Blood treatment device with membraned heat exchanger, and device for detecting a fluid leak

Abstract

A blood treatment device includes a heat exchanger having a first space and a second space, with a first fluid flowing through the first space and a second fluid flowing through the second space. The heat exchanger has a membrane which separates the first space from the second space, with the membrane forming a component of a capacitor having two capacitor plates, between which the membrane is located. A monitoring means is connected to the capacitor, and is configured to detect an electrical property of the capacitor, for the purpose of detecting a fluid leak from the first space to the second space.

Claims

1. A blood treatment device comprising: a heat exchanger having a first space and a second space, through which, during operation of the blood treatment device, a first fluid flows through the first space and a second fluid flows through the second space, a membrane which separates the first space from the second space, the membrane forming a component of a capacitor which has a first capacitor plate and a second capacitor plate, between which the membrane is located, a monitor which is connected to the capacitor and which is configured to detect an electrical property of the capacitor so as to detect a leak of the first fluid from the first space to the second space, and a test resistor for checking the monitor, the test resistor being connected in parallel with the resistor formed by the membrane.

2. The blood treatment device in accordance with claim 1, wherein the first capacitor plate and the second capacitor pate and the membrane are located between the first space and the second space.

3. The blood treatment device in accordance with claim 1, wherein the membrane is located between the first space and the second space, and the first space and the second space are arranged between the first capacitor plate and the second capacitor plate.

4. The blood treatment device in accordance with claim 1, wherein the monitor includes a DC or a AC voltage source having poles connected to the first capacitor plate and the second capacitor plate.

5. The blood treatment device in accordance with claim 1, wherein the first capacitor plate and the second capacitor plat contact the membrane directly and at both sides thereof to provide a sandwich-like structure.

6. The blood treatment device in accordance with claim 1, wherein the first capacitor plate and the second capacitor plate include a metal and/or the membrane is configured as an electrical insulator.

7. The blood treatment device in accordance with claim 1, wherein the monitor is configured to effect an impedance measurement or a capacitance measurement of the capacitor.

8. The blood treatment device in accordance with claim 1, wherein the capacitor is integrated into a resonant circuit and the monitor is configured to effect a measurement of a resonant frequency of the capacitor.

9. The blood treatment device in accordance with claim 1, wherein the monitor includes a measurement resistor over which a voltage is determined.

10. The blood treatment device in accordance with claim 9, wherein the measurement resistor is connected in series with the resistor provided by the membrane.

11. The blood treatment device in accordance with claim 9, wherein the monitor has a low pass filter for determining an average value of the voltage.

12. The blood treatment device in accordance with claim 9, wherein the blood treatment device is a dialysis device.

13. The blood treatment device in accordance with claim 12, wherein the blood treatment device is connected to a water supply, and the heat exchanger is connected to the water supply such that fresh water flows through the first space of the heat exchanger.

14. The blood treatment device in accordance with claim 12, wherein the second space of the heat exchanger is arranged such that consumed dialysis solution flows therethrough.

15. The blood treatment device according to claim 6, wherein the metal is steel or titanium.

16. The blood treatment device according to claim 6, wherein the electrical insulator includes Kapton.

17. The blood treatment device according to claim 13, wherein the fresh water is RO water from the water supply.

Description

(1) There are shown:

(2) FIG. 1: a schematic view of the water inflow, of the dialyzate outflow and of the heat exchanger;

(3) FIG. 2: a first variant of a direct electrical monitoring of the membrane;

(4) FIG. 3: a further realization possibility of the electrical membrane monitoring;

(5) FIG. 4: a direct electrical monitoring of the membrane corresponding to FIG. 2 with a test resistor;

(6) FIG. 5: a circuit diagram of the arrangement in accordance with FIG. 2 with a measurement resistor and a low pass filter for a voltage value determination;

(7) FIG. 6: a schematic view of a capacitor without and with a leak; and

(8) FIG. 7: a circuit diagram of the arrangement in accordance with FIG. 2 once a leak has occurred.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

(10) The fresh water inflow of a dialysis device is shown with the reference numeral 10 in FIG. 1. This fresh water is preferably RO water. The first space of the heat exchanger 100 is flowed through by this water and the schematically shown second space 2 is flowed through by consumed dialyzate which flows into the second space 2 through the line 20.

(11) A heating of the RO water by consumed dialyzate takes place in this manner.

(12) A heat-conductive and electrically insulating membrane is located between the two spaces 1 and 2 and is shown in the following Figures.

(13) FIG. 2 shows this membrane with the reference numeral 30. It is in this respect an electrical insulator which is adjacent to or is surrounded at both sides by metal layers 40 as capacitor plates. These two metallic layers can be formed, for example, by titanium membranes or steel membranes.

(14) A possibility of monitoring the membrane 30 thus comprises the membrane being surrounded by two steel membranes or capacitor plates 40.

(15) This overall arrangement of the membrane 30 and the plates 40 is arranged between the two fluid paths F1 and F2, wherein the fluid in accordance with fluid path F1 is the fresh water located in the first space 1 and the fluid in accordance with the fluid path F2 is the consumed dialyzate located in the second space 2.

