GB2172095A - Ripcord release valve - Google Patents

Abstract

A ripcord release valve allowing pressurised gas to be released from a cylinder to fill an inflatable raft for example, includes a valve body 2 having a sealing disc 16 sealing off an axial discharge passage 7 through which, when the disc 16 is pierced, gas can pass from the cylinder to flow, via a transverse passage 15, to the raft. The disc 16 can be pierced by a tappet 22 moveable longitudinally by a cam 55 formed on a ripcord disc 46 rotatable, in an axial plane of the tappet 22, about a rotational axis perpendicular to the tappet axis. The rotational mounting of the disc 46 is carried by a casing top part 3 from which the ripcord 51 extends and part 3 is freely rotatable relative to body 2 about the tappet axis. The form of the cam 55 allows a high mechanical advantage to be secured during the initial part of a pull on ripcord 51 to pierce disc 16, with a relatively rapid projection of tappet 22 through disc 16 after initial piercing of disc 16, followed in turn by withdrawal of tappet 22 from the disc under the action of a return spring 17. <IMAGE>

Description

SPECIFICATION Ripcord release valve THIS INVENTION relates to a ripcord release valve, that is to say, a valve for a vessel containing gas under pressure and which normally prevents escape of the gas from the vessel but which, when an operating ripcord is pulled, allows the rapid escape of gas from the vessel, for example to inflate an inflatable life raft or inflatable boat. Such a valve is herein referred to as being "of the kind specified".

A typical ripcord release valve of the kind specified is screwed into the opening of a gas vessel or tank or receptacle or the like by means of a conical screwthreaded spigot disposed on the valve body. The filling of the receptacle or the like usually takes the form of liquid CO2, with N2 as the propellant gas. The propellant gas is needed at low temperatures, at which liquid CO2 evaporates with difficulty, if at all. However, the gas receptacle can contain compressed air. A flexible riser having a weight at its end is screwed into the screwthreaded spigot of the valve body. A rise of this kind is needed to ensure operational reliability of the gas receptacle in all the positions in which it may be used in operation.

In one known ripcord release valve the rotational axis of the ripcord disc extends along the longitudinal axis of the valve body. The ripcord is introduced laterally into the top member extending around the ripcord disc and is introduced into the peripheral ripcord groove therein. Consequently, upon actuation of the ripcord the ripcord disc rotates, with the result that a screwthreaded spindle moves axially until it contacts the tappet and displaces the same towards the disc seal against the etainin g force of a spring. The tappet pierces the disc seal so that the liquid gas in the gas receptacle can expand by way of the valve body and be transferred, for instance, to an inflatable life raft or to an inflatable boat.

A disadvantage of the known ripcord release valve is the comparatively high release or triggering force needed to turn the ripcord disc and, therefore, for the tappet to pierce the seal, for bearing in mind that the most common case is that the ripcord release valve is actuated in emergencies-i.e., in situations in which the persons experiencing the emergency are often in a very weak state and do not always act with consideration-triggering or release forces of the order of approximately 120 N at a pressure of 200 bar in the gas receptacle are fairly high.

Another disadvantage of the known facility is that after piercing the disc seal the tappet remains in the throughflow zone, so that the flow cross-section is restricted and filling of the inflatable device is delayed unduly.

Another disadvantage of the prior art construction is that the top member, with the ripcord disc in it, is rotatable relatively to the valve body; it can therefore be moved into the operative position but must be located therein on the valve body. This may lead to the ripcord taking up an unfavourable position in the event of an emergency and may impede inflation of a life-saving device.

It is an object of the invention to provide an improved ripcord release valve which can be handled satisfactorily in any emergency and requires little force to operate.

According to the invention, there is provided a ripcord release valve of the kind specified having: a casing, a tappet retained in a standby position in the casing and moveable lengthwise to pierce a disc seal clamped in the casing below the tappet and separating from one another two ducts in said casing and a pivotable ripcord disc formed with a peripheral groove for the ripcord and operable to move the tappet lengthwise, wherein the ripcord disc is segment-shaped and is mounted for pivoting, relative to the casing, in the central longitudinal plane of the tappet, around a casing pivot, the ripcord disc having a control surface for engagement with the tappet, the distance between said contact surface and the casing pivot being considerably less than the distance between said peripheral groove for the ripcord and the casing pivot.

What is important in this connection is the fact that the ripcord disc is now pivotable in the central longitudinal plane of the tappet.

