NZ248878A - Drench gun for dispensing variable volumes of drench: piston rod has helically arranged stops - Google Patents

Description

patents Form # 5. 248878 NF.W ZEALAND Patents Act 1953 C.OMPI/RTK SPECIFICATION TITLE: Drench Gun We, Simcro Tech limited Address: 23 Bandoti Street, Hamilton, New Zealand Nationality: New Zealand hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: PF05.JWP FEE CODE - 1050 248878 This invention relates to drench guns, which expression includes manually operable positive displacement pumps adapted, when operated, to administer a predetermined volume of liquid to an animal, either internally or externally.

According to one aspect of the invention, there is provided a drench gun including at least one valve to allow passage of liquid therethrough in one direction but to inhibit flow of said liquid therethrough in the opposite direction, the valve including a static element, for attachment to the drench gun, a mobile sealing element and spring means to bias the mobile element against a portion of the gun and in which the static and mobile elements and the spring means are formed as an integral body of the same material.

Preferably said at least one valve is formed as a moulding of a flexible plastics material.

Conveniently, the gun includes two of said valves, a first being an outlet valve and a second being an inlet valve and in which the inlet valve is formed integral with a piston of the gun.

According to another aspect of the invention, there is provided a drench gun including a piston slidable in a cylinder, to pump liquid through the gun, the volume of liquid displaced by each stroke of the piston being determined by stop means limiting the travel of the piston and in which part of the stop means at one end of the travel is adjustable in position so as to define a selected quantity or dose of the liquid.

Preferably, the piston is mounted on a piston rod reciprocable in and out of the gun, the piston rod passing though a static member, the piston rod carrying another part of the stop means thereon, positioned to abut the said member at one end of the piston travel.

Conveniently, said another part of the stop means includes a plurality of protrusions on the piston rod, the ends of the protrusions facing the static member being at different distances along the piston rod, the static member being formed with internal grooves into which the protrusions can pass, the static member being indexable circumferentially relative to the piston rod and in which one of said grooves is omitted whereby a selected one of said protrusions will abut the face of the static menaberJo i limited the travel of the piston rod. 4 ^ (869KAM.896/bs/ms ■ - £ 5 1 V ^ 24887 The protrusions may be arranged in a helix on the piston rod, and are preferable within the gun.

According to another aspect of the invention, there is provided a drench gun including an oil reservoir associated with a piston thereof and means for replenishing said oil reservoir without dismantling said drench gun.

Preferably the drench gun includes an oil hole through which oil can be introduced, means to inhibit access of the oil hole to the reservoir in a normal mode of operation of the drench gun, and to allow access of the oil hole to the reservoir when required.

The drench gun may include a stop means to inhibit travel of the piston as far as the oil hole in said normal mode of operation and to allow travel of the p:.ston as far as the oil hole, when required.

Advantageously, the drench gun includes a tongue or similar protrusion on the piston or a member affixed thereto, the tongue or protrusion being adapted to abut an end face of a member of the gun which is axially static in said normal mode of operation and to enter a pocket, cavity or recess in said end face when access to the piston through the oil hole is required.

Alternatively, the drench gun may include a tongue or similar protrusion on a member of the gun which is axially static, the tongue or protrusion being adapted to abut an end face of the piston or of a member affixed thereto in said normal mode of operation and to enter a pocket, cavity or recess in said end face when access to the piston through the oil hole is required.

Preferably, the drench gun includes a cylinder in which the piston is slidable, the cylinder being fastened partly inside a co-axial bore in a handle part of the gun by a bayonet fixing of which at least two spigots protrude outwardly from the cylinder and engage in L-shaped slots in said co-axial bore, and in which at least one of said spigots protrudes into or through and open hole at the end of one of the L-shaped slots, and in which the oil hole is through the one of said spigots into the cylinder.

The cylinder may be fastened partly inside a co-axial bore in a handle part of thejgun, in which a plurality of flexible fingers forming part of said indexable sta^A^hib^x '''* St-X. — a 6869HAM.896/b*/ms ^ jggg ^ 248878 protrude into the co-axial bore and ribs on said fingers are caught behind a shoulder formed in said bore and in whita part of the cylinder inside the co-axial bore is a close fit within said flexible fingers, to inhibit inward flexure of said fingers clear of said shoulder.

Conveniently, a short flexible finger forming part of said indexable static member is positioned between two of said plurality of flexible fingers, the short finger not protruding as far as the part of the cylinder, so as to remain flexible, the short finger and part of the bore in the handle part of the gun being formed with a plurality of circumferential detent means, whereby the indexable static member can be indexed positively to set the selected quantity or dose of the liquid.

Preferably a or the piston is fastened onto a piston rod therefor by means of a bayonet fixing having two opposite pegs engaged in mating L-shaped grooves and in which one of said pegs and the mating groove is larger than the other peg and mating groove, whereby the piston and piston rod can be fitted together in only one circumferential position.