(16) Reference numeral 200 marks a housing of the arrangement of, for example, PPO (polyphenylene oxide) and reference symbol G marks the grounding of the two fluid paths F1 and F2.

(17) An AC voltage source is marked by the reference numeral 300 which is electrically connected via the cables 301 and 302 to the capacitor plates 40 and applies an AC voltage to them.

(18) The realization possibility in accordance with FIG. 3 differs from that in accordance with FIG. 2 in that the capacitor plates 40 are not arranged between the two fluid paths F1 and F2, but rather enclose them. In other words, the fluid paths F1 and F2 are received between the two capacitor plates 40. The electrical insulator in the form of the membrane 30 is located between the fluid paths F1 and F2.

(19) The housing is also marked by reference symbol 200 in accordance with FIG. 3.

(20) In the variant in accordance with FIG. 3, an electrical insulator 30 having sufficient thermal conductivity is used as an internal membrane. A capacitor whose inner space which is designed with a dielectric is obtained by attaching electrically conductive plates 40 in the outer region.

(21) In the case of an internal leak via the membrane 30, a liquid transfer takes place between the primary side and the secondary side, i.e. between the fluid paths F1 and F2. This liquid transfer has the consequence of a change of the dielectric properties. The resulting capacitance change can be measured and a leak which has occurred can thus be detected.

(22) A capacitor is thus also configured overall in accordance with FIG. 3, wherein, unlike the embodiment in accordance with FIG. 2, fluid paths form a component of the capacitor.

(23) All the variants shown are based on the principle of a varying impedance or capacitance in the case of a leak. All known possibilities for measuring these physical parameters or also other electrical or physical properties of the capacitor can thus be used to be able to draw a conclusion on a leak.

(24) This also includes, for example, the integration of the capacitor into a resonant circuit and the shift of the resonant frequency associated with a leak.

(25) FIG. 4 shows an arrangement corresponding to FIG. 2 in which a test resistor is additionally connected between the two capacitor plates 40. This test resistor simulates a leak taking place over the membrane 30 and in this manner allows a correct check of the response of the monitoring means for such a leak.

(26) The monitoring means can be formed, for example, by a measurement arrangement which is electrically connected to the capacitor plates 40 and which detects the AC or DC voltage and/or the current flow occurring between them.

(27) FIG. 5 shows a circuit diagram of the arrangement in accordance with FIG. 2, wherein the parameter R_F2 is the ohmic resistance which is formed by the consumed dialyzate in accordance with F2 and the parameter F_F1 is the ohmic resistance which is formed by the fresh solution or the inflowing water in accordance with F1.

(28) The parameter R_mem represents the ohmic resistance formed by the membrane and the parameter C_mem represents the capacitance of the capacitor formed by the capacitor plates 40 including the membrane 30.

(29) The capacitance of the lines 301 and 302 is marked by C_K; the ohmic resistance of the measurement arrangement or of the monitoring means is marked by R_m; and their capacitance is marked by C_m.

(30) As can be seen from FIG. 5, an AC voltage is applied at the input side.

(31) A leak or the interposition of the test resistor results in a varied amplitude of the measured voltage and also in a higher voltage over the measurement resistor which can be determined by the mean value formation by the low pass in accordance with FIG. 5.

(32) This average voltage value is marked by Vm in FIG. 5.

(33) FIG. 6 shows in a schematic view in the image a) the membrane 30 which is surrounded like a sandwich by the two capacitor plates 40. No leak is present in the state a).

(34) If a leak occurs which relates to the capacitor plate 40 and to the membrane 30, as can be seen from FIG. 6 b), an increased current flows through the measurement resistor R_m, whereby the measured voltage increases.

(35) FIG. 7 shows the circuit in accordance with FIG. 5 once a leak L has occurred.

(36) The occurrence of a leak case is thus directly measurable in this manner so that corresponding countermeasures can be taken. The monitoring means can, for example, initiate the closing of one or more valves and/or the stopping of one or more pumps.

(37) A test of the arrangement in accordance with FIG. 5 can be carried out, for example, in that a higher sine amplitude produces a higher voltage value at the measurement resistor R_m.

(38) The security of the monitoring in accordance with the invention is ensured in that a correspondingly lower signal is measured on a release of the cables 301 or 302 or on an absence of the voltage supply.

(39) The monitoring of at least one physical or electrical parameter, which is preferably carried out continuously by the monitoring means, makes it possible to detect the variation of the measured variable, such as the impedance or the capacitance of the capacitor, directly in the event of a leak at the membrane or at the capacitor plates.

(40) A preferred embodiment of the invention comprises the fact that the capacitor which comprises at least two plates and at least one insulator in the form of a membrane arranged therebetween is located between the two spaces of the heat exchanger or recuperator. In this case, the capacitor separates the two fluid paths or the first space and the second space of the heat exchanger.

(41) The invention being thus described, it will be apparent that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be recognized by one skilled in the art are intended to be included within the scope of the following claims.