Consequently the lever arm can now be so dimensioned between, on the one hand, the ripcord disc pivot and the ripcord groove, and, on the other hand, the pivot and the tappet contacting surface, that only a reduced force is needed to pierce the disc seal. Such force can vary between 55 and 60 N for a gas receptacle pressure of 300 bar. This kind of force can readily be provided even by weak adults or children in very serious emergencies.

In a preferred embodiment, a screw tappet filling spigot may be provided on the valve body. This, enables the gas receptacle to be filled through the valve body without elaborate manipulations. The filling spigot may recieve a check-type filling valve which is sealed externally by screwthreading.

A projecting pin of the check-type filling valve may be advantageous for a pressure gauge which can be fitted to the filling spigot, the screwthreading being omitted; the pressure gauge providing a constant check on pressure.

An embodiment of the invention is described hereinafter by way of example with reference to the accompanying drawings wherein: Figure 1 is a view in elevation, partly in vertical longitudinal section, of a ripcord release valve; Figure 2 is a side view of the body of the valve of Figure 1 looking in the direction of the arrow II and partly in vertical longitudinal section; Figure 3 is a vertical longitudinal section through the top member of the valve of Figure 1; Figure 4 is a side view of the top member of Figure 3, looking in the direction indicated by an arrow IV; Figure 5 is a partly sectioned plan view of the top member of Figure 3; Figure 6 is a partly sectioned view of a tappet of the valve of Figure 1; Figure 7 is a side view of the tappet of Figure 6, looking in the direction indicated by an arrow VII;; Figure 8 is a side view of the tappet of Figure 7 looking in the direction of the arrow VIII; Figure 9 is a view to an enlarged scale of the part IX of Figure 7, and Figure 10 is a view to an enlarged scale of the part X of Figure 8.

Referring to Figure 1, a ripcord release valve 1 is used in association with a gas receptacle or the like (not shown in greater detail) for pressurised gas. The valve 1 is of use, for example, for inflating inflatable life rafts and life saving inflatable boats. Accordingly, the receptacle is full of a mixture of liquid CO2, with N2 as propellant gas. The function of the propellant gas is to ensure discharge and gasification of the CO2 even at low temperature.

The valve 1 mainly comprises a body 2, a twopart top member 3 and a flexible riser 4 having at its end a weight 5. The function of the riser 4 is to ensure that the inflating gas (CO2) can be discharged from the gas receptacle by the propellant gas before the propellant gas is itself discharged, whatever the physical position of the gas receptacle. The riser 4 is screwed into a duct 7 extending through an externally screw-threaded frusto-conical spigot 6 of the valve body 2. In use, the spigot 6 is screwed into a correspondingly screwthreaded opening of the gas container (not shown). The axis of spigot 6 and duct 7 is hereinafter referred to as the longitudinal axis of the valve body.

As a study of Figures 1 and 2 together will show, the body 2 has in all five spigot-like projections, namely the spigot 6 already mentioned, a discharge spigot 8 having an external screwthread 9 and extending at right angles to the longitudinal axis of the valve body, a filling spigot 10 disposed opposite the spigot 8 and also at right angles to the longitudinal axis, the spigot 10 having an internal screwthread 11, a safety spigot 12 disposed at rightangles to the spigot 10 in substantially the same centre transverse plane and having an internal screwthread 13, and a holding member 14 for the top member 3, the member 14 being disposed opposite the spigot 6, and in axial alignment therewith.

An axial passage extending entirely through the valve body from the free end of spigot 6 to the free end of spigot 14 is divided into two parts sealed off from one another by a sealing disc 16, the part of the axial passage below the disc 16 comprising the duct 7. A duct 15 extends from the free end of spigot 8 to meet the axial passage at a position somewhat above the disc 16, the duct 15 extending transversely with respect to said axial passage. A part of said axial passage above the disc 16 is formed as an internally screwthreaded bore 17.

The disc seal 16 which is dished and is made of nickel thus separates the ducts 7, 15 in the spigots 6, 8 respectively when the valve 1 is in its standby position. An insert 18 screwed into the tapped bore 17 in the retaining spigot 14 presses the disc seal 16 sealingly against an annular bead 19 in the valve body 2. Insert 18 has an axial passage 20 therethrough and is also formed with cross-bores 21 intersecting the axial bore 20, and formed in a part of the insert 18 which is of reduced diameter relative to bore 17 and is spaced inwardly from the wall of the axial passage to provide space for gas to pass from bore 20, through bores 21 and the axial passage to duct 15.

