IMPROVEMENTS IN GASEOUS FLUID FLOW VALVES

Abstract: A gaseous fluid flow valve suitable for use in respiratory apparatus comprises a valve body (2) formed with an aperture (3) which is closed by a plate-like closure member (5). Spring biassing means (7), suitably in the form of a bowed spring (13), urge the closure member to the position in which it closes the aperture. Support means of the closure member constrain movement thereof to a predetermined path. To enable the force of the spring biassing means (7) on the closure member to be varied, the spring mounting means is adjustable. Where a bowed spring is employed the spring ends are supported in mountings secured to the valve body one or both of which is adjustable. Other spring configurations with adjustable mountings are referred to.

Description: The invention relates to gaseous fluid flow valves and, more particularly, but not exclusively to such valves through which exhaled gases in respiratory apparatus are exhausted. A gaseous fluid flow valve of the kind with which the invention is concerned comprises a valve body formed with an aperture, a valve seating provided around the aperture, a plate-like closure member engageable with the seating to close the valve, spring biassing means which exert a force on the closure member to urge said member towards engagement with the seating, support means for the closure member constraining movement of the closure member to a predetermined path between open and closed positions of the valve and adjustable mounting means on the valve body adjustment of which is effected to vary the force on the valve closure member exerted by the spring biassing means. Such a valve which is described and illustrated in GB-A-2,145,336 is hereinafter referred to as a valve "of the kind set forth". In certain usages of gaseous fluid flow valve of the kind set forth, for example, when used as a respiratory valve, it is desirable that the valve in operation should open rapidly. It is an object of this invention, accordingly, to provide a gaseous fluid flow valve of the kind set forth in which rapid opening during operation of the valve is achieved in a simple and effective manner. The present invention consists in a gaseous fluid flow valve of the kind set forth which is characterised in that said support means comprise a carrier arm pivotally mounted on the valve body and constraining movement of the closure member to an arcuate path and the spring biassing means are selected and disposed so that the moment of the force acting on the closure member attributable to the spring biassing means is greater in the closed than in the open position of the closure member. In one embodiment of the invention the spring biassing means comprises a bowed spring ends of which are engaged in respective mountings provided each on a fixed abutment on the valve body, one of the mountings being adjustable relatively to the abutment on which it is provided to vary the force exerted by the bowed spring on the closure member. Preferably each of the mountings is adjustable relatively to its supporting abutment to vary the force exerted by the bowed spring on the closure member. Advantageously, the or each mounting comprises a screw engaged in a threaded bore in the abutment on which it is provided, the screw having an end facing and engaged with the adjoining end of the spring. Suitably the end of the screw facing the adjoining end of the spring is formed with a cup-shaped seating. The seating is preferably of deep conical form. Suitably the valve body is apertured to enable a tool to be engaged with the adjustable means to effect adjustment thereof. In a further embodiment of the invention, the spring biassing means comprise a helical compression spring which at one end bears against the closure member and at the opposite end is engaged with an adjustable mounting carried on an abutment fixed to the valve body. Instead of a compression spring a tension spring may be employed in which case the spring is disposed to exert a pull on the closure member tending towards closure of the valve. In this arrangement the end of the spring remote from the closure member engages an adjustable mounting carried in an abutment on the valve body. In another embodiment of the invention, the carrier arm is connected on the side of the pivotal mounting thereof remote from the closure member to an end of a helical tension spring of which the other end is engaged with an adjustable mounting carried on an abutment fixed to the valve body, the spring being disposed to bias the closure member to the closed position thereof. Here again it will be appreciated that a tension spring may be employed