Pumps – Expansible chamber type – Elongated flexible chamber wall progressively deformed
Patent
1992-01-10
1993-10-05
Bertsch, Richard A.
Pumps
Expansible chamber type
Elongated flexible chamber wall progressively deformed
417476, F04B 4312
Patent
active
052499383
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
When peristaltic roller pumps are used, for example, for pumping blood, the blood pipe may suffer damage caused by the pipe being squeezed and twisted as it is loaded and unloaded into and out of the pumphead. This damage may cause the contamination or loss of the blood being pumped, as well as the destruction of the pipe.
Accordingly, a pumphead has been sought which enables easy loading and unloading of a pipe into the pumphead with the minimum amount of stress being brought to bear on the pipe, but which exerts the minimum necessary amount of force on the pipe during pumping.
SUMMARY OF THE INVENTION
According to the present invention, a head for a peristaltic roller pump comprises an occluder ring, having a pair of substantially tangential slots opening at an axial end of the ring to enable a flexible pipe to enter, lie around the inner wall surface of, and exit from, the ring; and a rotor concentrically and rotatably mounted within the occluder ring, the rotor having a circumferential array of guide and drive rollers respectively for locating the pipe axially within the ring and for squeezing the pipe against the inner wall surface of the occluder ring, the rotor also having a cover plate radially inwardly spaced from the inner wall surface of the occluder ring to provide a part annular gap of sufficient width for loading and unloading of the pipe into and out of the ring, the gap being substantially closed at at least one end by a radially outwardly projecting dog on the rotor, and the arrangement being such that the pipe can be loaded into the ring by placing a bight of the pipe in one of the slots and rotating the rotor so that the dog overrides the pipe and pushes it axially through the gap into the ring.
In use, the pipe may be held in position at both ends of the loop of pipe which extends through the ring by clamps which, along with the precise compression of the pipe by the drive rollers, prevent the pipe from creeping around the occluder ring.
The gap left between the cover plate of the rotor and the inner wall surface of the occluder ring gives the advantage that the pipe may be visually observed during pumping and any damage to the pipe can be spotted quickly and further damage can be prevented.
Preferably the dog is circumferentially positioned adjacent to, but ahead in the direction in which the dog faces, of one of the rollers and the part annular gap extends at least to the next roller positioned circumferentially around the rotor in the direction in which the dog faces. The pipe can then drop easily into the gap without being deformed excessively, but using its own natural tendency to unbend as the primary force moving it through the gap into the ring. Another advantage of this arrangement, if the dog is positioned adjacent to a guide roller, is that the entry and axial location of the pipe happen in quick succession, thus preventing the pipe from becoming snared in some part of the rotor mechanism.
The pumphead may be used with both disposable and re-usable pipes. In the case of re-usable pipes, where it is important that the pipes are not damaged on unloading, the dog may be used to underride the pipe loop and lift it out of the occluder ring through the gap. This will involve rotating the rotor in the same direction as on loading the pipe. However the pumphead may have a second dog facing in the opposite circumferential direction to the first. This may be used for underriding the pipe when the pipe is to be unloaded from the ring, upon rotation of the rotor in the opposite direction to that for loading with the first dog. Also, with this arrangement of two dogs, the pumphead offers the further, important advantage that the pipe may be loaded and unloaded in either a clockwise or anticlockwise direction, making the equipment easy to use and ergonomically efficient. The two dogs may be provided by the opposite ends of a common dog element which extends only a short angular distance around the ring.
Preferably, the pumphead consists of four equiangularly
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patent: 4702679 (1987-10-01), Malbec
patent: 4824339 (1989-04-01), Bainbridge
patent: 4861242 (1989-08-01), Finsterwald
patent: 4909713 (1990-03-01), Finsterwald
Bellhouse Technology Limited
Bertsch Richard A.
Koryinyk Peter
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