An elongate tappet 22 extends axially into the insert 18. The tappet 22 has a pointial lower end for piercing the disc 16 and has a cylindrical upper end which projects from the spigot 14. The tappet 22 passes through a bore formed in an insert 24 which is screwed into the bore 17 and has a flange engaging the upper end of the spigot 14. The tappet 22 has, adjacent its upper end, annular collars 27, 28. A lower part of the bore through insert 24 receives the collars 27, 28 as a sliding fit and is sealed with respect to the tappet by a sealing ring 26 fitted around the tappet 22 and located between the collars 27, 28. An upper end portion of the tappet of reduced diameter with respect to collars 27, 28, passes as a sliding fit through an upper part of the bore through insert 24, which is of reduced diameter with respect to the lower part, to project from the insert 24. The shoulder formed at the upper end of the wider part of the bore through insert 24 can, in principle, engage the upper collar 27 to retain the tappet in the valve body, although, as will appear, in the assembled valve upward movement of the tappet may actually be limited by engagement with a ripcord disc. A compression spring 23 bears at its lower end on the insert 18 and engages the collar 28 of the tappet at its upper end to press the tappet 22 upwardly. The collar 28 thus serves as abutment for the spring 23. A ring seal 25 provides a sealing-tight connection between the sleeve 24 and the spigot 14.

A check type filling valve 29 is screwed into the filling spigot 10 on the side opposite to the exit spigot 8. The valve 29 has a pin 30 which, as can be seen in Figure 1, engages in a bore 31 of a screwthreaded facility 32. The pin 30 can be engaged by a manometer fitting screwed into the spigot 29 instead of facility 32, whereby the pin can be displaced to open the check valve 29 and place the manometer in communication with the gas receptacle. This provision for fitting a manometer instead of the facility 32 makes it possible for a constant check to be provided on the pressure in the gas receptacle. The valve 29 communicates permanently with the duct 7 in the spigot 6, below seal 16, by way of a duct 33. The check-type filling valve 29 enables the gas receptacle to be filled without any manipulations of the valve body 2.

As can be gathered from Figure 2, the duct 7 in the spigot 6, below seal 16, communicates permanently by way of a branch duct 34 with the safety spigot 12. A frangible disc 35, secured in the spigot 12 by means of a screwthreaded sleeve 36, which has a protective plastics cap 37, normally seals off the outer end of the duct 7 but will rupture, to allow the escape of gas, if subjected to excessive gas pressure. The resistance of the disc 35 to rupture is adapted to the maximum permissible pressure of the valve arrangement.

The top member 3 is so mounted on the retaining spigot 4 as to be freely rotatable about the longitudinal axis of the valve body (Figures 1 to 4). To this end, a bottom part 38 of the top member 3 engages by way of a collar 39 over the spigot 14. The spigot 14 is formed externally with an annular groove 40 (Figure 2) registering with two parallel ducts 41 in the bottom part 38 of the top member.

Two screws 42 extend through the ducts 41, the shanks of the screws 42 sliding in the groove 40. A ring seal 43 provides the requisite sealing tightness between the spigots 14 and 39.

Four screws 45 connect a top part 44 of the top member 3 to bottom part 38 thereof (Figures 1 and 3 to 5). A quadrant-shaped ripcord disc 46 of polyamide is mounted in the top part 44 for pivoting around a pivot pin 47 secured in the top part 44 above the upper end of tappet 22 and displaced laterally of the axis of tappet 22. The tappet 22 projects vertically upwards from the valve body 2 to cooperate with disc 46. The pivotal axis of pivot pin 47 is perpendicular to the direction in which the longitudinal axis of the valve extends so that the pivoting plane of the disc 46 is coincidal with the longitudinal centreplane of the tappet 22.

The disc 46 is formed with a peripheral groove 48 to receive a ripcord 51 which has a thickened part 49 at one end and a loop 50 at the other end (Figure 3).

When in the standby position shown the disc 46 (Figures 1 and 3), is secured in the position shown in Figure 3 because the tappet 22 is urged by the spring 23 into engagement with a curved contact surface 54 of a pressing nose 55 of the ripcord disc which nose projects from the region of pivot 47 transversely of the longitudinal axis of the tappet 22.

