MXPA97006875A - Assortment device operated by reso - Google Patents

Abstract

The present invention relates to a needleless injector comprising: a first member attachable by the user, a second member that can move with respect to the first member, the second member has a liquid outlet for a liquid to be injected into a subject and an assortment member moving to eject the liquid through the outlet under the force of a spring that provides a storage of energy and damping means, comprising a viscous damping medium, operable to dampen the movement of the first member with respect to the second member

Description

SPRING-OPERATED ASSORTMENT DEVICE DESCRIPTION OF THE INVENTION This invention relates to an assortment device, which employs a spring (which may be, for example, metal or compressed gas) to push an assortment member to supply, for example, a dose of liquid, powder or liquid. lump. Spring-loaded jets are commonly used. For example, in the medical field, there are injectors automatically operated to supply medicines to the tissues. Generally, the device is placed on the patient's skin, and a release button is operated, which unlocks a pre-loaded spring that drives the hypodermic needle through the epidermis, and then pumps the medication into the tissues. At the time of release, the injector housing reacts against the mass of the driven piston in the reverse direction of the injection, ie, backs up. This is energy expended, although in the case of simple injectors, the recoil is resisted by the user's hand, and a greater proportion of the force of the spring is directed to move the needle and the medicament. More sophisticated devices aim to apply a predetermined force to the skin, so that the optimal positioning conditions are satisfied before the device can be operated. Examples of the latter can be found in the needleless injectors described in PCT / GB94 / 01608 (WO95 / 03844) by the inventor herein. In these examples, it is convenient to apply the force via a sleeve or ring acting through a spring, so that the user takes the sleeve or ring, and compresses the injector supply hole in the skin. When the displacement of the sleeve reaches a predetermined value corresponding to the desired contact force on the skin, it causes a release mechanism to operate, which performs the injection. At the time of release, the injector body, which is effectively "floating" within the operating sleeve, recedes from the injection site, reacting against the operating sleeve spring. This represents energy expended, since ideally, all the energy of the spring must be directed to direct the drug into the tissues, without moving the injector body in the opposite direction. It is possible to use a substantial spring to push the injector via the operating sleeve into the skin of the patient, and thus reduce recoil by engaging the injector body through the spring and the sleeve towards the mass of the user's hand. However, this results in an unacceptably high pressure on the skin and / or the trigger mechanism. For example, a needleless injector should be compressed in the skin with a relatively light force for a subcutaneous injection, otherwise the subcutaneous tissues are too compressed, resulting in an incorrect injection.

Other devices, which may employ pre-charged spring energy to deliver a metered dose of liquid or powder, include metered dose inhalers (MDI), automatic bactericidal dispensers, and guns. In all cases, when the user does not hold the device member on which the energy spring reacts, there is the potential for energy expenditure. Many of these devices are intended to be used individually, or they must be discrete, that is, small and lightweight, and it is important that the energy stored is efficiently used. According to the present invention, there is provided a device for dispensing a material or article comprising a mobile assortment member, to effect the assortment, under the force of a spring, which provides an accumulation of energy, and means of humidification, having a viscous wetting medium, to dampen the recoil of the device during the assortment. In a preferred embodiment, the invention is applied to a needleless injector. Significant improvements in the operating characteristics of an injector have been obtained by applying the contact force of the skin to the injector body via an operating sleeve coupled to the injector body through a highly viscous grease. The grease is soft enough to allow relatively slow displacement of the sleeve to operate the release mechanism, but at the time of release, the high viscosity grease prevents the rapid retraction of the injector body towards the operating sleeve. Of course, the injector is momentarily coupled to the operating sleeve, so that the combination tries to back off, but since at the time of release the user's hand is firmly holding the sleeve, most of the recoil is avoided, and it uses a greater proportion of the spring energy to supply the injectable product. An additional benefit that arises from the invention is that the risk of inadvertent operation is greatly reduced, since the operation of the trigger resulting from a sharply applied force (caused by the drop of the injector, clumsy handling, or an application too fast) is resisted by the wetting fat. In a preferred embodiment, a needleless injector having a cylindrical body is operated by compressing the discharge nozzle on the skin of the patient by operating in a concentric sleeve of narrow fit, which, when displaced relative to the injector body, releases the spring-loaded ram to perform the injection. A longitudinal groove in the wall of the injector body contains the high viscosity grease, and a cooperating wrench on the operating sleeve is a narrow sliding fit in the groove. A moderate pressure on the sleeve causes it to move on the injector body in a soft, cushioned movement; a fast movement is strongly resisted by the high viscosity grease, which inhibits the key of movement in the groove. When the injector "turns on", the injector body tries to react very quickly. However, it can only move a very small distance relative to the operating sleeve due to the grease, and thus it is coupled to the operating sleeve through said grease. The mass of the sleeve resists movement, and since the sleeve is held firmly by the user, the mass of the user's hand is added to that of the sleeve, thus further reducing the recoil movement. In the attached drawings Figure 1 shows a section on the longitudinal axis of a first embodiment of a needleless injector according to the invention, with the components positioned to show the device in mid section, Figure 2 is an enlarged portion of the injector shown in Figure 1, showing the slot and co-operation key, and the trigger mechanism before operation; Figure 3 is a section on the longitudinal axis of a second embodiment of the needleless injector, and showing the injector before use; and Figure 3a shows on a large scale a closure used in the Figure 3. With reference to Figure 1, which shows the first mode of the injector in a medium injection, the injector comprises an injector body 1, which is, in a close-up, placed inside, but free to slide longitudinally with with respect to an operating sleeve 2. The sleeve 2 has a safety latch 20 integral therewith and pivotal with respect to the rest of the sleeve through a live hinge 21. The closure is shown in the operating position in the Figures 1 and 2. The injector contains a medication cartridge 3, which is firmly attached to the body 1, and which has a piston 4 slidably located in seal form thereon, in contact with the medication 5. Considered from the extreme upper of Figure 1, the piston comprises a cylindrical portion, a cylindrical sealing portion of larger diameter, and a conical frusto portion. The cartridge 3 has a discharge orifice 6. Referring to Figure 2, which is an enlarged view of the trigger mechanism of the injector just prior to operation, the injector body 1 houses a helical compression spring 10, which pushes the a ram 11 in the direction of the arrow W, but the ram 11 has its movement restricted by a closure 8 which engages a slot 12 on the ram 11. The thrust of the ram 11 on the closure 8 is taken on one face 12 of the body 1, and the reaction of the spring 10 is taken on the face 14 of the body 1. The body 1 has a groove 15, and the operation sleeve 2 has a key 16, which is a narrow sliding fit within said groove . The groove 15 contains a viscous grease, which absorbs the relative movement of the key 16 in the groove 15: ipso facto, the relative movement between the sleeve 2 and the body 1 will be damped.

