MEASURING APPARATUS

Abstract

A measuring device for determining the CO.sub.2 content in the exhaled air of a living being, for example, a person or a mammal. The device may have a measuring tube defined by a wall, said measuring tube having an air inlet and an air outlet, with an inlet and an air outlet, with a CO.sub.2 measuring device having a sensor pot which is in fluid communication with the measuring tube. The sensor pot extends through the wall of the measuring tube into the interior of the measuring tube, wherein the diameter of the measuring tube is reduced in the region of the sensor pot. The sensor pot is substantially open towards the measuring tube, such that the sensor pot is configured for direct measurement of the CO.sub.2 content of air exhaled through the measuring tube, past the sensor pot.

Claims

1. A measuring apparatus for determining the CO.sub.2 content in the exhaled air of a living being including at least one of a person or a mammal, the apparatus comprising: a housing defining an air inlet opening and an air outlet opening; a wall disposed within the housing and defining a measuring space, wherein the measuring space is in communication with the air inlet opening and the air outlet opening, a CO.sub.2-measuring device which is in fluidic communication with the measuring space, the CO.sub.2-measuring device including a sensor pot; wherein the sensor pot extends at least in part into the measuring space; the sensor pot extends through the wall of the measuring space into the interior of the measuring space, wherein the diameter of the measuring space is reduced in the region of the measuring pot, the sensor pot is configured so as to be substantially open towards the measuring space, and the CO.sub.2-measuring device is arranged in the sensor pot and is configured to measure the CO.sub.2 content of the air in the sensor pot directly.

2. The measuring apparatus according to claim 1, wherein the measuring space has a constant diameter over its entire length from the air inlet opening to the air outlet opening, which diameter is reduced in one region by the sensor pot.

3. The measuring apparatus according to claim 1, wherein the ratio of a volume of the measuring space, disregarding the sensor pot, to a volume of the sensor pot is in the range of from 7:1 to 13:1.

4. The measuring apparatus according to claim 1, wherein the air inlet opening and the air outlet form opposite ends of the measuring space, and their prolongation forms a straight virtual measuring tube.

5. The measuring apparatus according to claim 4, wherein the sensor pot is arranged substantially perpendicular to a longitudinal axis of the virtual measuring tube.

6. The measuring apparatus according to claim 1, wherein an infrared-based sensor is provided in the CO.sub.2-measuring device.

7. The measuring apparatus according to claim 1, wherein the CO.sub.2-measuring device is configured to carry out a continuous measurement.

8. The measuring apparatus according to claim 1, wherein the interior of the measuring space is configured such that air, apart from the sensor pot, is able to flow from the air inlet opening to the air outlet opening substantially without turbulence.

9. The measuring apparatus according to claim 1, wherein the measuring space has a U-shaped cross section.

10. A method for determining the CO.sub.2 content in the exhaled air of a living being, having a measuring apparatus according to claim 1, wherein the living being exhales into the air inlet opening through the measuring space multiple times.

11. The method according to claim 10, wherein the CO.sub.2-measuring device carries out a continuous measurement of the CO.sub.2 content.

12. The method according to claim 10, wherein at least 7 maximum values determined by the CO.sub.2-measuring device are stored.

13. The method according to claim 10, wherein at least the two lowest maximum values of a plurality of maximum values are disregarded in the final evaluation.

14. The method according to any claim 10, wherein there is outputted as the output value a mean, in particular an arithmetic mean, of a plurality of maximum values.

15. The method according to claim 10, wherein the measured values determined by the CO.sub.2-measuring device are provided with a correction factor.

16. A method of determining a CO.sub.2 content in a quantity of exhaled air of at least one of a person or a mammal, the method including: providing a housing defining an air inlet opening and an air outlet opening axially aligned with the air inlet opening, with a non-straight wall disposed within the housing defining a measuring space between the air inlet opening and the air outlet opening, the measuring space forming a straight virtual measuring tube; using a CO.sub.2-measuring device having a sensor pot, and arranged partially within the measuring space and in fluidic communication with the measuring space, to receive exhaled air from the at least one of a person or mammal as the exhaled air flows initially through the inlet opening, then through the measuring space, and then out through the outlet opening; and using the sensor pot of the CO.sub.2-measuring device to measure the CO.sub.2 content of the exhaled air within the measuring space.

