The invention relates to a ventilator arrangement consisting of a ventilator housing with an inlet and an outlet and with a flow regulator which is arranged in the venti- lator housing in such a way that a movement of the ventilator housing relative to the flow regulator can be performed, whereby a proportional variation of the flow is achieved.

In the published US patent No. 5,845,633, a ventilator arrangement of the above type is described. The object of that ventilator arrangement is to dose small amounts of nitrogen oxide to a breathing gas, which gas is supplied to a patient for medical purposes. The ventilator housing is here a tube-shaped container in which the flow regulator in the form of a tube-shaped membrane is arranged, wherein the container and the end side of the membrane which is turned towards the breathing gas are made of a material which does not allow nitrogen oxide to pass through. The mem¬ brane is connected via a gas tube with a source for nitrogen oxide. The tube-shaped membrane is made using a material which allows nitrogen oxide through, e.g. TEF¬ LON. The tube-shaped membrane is also removably arranged in the container. The nitrogen oxide source is suitably regulated so that a constant pressure is prevalent in the membrane tube. This results in a constant difference in partial pressure for ni¬ trogen oxide on the in- and out-side of the membrane tube. Diffusion from the in¬ side of the membrane tube to the breathing gas, which depends on the size of the membrane tube's diffusion surface, is obtained. The dosing is regulated by exposing a suitable portion of the total diffusion surface. The exposure of the diffusion sur- face occurs by taking a suitable part of the surface out of the container. This de¬ scribed ventilator arrangement is only related to dosing of nitrogen oxide.

The object of the invention is to achieve a ventilator arrangement like that described above which is related to regulating the micro-flow for different sorts of gases as well as different sorts of liquids. This problem is solved in that the flow regulator consists of a porous body to block the flow between the inlet and the outlet except for through the porous body wherein, through relative movement, a progressive variation of an outer surface of the porous body is obtained, which outer surface is in flow-contact with the outlet. By organizing the ventilator according to the invention, and particularly because of the porous body through which a gas or a liquid can pass, a universal ventilator is obtained for micro-flows, which flows can easily be dosed.

In an advantageous further development of the ventilator arrangement according to the invention, it is proposed that the ventilator housing comprises a first part con¬ taining the inlet, which first part is provided with a sealing surface towards which at least a part of the porous body's outer surface lies, and a second part comprising the outlet, wherein the second part's inner diameter is larger than the body's outer di¬ ameter, and the relative movement is a displacement of the body between the first and the second part. Through a gradual displacement of the porous body within the second part of the ventilator housing, the dosing of gas or liquid is increased.

In another further development of the ventilator arrangement according to the pre¬ sent invention, it is proposed that the porous body comprises a first non-porous end part, which is turned towards the second part of the ventilator housing, and that the first part is so dimensioned that the non-porous end part can be placed in the first part of the ventilator housing. In this way, it is achieved that when the porous body has been displaced to a location where the non-porous end part is placed in the first part of the ventilator housing, the body's entire outer surface lies towards the seal- ing surface in the first part, wherein the ventilator arrangement is closed.

According to an advantageous embodiment of the ventilator arrangement according to the invention, it is proposed that the porous body is provided with at least one channel, the opening of which lies in the body's second end part which is turned towards the inlet. In this way it is achieved that gas or liquid can more quickly reach the porous body's interior and in that way have shorter routes through the pores to the outer surface of the body.

The invention will be explained in connection with the Figures in the attached draw- ings which show:

Fig. 1 a longitudinal section through a ventilator arrangement according to the invention in a closed position, Fig. 2 a ventilator arrangement according to Fig. 1 in a partially open position, Fig. 3 a ventilator arrangement according to Figs. 1 and 2 in a completely open position, and Fig. 4 a longitudinal section through a ventilator arrangement according to the invention, in a different embodiment than that shown in Figs. 1-3.

In Fig. 1, a ventilator arrangement 1 is shown in longitudinal section which is de¬ signed to regulate micro-flows for different sorts of gases. The ventilator arrange¬ ment 1 comprises a ventilator housing 2 with an inlet 3, one or more outlets 4 and a flow regulator 5 in the form of a porous body which is displaceably arranged in the ventilator housing 2 along a central axis 8.

Through this ventilator arrangement, gas can flow through the inlet 3 into the venti¬ lator housing 2 and in that way reach the porous body 5. The gas then passes over pores 20 in the body 5 to the outer surface 9 of the body 5, wherein gas can be emit¬ ted through the outlets 4. This will be described in detail below.