With reference to Figures 1 and 2, which show the safety latch already in the open position of the injector, it is operated by holding the operation sleeve 2 by hand, and, placing the hole 6 on the skin of the patient 7. , compressing in the direction of the arrow W. This causes the sleeve 2 to move relative to the body 1, causing a cam surface 9 to release the closure 8 from the slot 12 of the ram 11. The spring 10 accelerates the ram 11. rapidly in the direction of the arrow W, so that it hits the piston 4 in the cartridge 3 to supply the injectable product in a known manner. At the time of release, the spring 10 pushes the ram 11 in the direction of the arrow W, as described, but the spring also reacts on the body 1 on the face 14, so that the body 1 tries to move in the direction opposite to the arrow W. Two phases of reaction will be presented; the first at the time of release, when the reaction force that is on the body 1 is against the mass of the ram 11, and the second, when the reaction force is against the combined mass of the cartridge 3 and the body 1. However, this second reaction is within the closed combination of the firmly attached cartridge 3 and the body 1, and there are some losses. However, the first reaction represents a spent energy, and also tends to cause the body and cartridge combination to jump away from the injection site, thus breaking the hydraulic connection and resulting in the spillage of the medication. This first reaction is substantially reduced through the wetting fat in the groove 15. Many variations are possible in the described embodiment. For example, the wetting grease can be retained within a circumferential groove on the body 1, which is a narrow sliding fit within the operating sleeve 2 (see, for example, the embodiment of Figure 3). In all cases, it is simple to vary the viscosity or the stroke clearance to obtain the desired damping characteristics. More modifications to these characteristics are possible, using cutting agents or thickeners. The use of a wetting grease through which trigger release conditions apply results in a speed sensitivity, i.e., if the operator applies a very high operating thrust to trigger the nozzle, at least part This excessive force will be applied to the skin at the time of injection. However, in practice, the scale of forces applied by users is within sensible limits, and consistent results are obtained. The embodiment of Figure 3 is similar to that of Figures 1 and 2 in several aspects, and the elements in Figure 3, which correspond substantially to particular elements in Figures 1 and 2, are given the same reference numbers. , but increased by 100. In the embodiment of Figure 3, the mechanical spring used in the embodiment of Figures 1 and 2 is replaced by a compressed gas spring. This is provided through a cylinder 130, which is closed at its upper end and which contains gas, typically air, under a pressure, which is typically in the range of 5.5 MPa (56.24 kg / cm2) to 20.7 MPa (210.9 kg / cm2). The upper end of the ram 111 has a frusto-conical portion 131 and a flange 132 between which an O-shaped ring seal 133 is located. Before use, the ram 111 is held in the position illustrated by the latch 108 engaging in a slot in the ram, the upper surface of the slot forming a camming surface 109. The closure 108 is shown at a larger scale in Figure 3a. At this point, the closure can not move to the left, as it rests against the inner wall of the sleeve 102. The lower end of the cylinder 130 has an outwardly directed flange 130a, which allows the cylinder to be held holding the flange 130a below a flange 104a directed outwardly at the upper end of the coupling 140. The sleeve 102 is formed of an upper portion 102a, within which the cylinder is located, and a lower sleeve portion 102b. The sleeve portion 102b is connected to the coupling by interlocking screw threads 141, formed on the inner and outer walls of the sleeve portion 102b and the coupling 140, respectively. The hole 106 is sealed through an elastic seal 134, which is held in place by a seal carrier 135. The seal carrier 135 is connected to the lower sleeve portion 102b by a frangible union 136. As a precaution against accidental ignition, a release strip 137 is provided as the bottom portion of the upper sleeve portion 102a. The lower edge of the peel strip 137 abuts against a ring 142, which is attached to the outer surface of the coupling 140 or (not shown) integrally formed therewith. The function of the ring is to prevent downward movement of the sleeve portion 102a relative to the coupling 140, provided that the release strip 137 is present. Accordingly, the ring 142 does not need to extend completely around the periphery of the coupling, and may be replaced by one or more elements. An annular space 138 is formed in the inner wall of the sleeve 102. When the sleeve is adjacent to the cylinder 130, and the space is filled with the wetting grease (indicated diagrammatically by a succession of black bands), then the grease is in contact intimate both with the sleeve 102 and with the cylinder 130. It should be noted that although an annular space defined from the point of view of providing a particular location for the fat is desirable, it can be omitted and the fat simply greased on all or part of the outside of the cylinder 130 and / or inside the sleeve 102. When the embodiment of Figure 3 is to be operated, the user suddenly releases the seal carrier 135 into the frangible junction 136., which takes the seal 134 with it and exposes the hole 106.

