WO1994027553A1

WO1994027553A1 - Fluid control valve especially for use in lung ventilators

Info

Publication number: WO1994027553A1
Application number: PCT/GB1994/001121
Authority: WO
Inventors: Zamir Hayek
Original assignee: Dranez Anstalt
Current assignee: Dranez Anstalt
Priority date: 1993-05-24
Filing date: 1994-05-23
Publication date: 1994-12-08
Anticipated expiration: 1995-11-24
Also published as: GB9310649D0; AU6729394A

Abstract

A fluid control valve (10) for connection to the outlet of an air blower and the inlet of the blower and to a ventilation enclosure for assisted respiration comprising a valve body (40) having a first subsidiary port (14) for connection to said blower outlet, a second subsidiary port (16) for connection to said blower inlet and a main port (12) for connection to said ventilation enclosure, a first valve mechanism operable selectively to connect said first subsidiary port to said main port whilst blocking connection between said second subsidiary port and said main port and also to connect said second subsidiary port to said main port whilst blocking connection between said first subsidiary port and said main port and a similar second valve mechanism (76) co-operating with said first valve mechanism and serving to open a temporary connection to the exterior of the valve from whichever of the first and second subsidiary ports is blocked off from the main port.

Description

FLUID CONTROL VALVE ESPECIALLY FOR USE IN LUNGVENTILATORS

The present invention relates to a fluid control valve, e.g. for controlling flows of air or other gases, and has particular relevance to valves for use in connection with ventilator apparatus for ventilation of the lungs of a patient.

EP-A-0373153 describes ventilator apparatus in which separate sources of positive gas pressure and negative gas pressure are connected to a ventilator enclosure for a patient's chest via a fluid control valve which, through the operation of an electronic stepper motor turning a pivotable shutter member, alternately allows the application of positive pressure and negative pressure to the patient chest enclosure. It is necessary in this arrangement to use separate sources of positive and negative pressure such as two gas blowers. If a single gas blower were connected with its positive output connected to one side of the fluid control valve and its negative input connected to the other side of the fluid control valve, the arrangement would be inoperable because when the positive output of the blower was connected to the ventilator chamber, the negative input side of the blower would be choked off by the shut valve and no pressure would be produced. Similarly, when the valve connected the negative pressure side of the blower to the patient chest enclosure, the output from the blower would be choked off by the valve and there would be nowhere for the air withdrawn from the chest enclosure to be dumped so no negative pressure would result. US-A-2780222 purports to disclose a ventilation arrangement in which a pump has its positive output side and its negative input side both connected to a patient ventilator enclosure by a fluid control valve. The valve illustrated comprises a main valve chamber in which a reciprocating slide valve alternately connects the positive side of the pump and the negative side of the pump to the patient enclosure and further includes two bleeder valves which are intended to permit a supply of air into the pump when positive air pressure is applied to the ventilator chamber and to provide a path for the dumping of air from the pump when negative pressure is applied to the ventilator chamber. However, the arrangement depicted is impracticable as there is no fixed position of adjustment for these bleeder valves which in practice will provide a sufficient air path to or from the side of the pump which is currently shut off from the ventilator chamber by the main part of the valve but yet will not at the same time compete unduly with the ventilator chamber as a destination or source of air during the opposite part of the cycle of operation.

We have now devised a form of fluid control valve which can be connected to both the positive and negative pressure sides of a single fluid supply and allow each to be effectively connected to a closed system such as a patient ventilator enclosure to allow the supply and withdrawal of fluid from the closed system in alternation. Accordingly, the present invention now provides a fluid control valve for connection between a source of positive fluid pressure, a source of negative fluid pressure and a conduit to be connected alternately to said respective sources, said valve comprising a valve body having a first subsidiary port for connection to said source of positive pressure, a second subsidiary port for connection to said source of negative pressure and a main port for connection to said conduit and a valve mechanism operable selectively to connect said first subsidiary port to said main port whilst blocking connection between said second subsidiary port and said main port and also to connect said second subsidiary port to said main port whilst blocking connection between said first subsidiary port and said main port, said valve further including a second valve mechanism co-operating with said first valve mechanism and serving to open a temporary connection to the exterior of the valve from whichever of the first and second subsidiary ports is blocked off from the main port.

Preferably, the first valve mechanism comprises a valve seat in said valve body having openings therein communicating with respective ones of said first and second subsidiary ports and a shutter member having a sealing face overlying said valve seat and being moveable between a first range of positions in which the opening or openings in said valve seat communicating with said first subsidiary port is or are opened and said opening or openings communicating with said second subsidiary port is or are closed and a second range of positions in which the opening or openings of said valve seat communicating with said second subsidiary port is or are opened and said opening or openings in said valve seat communicating with said first subsidiary port is or are closed.