The surface 54 of the nose 55 comprises two longitudinal portions of different curvatures. In the standby position illustrated in Figure 1, the convex top surface of the tappet 22 is in engagement with the longitudinal portion having the rise which is shallower in relation to the pivot 47. Consequently, the leverages between, on the one hand, the groove 48 and the pivot 47 and, on the other hand, the pivot 47 and that portion of the surface 54 thus engaged by the tappet 22 are such that at a receptacle pressure of 300 bar a relatively reduced force of approximately 55 to 60 N suffices to drive the tip of the tappet 22 through the seal 16. As the disc 46 pivots further, the steeper rise of the surface 54 contacts the top surface of the tappet 22.

The steeper rise, associated with a faster movement of the tappet, is now possible because much smaller forces are needed for further cutting of the seal 16 once it has been pierced.

Thus, when the ripcord is pulled, for a given increment of pivotal movement of the ripcord disc, there is initially only a minor axial shift of the tappet, with a comparatively long lever arm between the ripcord and the pivot 47 and a short lever arm between the pivot and the contact surface 54. Substantial forces for piercing the sealing disc can therefore be applied. Much lower forces are needed for further cutting of the disc seal after the piercing thereof. To this end, the contact surface has an increasingly steeper rise as the ripcord disc pivots, with the result of increasing the speed of tappet displacement.

In the standby position the spring 23 presses the tappet 1 7 against the pressing nose 55 and thus blocks the ripcord disc 46.

The ripcord 51 is disposed in the cord groove 48 in the periphery of disc 66 and is located in this position by the wall of the top member 46 and by a thickened part 49 at one end of the ripcord. After the ripcord disc has pivoted through more than 90 , the ripcord disengages automatically from the quadrant-shaped ripcord disc 46 but remains in the top member 3.

There is therefore no need to open the top member in order to return the ripcord to its standby position. All that is needed is to disengage the top member 3 from the valve body 2 in order to be able to reposition the ripcord properly through the opening of the top member around which collar 39 extends.

When the disc 46 has pivoted clockwise through more than 90 , the tip of the nose 55 passes the upper end of the tappet 22 allowing the tappet to move upwardly again to engage in a recess 56 visible in Figure 3 and bounded on one side by a rear surface 57 of nose 55. The spring 23 moves the tappet 22 into this position to ensure that after the seal 16 has been pierced the tappet 22 does not continue to restrict the flow cross-section.

Thus, when the pressing nose has pushed the tappet completely through the sealing disc over the full tappet stroke, the nose 59 is disposed laterally of the tappet 22. The tappet is then pressed upwards into the recess 56 by the return spring 23 so that the gas flow cross-section in the valve body is not restricted by the tappet and is 100% available.

As can also be gathered from Figure 3, the disc 46 has a lateral telltale surface 58 and the top member 3 (Figure 1) has a telltale window 59 on both sides. In this connection, for example, the disc 46 can be coloured a luminous red and the telltale surface 58 can be coloured a luminous green. When the disc 46 is in the standby position shown in Figures 1 and 3 to 5, the green surface 58 is displayed in the windows 59, to give a visual indication that the device is properly in the standby position.

When the valve 1 has been actuated and the tappet 22 is disposed in the recess 56 adjacent the nose 55, the ripcord 51 has separated from the groove 48. The red surface of the remainder of the disc 46 is now visible through the windows 56 instead of the telltale surface 58 to indicate that the valve 1 is no longer in the standby state. The disc 46 has an enlargement 52 which, after the triggering and pivoting of disc 46 through about 90 , becomes visible through the window 59. The use of polyamide for the ripcord disc has the advantages, inter alia, that polyamide can readily be coloured completely or in parts and also, that polyamide further reduces friction.

The fact that the top member 3 is free to rotate through 360" ensures that the ripcord can be actuated in any position of the top member 2 relative to the valve body 2.

Jamming or seize-ups are substantially impossible.

A screwthreaded spigot 60 is screwed into the top part 44 of the top member 3 at the release cord opening and is provided with a sealing hood 61 secured to the top part 44 by a lead seal 62 (Figures 1 and 3).

It is therefore possible to detect at any time whether the ripcord release valve is still serviceable on the basis of whether the sealing hood 61 has still not been detached. If it has, it is possible that, for example, corrosive sea water has meanwhile entered the valve.

