Breathing apparatus comprising a differential pressure sensor

Abstract

A method and apparatus for breathing including a blower mounted in a specific part made of silicone, which reduces blower immissions and emissions. The conducting structure influences the flow of the respiratory gas in order to reduce interference when measuring the volumetric flow.

Claims

1. A ventilator apparatus, comprising: at least one differential pressure measurement path; and a differential pressure sensor, wherein the differential pressure measurement path has a flow channel with at least two measurement openings that are arranged between an inflow opening and an outflow opening of the flow channel and are joined by measurement lines arranged in measurement nozzles, wherein a respiratory gas is guided from the inflow opening to the outflow opening through the flow channel in a principal flow direction, wherein a volumetric flow rate/differential pressure characteristic curve is realized by the differential pressure measurement path in conjunction with the differential pressure sensor, said characteristic curve lying between a linear curve a.Math.X.sup.1.0+b and a curve describable by a.Math.X.sup.1.5+b, wherein b is approximately equal to 0, wherein, in the principal flow direction of the respiratory gas through the flow channel, the flow channel is at least partly ring-shaped or is a ring segment, wherein the measurement nozzles are flanged onto the flow channel so that an alignment of the measurement lines, at least in a region of the measurement openings, has a component that is tangential to an outer delimiting face of the flow channel and/or to the principal flow direction of the respiratory gas in the flow channel, and wherein the alignment of one of the measurement lines, at least in the region of the measurement openings, lies in an angular range of 0° to 60° about an axis defined by a local tangent in a direction of an axis that is orthogonal to the local tangent and extends in a radial direction, wherein the flow channel is arranged in an adapter that connects the ventilator apparatus with a respiration tube, and wherein the flow channel is limited in a radial inward direction and a radial outward direction by a material of the adapter.

2. The apparatus according to claim 1, wherein, given the principal flow direction of a respiratory gas through the flow channel of the differential pressure measurement path, a static pressure and a dynamic, volume flow dependent negative pressure are present in the region of a first of the measurement openings and a static pressure and a dynamic, volume flow dependent positive pressure are present in the region of a second of the measurement openings.

3. The apparatus according to claim 1, wherein the alignment of the measurement lines, in the region of the measurement openings, is realized approximately counter to the principal flow direction for the first measurement opening and approximately in the direction of the principal flow direction for the second measurement opening.

4. The apparatus according to claim 1, wherein the apparatus is an emergency ventilator.

5. The apparatus according to claim 4, wherein the apparatus is a mobile emergency ventilator.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Various exemplary embodiments and configurations of the invention are imaged in the figures below. In detail:

(2) FIG. 1: shows a perspective illustration of a ventilator according to the invention,

(3) FIG. 2: shows a block diagram of a differential pressure measuring apparatus, according to the invention, of a ventilator,

(4) FIG. 3: shows a perspective illustration of a differential pressure measurement path embodied according to the invention, integrated into an adapter,

(5) FIG. 4: shows a plan view of a section through the adapter in the region of the differential pressure measurement path and

(6) FIG. 5: shows a typical characteristic curve for a volumetric flow rate measurement.

DETAILED DESCRIPTION OF THE INVENTION

(7) FIG. 1 shows a perspective illustration of a ventilator apparatus (A) according to the invention, comprising a pressure connector (B) for connection to an oxygen source, a connector for a ventilation tube (C), by means of which the respiratory gas is guidable to a ventilation mask, and a combined connector for an oxygen tube (D) and a measuring tube system (E), embodied as a pressure measuring tube and a PEEP control tube. Furthermore, the ventilator apparatus (A) comprises an accessories connector (F), a display (G), an operating element (H) embodied as a rotary knob and an air inlet (I) and air outlet (J).

(8) FIG. 2 illustrates a sectional block diagram of an embodiment of a ventilator apparatus (A) according to the invention. The section shown relates to the differential pressure measuring apparatus (100) of the ventilator apparatus (A) according to the invention. A respiratory gas at a volumetric flow rate (V) flows into a differential pressure measurement path (1) having a flow channel (4) via an inflow opening (3) and flows out of said flow channel via an outflow opening (5) at the end of the flow channel (4). The volumetric flow rate (V) produces local pressures in the differential pressure measurement path (1), which are applied by way of two measurement openings (6) at an assigned measurement output (8) via a measurement line (11) in each case. A differential pressure sensor (12), which captures the pressures and, moreover, digitizes these in the illustrated exemplary embodiment, is connected to the measurement outputs (8). The pressure measurement data are readable from the differential pressure sensor (12) with the aid of a microcontroller (14) via an interface (13), which is realized as an I2C interface. On the basis of the system parameters and with the aid of the microcontroller (14), the volumetric flow rate (V) of the respiratory gas is determinable, and usable for closed-loop control, from the digital pressure measurement data.

