FR2474319A1 - Percutaneous injection pistol partic. for rapid mass vaccination - discharges high velocity liq. jet by trigger release of loaded spring - Google Patents

Abstract

The pistol has a very fine nozzle orifice through which a measured dose of the liq. is discharged at high velocity. The liq. is ejected by a piston which is suddenly displaced by trigger release of a powerful loaded compression spring. Retraction of the piston to the spring-loaded position is pref. by fluid power, e.g. from a foot pump. A liq. discharge chamber just behind ghe nozzle is fed at each cycle of the piston with a dose of liq. drawn from a renewable, exterior flask, pref. mounted on top of the pistol barrel. The liq. is conducted through passages in the pistol body via a shuttle sleeve around the piston to an intermediate chamber. The piston rod assembly has an intermediate, double-acting water collar which controls cyclic delivery of liq. from the intermediate chamber to the discharge chamber. The pistol is of simple, inexpensive design, and easy to use at great speed. It can be quickly sterilised by disinfectant liq. being pumped through; or easily dismantled for autoclaving.

Description

The present invention relates to a needle-less injection device for liquid medicinal substances.

 More specifically, the subject of the present invention is a jet injection device, intended for the needleless injection of medicinal substances by percutaneous route.

 It is known that the administration of certain medicinal substances, in particular vaccines, is often carried out collectively, for example during massive vaccination sessions, and it is advantageous, in particular in this case, to use an injection device without needle allowing to act quickly.

 A number of devices for injecting medicinal substances are already known, comprising a reserve of medicament, namely a bottle, an ejection chamber, the fixed front wall of which has a fine ejection nozzle and the rear wall of which is constituted by an ejection piston, means of communication between the reserve and the chamber, provided with suitable sealing means, for example valves or needles, as well as motor means, generally with spring returned by a fluid, for actuating the piston.

 The devices known up to now are often of complicated construction and do not allow easy sterilization of the parts in contact with the drug substance.

 In addition, the known devices have the disadvantage of not always ensuring sufficient accuracy of the volume ejected, since the transfer must be quickly carried out from the bottle to the ejection chamber over a relatively large distance and by passages narrow. In addition, air bubbles frequently occur, which is another cause of errors in the volume ejected.

The present invention proposes to remedy these drawbacks and to provide an injection device allowing the injection of an extremely precise volume and this at high speed.

 In addition, the invention proposes to provide such a device which is of simple construction and which has great ease of asepsis or sterilization.

The subject of the invention is a needle-less injection device for liquid medicinal substance, characterized in that it comprises, in a cylinder body,
(a) an ejection chamber whose front wall communicates with the outside, by means of a fine ejection passage, and whose movable rear wall is constituted by an ejection piston extended by a rod, said chamber ejection being located at the anterior end of said body,
(b) an intermediate chamber,
(c) passage means for the medicinal substance between a reserve of said substance and said intermediate chamber,
(d) passage means for the drug substance between said intermediate chamber and said ejection chamber,
(e) a valve, piloted by said rod, making it possible to open the passage between the intermediate chamber and the ejection chamber during at least the final part of the return movement of the ejection piston and to interrupt said passage during the final part of the ejection movement of the ejection piston, and
(f) means for depressurizing the ejection chamber with respect to the intermediate chamber during said final part of the return movement of the ejection piston, so as to fill said ejection chamber,
and by the fact that it includes:
(g) on said cylinder body a seat intended to receive a reserve of said medicinal substance, and
(h) motor means actuating the ejection piston.

The expression "the final part of the movement of a piston, used above, does not necessarily designate here the last part of said movement. This expression has been used only to indicate that the driving of the valves controlled by the piston rod does not take place at the very beginning of the movement of said piston rod. Indeed, if the piston rod slides freely, practically without friction, inside the piloted valve, on the other hand the latter is mounted with friction in the cylinder in which it can slide, this friction being due to the seals with which it is provided. Consequently the piloted valve can slide in the cylinder in which it is mounted only when a stop of the piston rod comes into contact and involves in its movement.

The device comprising the elements (a) to (g) mentioned above constitutes an injection head
The seat for the reserve of drug substance is a receptacle mounted on the body of the injection head and having a shape suitable for receiving, for example, the end of an inverted vial containing the liquid drug substance to be administered. This seat is preferably provided with a double needle system intended to pierce the stopper of the bottle and to act as an air intake so as to put the bottle in communication with atmospheric pressure. Said seat further comprises passage means for the drug substance towards the cylindrical body of the injection head.

