GB2033554A

GB2033554A - Compressed gas cartridges

Info

Publication number: GB2033554A
Application number: GB7931585A
Authority: GB
Original assignee: DAYSTATE ENG Ltd
Current assignee: DAYSTATE ENG Ltd
Priority date: 1978-09-12
Filing date: 1979-09-12
Publication date: 1980-05-21

Abstract

The invention is concerned with an arrangement for creating a propellant force and includes a reusable cartridge 34 for a pressurised gaseous medium and a plunger 26 for breaking a seal 43 of the cartridge. In an application these components are used in a hypodermic dart, inertia which results from the dart striking an animal, causing relative movement to break the seal. The gaseous medium released then expels a drug from the dart. In another application the components are located in a gun and operation of the gun causes the relative movement. The gaseous medium released is under such a pressure as to propel a bullet from the gun. <IMAGE>

Description

SPECIFICATION Improvements in and relating to propellant apparatus This invention relates to propellant apparatus, used for example in hypodermic darts for administering fluid in the form of drugs, medicines and the like to animals or birds while the user is at a distance therefrom.

According to the present invention there is provided propellant apparatus comprising a selfcontained reservoir for a pressurised gaseous medium, the reservoir having an inlet and an outlet, the inlet having valve means associated therewith and the outlet being closable by a puncturable seal, and puncture means for engaging with the seal of the reservoir, the reservoir and the puncture means being movable relative to one another in use to break the seal and enable release of the pressurised gaseous medium from the reservoir.

Preferably the self-contained reservoir is in cartridge form. The valve means associated with the inlet is preferably a one way valve enabling entry of the gaseous medium through the inlet for filling of the cartridge as necessary. The valve may include an indicator visible at the inlet end of the reservoir, the postion of the indicator relative to the reservoir being changed by the presence of the gaseous medium in the cartridge to thus indicate the condition of the cartridge.

The seal at the outlet of the reservoir may be formed of a thin piece of metal, preferably brass, which seats in a recess and is retained in position by means of a removable end piece of the reservoir which has an opening therethrough to allow passage of the puncture means to break the seal.

A projectile incorporating apparatus as described in any of the three preceding paragraphs may comprise a hollow body member wherein the reservoir and the puncture means are located, and injection means at one end of the body member, the hollow body member being capable of being filled with a fluid in the form of a drug, medicine or the like in the space defined between said one end thereof and the puncture means, whereby, upon impact of the projectile with an animal to be treated, relative movement occurs between the puncture means and the reservoir to break the seal of the reservoir and discharge the drug, medicine orthe like upon subsequent movement of the puncture means by the pressurised gaseous medium.

A gun incorporating apparatus as described in any of the last three but one preceding paragraphs may have a bore for projection of a missile therefrom whereby, upon firing of the gun, relative movement occurs between the puncture means and the reservoirto break the seal of the latter and project the missile by means of the pressurised gaseous medium.

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a sectional elevation of a projectile forming one embodiment of the invention; and Figure 2 is a sectional elevation of a cartridge of the projectile of Figure 1.

Referring to the drawings one embodiment of the invention comprises a projectile in the form of a hypodermic syringe having a hollow body member 10 of cylindrical form which is open ended but has an internally threaded section at each end. Afirst end piece 12 has an externally threaded section 14to enable the end piece 12 to be secured in one end of the body member 10. The end piece 12 mounts, on its axially outer facer, a hollow needle 16 having a barb 18 for a purpose hereinafter described. At its other end the body member 10 is adapted to receive an end piece 20 which has an externally threaded section 22 engageable with the internally threaded section of the body member 10, and which has secured in its axially outer face a flight 24 of any suitable form.

Within the hollow body member 10 there is movably located a piston 26 which is designed to be tight fit within the body member 10 and has a plurality of sealing 0-rings 28 around its periphery.