17. The method according to claim 16, wherein: the CO.sub.2-measuring device carries out a continuous measurement of the CO.sub.2 content; and at least 7 maximum values determined by the CO.sub.2-measuring device are stored.

18. The method according to claim 17, wherein at least the two lowest maximum values of a plurality of maximum values are disregarded in the final evaluation.

19. The method according to any claim 18, further comprising outputting as an output value an arithmetic mean of a plurality of the maximum values.

20. The method according to claim 19, further comprising providing a correction factor for the measured values determined by the CO.sub.2-measuring device.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0032] The invention will be explained in detail hereinbelow with reference to an exemplary embodiment and schematic drawings, in which show:

[0033] FIG. 1 a side view of a measuring apparatus according to the invention;

[0034] FIG. 2 a side view of the measuring apparatus according to the invention with some of the sides removed;

[0035] FIGS. 3 and 4 two perspective side views of the measuring apparatus according to the invention; and

[0036] FIG. 5 the measuring apparatus according to the invention of FIG. 4 with some of the sides removed.

DETAILED DESCRIPTION

[0037] A measuring apparatus 10 according to the invention will be explained in detail hereinbelow on the basis of the figures. FIG. 1 shows a side view of a measuring apparatus 10 according to the invention. FIG. 2 shows the same view of the measuring apparatus 10 according to the invention, wherein three side walls have been removed so that the interior is visible. FIGS. 3 and 4 are each views, slightly in perspective, from different sides of the measuring apparatus 10 according to the invention. Finally, FIG. 5 shows the measuring apparatus 10 according to FIG. 4, wherein three sides have again been removed so that part of the interior of the measuring apparatus 10 is visible.

[0038] The measuring apparatus 10 shown here has a substantially cuboidal housing. However, the invention is not limited to this shape of housing. An air inlet opening 31 and an air outlet opening 32 are further provided. During use of the measuring apparatus 10, exhalation is carried out through the air inlet opening 31 through a measuring space, which is also referred to as a measuring chamber 20. In principle, the air inlet opening 31 and the air outlet opening 32 can also be inverted.

[0039] The measuring chamber 20 is shown in particular in FIGS. 4 and 5. It is formed by a U-shaped wall 21 and a portion of the outer wall 22. As is apparent from FIGS. 1, 3 and 4, the air inlet opening 31 and the air outlet opening 32, which in this embodiment are formed circular, lead to the measuring space 20. Other opening cross sections are possible, however. The openings, as is apparent in particular from FIG. 1, are preferably formed exactly opposite one another, so that their prolongation forms a virtual measuring tube.

[0040] A CO.sub.2-measuring device 40 extends into the measuring space 20. Said device has a sensor pot 41, which protrudes into the measuring space 20. In the sensor pot 41 there is a CO.sub.2-measuring device 40, which measures the CO.sub.2 in the sensor pot 41 by means of infrared measurement, for example. The sensor pot is preferably equidistant from the air inlet opening 31 and the air outlet opening 32 and is located in the middle between them.

[0041] The sensor pot 41 is in fluidic communication with the measuring space 20. It can simply be designed openly. However, it is preferred if it has a filter or a membrane so as to prevent contamination of the interior of the sensor pot 41. It is important here that said filter or membrane has good air permeability.

[0042] As is apparent in particular from FIG. 1, the sensor pot 41 of the CO.sub.2-measuring device 40 protrudes into a virtual tube which is formed between the air inlet opening 31 and the air outlet opening 32.

[0043] According to the invention, it has been recognized that, on exhalation through the air inlet opening 31, a relatively constant pressure is established within the sensor pot 41, so that the measurement present there unexpectedly has a very high accuracy.