instead of a compression spring, the adjustable mounting being provided at the end of the spring remote from the carrier arm. In yet a further embodiment of the invention, the carrier arm is connected, at the side of the pivotal mounting thereof remote from the closure member, to an end of a tension spring of which the other end is engaged with an adjustable mounting carried on an abutment fixed to the valve body. In a still further embodiment of the invention, the carrier arm is connected to respective ends of a helical compression and a helical tension spring, said springs extending in opposite senses from the carrier arm, one end of one of the springs remote from the carrier arm being connected to a fixed abutment on the valve body and the end of the other spring remote from the carrier arm being engaged with an adjustable mounting carried on a further abutment fixed to the valve body. It will be appreciated that the ends of the respective springs remote from the carrier arm could be provided with adjustable mountings. In all embodiments of the invention the effective spring force acting on the closure member is less when the valve is open than when it is closed. The invention will now be described, by way of example, with reference to the accompanying drawings, in which: FIGURE 1 is a top plan view of a gaseous fluid flow valve according to the invention showing components of the valve structure in broken lines, the valve being of a form as used in a respirator helmet; FIGURE 2 a is a front elevation of the valve of Figure 1; FIGURE 2 b is a vertical sectional view taken on the line II-II of Figure 2; FIGURE 2 c is a sectional scrap view to an enlarged scale of a detail of Figure 2 b ; FIGURES 3 to 8 are diagrams illustrating further possible forms of valve according to the invention, and FIGURE 9 illustrates a preferred feature of the invention. In the drawings, like parts have been accorded the same reference numerals. Referring first to Figures 1 and 2, a gaseous fluid flow valve 1 comprises a valve body 2 formed with an aperture 3 in a plate-like part 4 of the valve body. Around the periphery of the aperture 3 is provided a valve seating 6 with which is engageable a peripheral part of a valve closure member 5 which is of kidney shaped, plate-like form. Spring biassing means 7 urge the closure member 5 towards engagement with the valve seating. Support means for the closure member comprise a generally U-shaped carrier arm 9 which at opposite ends thereof is pivotally carried on supports 10 provided on the underside of the plate-like part 4 of the valve body. The closure member 5 is secured to a central limb 12 of the arm 9 so as to be immovable relatively thereto. To this end the limb is formed with raised projections 12 a and 12 b to which the closure member is adhesively bonded. The arm 9 constrains movement of the closure member to a predetermined arcuate path between open and closed positions of the valve. The spring biassing means 7 comprise a bowed spring 13 formed from metal wire which, at its ends, is supported in adjustable mountings 15 carried in abutments 17 secured to the underside of the valve body part 4. A central part of the bowed spring 13 engages in apertures formed in a further raised projection 12 c at the centre of limb 12. The adjustable mountings 15 are provided by screws 19 which engage in threaded bores 191 of the abutments 17. At their ends adjoining the ends of the bowed spring 13, the screws 19 are each made with a cup-shaped recess 193 which is preferably deep and has a conical bottom 195 in which the adjoining spring end is seated. The valve body 2 is provided with two holes 21 through which a tool can be passed in order to effect adjustment of the screws 19 by engagement with internally shaped recesses 197 in the screws. The adjustment of the screws 19 effects adjustment of the force exerted by the spring 13 on the closure member 5 and enables the differential air pressure acting on the valve closure member 5 which is required to effect opening of the valve to be kept within predetermined limits. When employed in respirator headgear, the assembled valve is disposed adjacent the lower edge of the helmet visor to extend around and beneath the chin of the user. As the user exhales, a positive pressure relative to ambient pressure is created across the valve closure member which is sufficient to overcome the spring force acting thereon so that the valve opens. As shown in Figure 9, when the valve is open, the moment of the spring force acting about the pivot points of the carrier arm is less than the moment of the spring force acting when the valve closure member is in the closed position