WO2011006535A1

WO2011006535A1 - Safety valve and method for controlling flow through a conduit

Info

Publication number: WO2011006535A1
Application number: PCT/EP2009/059001
Authority: WO
Inventors: Ulrich Wernicke; Thomas Faulhaber
Original assignee: Fresenius Medical Care Deutschland Gmbh
Priority date: 2009-07-14
Filing date: 2009-07-14
Publication date: 2011-01-20

Abstract

The invention relates to a safety valve and method for controlling flow through a conduit, especially for use in dialysis. The safety valve comprises a housing having a chamber disposed therein, a slide at least partially disposed within the chamber, wherein the slide is movable between a first position in which the slide allows flow through a conduit and a second position in which the slide blocks flow through the conduit, a spring for forcing the slide to move from the first position into the second position, an electromagnet for holding the slide in the first position against the force of the spring when the electromagnet is energized, and a port for admitting pressurized fluid into the chamber wherein the pressurized fluid forces the slide to move from the second position into the first position against the force of the spring and for depressurizing the chamber when the slide is substantially in the first position. In case of loss of power, the electromagnet releases the slide which is then forced by the spring to move into the second position so that the slide blocks flow through the conduit.

Description

SAFETY VALVE AND METHOD FOR CONTROLLING FLOW THROUGH A CONDUIT

Field of the Invention

[0001] This invention pertains generally to safety valves, and more particularly to safety valves used in systems for performing dialysis.

Background of the Invention

[0002] In automated dialysis, it is of paramount importance that the dialysis systems used are fail-safe, particularly if the dialysis is performed at night while the patient is asleep. This involves the provision of safety valves which quickly and reliably block flow of fluids to and from the patient in case of a failure.

[0003] Many such safety valves are known in the prior art, each of which, however, has advantages and disadvantages.

[0004] Hence, there remains a need in the art for other, highly reliable safety valves, particularly for such safety valves which can handle cases of loss of power.

Brief Summary of the Invention

[0005] The present invention provides a safety valve comprising a housing having a chamber disposed therein, a slide at least partially disposed within the chamber, wherein the slide is movable between a first position in which the slide allows flow through a conduit and a second position in which the slide blocks flow through the conduit, a spring for forcing the slide to move from the first position into the second position, an electromagnet for holding the slide in the first position against the force of the spring when the electromagnet is energized, and a port for admitting pressurized fluid into the chamber, wherein the pressurized fluid forces the slide to move from the second position into the first position against the force of the spring, and for depressurizing the chamber when the slide is substantially in the first position.

[0006] According to some embodiments of the present invention, a safety valve further comprises a second port or a vent for depressurizing the chamber when the slide is substantially in the first position. [0007] In some embodiments of the present invention, a safety valve further comprises a control unit for controlling the admittance of pressurized fluid through the port into the chamber.

[0008] Furthermore, the present invention provides a method for controlling flow through a conduit. The method comprises the step of providing a safety valve comprising a housing having a chamber disposed therein, a slide at least partially disposed within the chamber, wherein the slide is movable between a first position in which the slide allows flow through a conduit and a second position in which the slide blocks flow through the conduit, a spring for forcing the slide to move from the first position into the second position, a port for admitting pressurized fluid into the chamber, and an electromagnet for holding the slide in the first position against the force of the spring when the electromagnet is energized. Further the method comprises the steps of energizing the electromagnet, introducing pressurized fluid through the port into the chamber wherein the pressurized fluid forces the slide to move from the second position into the first position against the force of the spring, and depressurizing the chamber when the slide is substantially in the first position. [0009] According to some embodiments of the present invention, a method for controlling flow through a conduit further comprises the step of ceasing the introducing of pressurized fluid through the port into the chamber when the slide is substantially in the first position.

[0010] Embodiments of the present invention are preferably used in dialysis, particularly in peritoneal dialysis. [0011] Preferably, a safety valve according to the present invention is part of a system for performing dialysis, particularly a system for performing peritoneal dialysis.

[0012] Other features and advantages of the present invention are set forth in the following specification and attached drawings.

Brief Description of the Figures

[0013] FIG. 1 shows a perspective view of a safety valve according to an embodiment of the present invention, wherein the safety valve is built into a system for performing dialysis.

[0014] FIG. 2A shows a side view of the single safety valve of FIG. 1 , wherein the slide is in the first position. [0015] FIG. 2B shows a side cross-sectional view of the safety valve of FIG. 2A in the direction of view arrows A - A of FIG. 2A.

