Diaphragm-valve Especially For A Respiratory-gas Supply System

Abstract

A diaphragm-valve, especially for a respiratory-gas supply system, comprising a flat diaphragm of revolution about an axis, a sealing lip adapted to cooperate with a seating and added to said diaphragm in the vicinity of its periphery, said lip having a substantially conical profile whose vertex is located on said axis on the gas inlet side of said diaphragm, and a bellows element which forms an extension of said flat diaphragm on the side remote from said lip, said bellows element being made integral at one end thereof with said diaphragm and secured in position at the other end thereof by means of an annular flange, said lip having a diameter of contact with said seating which is substantially identical with the effective diameter of said bellows element.

Description

This invention relates to a diaphragm-valve which is designed primarily for use in a system comprising a pressure and flow regulator for supplying a respiratory gas, although other applications may be contemplated.

As is well known, regulators have already been employed in the prior art for controlling the admission of a respiratory gas (air, oxygen or a mixture of these two gases) into breathing masks worn by aircraft pilots or by personnel working in a hazardous and noxious atmosphere. A regulator of this type comprises essentially a main valve which separates the breathing mask from the gas inlet pipe and the open or closed position of which is controlled by the pressure within an intermediate chamber or so-called "demand" chamber. This pressure is controlled by a "demand" valve which is in turn actuated by a "demand" diaphragm. The demand diaphragm is actuated by the depression produced as a result of inhalation by the wearer of the breathing mask. It should be noted in addition that, under certain conditions of use, it is necessary to supply the respiratory gas at overpressure. In this case, the breathing mask must be associated with an apparatus for regulating this overpressure which is applied to one face of the demand diaphragm.

Moreover, in the systems for supplying respiratory gas which are already in existence, it is also necessary to provide a second valve known as an expiratory valve whereby the exhaled gases are discharged from the mask to the ambient air, said expiratory valve being usually completely independent of that portion of the device which allows gas to enter the mask. However, in the case of operation at overpressure, the overpressure must be applied to one face of the expiratory valve which is then referred to as a compensated respiratory valve.

The aim of the present invention is to provide a diaphragm-valve which is fabricated from an elastomer such as silicone rubber, for example, which makes it possible to combine into a single element both a compensation bellows within which the overpressure is applied and the expiratory valve of systems which are already known.

With this objective, the diaphragm-valve which is formed of a flexible and deformable material essentially comprises a flat diaphragm of revolution about an axis, a sealing lip adapted to cooperate with a seating and added to said diaphragm in the vicinity of its periphery, said lip having a substantially conical profile whose vertex is located on said axis on the gas inlet side of said diaphragm, and a bellows element which forms an extension of said flat diaphragm on the side remote from said lip, said bellows element being made integral at one end thereof with said diaphragm and secured in position at the other end thereof by means of an annular flange, said lip having a diameter of contact with said seating which is substantially identical with the effective diameter of said bellows element.

Further properties and advantages of the invention will become apparent from the following description of a number of examples of construction of a diaphragm-valve in accordance with the invention which are given by way of indication without any limitation being implied, reference being had to the accompanying drawings in which:

FIG. 1 is a vertical sectional view depicting the diaphragm-valve of the present invention; and

FIGS. 2-6 are views similar to FIG. 1 but depicting alternate embodiments of the diaphragm-valve of the present invention.

In these different figures, identical reference numerals have been used to designate similar components.

As shown in FIG. 1, the diaphragm-valve 1 under consideration is essentially composed of a cup 2 which forms the diaphragm and terminates in an annular flange 3 for the purpose of clamping said diaphragm between a member 4 and a plate 5 which is inserted and locked in position with respect to said member by means of a retaining ring 6 which is screwed into this latter. The cup 2 has a general shape of revolution about an axis (not shown) and comprises a flat bottom portion 7 to which is added a peripheral lip 8 having a profile which is substantially that of a cone, the vertex of which is located on the axis of revolution of the cup. Said lip 8 constitutes the moving element of a valve whose seat is formed by the bevelled rim 9 of a flange 10 formed in a casing 11 inside which the diaphragm-valve under consideration is placed. There are formed inside said casing two ducts 12 and 13 which are separate from each other. The inspiratory duct 12 serves to connect the casing to a breathing mask (not shown in the drawings) and the expiratory duct 13 provides a vent to the surrounding atmosphere. There is formed between the cup 2 and the plate 5 a chamber 14 which communicates with the exterior via a bore 15 which is provided at the center of said plate.

