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Peristaltic pumpRelated Patent Categories: Pumps, Expansible Chamber Type, Elongated Flexible Chamber Wall Progressively Deformed, Deformation By Rolling Or Sliding Engagement Member, Plural Spaced Engagement Members Or Member Portions, Specific Backing Member For Flexible WallPeristaltic pump description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060177329, Peristaltic pump. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The invention relates to a peristaltic pump according to the preamble of claim 1. [0002] Peristaltic pumps essentially comprise a tube bed as a support for the tube and at least one element which squeezes the tube in a partial region. The pump action is produced by the fact that the squeezing element is moved in the longitudinal direction relative to the tube. Rams, fingers or rollers on a rotor are known as squeezing elements. The capacity of peristaltic pumps is chiefly determined by the structural design of the pump, by the tube dimension, by the tube material and by the pumped medium and the conditions of use. Decisive factors for the pump operation and the service life of the tubes are the dynamic-elastic properties, the creep resistance and alternating bending strength as well as the compressive and tensile permanent set of the tube material. These properties, for their part, are dependent on the pumped medium, on the specific conditions of use such as temperature and pressure, as well as the in-service age of the tubes, i.e. the number and the dynamics of the squeezing operations already performed in a specified time period. On account of the large number of influencing factors, in some cases time-dependent, it is very difficult to produce constant flow rates with peristaltic pumps. In practice, these flow rates generally diminish with time, whereby the trend over time and the extent of the drift are application-specific and cannot generally be predicted. Even under ideal conditions, therefore, a constant flow rate can only be produced over a period of minutes up to hours with known peristaltic pumps and tube materials. Two major effects are responsible for the drift in the flow rate. On the one hand, the tube material suffers from fatigue due to repeated squeezing, so that the tube cross-section and therefore the tube volume in the squeezing region increasingly diverges from the initial state over time. On the other hand, especially with pumps with a rotor, the rollers exert a tensile force on the tube, which increasingly stretches the latter in the longitudinal direction, so that in the squeezed region the tube cross-section and the tube volume diminish over time. The greater the contact pressure of the rollers on of the tube, the greater the tensile force acting on the tube will usually be, and the tube stretching resulting therefrom. [0003] Generally, the structure of peristaltic pumps is aimed at generating flow rates with a specific design of pump and a specific tube which, under identical conditions of use, can be predicted within narrow limits, and are reproducible and constant. [0004] Especially in the case of pumps with a rotor, it is necessary to prevent the tube in the squeezed region from being displaced in the longitudinal direction due to the tensile force of the rollers exerted on it. Pumps for tubing sold by the metre therefore usually have retaining devices for the tube, designed as clamps for example, on both sides of the tube bed. If the tube bed is designed as a tube cassette separable from the pump, said cassette often has lateral recesses for the accommodation of stoppers rigidly connected to the tube. Such retaining devices prevent the tube from being displaced in the pump, but do not prevent it from being stretched in the longitudinal direction in the squeezed region due to the tensile force of the rollers exerted on it. [0005] In order to prevent this, the tube in WO 95/11383 (D1) has a perforated longitudinal rib, which is rigidly screwed to a two-part tube bed. In this way, both the displacement of the tube in the tube bed and the stretching in the squeezing region is prevented. The assembly of the tube on the pump, however, is costly, and in the case of small tubes it is difficult to carry out. Furthermore, multi-channel pumps with such a structure can only be produced with difficulty. [0006] U.S. Pat. No. 4,494,285 (D2) describes a method for the production of an elastic lumen, which is injection-moulded directly onto a tube bed. The stretching of the lumen in the longitudinal direction is thus prevented. Widespread use of this solution, however, is opposed by the fact that the production method is costly and small lumina or multi-channel designs, for example, are only possible to a limited extent. For the assembly of the lumen, moreover, the whole pump unit with the rotor has to be dismantled. [0007] Despite their specific advantages, the solutions described in D1, D2 are scarcely used in practice, since they do not meet present-day demands for simplicity and reliability, as well as flexibility and rapid tube replacement, with at the same time lower production costs. [0008] Pumps with tube cassettes or tubes with stoppers such as described in EP 1 400 691 (D3) find widespread use, wherein the tube is not fixed in the squeezing region. With these and similar solutions, the tube is stretched by approx. 