thereof. Thus, F₁h₁ is greater than F₂h₂. The effective force acting on the closure member is thus less in the open than in the closed position of the valve and the valve is thus a quick opening valve. Thus, during inhalation if the pressure within the headgear is below the external pressure, the valve closure member is in a closed position and is rapidly opened during exhalation. The valve design is such that it is sensitive and responsive to small changes in pressure as occur during breathing of the user. Figures 3 to 8 show diagrammatically different possible forms of gaseous fluid flow valves according to the invention. Thus, in Figure 3, the spring biassing means 7 are in the form of a helical compression spring 131, one end of which bears against the valve closure member adjacent the connection thereof with the carrier arm 9. The other end of the compression spring is provided with the adjustable mounting 15 carried on a fixed abutment provided on the valve body. In the arrangement of Figure 4, the spring biassing means 7 is a tension spring 132 connected to the side of the valve closure member 5 opposite the arm 9. Again, the end of the spring remote from the valve closure member 5 is provided with an adjustable mounting 15 carried in a fixed abutment on the valve body and through which the spring force can be adjusted. Figures 5 and 6 show the use of respective tension and compression springs 133 and 134 attached to an end of the arm 9 at the side of the pivot support 10 thereof remote from the valve closure member 5. In the arrangement of Figure 5 the spring exerts a pull on the arm 9 such as to urge the closure member into closing engagement with the valve seat 6. In the arrangement of Figure 6, a compression spring acting on the arm 9 urges the closure member 5 into closing engagement with the seating 6. In the case of the arrangements of Figures 5 and 6, the end of the spring 7 remote from the arm 9 is provided with the adjustable mounting 15 for varying the force in the spring applied to the arm 9. In the arrangement of Figure 7, a torsion spring 135 is attached at one end thereof to an end of the carrier arm 9 on the side of the pivot 10 thereof remote from the closure member 5. The other end of the torsion spring is secured to the adjustable mounting 15 through which the location of that end of the spring in a direction transverse to that part of the spring can be adjusted to vary the spring force. In Figure 8, a combined arrangement of tension and compression springs 136 and 137 is employed. The springs are connected at an end thereof to the arm 9 and the remote ends of the springs are connected to adjustable mountings 15 for enabling variation of the compression in the compression spring or the tension in the tension spring to be effected. It is sufficient to effect variation of the force in one or other of the springs, in which case only one adjustable mounting need be provided, the mounting at the end of the other spring being, in that case, fixed. In all the arrangements, as has been previously intimated, it is desirable, where the valve is a respirator valve to arrange for the valve to be a quick opening valve as described previously in connection with Figure 9. The adjustability of the spring force acting on the valve closure member ensures that the requisite valve opening pressure can be obtained within close limits. Thus the need to change valve sub-assemblies or components is obviated. It will be appreciated that many changes can be made in the structures described without departing from the scope of the invention. Thus, for example, instead of the spring ends engaging in cups on the adjustable mountings, the spring ends could be formed with cupped members which engage on pointed ends of the screws comprising the adjustable spring mountings. Also, in the arrangement of Figures 1 and 2, the adjustability need only be provided at one end of the spring though by providing it at both ends, a wider range of adjustment is available. Where adjustability is provided at each end of the bowed spring, the valve cover is provided with respective holes to enable access of a tool to each of the adjustable screws in the adjustable mountings at the ends of the spring. Also, the spring can be tuned to provide the valve with a different opening pressure should it be required. It will be appreciated, also, that instead of the spring being made of steel wire, it could be made of steel strip or of wire or strip of any suitable material. The valve closure member 5 and carrier arm 9 are lightweight components to afford sensitivity and suitably are formed from plastics material as may also be the valve body components.