Within the scope of the application which is more especially contemplated for the diaphragm-valve according to the invention, the casing 11 is associated with a regulator unit for a respiratory-gas supply system. In this case, the chamber 14 can be maintained at an overpressure which can be regulated with respect to a reference pressure, especially as a function of the ambient air pressure. The overpressure which is thus maintained within said chamber 14 is such as to apply the lip 8 of the diaphragm-valve against its seating 9. During operation, inhalation by the wearer of the mask causes a main valve (not shown) to open, thereby allowing the respiratory gas to enter the mask. During the exhalation stage which immediately follows inhalation, the pressure exerted on the face of the diaphragm-valve 1 which is remote from the chamber 14 builds up and, when it attains a value which is higher than the overpressure in said chamber, causes the displacement of the bottom portion 7 of the cup 2. The lip 8 accordingly lifts from its seating 9 and permits the discharge of respiratory gas from the casing 11 through the expiratory duct 13.

In the alternative form of construction which is illustrated in FIG. 2, the assembly of the diaphragm-valve is identical with that which is contemplated in connection with FIG. 1. However, in this alternative form, the bottom portion 7 of the cup 2 is provided with an axial opening 16 in which is mounted a connector 17 and this latter is attached to the bore 15 which serves to produce the requisite operating overpressure within the chamber 14. This mode of assembly has the advantage of affording protection for the pipe 15 by placing this latter inside the casing 11. Moreover, the connector 17 which comes into contact with the plate 5 provides the diaphragm-valve 1 with a fixed point about which the edges of the bottom portion 7 are capable of pivoting when the lip 8 lifts from its seating.

In the alternative embodiments which are illustrated in FIGS. 3 and 4, the diaphragm-valve 1 is associated with an auxiliary valve 18 which performs the function of inspiratory valve in order that the oxygen or oxygen-air mixture which must necessarily be supplied to the user may thereby be permitted to pass through the duct 12 to the breathing mask. In the case of FIG. 3, said auxiliary valve comprises a central stem 19 which is fitted within a bore 20 formed at the center of the bottom portion 7 of the cup 2. Said stem is joined to a disc 21 of elastomer material which forms the active portion of the valve 18 and is adapted to cooperate with a seating 22 consisting of an annular bead which is formed in relief on the underface of the bottom portion 7. In this example of construction, the operation of the diaphragm-valve 1 is similar to that which has been described in reference to FIGS. 1 and 2. However, provision is made in this instance for a complementary arrangement which consists in the opening of the valve 18 during the inhalation stage in which the pressure existing in the duct 12 which is directly connected to the mask becomes lower than the pressure in the chamber 14. In Fig. 3, the reference numeral 23 designates a flexible hose which connects the casing 11 to the respiratory gas supply.

In the alternative embodiment of FIG. 4 in which the valve 18 is of slightly different design, provision is made for an accessory arrangement which makes it possible in particular to eliminate the effects of accidental pressure variations in the chamber 14 which may arise, for example, from an elongation stress exerted on the flexible hose 23. To this end, the lip 8 of the valve is joined to a flat portion 24 which is parallel with the bottom portion 7 of the cup and which is in turn joined to this latter by means of a ring 25, the stem of the auxiliary valve 18 being mounted within the bore 26 of said ring. Between the portion 24 of the lip 8 and the bottom portion 7, there is thus formed a free space 27, thereby permitting the cup 2 to undergo an accidental relative displacement along its axis without any influence on the position of the lip 8, which remains applied against its seating 9.

In the alternative embodiment which is shown in FIG. 5, the bottom portion 7 of the diaphragm-valve is fitted with a pad 28 placed at the center of the diaphragm and overlapping on both faces of this latter, said pad being mounted in such a manner as to cooperate with the extremity 29 of a lever 30 which is pivoted to the casing 11 about a pin 31. Said lever 30 is provided with a lateral toggle arm 32 fitted with a pin 33, said pin being slidably fitted in a fork 34 provided at the extremity of a second lever 35 which is in turn pivotally attached at 36. The stem 38 of a valve 39 is pivoted to said second lever 35 about a pin 37. Depending on its position, the valve 39 establishes a communication between the inspiratory duct 12 which links the casing 11 to the breathing mask and a duct 40 which can be the respiratory gas inlet duct. In this alternative design, the valve 39 which constitutes the main delivery valve of the apparatus is closed during the exhalation stage in which the lip 8 is lifted from its seating 9 in accordance with the process already described.