[0016] FIG. 3A shows a side view of the single safety valve of FIG. 1 , wherein the slide is in the second position. [0017] FIG. 3B shows a side cross-sectional view of the safety valve of FIG. 3A in the direction of view arrows A - A of FIG. 3A.

[0018] FIG. 4 shows a bottom view of the single safety valve of FIG. 1.

Detailed Description [0019] The present invention and its advantages are further illustrated in the following, non- limiting examples. In the drawings, like reference numbers generally refer to the same parts throughout the different views.

[0020] FIG. 1 shows a safety valve 1 according to an embodiment of the present invention, wherein the safety valve 1 is built into a system for performing dialysis, which is depicted only partially in FIG. 1. Systems for performing dialysis are called cyclers and are well known in the art.

[0021] Referring to FIGS. 2A and 2B, the single safety valve 1 of FIG. 1 is shown. FIG. 2A is a side view of the safety valve 1 and FIG. 2B is a side cross-sectional view in the direction of view arrows A - A of FIG. 2A. The safety valve 1 comprises a housing 2 having a chamber 3 disposed therein. A slide 4 having a shaft 41 and a top end 42 is partially disposed within the chamber 3. The shaft 41 of the slide 4 protrudes from the housing 2 through an aperture 21. The aperture 21 comprises a shoulder 22 for receiving gaskets 23 which seal the chamber 3. The gaskets 23 are held in place by holding-down element 24. The top end 42 of the slide 4 is formed as a flange around which gasket 43 is received, thereby dividing the chamber 3 into an area below the top end 42 of the slide 4 and an area above the slide 4 which are sealed from one another. [0022] The slide 4 is moveable between a first position, shown in FIGS. 2 A and 2 B, and a second position, shown in FIGS. 3A and 3B. FIGS. 3A and 3B differ from FIGS. 2A and 2B only in the position of slide 4. In the second position, the slide 4 protrudes further from the housing 2 than in the first position and is used to block flow through a conduit. Thus, when the slide 4 is in the second position, the safety valve 1 is closed while it is open when the slide 4 is in the first position. [0023] As best seen in FIG. 3B, on its top face, the slide 4 comprises a plate 44 made of a paramagnetic or ferromagnetic material so that the slide 4 is attracted magnetically and held by an electromagnet 5 when the slide 4 is in the first position and when the electromagnet 5 is energized. Otherwise, a coil spring 6 forces the slide 4 into the second position. [0024] For opening the safety valve 1 , the electromagnet 5 is energized. However, the magnetic attraction of the electromagnet 5 is not sufficient for moving the slide 4 from the second position into the first position against the force of the spring 6. Therefore, the housing 2 comprises a port 7 for introducing a pressurized fluid into the chamber 3. The pressurized fluid flows through the port 7 into the area of the chamber 3 below the top end 42 of the slide 4 and pushes the slide 4 towards the electromagnet 5. When the slide 4 is substantially in the first position, the magnetic attraction of the electromagnet 5 is sufficient to hold the slide 4 in the first position against the force of the spring 6 so that the introducing of pressurized fluid through the port 7 into the chamber 3 can be stopped, for example by closing the port 7, and the chamber 3 can be depressurized. The depressurization of the chamber 3 is done by means of a second port 8 or vent. For example, the port 8 may be in fluid communication with an aperture (not shown) in the chamber 3, wherein the aperture is only unblocked when the slide 4 is substantially in the first position. Alternatively, the port 7 may also be used for depressurizing the chamber 3. For example, the port 7 may be switchable between a supply of pressurized fluid and a drain having a pressure lower than the pressurized fluid or simply an opening, which is in fluid communication with the environment. After depressurizing the chamber 3, the slide 4 is held in its first position only by the energized electromagnet 5.

[0025] In case of loss of power, the electromagnet 5 is not energized anymore, and thus releases the slide 4 which is then forced by the spring 6 into the second position, thereby closing the safety valve 1 and blocking flow through a conduit. Hence, the safety valve 1 is fail-safe. [0026] For closing the safety valve 1 during regular operation, the energization of the electromagnet 5 is stopped.