One embodiment of the invention is described, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a side view of a drench gun, according to the invention, Figure 2 is a section along the line II - II in Figure 1.

Figures 3,4 and 5 are perspective views at enlarged scale of three components shown in Figure 2.

Figure 6 shows part of Figure 2 at enlarged scale, and Figure 7 shows another part of Figure 2, at enlarged scale.

In the drawings, a drench gun, as hereinbefore defined, includes a handle 10 to the bottom of which is pivoted the bottom of a trigger member 11. The upper end of the handle 10 is integral with a substantially cylindrical body 12 from which protrudes a coaxial transparent chamber 13. A nozzle 14 is fastened coaxially on the end of the chamber 13 remote from the body 12, conveniently by a threaded connection. N - / '•» ^ .-/ *• \\ -— <"> SEP 1996 " xPE1V* w ~ ^ r mad £B69KXM.696/bs/ms The handle 10 and trigger member 11 are of U-secdon and the arms of a hair-pin type spring (unshown) are located therein, to urge the trigger member 11 away from the handle 10. The bottom of the trigger member 11 carries a pair of outwardly facing spigots 50, which are sprung into holes 51 in the bottom of the handle 10, to act as the pivot.

An outlet valve 15, shown particularly in Figures 4 and 6 comprises an integrally formed plastics moulding having an annular flange 16 trapped between a shoulder on the nozzle 14 and the end of the chamber 13.

As shown in Figures 4 and 6, a first cylindrical portion 17 extends from the flange 16, and is a close fit in a bore 23 of the chamber 13, whereby the outlet valve 15 is radially located therein. A pair of curved diametrically disposed arms 18 carry a second cylindrical portion 19 closed by a diaphragm 20 adjacent the arms 18. A cruciform or three-lobed section locator 21 extends from the diaphragm 20 and is a sliding fit in a coaxial bore 22 in the outlet of the chamber 13. The internal surface of the chamber 13 between the bores 22,23 includes a conical portion 24, against which the free end of the second cylindrical portion 19 of the outlet valve 15 is urged by the arms 18, which also act as springs. Thereby, the free end of the second cylindrical portion 19 is sealed against the conical portion 24.

When the pressure within the chamber 13 becomes less than the pressure within the nozzle 14 the sealing of the second cylindrical portion 19 to the conical portion 24 inhibits the flow of any liquid or air from the nozzle 14 into the chamber 13. The spring arms 14 apply sufficient force to prevent fluid from escaping from the chamber 13 under the force of gravity. However, as the pressure within the chamber 13 is raised, the consequent axial force on the diaphragm 20 becomes greater that the axial force exerted by the arms 18, so that the latter flex, allowing the second cylindrical portion 19 to move axially from the conical portion 24, whereby the contents of the chamber 13 can be discharged through the nozzle 14.

As shown particularly in Figure 7 the right hand end of the body 12 carries an externally ribbed dose adjustment member 25 which can be rotated on the body 12 to a plurality of predetermined angular positions. The centre of the member 25 is formed as a bearing 26 in which a hollow piston rod 27 is slidable. The right hand end of the tl«K*2.l»4/b*/iu 24887 piston rod 27 is formed as a hose connection 28. The piston rod 27 is connected to the upper end of the trigger member 11, whereby movement of the trigger member J.l. A pair of inwardly-facing sprigots S3, moulded relative to the handle 10 moves the piston rod 27 in and out of the body 12.

Figure 1 shows that the piston rod 27 passes through an elongate aperture 52 in the top of the trigger tr.ember 11. A pair of inwardly-facing spigots 53, of different diameters moulded intejral with the trigger member 11, engage in transverse grooves 54, reflectively matching the unequal sprigot 53 in either side of the piston rod 27. Thereby, the piston rod 27 is driven back and forth by movement of the trigger member 11, the grooves 54 accommodating the fact that movement of the trigger member 11 is arcuate, while the piston rod 27 moves in a straight line.

The left hand end of the piston rod 27 has affixed thereto a combined piston 29 and inlet valve 30, all formed as a single integral plastics moulding. The piston 29 comprises a spigot 31 fastened on the outside of the piston rod 27 and a pair of discs 32 which are a sliding fit in the bore 33 of the chamber 13. Each disc 32 is formed with an outwardly directed flexible sealing lip 34., bearing and sealing against the bore 33 of the chamber 13. The spigot 31 also carries a pair of arms 35, which act in a manner analogous to the arms 18 and carry the inlet valve 30. The latter is identical in construction to the outlet valve 15, being a sliding fit in the bore 36 of the piston rod 27 and having a flexible third cylindrical portion 37 urged by the arms 35 into sealing engagement with a conical surface 38 extending from the bore 36. The outlet valve 15 may be smaller than the inlet valve.