 In general, the passage means for the drug substance can be any; these are for example radial, annular, axial conduits, etc. and combinations of these conduits.

In particular embodiments, the device of the present invention may also have the following characteristics, taken individually or in combination:
- The piloted valve is constituted by a socket in which the rod of the ejection piston can slide freely between two stops, the contact with one of the stops allowing said rod to drive in its return movement said socket and the contact with the other stop allowing said rod to drive said sleeve in its forward movement while interrupting the passage of said medicinal substance between said intermediate chamber and said ejection chamber.

 According to a particular embodiment, the middle part of said ejection piston rod and the rear part of said sleeve have a shape capable of constituting a system of needle and corresponding conical seat, and the contact of said needle with said seat allows the rod to drive said sleeve forward while closing the passage for the drug substance between said intermediate chamber and said ejection chamber.

 - Said means for depressurizing the ejection chamber with respect to said intermediate chamber can be constituted by a valve located between the ejection chamber and said end ejection passage, said valve allowing the fluids to pass only in the direction ejection.

 In this case the "intermediate chamber is constituted by the means of communication between the reserve of medicinal substance and the cylindrical body of the injection head.

It has a fixed volume. The depression is created by the increase in the volume of the ejection chamber during the return of the piston, and, the communication between the ejection chamber and the intermediate chamber (that is to say here in practice between the chamber ejection and the reserve) being then opened, the drug substance passes into the ejection chamber under the action of atmospheric pressure.

- the front part of the cylinder body, comprising the ejection chamber, the ejection piston and its rod, the intermediate chamber, the piloted valve or valves and the seat for the reserve of medicinal substance, constitutes an injection head removable which can be coupled with said motor means, or uncoupled,
The coupling and uncoupling of the injection head with the driving means can be carried out using additional quick coupling means such as for example a coupling nose and a corresponding groove, or a ball snap in a corresponding circular groove, and / or a threaded ring and a corresponding male thread.

When the injection head is removable, its disassembly, for autoclave sterilization, for repair or possible replacement, is greatly facilitated.

 - Said motor means comprise a spring, an arming piston sliding in an arming chamber, means for bringing a pressurized fluid into said arming chamber so as to move said arming piston backwards by compressing the spring, means for holding said spring in the compressed position, and means for releasing said spring so as to project said cocking piston forward; said device comprises means for coupling said rod with said cocking piston.

 According to a particular embodiment, the cocking piston has an anterior extension, and the rear end of the rod of the ejection piston and the front end of said extension include complementary means for quick coupling allowing coupling and uncoupling of said rod and / or of said injection head.

 Said additional rapid attachment means are in particular those which have been mentioned above.

 - According to another embodiment, said means for maintaining said compressed spring comprise a non-return valve of the pressurized fluid, and said means for releasing said spring comprise a lever capable of being actuated manually and of acting on said valve to allow the return of the pressurized fluid.

Such an arrangement notably makes it possible to considerably simplify the trigger and trigger mechanism for actuating the device.

 - Said cocking piston has a rear extension constituted by a rod provided with at least one mark, the marks becoming in turn visible as the cocking piston moves back.

 The operator can thus adjust the recoil of the arming piston and therefore the volume of drug substance to be injected. Indeed, as long as he does not see the chosen reference appear, he knows that he must continue to actuate the means making it possible to bring the fluid under pressure into the cocking chamber.

 - Said pressurized fluid is a liquid and said means for supplying said pressurized liquid comprise a piston pump and a conduit connecting said pump to the arming chamber.

 Said piston pump can be actuated in any way (with a pedal, electrically, etc.) by the operator. The hydraulic pressure can be established by means of a piston pump actuated by a pedal, having a support with a lever-shaped pedal pivoted on the support, and a piston pump body capable of being quickly mounted on the support. thanks to receiving means such as guides of said support, the small arm of the lever formed by the pedal then being capable of actuating the piston of the pump. In order to take account of the possible deformation of the conduits between the pump and the arming device, which can occur over time, means for adjusting the volume of the arming chamber can be provided.

 According to a particularly advantageous embodiment, said piston pump comprises, next to the main chamber of the pump body, regulating means comprising a compensation chamber filled, like the main chamber, with said pressurized liquid, and connected to the main chamber through a narrow passage, said compensation chamber being constantly under the pressure of a secondary piston urged by a spring, said narrow passage opening into the main chamber a short distance from the rest position of the main piston.

 These means for regulating the volume of the fluid under pressure make it possible to compensate for example the deformation of the conduits or the micro-leaks. When the main piston is actuated, it closes the passage between the two chambers. When returning to rest, this passage is again uncovered towards the end of the return stroke of the main piston and, in the event of loss of liquid volume, additional liquid is automatically supplied from the compensation chamber.