[0027] According to some embodiments of the present invention, the safety valve 1 comprises a control unit (not shown) for controlling the admittance of pressurized fluid through the port 7 into the chamber 3. The control unit ceases the introducing of pressurized fluid through the port 7 into the chamber 3 when the slide 4 is substantially in the first position, for example, by closing a valve which controls the supply of pressurized fluid. For this, the control unit preferably detects when the slide 4 is substantially in the first position. This may be done, for example, by measuring the period of time since the introducing of pressurized fluid was started or by measuring a reverse current induced in the coil of the electromagnet 5 when the slide 4 is substantially in the first position, and thus the magnetic circuit between the plate 44 and the electromagnet 5 is closed.

[0028] As set forth above, the shaft 41 of the slide 4 blocks flow through a conduit when the slide 4 is in the second position. This may be achieved, for example, by inserting the shaft 41 into a bore in the conduit, wherein the axis of the bore is substantially perpendicular to the longitudinal axis of the conduit. Many variations of this approach are known in the art.

[0029] Preferably, the conduit is a flexible tube 10, as shown in FIG. 1 , and the slide 4 squeezes closed the flexible tube 10 when the slide is in the second position. For this, the force of the spring 6 has to be accurately determined such that the flexible tube is squeezed tightly closed, but not damaged.

[0030] As best seen in FIG. 4, which shows a bottom view of the safety valve 1 , the slide 4 comprises a front face having an elongated projection 45 for squeezing closed the flexible tube. The elongated projection 45 is preferably aligned perpendicular to the longitudinal axis of the tube.

[0031] For preventing the slide 4, and thus the elongated projection 45 from being rotated, the safety valve 1 comprises a locking device. The locking device comprises a protrusion 9 at the housing 2 engaging a lateral groove 46 of the slide 4.

[0032] It will be apparent to those of skill in the art that many modifications and variations of the embodiments described herein are possible without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A safety valve com prisi ng :

a housing having a chamber disposed therein;

a slide at least partially disposed within the chamber, the slide being movable between a first position in which the slide allows flow through a conduit and a second position in which the slide blocks flow through the conduit;

a spring for forcing the slide to move from the first position into the second position;

an electromagnet for holding the slide in the first position against the force of the spring when the electromagnet is energized; and

a port for admitting pressurized fluid into the chamber wherein the pressurized fluid forces the slide to move from the second position into the first position against the force of the spring and for depressurizing the chamber when the slide is substantially in the first position.

2. The safety valve of claim 1 further comprising a second port for depressurizing the chamber when the slide is substantially in the first position.

3. The safety valve of claim 1 or 2 wherein the conduit is a flexible tube.

4. The safety valve of claim 3 wherein when the slide is in the second position, the slide squeezes closed the flexible tube.

5. The safety valve of claim 4 wherein the slide comprises a front face having an elongated projection for squeezing closed the flexible tube.

6. The safety valve of claim 5 further comprising a locking device for preventing rotation of the slide.

7. The safety valve of claim 6 wherein the locking device comprises a protrusion at the housing engaging a lateral groove of the slide.

8. The safety valve of any preceding claim further comprising a control unit for controlling the admittance of pressurized fluid through the port into the chamber.

9. The safety valve of claim 8 wherein when the slide is substantially in the first position, the control unit ceases the introducing of pressurized fluid through the port into the chamber.

10. A method for controlling flow through a conduit, the method comprising the steps of:

providing a safety valve comprising

a housing having a chamber disposed therein,

a slide at least partially disposed within the chamber, the slide being movable between a first position in which the slide allows flow through a conduit and a second position in which the slide blocks flow through the conduit,

a spring for forcing the slide to move from the first position into the second position, a port for admitting pressurized fluid into the chamber, and

an electromagnet for holding the slide in the first position against the force of the spring when the electromagnet is energized;

energizing the electromagnet;

introducing pressurized fluid through the port into the chamber wherein the pressurized fluid forces the slide to move from the second position into the first position against the force of the spring; and

depressurizing the chamber when the slide is substantially in the first position.

11. The method of the preceding claim further comprising the step of ceasing the introducing of pressurized fluid through the port into the chamber when the slide is substantially in the first position.

12. A system for performing dialysis comprising a safety valve according to any of claims 1 to 9.

13. The system of the preceding claim wherein the system is for performing peritoneal dialysis.

14. A use of a safety valve according to any of claims 1 to 9 in dialysis.

15. A use of a method according to any of claims 10 to 11 in dialysis.

16. The use according to any of claims 14 to 15 wherein the dialysis is peritoneal dialysis.