When the piston rod 27 is moved to the left, the rise in fluid pressure in the chamber 13 urges the third cylindrical portion 37 to move firmly against the conical surface 38. Conversely, when the piston rod 27 is moved to the right the reduced pressure in the chamber 13 causes the inlet valve 30 to open, whereby liquid can be drawn into the chamber 13 through the piston rod 27.

Clearly, the volume of the dose of liquid displaced from the chamber 13 through the nozzle 14 is proportional to the travel of the piston rod 27. The volume of the dose can be selected by providing a series of stops positioned at different axial positions along the piston rod 27. As seen in Figure 3 the stops comprise short lengths of helically MIKIi.lM/tll/u 2.4 8 B 7 located splines 39.

The bearing 26 in the dose adjustment member 25 is formed with circumferentially spaced axial grooves through which the splines 39 can pass, except that one of the grooves in the bearing 26 is omitted so that the spine 39 which is aligned with the missing groove will abut the external face of the bearings 26 and inhibit further left hand movement of the piston rod 27. By indexing the member 25 circumferentially on the body 12 the missing v/oove can be aligned with any one of the spines 39, so mat different axial travels of the piston rod 27 can be selected. By this arrangement pre-programmed multi-dose applications are possible. For example, an animal may have 2 ml applied to its ears, then 5 ml applied to the top of its head followed by 20 ml applied to its back. These different settings can be selected quickly and accurately and enable these various quantities to be applied successively by sequential movements of the piston rod 27 to the left The valves 15,30 and piston 29 are preferably made of a suitable plastics material having an adequate degree of flexibility and a good memory, such as acetal, nylon, polypropylene or a thermoplastic rubber. More than two of the arms 18, 35 may be used, if required.

For ease of tooling, moulding, assembly and dismantling, the piston rod 27 has bayonet slots 40 into which corresponding protrusions 41 on the piston 29 are fitted. Flats 42 are formed on the discs 32 for holding the piston 29 during fitting and dismantling.

The piston 29 is lubricated by oil injected through a hole 63, for which purpose the piston 29 can be retracted fully until the groove 44 between the discs 32 is aligned with the oil hole 63. The groove 44 may include oil-retaining felt or similar material. The flats 42 enable oil to pass to and from the small annuli between the discs 32 and sealing Hps 34. Since oil is trapped between the sealing lips 34, the action is lubricated with each stroke. Furthermore, because the oil can be readily replenished without dismantling the gun, a light action ensues, resulting in low hand fatigue. As can be seen particularly in Figure 7, the dose adjustment member 25 is formed with a circumferential ring of alternating long and short flexible fingers 55,56. The long fingers 55 spring outwardly, as the member 25 is pushed into engagement with the body 12, and become trapped behind a shoulder 57 thereon. A pair of diametrically «MIC«2.IS4/bt/a* 249378 opposed outward-facing spigots 58 on the outside of the chamber 13 comprise a bayonet fitting in slots within the body 12. After the member 2.5 has been pushed home into the body 12, the chamber 13 is fastened into the body 12 so that a skirt 59 at the end of the chamber 13, lies inside the long fingers 55 to prevent them springing inwards.

The &L. :t fingers 56 are formed with longitudinal ridges 60, which engage in grooves 61 with sloping sides, in the body 12. Thus, the member 25 can be indexed positively from one volume setting to the next. The serrated outer portion of the member 25 has a hole through which the various volume setting markings can be seen. The markings are made on the surface 62 of the body 12 or on a loose interchangeable ring circumferentially fixed thereon.

One of the spigots 58 has an oil hole 63 therethrough, for lubrication of the piston 29. The bearing 26 carries a tongue 64 which in general abuts the end face of the spigot 31 when the trigger member 11 is not operated. In this position, the piston lip 34 does not pass the oil hole 63. However, when the member 25 is rotated to a position indicating "oil", the tongue 64 is aligned with and enters a pocket 65 in the spigot 31, thus allowing the piston to move further towards the member 25, whereat the oil hole 63 is opposite the piston 29.

One of the protrusions 41 and the matching bayonet slot 40 are larger than the others, so that the piston 29 can be assembled onto the piston rod 27 in one orientation only, this ensures that the tongue 64 is aligned with the pocket 65 at the required angular position of the adjustment member 25.

Finally, it will be appreciated that various alterations or modifications may be made to the foregoing without departing from the spirit or scope of this invention. 61C9CS2•I94 /bfl/u 24 8®^

Claims (18)

WHAT WE CLAIM IS:

1. A drench gun including a piston slidable in a cylinder, to pump liquid through the gun, including an oil reservoir associated with the piston therein and means for replenishing said oil reservoir without dismantling the drench gun.