- Said cocking piston is traversed by a rod whose rear end carries a nut forming a shoulder for the rear end of the cocking piston, so that the operation of said nut makes it possible to adjust the volume of the chamber d weaponry.

 It is thus possible to adjust the volume of the dose injected, or to compensate for example of possible deformations of the conduits between the pump and the arming device.

- Said means for holding said compressed spring comprise a spout allowing to immobilize by hooking an anterior extension of the cocking piston, and said means for releasing said spring comprise a lever or a trigger for detaching said spout, whereby said spring projects said arming piston forward which in turn actuates the ejection piston while forcing the fluid out of the arming chamber.

 The choice of the attachment point during manufacture allows the adjustment of the retraction of the arming piston and the dose of drug injected. In fact, if the quantity of fluid under pressure is insufficient, there will be no latching and the spring not being maintained, there will be immediately and spontaneously ejection of the insufficient dose introduced into the ejection chamber.

 The invention also relates to the engine means described above, making it possible to actuate the injection heads described, or any other injection head for injection devices without a needle.

Other advantages and characteristics of the invention will appear on reading the following description of certain particular embodiments, given by way of nonlimiting example, with reference to the appended drawings in which:
FIG. 1 represents a schematic view in partial section of an embodiment of an injection head according to the invention,
FIG. 2 represents a schematic sectional view of an embodiment of an actuation system of the device of the invention,
- And Figure 3 shows a view of an improved hydrautic pump that can power the device.

The device shown is in the form of an automatic injection gun intended for collective vaccination.

 The injection head shown has a hollow body 65 of generally cylindrical shape in which a piston 66 can slide, the front part 67 of reduced diameter having flats such as 68.

The junction wall between the rear part and the front part of the piston 66 forms a needle 69. In the front end of the piston is fixed a screw 70 whose head forms a stop and includes radial notches such as 71. The front part of the piston can slide in the bore of the piloted valve 72, the front end of which comprises a recess for housing the screw head 70. The rear end wall 73 of the piloted valve 72 forms a seat for the needle 69. A l the front end of the body 65 is fixed by screwing a bushing 74 containing a valve 75 moved by a spring 76, said valve allowing fluids (air, liquids) to pass only in the direction of ejection. The front end of the screw head 70 and
The rear end of the sleeve 74 and the valve 75 define an ejection chamber 77. At the front end of the sleeve 74 is fixed by screwing an injection nozzle provided with a filter 79 and having a fine passage 80 .

 The body 65 is surmounted by a seat 81 for the reserve of medicinal substance (such as an inverted bottle). In Figure 1 there is shown a removable protective cap 82 which can be placed on said seat 81 when the device is not in use. On the seat 81 is fixed a double hollow needle 83 making it possible to pierce the cap of the inverted bottle containing the medicinal substance during use, said double needle communicating on the one hand with an air intake 84 and with a chamber 85 which plays here with the conduit 87, the role of the intermediate chamber mentioned in the description of the present application. A filter gasket 86 makes it possible to avoid the introduction into the device, in particular of plug debris from the bottle containing the medicinal substance. The chamber 85 communicates with the cylindrical chamber of the body 65 via the conduit 87.

The rear end of the body 65 has a hooking spout 88 and is surrounded by a ring 89 internally threaded.

Reference is now made to FIG. 2, which describes the actuation system on which the removable injection head shown in FIG. 1 can be mounted. This actuation device comprises a cylindrical body 90 extended by a handle or stock 90a . In the cylindrical body 90 can move a piston 91 extended forward by the rod 92 and rearward by the rod 93.

The piston 91 is actuated by a hydraulic fluid (oil) arriving in the chamber 94, comprising a bleed screw 95, via the conduit 96 and the flexible conduit 97. The communication between these two latter conduits is done by means of a non-return ball valve 98, held by a spring 99, circulation in the direction of return can be effected by pressing on the pusher 100 actuated by the trigger 101.

 In the rod 92 is screwed the intermediate piece 102 which can slide in the chamber 103 produced at the front end of the body 90. A groove 104 in the piece 102 and a pin 105 prevent the rotation of the piece 102. In addition, the part 102 is provided with grooves complementary to the ribs which is provided with the rear end of the piston 66 of FIG. 1, as can be seen in the drawing.

