GB2236055A

GB2236055A - Injection device

Info

Publication number: GB2236055A
Application number: GB9020667A
Authority: GB
Inventors: Hugh Robert Dent
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-09-22
Filing date: 1990-09-21
Publication date: 1991-03-27
Also published as: AU6304290A; GB9020667D0; GB8921455D0

Abstract

The device, which is used in the treatment of animals, comprises a handle 10, a barrel assembly 11 directly connected and secured to the handle and comprising a hollow plastics cylinder 12 to receive the liquid to be injected, a piston assembly 16 reciprocable within the barrel assembly and an operating lever 24 connected between the handle 10 and the piston assembly 17, the barrel assembly being formed with a socket 29 for attachment of an outlet tube 32 or an injection needle. One and 13 of the cylinder 12 may be externally screw-threaded for receipt in an aperture in the upper end of the handle, a flange 15 on the cylinder abutting the surface of the handle when the cylinder is fully screwed in. The cylinder may be of translucent polypropylene. <IMAGE>

Description

"ImDrovements in or relating to Infection Devices" The invention relates to injection devices and in particular to devices for use in the treatment of animals, such as farm livestock.

The invention relates to injection devices of the kind comprising a handle, a barrel assembly mounted on the handle, to receive the liquid to be injected, a piston assembly reciprocable within the barrel assembly, manipulating means connected to the piston assembly whereby it may be reciprocated in the barrel assembly, and means for mounting an outlet device on the barrel assembly. The outlet device may be an elongate tubular nozzle so that the injection device may be used for giving oral drenches to livestock, or it may be in the form of a hollow needle so that the device may be used for giving an animal a subcutaneous injection.

Known injection devices of this general type are fairly complex in construction and therefore comparatively costly to manufacture. For example, the barrel assembly usually comprises a hollow casing or frame which is secured to the handle and which contains a separate cylinder to receive the liquid to be injected and in which the piston assembly reciprocates. Also, the piston assembly itself usually comprises a number of parts assembled together including, for example, a piston provided with peripheral O-ring seals to sweep the internal surface of the cylinder.

The present invention sets out to provide a simplified construction of injection device which is assembled from fewer components and which may thus be cheaper and easier to manufacture. An injection device according to the invention may also be largely formed of plastics material.

According to the invention, an injection device of the kind first referred to is characterised in that the barrel assembly comprises a hollow cylinder of plastics material the interior surface of which is swept by a piston member of the piston assembly, the cylinder being directly connected and secured to the handle and being formed, at the end thereof remote from the piston assembly, with said means for attaching an outlet device thereto.

Since the cylinder containing the piston assembly is itself directly connected to the handle and has the outlet device directly connected to itself, there is no requirement for the separate housing or frame of the prior art devices, nor for the necessary seals between the cylinder and such housing or frame.

In order to secure the cylinder to the handle, one end of the cylinder, or a part secured thereto, may be entered into an aperture in the handle, means being provided to retain the end of the cylinder in the handle. The handle may also be formed from plastic material. The cylinder may be formed, adjacent said one end, with an outwardly projecting element, such as a peripheral flange, to limit the extent to which the end of the cylinder may be entered into the aperture in the handle.

In a preferred embodiment, the end of the cylinder and the aperture in the handle are formed with inter-engaging screw threads so that the cylinder may be secured by screwing it into the aperture in the handle.

The means for mounting an outlet device on the cylinder may comprise a socket formed in one end of the cylinder, and communicating with the interior thereof, into which socket said outlet device is received, in use.

Preferably the cylinder is formed from translucent plastics material, and in this case the outer surface of the cylinder may be formed with a longitudinal scale indicating the volume of the cylinder.

In any of the above arrangements the piston assembly may comprise a piston which sweeps the interior surface of the cylinder, and an operating plunger connected to the piston and extending out of the end of the cylinder.

The piston and plunger may be integrally moulded from plastics material, and in this case the plunger may comprise an elongate tubular member, the piston comprising an integral enlargement at one end of the tubular member.

The piston may include two substantially conical resilient flanges extending outwardly from one end of the plunger, the flanges being inclined in opposite directions with respect to the longitudinal axis of the plunger.

In any of the above arrangements spring means are preferably provided to bias the piston assembly to an inoperative position. For example the spring means may comprise a helical compression spring located within the cylinder and disposed between a fixed abutment and the piston assembly.

The manipulating means for the piston assembly may comprise a lever pivotally connected at one end to the handle and engageable with the piston assembly, whereby pivoting movement of the lever relatively to the handle causes the piston assembly to be moved longitudinally. In this case the spring means may be connected between the handle and the lever. Preferably means are provided for adjustably limiting the pivotal movement of the lever relatively to the handle.

