A PUMP DEVICE

Abstract: A pump device for a flowable product comprising a housing (10) and at least two pair of connection pieces (12, 13) on the housing (10). One connection piece in each pair of pieces forms the inlet means to the chamber (16) and the other the outlet means. One pair of an inlet means and an outlet means are operatively interconnected via a sub-chamber forming, not pressure resistant, resilient, tube-shaped hose (11) in the chamber (16). Truncated, perforated, conical hose connection means (17, 18) are arranged at opposite ends of the elongated housing. Check valves (21, 22) of the flap type are arranged for alternatingly opening and closing the inlet and outlet of each pair of connection pieces. Means (24-27) are arranged for pressurizing the hose (11) either internally or externally for operating the pump such that it pumps the product either through the chamber (16) or through the hose.

Description: The present invention relates to a pump device of the pressurized fluid operated type comprising a pair of chambers divided by a movable partition wall, where one of said chambers forms a dosing chamber and the other a working chamber. The problem behind the invention is to design the pump device such that it allows shifting between the functions dosing chamber and working chamber without major rebuilding of the structure. A further problem is to provide an accurate dosing and discharge operation, at least when operating the pump according to one of said operation modes. An overall problem is to realize that which has been said by means of a structure which from a general point of view is well suited for sterile systems. Pressurized air pumps having a tube-shaped membrane between a dosing chamber and an working chamber are previously known and are for instance disclosed in SE-B-412939, (GB-A-2003976) and DE-A-3000142. Basically, pumps of the present type are of the peristaltic type. A further example of such pumps is shown in US-A No. 3 427 987. Furthermore, US-A-2 626 569 discloses a prior art pump device comparable to the present invention. However, the known pumps do not allow shifting of operation mode, do not have a basic structure for toolfree assembling and disassembling in sterile systems, do not eliminate product wear due to shearing forces, do not allow in-line sterilization, and do not withstand high pressures and high temperatures. Said shearing forces are a problem with prior art pumps when pumping blood-plasma, in which the delicate blood-plates maybe damaged. Furtheron, the dosing chambers of the known pumps generally cannot be emptied completely. In order to eliminate said deficiencies the present invention provides a pump device for a flowable product, comprising an elongated housing and at least two pairs of connection pieces arranged on the housing, where each pair forms an inlet and an outlet, respectively, to and from a chamber in said housing, said one pair of inlet and outlet are operatively interconnected via a sub-chamber forming, not pressure resistant, resilient, pipe shaped hose in the chamber, and means are arranged for alternatingly opening and closing the inlet and outlet of each pair of connection pieces. The device is characterized in that perforated, truncated conical hose connection means are arranged at opposite ends of the elongated housing, and that means are arranged for pressurizing the hose either internally or externally in order to pump the product either through the chamber or the hose. In the embodiment presently preferred the internal surface of the chamber is formed as a pressure resistant surface which resists the strain arising from pressurizing the interior of the tube. Preferably said means for pressurizing the tube interiorly comprises a source for pressurized fluid connectable to the inlet of said pair of connections, and said means for externally pressurizing the tube comprises a source for pressurized fluid connectable to the inlet of the other pair of connections. The successive or alternating operation of opening and closing the inlet and outlet in a respective one of the connection pieces preferably is accomplished by check valves. In order to use the natural basic shape of the tube for forming a dosing chamber outside the tube, the cross section area of the tube preferably is less than the cross section area of the chamber, at least along a certain length of the chamber. An example of a preferred tube material is a highly stretchable latex material. The invention will now be exemplified by reference to the accompanying drawing, which partly in cross section, partly in an elevation view by means of broken lines, show different embodiments of pump devices according to the present invention. The reference numeral 10 indicates a generally cylindric pump housing where a tube or hose 11 of a stretchable or resilient material is arranged for withstanding high temperatures but which is not pressure resistant, but basically of the type which resiliently reassumes its original shape, for instance a hose of a highly stretchable latex material. The tube or hose 11 is connected such that it forms a partition element inside the chamber 16 of the housing 10 and provides communication between a connection piece 12 and a connection piece 13, provided the tube is not fully compressed. Either one of said connection pieces forms an inlet to or outlet from a chamber 16. In the figure it may for instance be supposed that 14 is an inlet and 15 an outlet. The inlet and the outlet have been accomplished by means of perforated, truncated cones which are maintained inside the housing 10 by means of clamps 17, 18 which are operable without tools for assembling and disassembling of the pump. Further clamps 19, 20, of the same type as the previous ones, connect pipe pieces to the housing 10 for forming inlet and outlet connection pieces for sterile flow conduits. The perforated, truncated cones 14 and 15 counteract most efficiently any tendency of laminar flow inside the hose 11. Thus, shearing forces are avoided and the product will not suffer seriously from wear due to internal friction. Additionally, when compressing the hose 11, the conical exterior of the pieces 14, 15 forms a support for squeezing the hose completely flat, leaving no rest volume, without seriously stressing the hose. At either end of the housing 10 there is a check valve 21, 22 which for instance nay be such that one is closed and the other one opened when an over pressure acts externally onto the pipe. The dashed line 11a indicates an alternative extension of the hose or pipe 11, implying that the natural dimension of the pipe is somewhat less than the cross section of the pump housing 10. In this manner there is obtained a division of the chamber 16 into two chambers where each one already from the very beginning has a certain nominal volume. Such partial chambers may also be obtained by initially creating an under-pressure in the pipe. The dashed line 23 indicates a chamber design basically of a double conic type. The pipe 11 forms the partition element between two distinct chambers 16a, 16b. The numerals 24, 25 indicate an inlet to or an outlet from the chamber or more precisely the sub-chamber 16a after the hose or pipe 11 has been mounted. The numerals 26, 27 denote check valves basically of the same type as the valves 21, 22 implying that one of the valves is closed while the other is open. The inside of the wall 23 as well as the inside of the cylindric housing form a pressure resistant surface which resists the strain acting on the pipe as a result from the internal over-pressure. In that case where the hose or pipe forms the working chamber, i.e. the chamber which is arranged for driving the product from for instance the inlet 24 to the outlet 25, a source for pressurized fluid (not shown) is connected to either one of the connection pieces 12, 13. The pressure inside the pipe pushes the hose or pipe against the pressure resistant surface 23, such that the chamber 16a is completely emptied from product. As soon as the pressure inside the hose or pipe returns to a lower level, the pipe assumes its original shape and the product is pushed into or sucked out through the connection piece 24, 25 selected as an inlet while the other connection piece is closed. As soon as the input of product is finalized the pipe 11 is pressurized and the operation mode of the valve 26, 27 reverted, implying that the product now is discharged from the chamber 16a. All check valves 21, 22, 26 and 27 are of the flap type comprising flaps 21a and 22a flexible in one direction only for opening up valve openings in support plates 21b and 22b for establishing communication to the interior of the hose 11. As appears from the figure, the flaps 21a and 22 operate in different directions for providing the proper opening and blocking function at respective ends of the pump housing 10. Product wear is minimized also at the specific check valves which do not "crush" the product as would be the case with ball valves. If one choses to let the sub-chamber 16a, 16b shift operation modes, i.e. when the product is allowed to pass through the pipe 11 and if the chamber 16a alternatingly is pressurized and evacuated, respectively, the product discharge through the one of the connection pieces 12, 13 elected as an outlet will be a pulsating one. The pulsating outflow from the pump may be equalized by parallel connecting two or more of pumps of the type described arranged such that there is a certain phase lag.

