Including means for imparting other movement to bowl in...
494 84, B04B 110, B04B 114
Patent
active
051803585
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates in general to a compact, inexpensive low speed centrifuge primarily useful to microbiologists. In particular it relates to improvements in adjusting and controlling the operation of such centrifuges.
BACKGROUND ART
When attempting to separate particulate matter from a fluid, it is known that very small (slowly settling) particles are exponentially more difficult to separate by centrifugation than larger particles. Accordingly, most disc-type centrifuges are designed to spin at extremely high speeds in order to separate the smallest particles at a reasonable rate. High speeds mean high stress on the equipment and on the particulate matter being separated. On the other hand, it is not always necessary for a centrifuge to be capable of separating extremely small particulate matter, especially if the operator is only interested in larger material.
However, there has not been any consideration given in the past to a disc-type centrifuge dedicated to larger particle separation such that the centrifuge could operate at relatively low speeds, resulting in less stress on the equipment and permitting the utilization of less exotic construction material and techniques.
Commonly assigned Canadian patent application Ser. No. 579,008 filed Sep. 30, 1988 discloses and claims a low speed particle concentrator or centrifuge which overcomes the above-enumerated problems. That device includes as a feature thereof a mechanism for controlling the particulate outflow by controlling or adjusting the operating gap between the upper and lower bowls thereof. Adjustment is effected manually, by rotating an adjusting nut relative to the upper bowl member, the nut defining or setting an upper limit to the available upwards movement of the upper bowl member. The mechanical adjustment must be effected while the concentrator is at rest.
There are instances and circumstances which necessitate, or at least make it desirable, to have automatic or powered adjustment of the inter-bowl gap available. For example it may be desirable to have the gap increase automatically at preset intervals of time to flush out oversized particles, or to change back and forth between different gap settings for culture mode and separation mode as in semi-continuous culture. Also, after the device has been stopped completely the impeller pump must be re-primed, further complicating the procedure for automated adjustment.
DISCLOSURE OF INVENTION
The present invention provides certain improvements over the concentrator or centrifuge of the aforementioned Canadian patent application No. 579,008. In particular the present invention provides means for achieving automatic control or movement of the upper bowl member to control thereby the gap between the upper and lower bowl members. Such control may be the result of input from an operator who, through appropriate equipment, can raise or lower a limit setting element within the centrifuge while it is running, following a preset programme or in response to his observations and his knowledge of the consequences thereof. Alternatively the limit setting element could be computer controlled to follow a preset programme of movement or to respond to sensor inputs as part of a feedback circuit.
In one embodiment the drive motor is fixedly connected to the upper bowl member but is adjustably and resiliently mounted on the centrifuge housing so that it can be set at an appropriate maximum elevation as desired. The motor and the upper bowl member are biased towards a closure position with the lower bowl member but during operation the upper bowl member (and the motor) will lift when there is sufficient pressure in the centrifuge chamber. The maximum lift height is controlled externally of the housing by controlling, through a set of gears, the maximum height of the motor.
In the second embodiment the upper bowl is resiliently biased relative to an adjusting nut as in the earlier application referred to herein. In this case appropriate gear means are carried by the adjusting nut
REFERENCES:
patent: 1381330 (1921-06-01), Pechstein
patent: 1395517 (1921-11-01), Peck
patent: 1613579 (1927-01-01), Hinchley et al.
patent: 4083488 (1978-04-01), Gunnewig
patent: 4113172 (1978-09-01), Pautsch
Jenkins Robert W.
Occam Marine Technologies Ltd.
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