Humidifier for a system for providing a flow of breathable gas

Abstract

The present invention relates to a humidifier (10) for a system for providing a flow of breathable gas to an airway of a patient, wherein the humidifier (10) comprises: a casing (12) configured to contain a liquid reservoir (20); an air inlet (14) which is arranged at the casing (12); an air outlet (16) which is arranged at the casing (12); and a flow passage (18) connecting the air inlet (14) with the air outlet (16), wherein the flow passage (18) is in fluidic communication with the liquid reservoir (20), and wherein the humidifier (10) comprises a heat pipe (24) having a hot end (26) and a cold end (28), wherein the hot end (26) of the heat pipe (24) is arranged outside the casing (12) and the cold end (28) of the heat pipe (24) is arranged in the liquid reservoir (20).

Claims

1. A humidifier for a system for providing a flow of breathable gas to an airway of a patient, wherein the humidifier comprises: a casing configured to contain a liquid reservoir; an air inlet which is arranged at the casing; an air outlet which is arranged at the casing; and a flow passage connecting the air inlet with the air outlet, wherein the flow passage is in fluidic communication with the liquid reservoir; a heat pipe having a first end and a second end, wherein the first end of the heat pipe is arranged outside the casing and configured to be heated by an ambient environment relative to the humidifier and the second end of the heat pipe is arranged in the liquid reservoir.

2. The humidifier according to claim 1, wherein the first end of the heat pipe is arranged distanced from an exterior of the casing of the humidifier.

3. The humidifier according to claim 1, wherein a heat exchanger is arranged at the first end of the heat pipe.

4. The humidifier according to claim 3, wherein the heat exchanger comprises a cooling fin.

5. The humidifier according to claim 1, wherein the heat pipe contains a fluid pressurized at a first pressure, wherein the fluid is configured to evaporate at an evaporation temperature of 10 to 40° C. at the first pressure.

6. The humidifier according to claim 1, wherein the heat pipe is of a substantially tubular shape.

7. The humidifier according to claim 1, wherein parts of the first end and/or parts of the second end of the heat pipe are of a substantially U-shape.

8. The humidifier according to claim 1, wherein the first end of the heat pipe is positioned below the second end of the heat pipe.

9. The humidifier according to claim 1, wherein a cross-section of the heat pipe is substantially U-shaped.

10. A system for providing a flow of breathable gas to an airway of a patient, comprising a humidifier according to claim 1.

11. The system according to claim 10, further comprising: a pressure generator; a patient interface; and a hose assembly connecting the pressure generator to the patient interface.

12. The system according to claim 11, further comprising a housing which is configured to contain the pressure generator and the humidifier.

13. The system according to claim 11, wherein the humidifier is arranged in a flow path between the pressure generator and the patient interface.

14. The system according to claim 10, further comprising an exhaust air outlet, wherein the first end of the heat pipe is arranged at or in the vicinity of the exhaust air outlet.

15. The system according to claim 14, further comprising a fan or blower configured to direct a convective flow of exhaust air exiting the exhaust air outlet to the first end of the heat pipe.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. In the following drawings

(2) FIG. 1 shows a first embodiment of the humidifier according to the present invention;

(3) FIG. 2 shows a second embodiment of the humidifier according to the present invention;

(4) FIG. 3 shows a third embodiment of the humidifier according to the present invention;

(5) FIG. 4 shows a first embodiment of the system according to the present invention; and

(6) FIG. 5 shows a second embodiment of the system according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(7) FIG. 1 shows a first embodiment of the humidifier for a system for providing a flow of breathable gas to an airway of a patient. The humidifier is therein in its entirety denoted by reference numeral 10.

(8) The humidifier 10 comprises a casing 12 with an air inlet 14 arranged at the left sidewall of the casing 12 and an air outlet 16 arranged at the right sidewall of the casing 12 (regarding a plane view perspective). The air inlet 14 and the air outlet 16 are connected via a flow passage 18, which is located inside the casing 12 and which is in fluidic communication with a liquid reservoir 20.

(9) In FIG. 1, this fluidic communication mainly takes place at a boundary surface 22 between the flow passage 18 and the liquid reservoir 20 and thus, directly on or slightly above the surface 22 of the liquid reservoir 20.

(10) The liquid reservoir 20 may e.g. contain water as a liquid. A flow of breathable gas, in this case air, may enter the humidifier 10 through the air inlet 14, accumulate evaporating water from the liquid reservoir 20, and leave the casing 12 through the air outlet 16 at a higher humidity level.

(11) Due to evaporation, the liquid inside the liquid reservoir 20 cools down. In order to prevent a too severe temperature drop of the water, a heat pipe 24 having a hot end 26 and a cold end 28 is arranged at the humidifier 10 in such a manner that the cold end 28 of the heat pipe 24 is arranged inside the liquid reservoir 20 and the hot end 26 of the heat pipe 24 is arranged outside the casing 12.

(12) In FIG. 1, the heat pipe 24 is of a substantially tubular shape and furthermore shows a U-shaped design, where the hot end 26 is located between the cold end 28 of the heat pipe 24. The hot end 26 of the heat pipe 24 is positioned below the cold end 28 of the heat pipe 24. Such a location of the hot end 26 enhances the reflux of the pressurized fluid inside the heat pipe 24 by gravity.

