GB2190590A

GB2190590A - Actuator mechanism for implanters

Info

Publication number: GB2190590A
Application number: GB08612271A
Authority: GB
Inventors: Roger Turley
Original assignee: Hundon Forge Ltd
Current assignee: Hundon Forge Ltd
Priority date: 1986-05-20
Filing date: 1986-05-20
Publication date: 1987-11-25
Anticipated expiration: 2006-05-20
Also published as: GB8612271D0; GB2190590B

Abstract

An actuator mechanism, particularly in an implanter for injecting pellets below the skin of an animal, includes a carriage 14 mounted in a gun-like housing 12, and an endless belt 18 extending around the carriage. One side of the belt is fixed at 32 to the housing and the other side to the inboard end of an actuator pin 16. A trigger 38 acts through linkages 30, 48 to move the carriage forward so as to propel the pin 16 forward at twice the speed. The pin then engages a pellet 60 and forces it through a hypodermic needle 58. An abutment 62 (Figures 4 to 7 not shown) is moved by the pin 16 during the final travel of the pin to assist withdrawal of the needle 58 and ensure that the pellet is at a given depth below the animal's skin. <IMAGE>

Description

SPECIFICATION Improved Actuator Mechanism for Implanters Field of Invention This invention concerns actuator mechanisms applicable particularly, but not exclusively, to implanters and an improved implanter incorporating such mechanism.

Although described in relation to implanters, the invention is of general application to any device in which the movement of a squeeze action trigger is to be magnified to produce a much greater linear travel of a plunger or like member.

Background to the Invention It has become commonplace to inject hormone materials below the skin of animals, to improve the growth and fattening process. The injection of such materials, usually in pellet form, has necessitated the development of implanters by which a veterinary surgeon or farmer can inject one or more pellets of the hormone material just below the skin.

Typically such implanters take the form of a gunlike housing having a trigger which on being squeezed forces a pin in a forward direction to inject one or more pellets through a hollow needle which protrudes forwardly of the housing and has a sharpened end for penetrating the animal's skin.

The principal difficulty with all such known devices has been that in order to produce a few centimetres of stroke of the pin, excessive movement of the actuating trigger has been required, making such units difficult to hold and operate with one hand, as is desirable.

It is an object of the present invention to provide an improved actuator mechanism for such devices (although it is to be understood that the invention is not in any way limited to use in such implanters) and to an improved implanter incorporating such a mechanism.

Summary of the Invention According to one aspect of the present invention an actuator mechanism by which a pin is moved in a forward direction by movement of a trigger in the opposite sense, comprises: 1. a lever mechanism linking the trigger to a carriage assembly for translating rearward movement of the trigger into forward linear movement of the carriage and vice versa, 2. an endless belt stretched between pulleys or like rolling members at opposite ends of the carriage, the belt having secured thereto a mounting for attachment to the inboard end of a plunger, 3. a slidewaywithin the carriage for the mounting to guide the latter and constrain it to move in a linear sense within the carriage, 4. a guide for the carriage to constrain the latter to move in a linear sense, and 5. means attaching the endless belt to a point which is fixed relative to the carriage guide, the point of attachment to the fixed point being equidistant from the point of attachment of the plunger mounting when measured around the length of the endless belt.

The guide for the carriage may be in the form of an elongate housing having guide means therein for constraining the carriage and causing the latter to move in a linear sense.

Where the carriage is located within a housing, the latter is preferably formed with an elongate groove through which a lug protruding from the carriage extends, to provide a point of attachment to the lever mechanism and to serve as a guide for the carriage within the housing.

Typically the fixed point to which the endless belt is attached is fixed in relation to the housing or forms partofthe housing: in one embodiment, the housing is approximately twice as long as the carriage and the fixed point is located approximately midway along the length of the housing.