10-30% in the longitudinal direction when it is inserted into the tube cassette and also when the tube cassette is fixed onto the pump. This prestressing is able to reduce somewhat the additional longitudinal stretching of the tube caused by the tensile force of the rollers, but it cannot prevent it, so that the tube cross-section and the flow rate diminish with increasing longitudinal stretching. On the basis of the principle, therefore, the reproducibility of flow rates produced with tube cassettes and tubes with stoppers cannot be better than the reproducibility of the tube prestressing. And the constancy of the flow rate is at best as good as the temporal progression of the tube stretching in the squeezing region. [0009] The reproducibility of the tube prestressing in tube cassettes is adversely affected by the following inadequacies: in the first place, the stoppers usually vary in size depending on the tube dimension, so that their position in the recesses of the tube cassettes designed for the largest stoppers is often not defined sufficiently precisely. In the second place, the tubes may be inserted into the tube cassette twisted about their longitudinal axis. In the third place, the preset spacing between the stoppers often cannot be complied with sufficient reproducibility using present-day production methods and in the fourth place the different tube materials and dimensions would require an optimised prestressing with a specific stopper spacing, something which is usually discounted in favour of standardised production. Since tube cassettes are also fitted repeatedly with new tubes and used again, their properties can change over time due to fatigue, defect or the influence of chemicals, as a result of which the reproducibility and the constancy of the flow rates produced are also adversely affected. There is also the risk of the unfixed tube in the tube bed being nipped and damaged due to operator error when the tube cassette is fitted onto the pump. [0010] Since the reproducibility and the constancy of the flow rates produced with known peristaltic pumps, especially of those with tube cassettes as a tube bed and rollers on a rotor as squeezing elements, are often inadequate for special requirements, the desired flow rate regularly has to be re-established by changing the rotor speed. This is not possible in the case of pumps with a constant, non-variable speed, and only to a limited extent in the case of multi-channel pumps with a common drive for all channels. [0011] To sum up, it can be stated that, for special requirements, it is only possible to a limited extent with peristaltic pumps having the present design to achieve desired flow rates with the necessary reproducibility and constancy. [0012] The problem of the invention is to improve peristaltic pumps according to the preamble of claim 1 in such a way that, with low structural and production outlay, straightforward and reliable handling and a maximum of reproducibility and constancy of the flow rate are achieved at the same time. [0013] The solution to the problem is set out in the characterising part of claim 1 in terms of its main features, and in the further claims in terms of further advantageous developments. [0014] The invention is explained below with the aid of the appended drawings. In the drawings: [0015] FIG. 1A-D tube/tube-bed unit with tube bed produced by injection moulding in view from beneath, plan view, view from above and in cross-section, [0016] FIG. 2A-C tube/tube-bed unit with tube bed made from strip material in view from beneath, plan view and view from above, [0017] FIG. 3 cross-section of a first example of embodiment of the tube/tube-bed unit, [0018] FIG. 4 cross-section of a second example of embodiment of the tube/tube-bed unit, [0019] FIG. 5 cross-section of a third example of embodiment of the tube/tube-bed unit, [0020] FIG. 6 cross-section of a fourth example of embodiment of the tube/tube-bed unit, [0021] FIG. 7 cross-section of a fifth example of embodiment of the tube/tube-bed unit, [0022] FIG. 8 cross-section of a sixth example of embodiment of the tube/tube-bed unit, [0023] FIG. 9 cross-section of a seventh example of embodiment of the tube/tube-bed unit, [0024] FIG. 10A-B a first example of embodiment of the tube clamping region in view from above and side view, Continue reading about Peristaltic pump... Full patent description for Peristaltic pump Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Peristaltic pump patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Peristaltic pump or other areas of interest. ### Previous Patent Application: Peristaltic pump providing simplified loading and improved tubing kink resistance Next Patent Application: Pump valve with controlled stroke Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Peristaltic pump patent info. IP-related news and info Results in 0.14764 seconds Other interesting Feshpatents.com categories: Computers: Graphics , I/O , Processors , Dyn. Storage , Static Storage , Printers 174 |
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