GB2454446A - Device for allowing a bypass flow of respiratory gas - Google Patents

Abstract

A device for allowing a bypass flow of respiratory gas in which constant conditions governing flow are set for the emerging respiratory gas. In an annular connecting member (6) is provided between an outer part (2) and an inner part (4), an outflow gap (7) being formed between the connecting member (6) and the outer part (2).

Description

Device for allowing a bypass flow of respiratory gas The Invention relates to a device for allowing a bypass flow of respiratory gas.

A device of the kind mentioned is known from DE 198 40 760 Al. Devices of this kind are used in conjunction with what are termed CPAP (Continuous positive airway pressure) ventilators, which are used to set for the patient a constant airway pressure which assists the spontaneous breathing process, e.g. in connection with the treatment of sleep apnoea.

The known device comprises an outer part and an inner part which can be turned relative to one another and which can be plugged together by means of a latching connection. The outside diameter of the inner part and the inside diameter of the outer part are sized in such a way that an annular gap is formed through which the respiratory gas can flow out from the interior into the surroundings. The two free ends of the known device are connected at one side to a respiratory mask and at the other side to a respiratory hose, in which case any torques which may possibly be exerted on the respiratory hose can be largely relieved by virtue of the rotatability of the inner part relative to the outer part.

The diameters of the outer part and the inner part which define the size of the annular gap must be accurately matched to one another so that, on the one hand, a sufficiently high pressure can be generated in the respiratory hose and, on the other hand, flow-related noises caused by the respiratory gas as it flows out of the annular gap are reduced. Because of manufacturing tolerances, the width of the annular gap varies and it is also impossible to slop the inner part from leaning against the outer part on one side, as a result of which the annular gap becomes asymmetrical, which has a disadvantageous effect on the conditions governing pressure and on the noises caused by flow.

The present invention is as claimed in the claims.

The present invention provides an improved device of the kind mentioned in which constant flow conditions are set for the respiratory gas emerging from the annular gap.

Advantageous embodiments of the invention can be seen from the dependent claims.

The advantage of the device according to the invention lies in the fact that there is provided in addition an annular connecting member which on the one hand forms a constant outflow gap in conjunction with the outer part and on the other has a receiving sleeve for the inner part. Because the inner part is fastened in place by means of the receiving sleeve, the rotary movement of the inner part is decoupled from the outer part.

Due to the connecting member, no reactive effects occur when the inner part is moved relative to the outer part and the geometry of the outflow gap remains unchanged.

The external outline of the connecting member may be so configured in relation to the internal outline of the outer part that the conditions governing flow which arise are optimum while the smallest possible amount of noise is generated. The length and width of the outflow gap may be sized in this case in such a way that acceptable figures for flow are obtained.

A repeatable width can advantageously be obtained for the outflow gap by means of spacer elements which are located on the circumference of the connecting member.

In addition to the receiving sleeve, the connecting member also has an abutment for the sliding surface of the inner part.

It is particularly advantageous for the connecting member to be fixed in place in such a way as to be locked against rotation relative to the outer part by giving the spacer elements latching lugs which latch into groove-like depressions in the outer part. The way in which the locking against rotation can be achieved in this case is for the spacer elements to be slid into associated grooves in the outer part, which produces a preferred position for the connecting member relative to the outer part. As an alternative however, the possibility also exists of the locking against rotation being achieved solely by the retention of the latching lugs in the groove-like depressions by friction. A further possible way of providing the locking against rotation is for the connecting member to be adhesive-bonded or welded to the outer part.

An improvement in the centring of the inner part relative to the outer part is obtained by means of a guiding portion which is connected to the inner part and which is inserted in a contacting surface in the outer part which is produced to correspond to it. The guiding portion is connected to the sliding surface of the inner part by means of the struts. The guiding portion in conjunction with the contacting surface, and the sliding surface in conjunction with the abutment, together form an axial guiding means for the inner part relative to the outer part.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, of which: Fig. 1 is a schematic side view of a device according to the invention for allowing a bypass flow of respiratory gas, Fig. 2 is a schematic view of the device shown in Fig. 1 in longitudinal section, Fig. 3 is a schematic side view of an outer part, Fig. 4 is a schematic side view of the outer part shown in Fig. 3 in longitudinal section, Fig. 5 is a schematic detail of A as indicated in Fig. 4, Fig. 6 is a schematic side view of an inner part, Fig. 7 is a schematic side view of the inner part shown in Fig. 6 in longitudinal section, Fig. 8 is a schematic side view of a connecting member, Fig. 9 is a schematic side view of the connecting member shown in Fig. 8 in longitudinal section.