The plunger conveniently comprises an elongate pin attached at one end to the mounting which is attached to the endless belt, and an aperture may be provided at one end of the guide, e.g. housing, within which the carriage is located to serve as a guide for the plunger pin.

As applied to an implanter, the housing containing the carriage and plunger pin is located in an upper region of a gun-like housing with the opening of the housing through which the plunger pin passes being situated to the rear of a chamber in which a pellet package can be located, forward movement of the plunger pin serving to displace pellets into and through a hollow sleeve in the form of a hypodermic type needle which protrudes from the forward end of the gun-like housing. The trigger and lever mechanism linking the trigger to the carriage is then located within the body of the gunlike housing, the trigger forming part of a handgrip.

The advantage of the invention over previous mechanisms is that not only does the lever mechanism magnify the rearward movement of the trigger, but the anchored endless belt further magnifies the movement of the carriage because for each unit of linear movement of the carriage in a forward direction, the plunger pin is displaced forwardly by two units.

The endless belt may be formed from stretch resistant material in which event the squeeze action is entirely positive.

Alternatively, the endless belt may be formed from a material having a natural stretch ability which will introduce a degree of shock absorption into the action.

Preferably a return spring acts on the lever mechanism to return the carriage and trigger mechanism into a rest position when the squeeze action on the trigger is released.

The invention is applicable to all types of implanter in which pelleted drugs or other materials are to be injected in a forward direction and may for example be incorporated into an implanter which includes a mechanism for reversing the action of the implanter during the implanting action so as to leave the pellets embedded at a given depth below the skin whilst withdrawing the cylindrical sleeve needle relative to the pellets.

The invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view, partly in section, of one embodiment of implanter in accordance with the invention, Figure a a cutaway view of the actuator mechanism of the implanter of Figure 1, with the carriage in its rearmost position.

Figure 3 is a view similar to Figure 2, with the carriage displaced to its forward position so as to fully advance the plunger pin, Figure 4 is a side view of a modified form of the implanter of Figure 1, which includes a mechanism for causing withdrawal of the sleeve needle during implanting., Figure 5 is a top view of the implanter of Figure 4, Figure 6 is a front end view in the direction of the arrow A in Figure 5 of the implanter shown in Figures 4 and 5, and Figures 7a, b and c illustrate functioning of the implanter of Figures 4,5 and 6.

Detailed Description of the Drawings Referring to Figures 1,2 and 3, the actuator of the invention is embodied within the linear actuator illustrated in Figures 2 and 3. This actuator comprises an elongate housing 10 which is located in the upper region of the gun-like housing 12 (Figure 1) and serves to accommodate a carriage 14 and an elongate plunger pin 16. The carriage includes an endless belt 18 to which is attached a mounting block 20 forming a fixing for the inboard end of the plunger pin 16.

One end of the housing 10 includes an aperture 22 through which the pin 16 protrudes, the aperture serving as a guide for the pin 16.

The endless belt 18 passes around two rollers 24 and 26 located at opposite ends of the carriage.

Protruding below the underside of the carriage is a lug 28 which protrudes through a slot (not shown) in the wall of the housing 10 so as to provide a guide for the carriage (to cause the latter to slide in a linear sense within the housing) and to provide a pivotal mounting pointfora rigid link30forming partofa lever mechanism for moving the carriage within the housing.

Lastly, a point on the endless belt is attached to an anchorage 32 (Figure 1) fixed with respect to housing 12 so that the belt is prevented from freely rotating around the rolling members 24 and 26 but can only be so rotated upon linear movement of the carriage 14.

A further guide for the carriage 14 is provided by two upstanding lugs 34 and 36 at opposite ends of the carriage which protrude through a second slot (not shown) formed in an opposed wall section of the housing 10 parallel to the first mentioned slot (not shown).

The advantage of the actuator shown in Figures 2 and 3 is that a unit of movement of the carriage produces two units of movement of the plunger pin 16.