The second valve mechanism preferably comprises a second valve seat in said valve body having openings therein communicating with respective ones of said first and second subsidiary ports and a shutter member having a sealing face overlying said valve seat and being moveable between a first range of positions in which the opening or openings in said valve seat communicating with said second subsidiary port is or are opened and said opening or openings communicating with said first subsidiary port is or are closed and a second range of positions in which said opening or openings communicating with said first subsidiary port is or are opened and said opening or openings connected with said second subsidiary port is or are closed, said first shutter member and said second shutter member being linked together to move in synchrony between their said first and second ranges of position.

Preferably, the first and or second valve mechanism shutter members are rotary shutter members each pivotable about an axis to move between the said first and second ranges of position. Each may comprise a rotatable shaft member defining said axis and carrying both said first and said second valve mechanism shutter members thereon.

Preferably, the two shutter members are positioned 180° out of phase with respect to one another.

The use of a shutter member capable of .movement over a range of position in which it progressively closes the communication between the main port and a subsidiary port, whether the shutter member slides linearly or is pivoted, is preferred in comparison to the use of the type of slide valve shown in US-A-2780222 where each subsidiary port is essentially either wholly closed off from the main port or wholly connected to it. Using an arrangement of this type provides much greater control over the shape and intensity of the positive and negative pressure pulses applied through the main port.

Thus, generally it is preferred that the first valve mechanism is operable in a progressive manner so as to allow the user the select from within a range the maximum effective cross-sectional area of the path of communication open between the main port and each of said first and second subsidiary ports during operation of the valve. Preferably the second valve mechanism operates similarly.

Also, it is preferred that between the position of adjustment of the first valve mechanism which connects the subsidiary port to the main port and the position of operation of the first valve mechanism which connects the second subsidiary port to the main port, there is a position of operation in which neither the first subsidiary port nor the second subsidiary port is connected to the main port. This avoids the situation which arises in the operation of the valve shown in US-A-2780222 as the sliding valve member is moved in the main part of the valve to a central position within its range of movement whereby all of the ports of the valve are connected together momentarily allowing the positive side of the pump connected to the valve to be short-circuited through the valve directly to the negative side of the pump. However, it will be appreciated that it is within the scope of the broad aspect of the invention to utilise an arrangement as shown in US-A-2780222 supplemented by a second main valve chamber with a valve member moving in synchrony with the sliding valve member shown in the embodiment illustrated in Figure 7 thereof, the second main valve chamber being connected to each of the illustrated bleeder valves and the connection of the illustrated bleeder valves to atmosphere being closed. The operation of the valve member in the second main valve chamber will be out of step with that of the valve member in the illustrated main valve chamber so that when the main port of the illustrated main valve chamber (connecting to the ventilator enclosure) is in communication with one of the illustrated bleeder valves, that bleeder valve will be shut off from communicating with atmosphere through the second and additional main valve chamber but the other bleeder valve will be connected to atmosphere through the second, added, main valve chamber.

Where the first valve mechanism of a valve according to the invention includes a rotary shutter member, this is preferably connected to an electronic stepper motor for control of its position and electronic circuitry may be • provided for controlling the stepper motor to produce movement of the shutter member to provide a desired pattern of pressure changes or fluid flows through the main port of the valve.

The invention includes ventilator apparatus for use in ventilation of the lungs of a patient, comprising a ventilator enclosure for receiving at least the chest region of the patient's body, and means for varying the pressure in the enclosure to produce ventilation, said pressure varying means comprising a source of positive gas pressure, a source of negative gas pressure, and a valve according to the invention connected between the said sources and said housing. Preferably, the source of positive pressure and the source of negative pressure are provided by the inlet and the outlet of a pump.

The pump may be of any desired type but is preferably a gas blower. A preferred embodiment of the invention will be described with reference to the accompanying drawings in which:-

Figure 1 shows in plan view a valve according to the invention connected to a blower and to a motorised valve control unit; Figure 2 is an elevation on the line II-II in Figure 1; Figure 3 is a section on the line III-III in Figure 2; Figure 4 is a view in the direction of the arrow IV in Figure 3 of the central body portion of the valve illustrated; Figure 5 is a schematic illustration of ventilator apparatus according to the invention.

As shown in Figure 1, a valve 10 according to the invention has a main port 12 communicating with a ventilator enclosure schematically shown at 13 and first and second subsidiary ports 14, 16 providing access to the interior of the valve. A blower 18 has an outlet 29 for air connected via a conduit 22 to subsidiary port 14 of the valve and an inlet 24 for air connected via a conduit 26 to port 16 of the valve. An electronic stepper motor 30 is connected to the valve by a rotatable shaft 32 in a manner described in further detail hereafter to control the action of the valve. By the operation of the stepper motor 30, the main port 12 of the valve is communicated with the outlet 20 for compressed air from the blower and with the inlet 24 to the blower in alternating succession. Third and fourth subsidiary ports 34, 36 communicating with atmosphere are provided in the valve body as further described below.