(9) FIG. 3 shows a perspective illustration of a section of an embodiment according to the invention of a differential pressure measurement path (1), which is integrated into an adapter (2). The differential pressure measurement path (1) has a circular segment-shaped inflow opening (3), through which a respiratory gas flows into the differential pressure measurement path (1) at a pressure and/or volumetric flow rate (V) that is regulated by the ventilator apparatus (A). The respiratory gas is guided away from the inflow opening (3) through a flow channel (4), which has a ring segment-like embodiment and a rectangular cross section. At its upper side, the flow channel (4) is delimited and sealed by a cover that is not illustrated here. At its other end, the flow channel (4) has an outflow opening (5), through which the respiratory gas escapes from the flow channel (4).

(10) In particular, a rectangular, square or circular cross section of the flow channel (4) is considered since the properties of the flow are known for channels with such an embodiment and the cross section is easy to calculate. However, other cross sections for a flow channel (4) for a differential pressure measurement path (1) of a ventilator apparatus (A) according to the invention are also conceivable.

(11) Two measurement openings (6) are arranged on the radially outer delimiting face of the flow channel (4). The measurement openings (6) are adjoined by pressure measurement nozzles (7), which are arranged with an essential tangential directional component in relation to the local principal flow direction of the respiratory gas. At the other end, the pressure measurement nozzles (7) each have a measurement output (8), to which a pressure measuring unit is couplable. Three fastening apparatuses (9) are arranged radially on the outside of the adapter (2) that integrates the differential pressure measurement path (1), said fastening apparatuses being embodied as a screw thread and serving for a secure attachment of the adapter (2) within the ventilator apparatus (A).

(12) Furthermore, a sprung positive pressure valve (10) is arranged in the region of the inflow opening (3) of the differential pressure measurement path (1), said positive pressure valve opening in the case of positive pressure in the respiratory gas line and reducing the pressure.

(13) FIG. 4 illustrates a section of the differential pressure measurement path (1). The flow channel (4) is delimited on the radial inner and outer side by the material of the adapter (2) in a ring segment-like contour. A particularly compact structure of the differential pressure measurement path (1) is realized by the ring-like embodiment of the flow channel (4). Moreover, the illustrated arrangement of the pressure measurement nozzles (7) or of the measurement lines (11) within the pressure measurement nozzles (7) is particularly advantageously realizable with an essential directional component tangential to the local principal flow direction (S) of the respiratory gas or to the local outer delimiting face of the flow channel (4) in the region of the measurement opening (6).

(14) A locally (in the region of the measurement opening) tangentially aligned axis (T) spans a plane with a locally radially aligned axis (R), in which plane the alignment (M) of a measurement line (11) lies in a range from 0° to 60° about the tangentially aligned axis (T).

(15) Within the flow channel (4) with the ring segment-like embodiment, the local principal flow direction (S) of the respiratory gas is substantially tangential to the circular form of the radially outer channel boundary. If the measurement lines (11) are arranged with an essential directional component (M) in this tangential direction T, at least in the region of the measurement openings (6), this, according to the invention, influences the volumetric flow rate/differential pressure characteristic of the differential pressure measurement path (1) in such a way that the volumetric flow rate/differential pressure characteristic of the differential pressure measuring apparatus approaches a linear characteristic from the direction of the known quadratic dependence of the characteristic.

(16) FIG. 5 shows a diagram with different volumetric flow rate/differential pressure characteristics, which each represent the system characteristic by way of the differential pressure measurement path and pressure sensors. In this illustration, a sought-after volumetric flow rate measurement range of 20 L/min STPD (standard temperature and pressure dry) is set and a maximum measurement range of 500 Pa is given by the employed differential pressure sensor.

(17) For an ideal resolvability, the differential pressure increases linearly (dP1). In this case, the differential pressures are already sufficiently high in the lower volumetric flow rate range in order to be well resolvable.

(18) In the case of a conventional differential pressure measurement path (simple stop or simple resistor), a behavior of the differential pressure proportional to the square of the volumetric flow rate (dP2) is typically exhibited. In this case, the differential pressure measurement values are very small in the lower volumetric flow rate range.

(19) The structure according to the invention described here facilitates, by way of a simple design, a characteristic (differential pressure versus volumetric flow rate) in which the differential pressure is approximately proportional to the 1.5-th power of the volumetric flow rate (dP1.5).

(20) A pressure measurement using a differential pressure measuring apparatus according to the invention exhibited a volumetric flow rate/differential pressure characteristic that was proportional to the 1.3-th power (dPA).