The following is a more detailed description of embodiment of the invention, reference being made to the accompanying drawings in which: Figure 1 is a diagrammatic longitudinal section through an injection device according to the invention, and Figure 2 is a longitudinal section through part of an alternative form of device employing a different type of piston assembly.

The injection device comprises a handle 10 which may conveniently be moulded from plastics material. Secured to the upper end of the handle 10 is a barrel assembly 11.

In accordance with the invention, the barrel assembly 11 comprises a cylinder 12 of plastics material, such as translucent polypropylene.

One end of the cylinder 12 is externally screw threaded as indicated at 13 and is screwed into engagement with corresponding screw threads 14 in an aperture in the upper end of the handle 10. The aperture extends only partly through the thickness of the handle 10 and the cylinder 12 is formed with an external peripheral flange 15 which abuts the surface of the handle 10 around the aperture when the end of the cylinder is fully screwed into the aperture.

A piston assembly 16 comprises an elongate tubular member 17 which passes through an aperture 18 in the handle 10 which is coaxial with the threaded aperture. At its end within the cylinder 12 the piston assembly has a piston member comprising a portion 19 of enlarged external diameter and outwardly diverging internal section. Integrally moulded with the portion 19 are conical resilient flanges 20 which are inclined outwardly in opposite directions to the longitudinal axis of the piston assembly and bear against the internal wall surface of the cy,linder 12.

At its end remote from the cylinder 12, there is secured to the tubular member 17 a tubular housing 21 which retains a spring-loaded non-return valve 22 within the end of the tubular member 17. The housing 21 has a reduced diameter portion 23 to which may be connected a flexible supply pipe for the liquid to be injected by the device.

A lever 24 is pivotally connected at 25 to the lower end of the handle 10, and at its upper end is formed with a stirrup 25 which engages the housing 21 on the end of the piston assembly. The stirrup 25 may be generally U-shaped so that the housing sits in it, or it may be formed with an aperture so as partly or totally to embrace the housing 21.

A flange 26 projects downwardly from the lower end of the handle 10 and receives an adjusting screw 27, the end of which bears against a corresponding flange 28 on the lower end of the lever 24.

The end of the cylinder 12 remote from the handle 10 is formed with a re-entrant tubular socket 29 in which is received an end portion 30 of an outlet assembly 31. The assembly 31 further comprises a cranked tube 32 and a spring-loaded non-return valve 33 is provided between the end of the tube 32 and the end portion 30.

A helical compression spring 34 is disposed within the cylinder 12. One end of the spring 34 abuts the closed end 35 of the cylinder, around the socket 29, and the opposite end of the spring 34 abuts one of the flanges 20 on the piston assembly.

The device operates as follows: By squeezing the lever 24 towards the handle 10 the piston assembly 16 is moved longitudinally of the cylinder 12. As previously mentioned, the end of the piston assembly is connected by a flexible tube to a supply of liquid to be injected. Initially the cylinder 12 and tube 17 are empty. As the lever 24 is first squeezed towards the handle 10, the piston moves to the left, as seen in the drawing, expelling air from the cylinder 12. When the lever 24 is released, the piston assembly and lever 24 are returned to the right under the action of the return spring 34. The reduction in pressure in the cylinder 12 closes the valve 33 and opens the valve 22, causing liquid to be drawn into the cylinder.

The next time the lever 24 is squeezed towards the handle 10 the valve 33 opens and the valve 22 closes so that the liquid previously drawn into the cylinder is expelled through the outlet tube 32. Upon release of the lever 24 the piston assembly again returns and the cylinder 12 is refilled with liquid so that the process may be repeated.

Adjustment of the screw 27 adjusts the initial position of the lever 24 relatively to the handle 10 and hence adjusts the initial position of the piston within the cylinder. This therefore regulates the quantity of liquid which is drawn into the cylinder and hence regulates the dose given to the animal. As previously mentioned the outer surface of the plastics cylinder 12 may be formed with a longitudinal scale indicating the volume of liquid corresponding to the various initial positions of the piston within the cylinder.

In the arrangement shown the outlet device 3t is of a form suitable for oral drenching of livestock, but it will be appreciated that other forms of device may be fitted into the socket 29 of the cylinder 12. In particular, the outlet device may be in the form of an injection needle.

Since the cylinder 12 constitutes both the operating cylinder and also a structural element of the device, the number of components is reduced compared with known devices where the barrel assembly comprises an operative cylinder contained within a structural housing or frame connected to the handle. Also, the cylinder 12 and piston assembly 16 may each be moulded in one piece from plastics material thus considerably simplifying the manufacture of these components and their assembly.

Simplicity is also achieved by the return spring being in the form of a simple, comparatively light, helical compression spring within the cylinder 12. In known arrangements the return spring has normally been in the form of a coil spring encircling the pivot between the lever and handle. Although such a spring might be used in the present invention, the internal compression spring indicated is preferred.