2. A drench gun according to claim 1 including an oil hole through which oil can be introduced, means which optionally prevents communnication between the oil hole and the reservoir in a normal mode of operation of the drench gun, or allows communication between the oil hole and the reservoir when required.

3. A drench gun according to claim 2, including a stop means which optionally inhibits travel of the piston as far as the oil hole or allows travel of the piston as far as the oil hole when required.

4. A drench gun, according to claim 3, including a tongue or similar protrusion on the piston or a member affixed thereto, the tongue or protrusion being adapted to abut an end face of a member of the gun which is axially static or to enter a pocket, cavity or recess in said end face when access to the piston through the oil hole is required.

5. A drench gun, according to claim 3, including a tongue or similar protrusion on a member of the gun which is axially static, the tongue or protrusion being adapted to abut an end face of the piston or of a member affixed thereto or to enter a pocket, cavity or recess in said end face when access to the piston through the oil hole is required.

6. A drench gun according to any of claims 1 to 5, the cylinder being fastened partly inside a co-axial bore in a handle part of the gun by a bayonet fixing of which at least two spigots protrude outwardly from the cylinder and engage in L-shaped slots in said co-axial bore, and in which at least one of said spigots protrudes into or through an open hole at the end of one of the L-shaped slots, and in which the oil hole is through the one of said spigots into the cylinder. 6869HMt.297/ba/aw -10- 24 8 8 78

7. A drench gun according to any preceding claim including at least one valve to allow passage of liquid therethrough in one direction but to inhibit flow of said liquid therethrough in the opposite direction, the valve including a static element, for attachment to the drench gun, a mobile sealing element and spring means to bias the mobile element against a portion of the gun and in which the static and mobile elements and the spring means are formed as an integral body of the same material.

8. A drench gun according to claim 7 in which said at least one valve is formed as a moulding of a flexible plastics material.

9. A drench gun according to claim 7 or 8 in which the gun includes two of said valves, a first being an outlet valve and a second being an inlet valve and in which the inlet valve is formed integral with the piston of the gun.

10. A drench gun according to any preceding claim, the volume of liquid displaced by each stroke of the piston being determined by stop means limiting the travel of the piston and in which part of the stop means at one end of the travel is adjustable in position so as to define a selected quantity or dose of the liquid.

11. A drench gun according to claim 10, in which the piston is mounted on a piston rod reciprocable in and out of the gun, the piston rod passing through said member of the gun which is axially static, the piston rod carrying another part of the stop means thereon, positioned to abut the said member at one end of the piston travel.

12. A drench gun according to claim 11 in which said another part of the stop means includes a plurality of protrusions on the piston rod, the ends of the protrusions facing the static member being at different distances along the piston rod, the static member being formed with internal grooves into which the protrusions can pass, the static member being indexable circumferentially relative to the piston rod and in which one of said grooves is omitted whereby a selected one of said protrusions will abut the face of the static member to limited the travel of the piston rod. 6869KMf.297/bs/ma

13. A drench gun according to claim 12 in which said protrus 248 878 - 11 - helix on the piston rod.

14. A drench gun, according to claim 13, in which the protrusions are located within 5 the gun.

15. A drench gun, according to any of claims 12 to 14: in which the cylinder is fastened partly inside a co-axial bore in a handle part of the gun, in which a plurality of flexible fingers forming part of said indexable static member 10 protrude into-the co-axial bore and ribs on said fingers are caught behind a shoulder formed in said bore and in which a part of the cylinder inside the co-axial bore is a close fit within said flexible fingers, to inhibit inward flexure of said fingers clear of said shoulder. 15

16. A drench gun, according to claim 15, in which a short flexible finger forming part of said indexable static member is positioned between two of said plurality of flexible fingers, the short finger not protruding as far as the part of the cylinder, so as to remain flexible, the short finger and part of the bore in the handle part of the gun being formed with a plurality of circumferential detent 20 means, whereby the indexable static member can be indexed positively to set the selected quantity or dose of the liquid.

17. A drench gun, according to any preceding claim, in which a or the piston is fastened onto a piston rod therefor by means of a bayonet fixing having two 25 opposite pegs engaged in mating L-shaped grooves and in which one of said pegs and the mating groove is larger than the other peg and mating groove, whereby the piston and piston rod can be fitted together in only one circumferential position. 30

18. A drench gun, constructed and arranged and adapted to operate substantially as described herein and as shown in the accompanying drawings. Reference has been SIMCRO TECH LIMITED directed, in By their attorneys pursuance of sectio: 35 JAMES WPIPER & CO J6!1 )4.of oco 4, Patents Act 1953, Assistant Conrntxssiorfe&K 6B69MAM. 696/bs/ma PatetttS ' ^ END OF CLAIMS e■ J