Claims: A pump device for a flowable product, comprising an elongated housing (10) and at least two pairs of connection pieces (12, 3; 24, 25) arranged on the housing, where each pair forms an inlet means to and an outlet means from a chamber in the housing, said one pair of inlet means and outlet means (12,13) are operatively interconnected via a sub-chamber (16b) forming, not pressure resistant, resilient pipe-shaped hose (11) in the chamber, and means (21, 22; 26, 27) are arranged for alternatingly opening and closing the inlet and outlet of each pair of connection pieces (12, 13), characterized in that perforated, truncated, conical hose connection means (14; 15) are arranged at opposite ends of the elongated housing, and that means are arranged for pressurizing the hose either internally or externally in order to pump the product either through the chamber (16a) or the hose (11). A pump as in claim 1, wherein the internal surface of the chamber is formed as a pressure resistant surface which resists the strain arising from pressurizing the hose (11) internally. A pump as in claim 2, wherein the pressure resistant surface forms a double truncated cone having the base thereof generally at the mid portion of the chamber and the ends thereof at the base of each one of the hose connection means. A pump as in claim 3, wherein said means for pressurizing the hose (11) internally comprises a source for pressurized fluid connectable to one of said inlet means (14; 15) of said one pair of connection pieces (12, 13), and that said means for pressurizing the hose externally comprises a source for pressurized fluid connectable to the inlet means (24; 25) of the other pair of connection pieces. A pump as in claim 4, wherein said means for alternatingly opening and closing the inlet and outlet comprises check valves (21, 22; 26, 27) of the flap type. A pump as in claim 5, wherein the cross section area of the tube (11) is less than the cross section of the chamber, at least along a distance along the chamber. A pump as in claim 6, wherein the tube (11) is manufactured from a highly resilient latex material.

Inventors: ALBINSSON, URBAN
Applicants: STERIDOSE SYSTEMS AB
Application year: 1987
Main classification: F04B43
IPC codes: F04B43