The user then removes the detachable band 137, and holding the upper part of the sleeve 102 pushes the hole against the substrate (for example, the user's own skin), which is to be injected. This moves the upper sleeve portion 102a downward with respect to the lower sleeve portion 102b. This leads to the opening 130 in alignment with the closure 108, which is thus able to move laterally towards the opening under the influence of the force of the gas inside the cylinder 130 acting on the closure via the cam surface 109 formed in the ram 111. The injector in this way is turned on. As a precaution, in case the closure fails to move under the influence of the camming surface 109, an auxiliary cam surface 109a is provided on the inside of the sleeve portion 102a. As with the embodiment of Figures 1 and 2, the resulting recoil is damped by the wetting fat. By way of example only, the following are typical measurements for the embodiment of Figure 3: Diametral glare between the external diameter of the gas cylinder and the internal diameter of the sliding sleeve 0.05 mm Area of shear stress (that is, the cross section of the fat) approx. 375 mm2 Viscosity of fat 2.2 Kilopoise Moment of ram at impact 0.06kg.m / s Mass of sleeve portion 102a 1.3 g Ram mass 2.5 g Impact gap between ram and piston 4 mm Gas pressure 6.2 MPa Gas cylinder hole 5.0 mm Since fat has been discussed as a preferred damping medium, similar results can be obtained using air or oil damping devices, usually a cylinder-piston combination, ie a so-called "shock absorber", where a fluid substance it is flowed through a restriction, in order to resist movement. Other viscous damping devices employ a blade, or a plurality of blades, rotating in a damping means, for example air, and these can be used, if appropriate, for the particular application.

Claims (10)

1. - A needleless injector comprising a first member attachable by the user, and a second member having a liquid outlet for the liquid to be injected into a subject, and an assortment member that moves to expel the liquid to through said outlet under the force of a spring, which provides an energy storage, the first and second members being movable with respect to each other, and wetting means, which have a viscous wetting medium, operable to dampen the movement of said first member with respect to said second member.

2. A device according to claim 1, comprising a cartridge, which contains said liquid and has a free piston therein in contact with the liquid, the assortment member being in the form of an impact member pushed by the spring and temporarily retained by the closure, the impact member being movable in a first direction under the force of the spring to a first stroke of the free piston and then, to continue the movement of the piston in the first direction to eject a dose of the liquid through the liquid outlet.

3. A device according to claim 2, wherein the closure is arranged to be released by the movement of the first member with respect to the second member in the first direction. 4 - .

4 - A device according to any of the preceding claims, wherein said wetting means comprise a groove formed in one of the first and second members and having a wetting means therein, and an element, which is formed on the other of the first and second members and is arranged, during use, to travel through the viscous wetting medium to effect the damping.

5. A device according to any of the preceding claims, wherein said viscous wetting means is a grease.

6. A device according to any of claims 1 to 4, wherein said wetting means is an oil.

7 - A device according to any of claims 1 to 4, wherein said wetting means are air.

8 - A device according to any of claims 1 to 4, wherein said wetting means comprise a cylinder and piston arrangement forming a damper.

9. A device according to any of claims 1 to 4, wherein said wetting means comprise a device having at least one blade rotating in the viscous wetting medium.

10. - A device according to any of the preceding claims, wherein said spring is a mechanical spring. 1 - A device according to any of claims 1 to 9, wherein said spring is a compressed gas spring. 12. An adapted actuator, together with a cartridge, for forming a needleless injector, the needleless injector according to claim 2, or any of claims 3 to 11 as dependent of claim 2, minus the cartridge.