Although it is convenient to secure the end of the cylinder 12 to the handle 10 by screw-threaded engagement, as shown, the invention includes within its scope other forms of fixture. For example the end of the cylinder 12 may be attached within an aperture in the handle 10 by a bayonet-type fitting, or the handle may incorporate a collar or other part which may be clamped around the end of the cylinder to secure it to the handle.

Figure 2 illustrates, on an enlarged scale, an alternative form of piston assembly which is made up of three separate components instead of being integrally moulded in one piece as in the arrangement of Figure 1.

Referring to Figure 2, the plunger is in the form of a hollow moulded plastics tube 35 formed adjacent one end with a stepped enlargement of 36 which provides an annular shoulder 37 spaced a short distance from the end of the tube.

Abutting the shoulder 37 is a piston member 38 which is moulded from resilient plastics material and comprises a central annular portion 39 from the outer periphery of which extend two substantially conical resilient flanges 40 which are inclined in opposite directions with respect to the longitudinal axis of the tube 35 and bear in liquid-sealing manner against the internal surface of the cylinder 12.

The piston member 38 is kept in position on the end of the tube 35 by an annular plastics retaining collar 41 having a cylindrical portion 42 which frictionally engages the end of the tube 35 and is formed with an internal peripheral bead 43 which snaps into a peripheral groove extending around the end of the tubular member 35. The end of the retaining collar t41 is formed with a radial flange 44 which is of smaller diameter than the interior of the cylinder 12.

Claims

1. An injection device comprising a handle, a barrel assembly mounted on the handle, to receive the liquid to be injected, a piston assembly reciprocable within sthe barrel assembly, manipulating means connected to the piston assembly whereby it may be reciprocated in the barrel assembly, and means for mounting an outlet device on the barrel assembly, the barrel assembly comprising a hollow cylinder of plastics material the interior surface of which is swept by a piston member of the piston assembly, the cylinder being directly connected and secured to the handle and being formed, at the end thereof remote from the piston assembly, with said means for attaching an outlet device thereto.

2. An injection device according to Claim 1, wherein one end of the cylinder, or a part secured thereto, is entered into an aperture in the handle, means being provided to retain the end of the cylinder in the handle.

3. An injection device according to Claim 1 or Claim 2, wherein the handle is formed from plastics material.

4. An injection device according to any of Claims 1 to 3, wherein the cylinder is formed, adjacent said one end, with an outwardly projecting element, to limit the extent to which the end of the cylinder may be entered into the aperture in the handle.

5. An injection device according to Claim 4, wherein the outwardly projecting element is a peripheral flange.

6. An injection device according to any of Claims 1 1 to 5, wherein the end of the cylinder and the aperture in the handle are formed with inter-engaging screw threads so that the cylinder may be secured by screwing it into the aperture in the handle.

7. An injection device according to any of Claims 1 1 to 6, wherein the means for mounting an outlet device on the cylinder comprise a socket formed in one end of the cylinder, and communicating with the interior thereof, into which socket said outlet device is received, in use.

8. An injection device according to any of Claims 1 to 7, wherein the cylinder is formed from translucent plastics material.

9. An injection device according to Claim 8, wherein the outer surface of the cylinder is formed with a a longitudinal scale indicating the volume of the cylinder.

10. An injection device according to any of Claims 1 to 9, wherein the piston assembly comprises a piston which sweeps the interior surface of the cylinder, and an operating plunger connected to the piston and extending out of the end of the cylinder, the piston and plunger being integrally moulded from plastics material.

11. An injection device according to Claim 10, wherein the plunger comprises an elongate tubular member, the piston comprising an integral enlargement at one end of the tubular member.

12. An injection device according to any of Claims 1 1 to 11, wherein the piston assembly comprises a piston which sweeps the interior surface of the cylinder and an operating plunger connected to the piston and extending out of the end of the cylinder, the piston including two substantially conical resilient flanges extending outwardly from one end of the plunger, the flanges being inclined in opposite directions with respect to the longitudinal axis of the plunger.

13. An injection device according to any of Claims 1 to 12, wherein spring means are provided to bias the piston assembly to an inoperative position.

14. An injection device according to Claim 13, wherein the spring means comprise a helical compression spring located within the cylinder and disposed between a fixed abutment and the piston assembly.

15. An injection device according to any of Claims 1 to 14, wherein the manipulating means for the piston assembly comprise a lever pivotally connected at one end to the handle and engageable with the piston assembly, whereby pivoting movement of the lever relatively to the handle causes the piston assembly to be moved longitudinally.

16. An injection device according to Claims 13 and 15, wherein said spring means are connected between the handle and the lever.

17. An injection device according to Claim 15 or Claim 16, wherein means are provided for adjustably limiting the pivotal movement of the lever relatively to the handle.

18. An injection device substantially as hereinbefore described with reference to the accompanying drawings.