Extending axially and centrally from the side of the piston 26 remote from the end piece 12 there is a needle point 30 which can be a push fit within a recess in the piston 26. A fluid in the form of a drug, medicine or the like can be introduced into the space defined between the piston 26 and the end piece 12 by first of all removing the platter, the position of the piston 26 within the body member 10 having been previously determined as hereinafter described.

To enable discharge of the fluid the projectile includes a self-contained reservoir of a pressurised gaseous medium, e.g. compressed air, in the form of a cartridge 32. The latter is of such cross section as to removably locate snugly within the hollow body member 10 and is arranged to be received between the piston 26 and the end piece 20. The cartridge 32 is defined by a casing 34 having an internal cavity 36 which opens on to one end of the casing 34, said one end having an internally threaded section. An end member 37 has an externally threaded section 38 engageable in the internally threaded section of said one end of the casing 34 and has an axially extending through bore 40. The other end of the casing 34 has an axially extending central recess 39 which is internally threaded to receive an externally threaded neck section 44 of an end cap 46.The recess 39 communicates with the cavity 36 by means of a central axial bore 42 and a thin metallic seal 43, for example of brass, is arranged to seat in the recess across the bore 42 and be held in place by the neck section 44 of the end cap 46. The latter has a through bore 48 aligned with the bore 42.

Within the cavity 36 and associated with the inlet end of the casing 34 there is provided a valve 50 having a pin 52 on one axial side thereof arranged to extend into and through aperture 40 of the end piece 36. A sealing 0-ring 54 is located around the pin 52. A compression spring 56 has one end seated on the valve 50 at the axial side thereof remote from the pin 52 and its other end seated against the end of the cavity 36 adjacent to the bore 42. Compressed air can be introduced into the casing 34 of the cartridge 32 through the inlet aperture 40 by opening the valve 50, i.e. moving the latter away from the end member 37, and the compressed air is retained in the cavity 34 once the valve 50 returns to its closed position.

When the cartridge is filled with the compressed air the pressure applied to the valve 50 compresses the sealing ring 54 and enables the pin 52 to project slightly beyond the end of the end member 37 thus indicating that the cartridge is full. When the cartridge is empty the pin 52 does not project beyond the member 37.

In operation, the projectile or dart can be fired by any covenient means such as a compressed air gun, an explosive charge gun, a gas gun or crossbow.

Relative movement between the piston 26 and the cartridge 32 is prevented during travel of the dart through the air but on impact with the animal to be injected, inertia causes movement of the cartridge relative to the piston 36 such that the needle point 30 engages against the seal 43 to break same. The compressed air can therefore escape from the cartridge 32 and causes the piston 26 to move towards the needle end of the body member 10 thus discharging the drug, medicine or the like through the needle 16.

The needle 16 is so designed that the drug, medicine or the like cannot pass through, by virtue of capillary action, until an external pressure is applied. As there is no requirement for any external fitting on the dart which would be operative on impact to cause breakage of the seal,the dart has a substantially true flight as there is no obstruction to the aerodynamics. The barb 18 on the needle 16 penetrates the flesh of the animal on impact and prevents dislodging of the needle therefrom.

The cartridge 32 can be of relatively small volume possibly filled with compressed air to a pressure of 2000 Ibslsq in. After use the cartridge 32 can be removed and either refilled, with a new seal 43, or replaced with another filled cartridge. To position the piston 26 within the body member 10, the cartridge 32 is introduced through the open needle end of the body member 10 to engage with the piston 26 and push the latter within the body member 10 until the cartridge 32 moves substantially within the body member 10. The cartridge is then removed and a filled cartridge located through the other end of the body member 10.

The projectile is therefore extremely simple and quick to reload and all parts can be re-used with the exception of the thin metal seals. The projectile is extremely efficient as the pressurised air is extremely effectively controlled and the projectile cannot be discharged by any pressure applied externally thereto, the actuating arrangement being completely enclosed. In addition the same principle can be applied to projectiles or darts used for any type of animal or bird. Sealing 0-rings are provided around the end pieces 12 and 20 and the end member 37 of the cartridge 32.