Fig. 1 is a schematic view from the side of a device according to the invention for allowing a bypass flow of respiratory gas, comprising an outer part 2 having a mask connection 3 and an inner part 4 having a hose connection 5.

Fig. 2 shows the device 1 shown in Fig. 1 in longitudinal section. The same components are given the same reference numerals as in Fig. 1. The inner part 4 is rotatably fastened in place within the outer part 2 by means of a connecting member 6. An annular outflow gap 7 for respiratory gas is formed between the connecting member 6 and the outer part 2.

The inner part 4 has a cylindrical sliding surface 8 which is situated within a receiving sleeve 9 which is configured to correspond thereto and which has an abutment 10.

Connected to the sliding surface 8 by means of struts 11 is a disc-like guiding portion 1 2 which rests against a contacting surface 13 in the outer part 2. The contacting surface 1 3 and the abutment 1 0 limit the axial play of the inner part 4 relative to the outer part 2.

Fig. 3 is a view of the outer part 3 from the side. The mask connection 3 is so designed that it comprises a 22 mm outer cone and a 1 5 mm inner cone arranged within the latter, as can be seen from Fig. 4. Fig. 4 is a longitudinal section through the outer part 2. The mask connection 3, which has an outside diameter of 22 mm, widens out, via a step, into an outflow section 14 having an outside diameter of 36 mm. In its inside face 1 5, the outflow section 1 4 has axially extending grooves 16 which are provided, close to the front end 1 7, with grooves 18 for latched engagement.

Shown enlarged in Fig. 5 is detail A of Fig. 4, which is situated in the region of the groove 16 and the groove 1 8 for latched engagement.

Fig. 6 is a view from the side of the inner part 4. In Fig. 7, the inner part 4 is shown in longitudinal section. The sliding face 8 has a shoulder 1 9 against which the abutment on the connecting member 6 rests.

Fig. 8 is a view from the side of the connecting member 6. Located on the outside 20 of the connecting member 6 are axially extending bar-like spacer elements 21 which are configured to correspond to the grooves 16 in the outer part 2 (Fig. 4) and which have latching lugs 22 directed towards the end face 1 7.

Fig. 9 shows the connecting member 6 shown in Fig. 8 in longitudinal section. Situated in the region of the abutment 10, there is an aperture for the insertion of the inner part 2.

To assemble the device according to the invention, the inner part 4 is first inserted in the connecting member 6 in such a way that the sliding surface 8 is situated inside the receiving sleeve 9 and the abutment 10 is butting against the shoulder 19. The inner part 4, together with the connecting member 6, is then inserted in the outer part 2 in such a way that the spacer elements 21 are situated in the grooves 16. Once the latching lugs 22 have snapped into the grooves 18 for latching engagement, the inner part 4 is non-releasably connected to the outer part 2 and the outflow gap 7 is formed between the connecting member 6 and the outer part 2.

Claims (7)

1. A device for allowing a bypass flow of respiratory gas having: an outer part, an inner part which has a cylindrical sliding surface and an annular connecting member, the annular connecting member having an internal receiving sleeve which is configured to correspond to the cylindrical sliding surface of the inner part and having an abutment to fix the inner part in place, an outflow gap being formed between the connecting member and the outer part.

2. The device according to claim 1, in which the outflow gap is formed between the connecting member and the outer part by spacer elements.

3. The device according to claim 2, in which the spacer elements are so configured that the connecting member is fixed in place relative to the outer part in such a way as to be locked against rotation.

4. The device according to claim 2 or 3, in which the spacer elements have latching lugs which can be connected to the outer part.

5. The device according to one of claims 1 to 4, in which the inner part has a guiding portion which is connected to the region of the sliding surface by means of struts.

6. The device according to claim 5, in which the outer part has a contacting surface which is configured to correspond to the guiding portion.

7. A device substantially as hereinbefore described with reference to and/or as shown in the accompanying drawings.