Pumps – Expansible chamber type – Elongated flexible chamber wall progressively deformed
Reexamination Certificate
2000-12-14
2002-10-22
Freay, Charles G. (Department: 3746)
Pumps
Expansible chamber type
Elongated flexible chamber wall progressively deformed
C417S477200, C417S477300
Reexamination Certificate
active
06468059
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a hose cassette for a peristaltic pump, comprising a cassette housing, a flexible hose extending through the cassette housing, the hose being guided in the cassette housing along a circular segment and the cassette housing having a cutout for the engagement of a roller wheel of the peristaltic pump into the interior of the circular segment, arid comprising connection elements for connecting the cassette housing to the peristaltic pump. The invention further relates to a peristaltic pump comprising such a cassette. Hose cassettes of the type mentioned above are in particular used as sucking and rinsing pumps for medical applications. Insofar the hose may perform the function of a rinsing or a sucking line. Examples for medical applications are the arthroscopy, the hyteroscopy and the cystoscopy. For medical applications, particularly sterility satisfying all requirements, is important, and therefore the hose is normally disposed of after an application, so to avoid cross contamination between different patients. The hose cassettes have thus to be economic to make, on one hand, and to permit simple handling, on the other hand.
BACKGROUND OF THE INVENTION
As to prior art peristaltic pumps, there are in principle two different basic configurations. The first basic con figuration consists in that the hose disposed around the roller wheel is pressed against the roller wheel by means of a pressure bracket or the like. Such embodiments are for example known from documents U.S. Pat. No. 4,798,580 and U.S. Pat. No. 5,044,902. Of a substantially similar mode of operation is the subject matter of document U.S. Pat. No. 4,798,580, according to which a cassette with a pressure bracket is provided behind the hose. The cassette is fixed by a lever closure mechanism, and simultaneously the hose is pressed by the pressure bracket against the roller wheel at the pump housing. In the subject matter of document U.S. Pat. No. 5,044,902, the roller wheel is integrated in the cassette, and when mounting in the cassette, the hose is pressed towards the cassette wall and against the latter by centering the roller wheel on its guiding portion.
The second basic configuration, on which the invention in principle relies, consists in that the hose is pulled with sufficient enclosing angle around the roller wheel by a tensional force of suitable size. Hereby a pressure bracket or the like will not be needed. The tensional force has to be adjusted, according to the elastic properties of the hose, such that in the area of a roller of the roller wheel, the inner cross section of the hose is reduced to virtually zero. Examples can be found in documents U.S. Pat. No. 4,537,561 and U.S. Pat. No. 5,213,483. In the insofar prior art embodiments, the hose is fixed at opposite ends of the cassette and extends in a straight line between such ends. The cassette is then pressed on in a radial direction, in relation to the roller wheel, towards the roller wheel and is fixed with suitable fixing elements. Hereby, by dimensioning the geometry of the cassette and of the connection elements according to the elasticity of the hose, a tensional force on the hose portion interacting with the roller wheel and meeting the requirements will be achieved; handling is however relatively complicated, and it is regularly necessary to use both, hands for putting the cassette in place. This is also caused by that the forces required to press the cassette on may be rather substantial, and some finesse will be required for precise positioning by manual operation against these forces.
SUMMARY OF THE INVENTION
In contrast thereto, the invention is based on the technical object to provide a hose cassette and a peristaltic pump permitting connection of the cassette to a pump housing in a particularly simple and handy manner.
For solving this object the invention teaches that at least one hose leg to be connected to the circular segment is displaceably held between a mounting position and an operating position in the cassette housing. Displaceability may be provided in a straight line or along a curve. The basic concept of the invention consists in that in a first mounting step, the cassette with the hose leg being in the mounting position is put in place at a pump housing, and in a second mounting step, by pulling at the displaceable hose leg, the hose will rest against the roller wheel with the required pressure. This is then the operating position of the hose leg. Hereby it is achieved that the hose cassette can in a simple way be mounted at a pump housing, and that without counter pressure from elastic forces of the hose. The cassette can thus easily be mounted with one hand. Immediately thereafter the required pressure of the hose around the roller wheel with sufficient tensional force is adjusted by a simple pull at the displaceable hose leg. It is understood that the displaceable hose leg is fixable in a suitable manner in the operating position, for example by latching. For this, too, one hand only is required, since the weight of the peristaltic pump generates sufficient counter force against the elastic forces of the hose.
It is preferred to adjust the operating position by that, when the cassette is mounted at the peristaltic pump, the displaceable hose leg is adjustable by pulling at the hose portion immediately following the displaceable hose leg and being disposed outside the cassette, the displaceable hose leg latching in the operating position. Basically, both hose legs may be held in a displaceable manner. In conjunction with other functions possibly to provide, it is however recommended that only one hose leg is displace able between the mounting position and the operating position, and that the other hose leg is fixed in the longitudinal direction of the hose.
In principle, the enclosing angle of the hose around the roller wheel is arbitrary, as long as a sufficient crosssection reduction will result with corresponding tensional force on the hose in the area of a roller. It is preferred that the circular segment and thus the enclosing angle of the hose around the roller wheel will extend over at least 90°, preferably 170° to 190°, most preferably 180°. It is suitable to form the hose at least in the area of the circular segment from a rubber-elastic material, in particular a natural or synthetic elastomer material, preferably a silicone caoutchouc or an elastomer polyurethane(co)polymer. The higher the modulus of elasticity, the lower the necessary tensional force at the displaceable hose leg.
In the embodiment with only one displaceable hose leg it is preferred that the fixed hose leg comprises a connection element having stop surfaces preferably extending orthogonally to the longitudinal extension of the hose, said stop surfaces resting against fixing surfaces in the cassette housing. By interaction of the stop surfaces with the fixing surfaces, the connection element and thus the hose leg are fixed virtually without any clearance. This embodiment permits that the connection element of the fixed hose leg comprises a pressure sensor communicating with the peristaltic pump, when the cassette is mounted at the peristaltic pump. The pressure sensor being in hydrostatic connection with a fluid flowing through the hose, may be adapted as a pressure transducer, the pressure acting on the sensor being transformed into an electrical value or an electrical signal, respectively. Communication with the peristaltic pump will then operate over complementary contacts at the pressure sensor and at the peristaltic pump. It is however also possible that the pressure sensor is adapted as a pressure membrane and is in mechanical connection with a pressure transducer provided in the peristaltic pump, when the hose cassette is mounted. This is particularly advantageous with regard to cost.
Preferably the displaceable hose leg is provided with a connection element comprising a latch element. In detail, the latch element may comprise a stop surface, by means of which for a cassette mounted at the per
Haser Christian
Mehner Gotthilf
Zentner Peter
Freay Charles G.
Liu Han Lieh
McGlew and Tuttle , P.C.
W.O.M. World of Medicine GmbH
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