Finally, in the alternative embodiment shown in FIG. 6, the diaphragm-valve 1 directly performs the function of demand valve by means of its pad 28. In this case, the pad normally closes off the end of a duct 41 which is put into communication with a chamber 42 formed within the casing 11. Said chamber 42 is delimited by a diaphragm 43 and is supplied with respiratory gas or with one of the constituents of the breathing mixture across a flow-limiting element 45 which is connected into the general supply pipe 46 of the device and via a duct 44. In the example which is illustrated in FIG. 6, said pipe 46 serves to supply oxygen which can be mixed in a suitable proportion with air, the air being admitted through a second pipe 47 which is independent of the first. The diaphragm 43 is in contact with a seating 48 so as to close off a duct 49 through which the air-oxygen mixture derived from the pipes 46 and 47 and constituting the respiratory gas supply is delivered to the breathing mask. The portion of the pad 28 which is remote from the chamber 14 can be subjected to the action of a positionally adjustable spring 50 which is applied against the corresponding face of the diaphragm-valve 1 under the action of a screw 51. Finally, the chamber 14 can be connected by way of a pipe 52 to a regulating system (not shown in the drawings) whereby the overpressure within the chamber 14 can be regulated in accordance with a predetermined law.

In the exemplified embodiment thus contemplated in FIG. 6, the chamber 14 is maintained at a variable overpressure as previously stated. In this case, the diaphragm-valve 1 performs the function of a compensated expiratory valve. When the pad 28 closes the pipe 41, the pressure in the chamber 42 is such that the diaphragm 43 is applied against its seating 48. As soon as the user of the mask inhales from the apparatus, the depression produced beneath the diaphragm-valve 1 which communicates with the mask via the inspiratory duct 12 causes the pad 28 to disengage from the end of the duct 41; the pressure within the chamber 42 thus drops rapidly, the diaphragm 43 lifts from its seating 48 and permits the respiratory gases to flow out through the duct 49. On the other hand, during the exhalation, the pad 28 again closes off the end of the duct 41; the pressure in the chamber 42 builds up, the diaphragm 43 returns to its seating and shuts off the flow through the duct 49. The lip 8 lifts so as to permit the discharge of the exhaled gases through the duct 13. In this alternative embodiment, in which the operation is very similar to that of the outer variants described earlier, it is the flow through the duct 41 which directly supplies the chamber 14 at overpressure. By means of this arrangement, it is possible in particular to dispense with the need for a separate supply through a calibrated leakage in the general respiratory-gas supply pipe as was provided in conventional prior art systems, any such loss being consequently avoided.

In all cases, and irrespective of the design adopted, the diaphragm-valve under consideration offers a large number of advantages which essentially arise from its simplicity of construction and from the fact that a shutoff valve and a diaphragm or compensation bellows can be manufactured as a single component. By virtue of a suitable choice of elastomer as constituent material of the diaphragm-valve, it is also possible to obtain excellent leaktightness which is maintained in all possible orientations of the apparatus. Finally, by virtue of the very light weight of the member which constitutes the diaphragm-valve, the influence of accelerations can be considered as practically zero.

As will be readily understood, the invention is not limited in any sense to the examples which have been more especially described and illustrated but extends to all alternative forms of construction.

Claims

What is claimed is:

1. A fluid flow control device comprising a hollow casing having an inlet and an outlet; a circular valve seat extending between said inlet and outlet; a membrane disposed in said casing and comprising a flat portion having one face exposed to said inlet, a bellows portion extending from the other face of the flat portion and fixed with respect to said casing, said bellows portion having an effective diameter substantially equal to the diameter of said valve seat, and a frustoconical lip portion extending from the rim of said flat portion for contacting said valve seat; and means to exert a predetermined pressure against said other face of said flat portion to urge the inner surface of said lip portion against said valve seat and prevent fluid flow through said casing, whereby a fluid introduced into said casing through said inlet of a pressure greater than said predetermined pressure moves said lip portion away from said valve seat to permit fluid flow through said casing.

2. The device of claim 1 wherein said flat portion is provided with a central opening and an annular bead, and further comprising an auxiliary valve adapted to cooperate with said annular bead to control the flow of fluid through said casing.

3. The device of claim 1 wherein said flat portion is adapted to move relative to said lip portion when the latter is engaging said valve seat in response to a negative pressure occuring at said inlet, and further comprising an actuating member engaging said flat portion and adapted to move therewith in response to said relative movement, and means disposed in said casing and operable in response to movement of said actuating member for controlling the flow of additional fluid through said casing.