(13) The heat pipe 24 contains a fluid pressurized at a first pressure p1, wherein the fluid evaporates at an evaporation temperature T1 at the hot end 26 of the heat pipe 24 and flows in the vaporized state along a first flow direction 30 to the cold end 28 of the heat pipe 24, where condensation of the pressurized fluid takes place. The condensing fluid passes its heat through the walls of the heat pipe 24 to the surrounding water of the liquid reservoir 20 and flows back along a second flow direction 32 where the pressurized fluid evaporates again.

(14) The circulation of the pressurized fluid inside the heat pipe 24 is enabled as a certain amount of heat is collected from the surrounding of the hot end 26 of the heat pipe 24 in its location outside the casing 12.

(15) In FIG. 2, the heat pipe 24 shows, different from the heat pipe 24 in FIG. 1, a plate-like, U-shaped design of the hot end 26 and the cold end 28. With such a shape, the surface area of the heat pipe 24 is increased, which increases the rate of heat transfer at the cold end 28 of the heat pipe 24 as well as at the hot end 26 of the heat pipe 24. The functionality of the humidifier 10 shown in FIG. 2 is similar to FIG. 1.

(16) FIG. 3 shows a third embodiment of the humidifier 10 according to the present invention. In this embodiment, the hot end 26 of the heat pipe 24 protrudes in a rectangular angle from the casing 12 of the humidifier 10, wherein the heat pipe 24 shows a substantially tubular shape. Additionally, at the end of the hot end 26 of the heat pipe 24 a heat exchanger 34 is arranged in form of fins 36, which are in thermal contact with the surface of the hot end 26 of the heat pipe 24. It is clear that the angle between the hot end 26 of the heat pipe 24 and the casing 12 does not necessarily have to be a right angle. It is however preferred that the hot end 26 protrudes from the casing 12 such that at least parts of the hot end 26 are arranged distanced from the casing 12 and are exposed to the ambient environment. The hot end 26 of the heat pipe 24 is positioned below the cold end 28 of the heat pipe 24.

(17) FIG. 4 shows a first embodiment of a system 100 for providing a flow of breathable gas to an airway of a patient, wherein the system 100 comprises a humidifier 10 according to the present invention.

(18) In this embodiment, the humidifier 10 is located inside a housing 38 together with a pressure generator 40 which is driven by a motor 42. The pressure generator 40 is connected airtight to the air inlet 14 of the humidifier 10 via parts of a hose assembly 44. The air outlet 16 of the humidifier 10 is connected via parts of the hose assembly 44 with a patient interface 46, configured to deliver breathable gas to the airway of the patient via the nose and/or mouth.

(19) The pressure generator 40 intakes breathable gas through an inlet 48 (i.e. from the surrounding) and pressurizes the intake gas via the driving force of the motor 24. The pressurized air flows through the humidifier accumulating water from the liquid reservoir 20.

(20) The humidified flow of breathable gas exits the humidifier 10 through the air outlet 16 flowing through the hose assembly 44 into the patient interface 46 delivering the patient's airway with the flow of breathable, humidified gas.

(21) In FIG. 4, the motor 42 for running the pressure generator 40 produces exhaust air with a higher temperature compared to the surrounding outside the housing 38, wherein the exhaust air exits the housing 38 through an exhaust air outlet 50. The exhaust air outlet 50 is, in this case, located at the bottom part of the back wall of the housing 38. The hot end 26 of the heat pipe 24 is exposed to the space inside the housing 38 outside the casing 12 of the humidifier 10. In this arrangement, the hot end 26 of the heat pipe 24 can collect heat from the exhaust air produced by the motor 42. Due to this hot exhaust air, heat intake at the hot end 26 of the heat pipe 24 is increased, which increases in turn the evaporation rate of the pressurized fluid inside the heat pipe 24 and thus the amount of heat which can be transferred through the walls of the heat pipe 24 to the surrounding liquid of the liquid reservoir 20.

(22) FIG. 5 shows an embodiment of the device 100, where the humidifier 10 is located outside the housing 38. The pressure generator 14 is connected to the humidifier 10 via parts of the hose assembly 44. In this embodiment, the hot end 26 of the heat pipe 24 is located on the upper side of the casing 12 of the humidifier 10 and shows a plate-like shape. In further embodiments, the hot end 26 of the heat pipe 24 could also be located below the casing 12, depending on the location of the exhaust air outlet 50 of the pressure generator 40 and the relative position of the humidifier 10 to the pressure generator 40. In this arrangement, a fan 52 is arranged in the flow direction of the exhaust air outlet 50 forcing the flow of exhaust air to penetrate the surface of the hot end 26 of the heat pipe 24 to increase the heat transfer to the liquid reservoir 20 inside the humidifier 10. It is clear that such a fan 52 could similarly be used in an arrangement as shown in FIG. 4, where the humidifier 10 is arranged together with the pressure generator 40 inside the housing 38. It should also be mentioned that the embodiment shown in FIG. 5 would also work without the additional fan 52, i.e. in case where the hot end 26 of the heat pipe 24 is located near the exhaust air outlet 50 of the pressure generator 40.

(23) While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

(24) In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

(25) Any reference signs in the claims should not be construed as limiting the scope.