As shown in Figure 3, the valve 10 in greater detail comprises a main body portion 40 which is generally in the form of a hollow cylinder with a central tubular member 42 supported on the axis thereof by webs 44, 46, 48, 50 (Figure 4) . The tubular member 42 has a bore 52 therethrough which at each end has a wider diameter counter-bore 54, 56.

At locations spaced around the exterior of the body 40 by 90° there are provided the subsidiary ports 14, 16. The webs 44-50 divide the interior of the body portion 40 into four quarter-cylindrical segments 58, 60, 62, 64. The webs 48 and 44 are solid whilst the webs 46 and 50 are windowed so that within the hollow cylindrical body portion 40 there is gas communication between the segments 58 and 60 and between 62 and 64 but the segments 64 and 58 are isolated from one another as are the segments 60 and 62.

The face of the body portion 40 seen in Figure 4 has a semi-circular rear wall 66 covering the segments 58 and 64. At the opposite end of the body portion 40 there is a similar semi-circular wall 68 covering the opposite end of the segments 60, 62. Thus, the semi-circular walls 66 and 68 are 180° out of phase with one another. Four quarter circular windows are thereby provided to the body portion 40, two on the right hand face of the body portion shown in Figure 3 and two on the left hand face of the body portion shown in Figure 3. The quarter circular windows in the rear or right hand face of the body portion as shown in Figure 3 constitute the ports 34 and 36 referred to above. A shaft 70 extends through bore 52 in the body portion 40 supported upon bearings 72 received in the counter-bores 54, 56. Pinned on the left-hand end (Figure 3) of the shaft 70 is a first shutter member 74 which takes the form of a semi-circular metal plate. A second similar semi-circular metal plate shutter member 76 is pinned to the shaft 52 adjacent the opposite end of the body portion 40 and is arranged 180° out of phase of the shutter member 74. Thus, the two shutter members can be arranged such that shutter member 74 covers both of the windows out of the left hand end of the body portion 40 in Figure 3 whilst shutter member 76 simultaneously covers both of the ports 34, 36 at the right hand end of the body portion as shown in Figure 3. The shaft 52 is connected at its right hand end (in Figure 3) to the stepper motor 30.

The body of the valve is completed by a front member 78 having a front wall 80 containing the main port 12 located eccentrically thereon and having a circular flange 82 received as a push-fit over a boss on the body portion 40 surrounding the area swept out by rotation of the shutter 7 . The port 12 (which is shown slightly out of position in Figure 3) lies equi-angularly between the subsidiary ports 14 and 16 and hence lies directly over the web 44.

An electronic control circuit 84 is provided for controlling movement of the electronic stepper motor.

The operation of the illustrated embodiment is as follows. Starting from a position in which the two shutter members are positioned totally covering their respective openings in the body portion 40 of the valve, the electronic stepper motor is operated to rotate the shaft 52 and hence the shutter members 74 and 76 by up to a quarter turn so as to uncover the window at the front end of the segment 64 which is thus in communication with the main port 12 so that the main port 12 is communicated with the subsidiary port 14. The shutter member 74 slides in an airtight manner on the front (or left hand in Figure 3) face of the body portion 40 which constitutes a valve seat for it and with said valve seat constitutes a first valve mechanism.

At the same time, the second shutter member 76 sliding upon the rear (right hand in Figure 3) face of the body portion 40 which acts as a valve seat uncovers the port 34 which via the window in web 46 communicates the segmental chamber 60 with the segmental chamber 58 which in turn is in communication with the subsidiary port 16. Positive air pressure applied from the blower through its port 20 to the port 14 of the valve is thereby communicated out of the main port 12 of the valve which may be in connection with a patient ventilator chamber and the necessary air supply to the negative pressure side of the blower is provided through port 16 and the subsidiary port 34.

The shutter member assembly is rotated back in the opposite direction to carry both shutter members back by up to 180° so that the front shutter member 74 now opens the window at the front of the segmental chamber 58 in the body portion 40 which communicates with the subsidiary port 16 whilst the rear shutter member 76 opens the subsidiary port 36. Positive pressure from the blower entering the valve through the port 14 is now dumped through the subsidiary port 36 while negative pressure from the blower in the form of suction applied at the subsidiary port 16 is communicated through to the main port 12 and hence to the patient ventilation chamber. By varying the speed of movement of the shutters and the amount of opening of the ports both in the positive and in the negative pressure phases at the main port 12, one can with great flexibility vary the pressure regime applied through the port 12 to a patient ventilator chamber. One may alter the shape of the pressure pulses applied, their duration and their frequency.