As shown in Figure 1, a squeeze action trigger 38 is pivoted at 40 at the upper end of a handle 42 and although not shown, can be moved under a squeeze action into the section of the handle 42. In so doing, a pivoting lost motion connection 44 and 46 between the trigger 38 and lower end of a lever 48 transmits pivotal movement of the trigger 38 to the lever 48 which itself is pivoted about a fixed pivot 50. This causes the upper end of the lever 48 to rotate in the direction of the arrow B and the pivotal connection 52 between the upper end of the lever 48 and the link 30 causes the latter to move in a forward sense and pull the carriage 14 likewise in a forward direction.

A return spring 54 acting on the lever 48 acts to return the latter to its rest position with the carriage 14 at the rearmost position within its housing 10 on release of the trigger 38.

In Figure 2, the carriage 14 is shown towards its home position whilst in Figure 3 the carriage is shown in its displaced position in which the plunger pin 16 has been advanced almost to its maximum extent.

The movement of the trigger 38 is magnified on the one hand by virtue of the ratio between the pivots 50 and 52 and between the pivots 44 and 50, and additionally by virtue of the two to one magnification of the movement of the plunger pin 16 to the carriage 14.

As shown in Figure 1, a cartridge receiving bay 56 is provided between the forward end of the pin 16 and an aligned cylindrical sleeve needle 58 into which a cartridge 60 containing pelleted hormone material of the like can be fitted. When so fitted, forward movement of the pin 16 penetrates the rear of the cartridge 60 forcing pellets therein out of the forward end of the cartridge and into the hollow cylindrical sleeve needle 58 to be ejected from the forward end thereof with continued forward movement of the pin 16.

Figures 4to 7 illustrate an alternative implanter which is of particular application where it is essential that the pellets are located at a particular distance below the skin of the animal and are left in position on withdrawal of the implant needle and are not accidentally partially pulled out, as can sometimes be the case with the simple arrangement of implanter shown in Figures 1 to 3. The mechanism within the implanter of Figure 4 is identical to that of Figures 1 to 3 and the only difference lies in the addition of a horseshoe-like abutment 62 which straddles the needle 58 and is itself at its crown attached to a thrust pin 64 which extends through guides rearwardly in the housing of the implanter and is attached at its inboard end to a return spring 66. At the junction between the pin 64 and the spring 66 is an actuating lug 68 and the only modification required of the operating mechanism within the implanter is the provision of a thrust actuator 70 on the pin 16 which is positioned therealong so as to engage the actuating lug 68 when the pin 16 has been advanced to the position shown in Figure 7b. In this position the pellets 72 are located at the exit end of the cylindrical sleeve needle 58 and are at a correct depth within the animal.

The engagement of the actuators 68 and 70 at that point means that continued forward movement of the pin 16 does not result in continued penetration of the leading end of the pin 16 (and therefore further penetration by the pellets 72) but instead the horseshoe-like abutment 62 begins to move in the same direction as the advancing pin 16 and since it is in contact with the skin of the animal, the end result is a rearward displacement of the implanter housing 12', the pellets 72 remaining where they are and the sleeve-like needle 58 being withdrawn relative to the pellets.

Finally, in the position of maximum displacement, the sleeve-like needle 58 is withdrawn completely to the rear of the pin 16 and the pellets are completely abandoned within the skin of the animal so that normal withdrawal of the implanter does not affect the depth at which the pellets have been pushed.

Releasing the trigger 38' results in the return spring 54 within the handle, withdrawing the pin 16 and returning the carriage of the actuator to its normal home position.

The horseshoe-like abutment 62 is returned to its normal home position under the action of the return spring 66.

Although not shown in detail, the mechanism for holding the cartridge of pellets in position may conveniently comprise a displaceable rear end to the chamber 56 formed by an abutment 74 having a serrated upper edge 76 by which the latter can be gripped by the thumb and pulled rearwardly against a spring 78 which on being released returns the abutment 74 in a forward direction to grip the rear of a cartridge such as 60 which has been located in position.