As can be gathered from Figures 6 to 8, the tappet is in two parts, comprising a split sleeve 64 which is ground obliquely at its free end 63 to provide a laterally offset point. The sleeve 64 is received in a thrust pin 65 which provides the upper end of the tappet and the collars 27, 28. This construction greatly simplifies the manufacture of the tappet.In order to provide a tip or apex 63 which requires only a comparatively short operative movement H (Figure 9) of the tappet 22 and ensures rapid opening in association with a reduced cut surface with a large piercing force for the initial piercing of the disc 16, the tip or apex 63 is embodied by a concave cylindrical ground part 66 (Figures 7 and 9), a peripheral clearance ground part 67 (Figures 7 and 9) and a lateral inclined ground part 68 (Figures 8 and 10); the angle of the part 67 and the angle of the part 68 can be about 15". The radius R of the part 66 can be in a ratio of approximately 4:3 to the operative movement H of the tappet 22.

The special construction of the tappet tip described further reduces the release or triggering force necessary. The tappet is so ground that the required operative movement of the tappet is much less, as compared with the prior art, than in the case of a straightground inclined tappet tip. The disc seal opens faster too. Also, the special grindings provide a very small cut surface, so that even less force is required for the initial piercing of the disc seal.

The dished disc seal 16 is preferably produced electrolytically. The dished shape is to facilitate fitting and dismantling and also improves the centring of the disc seal.

Claims (21)

1. A ripcord release valve of the kind specified having: a casing, a tappet retained in a standby position in the casing and moveable lengthwise to pierce a disc seal clamped in the casing below the tappet and separating from one another two ducts in said casing and a pivotable ripcord disc formed with a peripheral groove for the ripcord and operable to move the tappet lengthwise, wherein the ripcord disc is segment-shaped and is mounted for pivoting, relative to the casing, in the central longitudinal plane of the tappet, around a casing pivot, the ripcord disc having a contact surface for engagement with the tappet, the distance between said contact surface and the casing pivot being considerably less than the distance between said peripheral groove for the ripcord and the casing pivot.

2. A valve according to claim 1, wherein said contact surface is provided by a pressing nose of the ripcord disc and is a curved contact surface.

3. A valve according to claim 2, wherein said contact surface of the pressing nose has two longitudinal portions of different curvatures.

4. A valve according to claim 2 or 3, in which the rear surface of the pressing nose is formed with a recess adapted to receive the tappet.

5. A valve according to any of claims 1 to 4, in which the ripcord disc has a lateral tell tale surface and a top part of the valve casing is formed with a display window through which the lateral surface of the disc can be viewed.

6. A valve according to any of claims 1 to 5, in which the ripcord is made of plastics.

7. A valve according to claim 6 in which the ripcord is made of polyamide.

8. A valve according to any of claims 1 to 7, in which the valve casing comprises a valve body provided with said ducts and in which valve body said disc seal is clamped and a top member in which said ripcord disc is pivotally mounted and wherein said top member is in all its operative positions freely rotatable around the longitudinal axis of the valve body corresponding with the longitudinal axis of the tappet.

9. A valve according to any of claims 1 to 8 in which a hood adapted to be secured by a lead seal is disposed at the ripcord opening in the valve casing.

10. A valve according to any preceding claim wherein said tappet is mounted for longitudinal movement in an axial passage and projects from said axial passage into the zone of action of the ripcord disc and is moved by a spring longitudinally towards its standing position of engagement with the seal disc.

11. A valve according to claim 10 in which the tappet includes a longitudinally split sleeve which is bevelled so as to come to a point at its free end, said sleeve being received in a thrust pin mounted for sliding in said axial passage, said thrust pin providing the end of the tappet which projects from said passage to cooperate with the ripcord disc.

12. A valve according to claim 11, in which said thrust pin is sealed with respect to said axial passage by means of a sealing ring, which is retained between two annular collars on the thrust pin and wherein the collar nearer the tappet tip also serves as an abutment for the spring which retains the tappet in the standby position.

13. A valve according to claim 10 or 11, in which the tappet tip has a concave cylindrical ground part, a peripheral relief ground part and a lateral inclined ground part.

14. A valve according to any preceding claim in which the dished disc seal is made of nickel.

15. A valve according to any preceding claim in which a screw-tapped filling spigot is provided on the valve body.

16. A valve according to claim 15, in which the filling spigot receives a check type filling valve.

17. A valve according to claim 15 or 16, in which a manometer can be connected to the filling spigot.

18. A valve according to any preceding claim, in which a safety spigot having a clamped-in frangible disc is disposed on the valve body.

19. A valve according to any preceding claim wherein the casing pivot about which the ripcord disc is pivotable is disposed above the tappet and laterally of the longitudinal axis of the pivot.

20. A ripcord release valve substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

21. Any novel feature or combination of features described herein.