As compared with the arrangements described in European Specification No. 0373153, there is a substantial saving in avoiding the use of two independent blowers. This enables one essentially to halve the power consumption of the device and to reduce its size and these changes are of particular and crucial relevance to the provision of emergency resuscitation equipment in mobile vehicles such as ambulances and helicopters. Sensors may be provided in the apparatus to detect the rotational position of the shaft 52 so as to provide feed-back to the circuitry 84 controlling the motor 30. Many other variations and modifications of the illustrated embodiment are also possible within the scope of the invention.

Claims

1. A fluid control valve (10) for connection between a source of positive fluid pressure, a source of negative fluid pressure and a conduit to be connected alternately to said respective sources, said valve comprising a valve body (40) having a first subsidiary port (14) for connection to said source of positive pressure, a second subsidiary port (16) for connection to said source of negative pressure and a main port (12) for connection to said conduit, and a first valve mechanism (74) operable selectively to connect said first subsidiary port to said main port whilst blocking connection between said second subsidiary port and said main port and also to connect said second subsidiary port to said main port whilst blocking connection between said first subsidiary port and said main port, said valve further including a second valve mechanism (76) co-operating with said first valve mechanism and serving to open a temporary connection to the exterior of the valve from whichever of the first and second subsidiary ports is blocked off from the main port.

2. A valve as claimed in Claim 1, wherein the first valve mechanism comprises a valve seat in said valve body (40) having openings therein communicating with respective ones of said first and second subsidiary ports and a shutter member (74) having a sealing face overlying said valve seat and being moveable between a first range of positions in which the opening or openings in said valve seat communicating with said first subsidiary port (14) is or are opened and said opening or openings communicating with said second subsidiary port (16) is or are closed and a second range of positions in which the opening or openings of said valve seat communicating with said second subsidiary port (16) is or are opened and said opening or openings in said valve seat communicating with said first subsidiary port (14) is or are closed.

3. A valve as claimed in Claim 1 or Claim 2, wherein the second valve mechanism comprises a second valve seat in said valve body having openings (34, 36) therein communicating with respective ones of said first and second subsidiary ports (14, 16) and a shutter member (16) having a sealing face overlying said valve seat and being moveable between a first range of positions in which the opening or openings in said valve seat communicating with said second subsidiary port (16) is or are opened and said opening or openings communicating with said first subsidiary port (14) is or are closed and a second range of positions in which said opening or openings communicating with said first subsidiary port (14) is or are opened and said opening or openings connected with said second subsidiary port (16) is or are closed, said first shutter member and said second shutter member being linked together to move in synchrony between their said first and second ranges of position.

4. A valve as claimed in Claim 2 or Claim 3, wherein the first and second valve mechanism shutter members (74, 76) are rotary shutter members each pivotable about an axis to move between said first and second ranges of position.

5. A valve as claimed in Claim 4, comprising a rotatable shaft member (70) defining said axis and carrying both said first and said second valve mechanism shutter members (74, 76) thereon.

6. A valve as claimed in Claim 4 or Claim 5, wherein the first and the second valve mechanism shutter members (74, 76) are positioned 180° out of phase with respect to one another.

7. A valve as claimed in any preceding claim, wherein the first valve mechanism is operable in a progressive manner so as to allow a user to select from within a range the maximum effective cross-sectional area of the path of communication opened between the main port and each of the first and second subsidiary ports during operation of the valve.

8. A valve as claimed in any preceding claim wherein, between the position of adjustment of the first valve mechanism (74) which connects the first subsidiary port (14) to the main port (12) and the position of operation of the first valve mechanism (74) which connects the second subsidiary port (16) to the main port (12) , there is a position of operation in which neither the first subsidiary port nor the second subsidiary port is connected to the main port.

9. A valve as claimed in Claim 4, wherein the rotary shutter members are connected to an electronic stepper motor (30) for control of their position.

10. A valve for controlling fluid flow, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

11. Ventilator apparatus for use in ventilation of the lungs of a patient, comprising a ventilator enclosure (13) for receiving at least the chest region of the patient's body, and means for varying the pressure in the enclosure to produce ventilation, said pressure varying means comprising a source of positive gas pressure (18) , a source of negative gas pressure (18) , and a valve (10) connected between the said sources and said housing, a valve body (40) having a first subsidiary port (14) for connection to said source of positive pressure, a second subsidiary port (16) for connection to said source of negative pressure and a main port (12) for connection to said conduit, and a first valve mechanism (74) operable selectively to connect said first subsidiary port to said main port whilst blocking connection between said second subsidiary port and said main port and also to connect said second subsidiary port to said main port whilst blocking connection between said first subsidiary port and said main port, said valve further including a second valve mechanism (76) co-operating with said first valve mechanism and serving to open a temporary connection to the exterior of the valve from whichever of the first and second subsidiary ports is blocked off from the main port.