Claims

1. An actuator mechanism by which a plunger is moved in a forward direction by movement of a trigger in the opposite sense, comprising:~ a) a lever mechanism linking the trigger to a carriage assembly for translating rearward movement of the trigger into forward linear movement of the carriage and vice versa, b) a belt passing movably around at least the forward end of the carriage, the belt being secured at one side to a mounting for attachment to the inboard end of a plunger so as to move the plunger forward,

c) retraction means acting on the mounting so as to retract the plunger, d) a slideway within the carriage forthe mounting to guide the latter and constrain it to move in a linear sense within the carriage, e) a guide for the carriage to constrain the latter to move in a linear sense, and f) means attaching the other side of the belt to a point which is fixed relative to the carriage guide.

2. A mechanism is claimed in claim 1, in which the guide for the carriage is in the form of an elongate housing having guide means therein for constraining the carriage and causing the latter to move in a linear sense.

3. A mechanism as claimed in claim 2 in which the carriage is located within the housing, which is formed with an elongate groove through which a lug protruding from the carriage extends, so as to provide a point of attachment to the lever mechanism and to serve as a guide for the carriage within the housing.

4. A mechanism as claimed in claim 2 or claim 3 in which the fixed point to which the endless belt is attached is fixed in relation to the housing or forms part of the housing.

5. A mechanism is claimed in claim 4, in which the housing is approximately twice as long as the carriage and the fixed point is located approximately midway along the length of the housing.

6. A mechanism as claimed in any preceding claim in which the plunger comprises an elongate pin attached at one end to the mounting which is attached to the belt, and in which an aperture is provided at one end of the guide, within which the carriage is located to serve as a guide for the plunger pin.

7. A mechanism as claimed in any preceding claim in which the belt is formed from a stretch resistant material, so that the squeeze action of the trigger is entirely positive.

8. A mechanism as claimed in any of claims 1 to 6 in which the belt is formed from a material having a natural stretch ability, which will introduce a degree of shock absorption into the action of the mounting movement.

9. A mechanism as claimed in any preceding claim in which the belt is endless and extends around rollers at opposite ends of the carriage, thereby constituting said retraction means.

10. A mechanism as claimed in claim 9 in which the fixed attachment print is substantially equidistant from the mounting point of the plunger mounting, as measured around the length of the endless belt.

11. A mechanism as claimed in any preceding claim in which a return spring acts on the lever mechanism to return the carriage and the trigger and lever mechanism into a rest position when the squeeze action on the trigger is released.

12. An implanterfor injecting pellets comprising an actuator or mechanism as claimed in any preceding claim, in which the housing containing the carriage and plunger is located in an upper region of a gun-like housing with the opening of the housing through which the plunger passes being situated to the rear of a chamber in which a pellet package can be located, forward movement of the plunger serving to displace pellets into and through a hollow sleeve in the form of a hypodermic type needle which protrudes from the forward end of the gun-like housing.

13. An implanter as claimed in claim 12 and further comprising an abutment extending about said hypodermic needle and being slidably mounted for movement with the plunger along the needle during the final part of the forward movement of the plunger, thereby assisting withdrawal of the needle while leaving an injected pellet embedded at a given depth.

14. An implanter as claimed in claim 13 in which the abutment includes a thrust member engageable with a corresponding member formed on the plunger, and spring means operable on the abutment to withdraw the abutment after the plunger has retracted.

15. An implanter as claimed in any of claims 12 to 14 in which the trigger and lever mechanism linking the trigger to the carriage is located within the body of the gun-like housing, the trigger forming part of a handgrip.

16. An actuator mechanism substantially as herein described with reference to, and as illustrated in, Figures 1 to 3 of the accompanying drawings.

17. An implanter for injecting pellets substantially as herein described with reference to, and as illustrated in, the accompanying drawings.