In another embodiment, the cartridge 32 together with means for puncturing the seal therein, are located within a suitable gun, for example in, or aligned with, a barrel of the gun. The puncture means and the cartridge 32 are so positioned relative to one another that little relative movement is required to enable the puncture means to break the seal of the cartridge and release the pressurised gaseous medium. Such small relative movement can be achieved by any suitable means on operation of the gun.

Release of the pressurised gaseous medium, which may be air compressed to a suitably high pressure, ejects from the gun a missile such as a bullet positioned in the barrel of the gun. This arrangement is particuiarly suitable for use in firing training rounds for example from air rifles.

It will be appreciated that the relative positions of the puncture means and the cartridge can vary provided that, on movement of one of the components relative to the other, the seal in the cartridge is broken and the pressurised gaseous medium is released to effect ejection of the missile. The gaseous medium may be arranged to engage directly with the missile or engage therewith the puncture means, such as the piston 26.

Various modification may be made without departing from the invention. For example the cartridge may be of any other desired form provided it has a puncturable seal for closing of an outlet and an inlet for the gaseous medium. It is of course possible to dispense with any arrangement for indicating the condition of the cartridge if desired. The arranged ment of the plunger and the cartridge may be utilised in applications other than those described where relative movement effected in any suitable manner causes release of the pressurised gaseous medium to carry out a desired function.

Claims

1. Propellant apparatus comprising a selfcontained reservoir for a pressurised gaseous medium, the reservoir having a inlet and an outlet, the inlet having valve means associated therewith and the outlet being closable by a puncturable seal, and puncture means for engaging with the seal of the reservoir, the reservoir and the puncture means being movable relative to one another in use to break the seal and enable release of the pressurised gaseous medium from the reservoir.

2. Apparatus according to Claim 1, wherein the self-contained reservoir is in cartridge form.

3. Apparatus according to Claim 1 or 2, wherein the valve means is a one-way valve enabling entry of the gaseous medium to the reservoir.

4. Apparatus according to Claim 3, wherein the valve includes an indicator visible at the inlet, the position of the indicator relative to the reservoir being changed by the presence of the gaseous medium in the reservoir.

5. Apparatus according to any of the preceding claims, wherein the seal is formed of a thin piece of metal which seats in a recess and is retained in position by a removable end piece of the reservoir, the end piece having an opening therethrough to allow passage of the puncture means to break the seal.

6. A projectile incorporating apparatus according to any of the preceding claims, the projectile comprising a hollow body member wherein the reseroir and the puncture means are located, and injection means at one end of the body member, the hollow body member being capable of being filled with a fluid in the form of a drug, medicine or the like in the space defined between said one end thereof and the pucture means, whereby, upon impact of the projectile with an animal to be treated, relative movement occurs between the puncture means and the reservoid to break the seal of the reservoir and discharge the drug, medicine or the like upon subsequent movement of the puncture means by the pressurised gaseous medium.

7. A projectile according to Claim 6, wherein the injection means comprises a hollow needle fixed on a member which is releasably secured to said one end of the body member, and which has an opening therethrough aligned with the hollow space of the needle.

8. A projectile according to Claim 7, wherein the hollow needle is arranged to retain the drug, medicine or the like within the body member by means of capillary action.

9. A projectile according to any of Claims 6 to 8, wherein the puncture means comprises a piston which is movable in the hollow body member, has a peripheral sealing arrangement and is designed to be a tight fit.

10. A gun incorporating apparatus according to any of claims 1 to 5, the gun having a bore for projection of a missile therefrom whereby, upon firing of the gun, relative movement occurs between the puncture means and the reservoirto break the seal of the latter and project the missile by means of the pressurised gaseous medium.

11. Propellant apparatus substantially as hereinbefore described with reference to the accompanying drawings.

12. Any novel subject matter combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.