The ventilator housing 2 can be divided into a first and a second part 6 and 7. The inlet 3 is arranged in the first part 6. The inner diameter of the first part 6 of the ven¬ tilator housing 2 is dimensioned so that the outer surface 9 of the porous body 5 lies tight to the inner wall 10 of the ventilator housing 2, which inner wall 10 here serves as sealing surface. In the second part 7 of the ventilator housing 2, the outlets 4 are arranged. The inner diameter of the second part 7 is larger than the outer diameter of the porous body 5. The porous body 5 comprises a first non-porous end part 11, which is turned to¬ wards the second part 7 of the ventilator housing 2. The porous body 5 is provided with a channel 12, the opening of which lies in the second end part 14 of the porous body 5, which end part 14 is turned towards the inlet 3.

The end side 16 of the second part 7 of the ventilator housing 2 is provided with a through-passing opening 17, through which an actuator 15 in the form of a straight peg extends, wherein the opening 17 is preferably arranged in such a way that the actuator 15 is displaceable along the central axis 8.

A spring 19 is placed between the second end part 14 of the porous body 5 and the inner wall 18 in the first part 6 of the ventilator housing 2, which is turned towards the end part 14.

In Fig. 1, the porous body 5, with help of the actuator 15 pushing towards the body's non-porous end part 11, has been displaced in the ventilator housing 2 along the central axis 8 so that the entire body 5 is placed in the first part 6 of the ventila- tor housing 2, wherein the spring 19 in this position is pressed together. Because of the inner wall 10 which seals against the entire jacket surface 9 of the body 5, and because of the first non-porous end part 11 of the body 5 which has an axial sealing function, the ventilation in this position is closed.

In Fig. 2, it is shown that the porous body 5 with help of the spring 19 and the ac¬ tuator 15 has been displaced in direction towards the second part 7 of the ventilator housing 2, wherein a part of the jacket surface 9 of the body 5 has been exposed in that, as earlier described, the inner diameter of the second part 7 of the ventilator housing 2 is larger than the outer diameter of the body 5. In this way, gas comes from pores 20 in the body 5 which results in the exposed jacket surface 9 being in flow-contact with the outlets 4. In Fig. 3, it is shown that the porous body 5 has been displaced to a position where the ventilator arrangement 1 is completely open. In this position a maximum jacket surface 9 of the body 5 is exposed. In this way, a maximum number of pores 20, re- suiting in the exposed jacket surface 9 of the body, have flow-contact with the out¬ lets 4. Only a few pores 20 have been depicted in the Figures.

The in connection with Fig. 1 described channel 12 serves to easily and quickly dis¬ tribute the gas in the porous body 5.

In Fig. 4, a further example of a ventilator arrangement 21 for regulating micro- flows for gases is shown in longitudinal section. In the description of this ventilator arrangement 21, the same reference numerals as in Figs. 1-3 have been used as much as possible.

The ventilator arrangement 21 consists of a ventilator housing 2 with an inlet 3 and an outlet 4, and a flow regulator 5 in the form of a porous body. The interior of the ventilator housing 2 is dimensioned so that the body 5 can only rotate around the central axis 8 with help of the actuator 15 which is solidly fixed to the body 5. The outer surface 9 of the body 5 is for the most part provided with a coating which serves as sealing layer for gases. Only a smaller surface 23 is exposed. The inner wall 10 of the ventilator housing 2 has in connection with the outlet 4 a recess 22 which extends along part of the outer surface of the body 5. With a turning of the body 5 so that the surface 23 is in front of or partially in front of the recess 22, the pores 20 resulting in this surface have more or less flow-contact with the outlet 4. When the body 5 has been turned to a position where the sealing layer completely covers the recess 22, the ventilator arrangement 21 is closed. Even this ventilator arrangement 21 can preferably be provided with a channel 12 in the porous body 5, the benefits of which have earlier been described. Thanks to the relative movement between the ventilator housing 2 and the porous body 5, described in connection with Figs. 2, 3 and 4, a progressive variation of the outer surface of the porous body 5 is achieved, which surface is in flow-contact with the outlets 4, wherein an extremely careful micro-dosing of gas can be reached.

The ventilator arrangements according to the invention described herein can also preferably regulate micro-flows for liquids.

The ventilator arrangements described can also be used in connection with anaes- thetic systems. In this way, an anaesthetic liquid can be supplied to the ventilator housing, which liquid is vaporized in the porous body, wherein the body preferably is heated so that the liquid will more easily be vaporized. Reference numerals:

1 Ventilator arrangement 2 Ventilator housing 3 Inlet 4 Outlet 5 Flow regulator, porous body 6 First part 7 Second part 8 Central axis 9 Outer surface of flow regulator, jacket surface 10 Inner wall, sealing surface 11 First non-porous end part 12 Channel 13 Opening 14 Second end part 15 Actuator 16 End side 17 Through-opening 18 Inner wall in the first part 19 Spring 20 Pore 21 Ventilator arrangement 22 Recess 23 Smaller surface