Claims: A gaseous fluid flow valve (1) comprising a valve body (2) formed with an aperture (3), a valve seating (6) provided around the aperture, a plate-like closure member (5) engageable with the seating to close the valve, spring biassing means (7) which exert a force on the closure member to urge said member towards engagement with the seating, support means (9) for the closure member constraining movement of the closure member to a predetermined path between open and closed positions of the valve and adjustable mounting means (15) on the valve body adjustment of which is effected to vary the force on the valve closure member exerted by the spring biassing means, characterised in that said support means comprise a carrier arm (9) pivotally mounted on the valve body and constraining movement of the closure member to an arcuate path and the spring biassing means are selected and disposed so that the moment of the force acting on the closure member attributable to the spring biassing means is greater in the closed than in the open position of the closure member. A valve as claimed in Claim 1, characterised in that the spring biassing means comprises a bowed spring (7) ends of which are engaged in respective mountings provided each on a fixed abutment (17) on the valve body, one of the mountings being provided with means (19) which are adjustable relatively to the abutment on which said means is provided to vary the force exerted by said bowed spring on the closure member. A valve as claimed in Claim 2, characterised in that each of the mountings is provided with means (19) which are adjustable relatively to its supporting abutment to vary the force exerted by said bowed spring on the closure member. A valve as claimed in Claim 2 or Claim 3, characterised in that the or each mounting comprises a screw (19) engaged in a threaded bore (191) in the abutment (17) on which it is provided, the screw having an end facing and engaged with the adjoining end of the spring. A valve as claimed in Claim 4, characterised in that the end of the screw (19) facing the adjoining end of the spring is formed with a cup-shaped seating (193). A valve as claimed in Claim 5, characterised in that the cup-shaped seating has a conical bottom (195). A valve as claimed in any one of Claims 2 to 6, characterised in that the bowed spring (13) at a central part thereof is secured to the support means (9) of the closure member. A valve as claimed in any preceding claim, wherein the valve body is apertured to enable a tool to be engaged with the adjustable means (15) to effect adjustment thereof. A valve as claimed in Claim 1, characterised in that the spring biassing means (7) comprise a helical compression spring which at one end bears against the closure member (131) and at the opposite end is engaged with an adjustable mounting carried on an abutment fixed to the valve body. A valve as claimed in Claim 1, characterised in that the carrier arm (9) is connected on the side of the pivotal mounting (10) thereof remote from the closure member to an end of a helical tension spring (133) of which the other end is engaged with an adjustable mounting carried on an abutment fixed to the valve body, the spring being disposed to bias the closure member to the closed position thereof. A valve as claimed in Claim 1, characterised in that the carrier arm (9) is connected on the side of the pivotal mounting (10) thereof remote from the closure member to an end of a helical compression spring (134) of which the other end is engaged with an adjustable mounting carried on an abutment fixed to the valve body, the spring being disposed to bias the closure member to the closed position thereof. A valve as claimed in Claim 1, characterised in that the valve closure member (5) is secured at one side thereof on said carrier arm (9) and at the opposite side thereof to one end of a helical tension spring (132) of which the other end is engaged with an adjustable mounting carried on an abutment fixed to the valve body. A valve as claimed in Claim 1, characterised in that the valve closure member (5) is secured on a carrier arm (9) pivotally mounted on the valve body, the carrier arm (9) is connected, at the side of the pivotal mounting thereof remote from the closure member, to an end of a tension spring (7) of which the other end is engaged with an adjustable mounting carried on an abutment fixed to the valve body, the spring being disposed to bias the closure member to the closed position thereof. A valve as claimed in Claim 1, characterised in that the carrier arm (9) is connected to respective ends of a helical compression (137) and a helical tension spring (136), said springs extending in opposite senses from the carrier arm, one end of one of the springs remote from the carrier arm being connected to a fixed abutment on the valve body and the end of the other spring remote from the carrier arm being engaged with an adjustable mounting carried on a further abutment fixed to the valve body. A valve as claimed in Claim 1, characterised in that the carrier arm (9) is connected to respective ends of a helical compression (137) and a helical tension spring (136), said springs extending in opposite senses from the carrier arm, the ends of the springs remote from the carrier arm being engaged with respective adjustable mountings provided each on an abutment fixed to the valve body.

Inventors: BRIGGS, MICHAEL, SMITH, SIMON PETER
Applicants: HELMETS LIMITED
Application year: 1987
Main classification: A62B18
IPC codes: A62B18