 At the rear end of the body 90 is fixed a removable sheath 106 in which is housed a spring 107 resting at rest on a stop ring 108 intended to facilitate disassembly of the sheath. The rod 93 has a stop 109 making it possible to compress the spring 107 when the piston moves backwards. In addition, in the front end of the rod 93 is fixed a control rod 110 protruding from the sheath by a central orifice located at the rear end thereof. The control rod 110 has a mark 111.

The hose 97 is connected to a hydraulic pump, not shown.

 To set up the injection head shown in Figure 1 on the actuating device shown in Figure 2, simply hook the spout 88 in a corresponding groove in the front end of the body 90 and then screw the ring 89 on a corresponding external thread from the front end of the body 90. The piston 66 is then secured to the piston 91 by means of the rod 92 and the part 102.

The operation of the mounted device is as follows.

 Figures 1 and 2 show the position of the moving parts at the end of injection. By actuating the pump (not shown), the pressurized oil arrives via the non-return valve and the conduit 96 in the chamber 94 and pushes back the piston 91 which compresses the spring 107. When the mark 111 appears at the outlet from the central passage of the rear end 112 of the sheath 106, this means that the retraction of the piston is sufficient to allow the injection of the desired dose of the medicinal substance.

 In its rearward stroke the piston 91 has driven the piston 66. At the start of the recoil movement of the piston 66, the wall 69 moves away from the wall 73 because the part 72 remains stationary due to the friction against the body 65 This results in the opening of a passage for the medicinal substance between the conduit 87 and the conduit formed along the rod 67 thanks to the flat 68. When the piston 66 continues its recoil movement the screw head 70 abuts against the bottom of the recess provided at the front end of the part 72 which is then driven in the same recoil movement as the piston 66.

Because of this decline, the volume of the chamber 77 increases, but, the valve 75 not allowing air to pass from the outside, the chamber 77 is in depression relative to the intermediate chamber 85. The protective cap 82 having been removed and replaced by a bottle fitted with a drug substance before the start of the operation, said drug substance will flow, due to this depression, via conduit 87, the passage formed between the walls 73 and 69 which are spaced from each other, the flat 68 and the notches 71, and will fill the chamber 77. After the movement of the mobile assembly has receded, the operator presses the trigger 101 which by through the pusher 100 pushes the ball 98 to the right, which allows the return of the pressurized oil contained in the chamber 94 and in the conduit 96 to the hose 97 and the pump body. Under the action of the spring 107 the piston 91, the part 102 and the piston 66 are projected. brutally forward. At the start of this movement, the valve 72 remains stationary due to the friction against the body 65. But when the needle 69 comes into contact with the wall 73, the communication between the conduit 87 and the conduit formed by the flat 68 is interrupted, and the part 72 will then be pushed forward by the piston 66 which continues its movement. The volume of the chamber 77 decreases and the communication with the intermediate chamber being interrupted, the pressure inside the chamber 77 increases sharply, which has the effect of pushing back the valve 75, allowing the drug substance contained in the chamber 77 to pass into the ejection nozzle 78. Finally, the liquid substance is ejected in a powerful jet through the fine passage 80.

Referring to Figure 3. In the pump variant shown, the interior of the cylinder 58a of the pump forms the chamber in which the piston 57a actuated, via 56, for example by means of a pedal (not shown) ). A single conduit 45a goes to the device. Attached to the cylinder 58a is a compensating cylinder 61 communicating with the cylinder 58a by a thin transverse passage 62. In the cylinder 61 can slide a secondary piston 63 urged by a spring 64 so as to tend to decrease the volume of the chamber in the cylinder 61. When, starting from the starting position shown in the figure, the user presses the pedal, the piston 57a is driven upwards and quickly closes the passage 62. The liquid is then driven out through the conduit 45a. During the return of the piston 57a, if there is a loss of liquid (due for example to a micro-leak, or to a deformation of the flexible conduits), liquid is then brought from the cylinder 61 to the cylinder 58a to compensate for the loss of liquid and thus ensure in all cases the constancy of the action of the piston 57a and consequently of the injection volume.

 In addition, this arrangement also allows perfect adaptation to changes in volume caused either by mechanical deformation or by temperature variations.

Claims (14)

1. A needle-less liquid drug injection device, characterized in that it comprises, in a cylinder body 65,  (a) an ejection chamber (77) whose front wall communicates with the outside, by means of a fine ejection passage (80), and whose movable rear wall is constituted by an ejection piston ( 66, 67) extended by a rod, said ejection chamber being situated at the anterior end of said body,  (b) an intermediate chamber (85),  (c) passage means (83) for the drug substance between a reserve of said substance and said intermediate chamber,  (d) passage means (87, 68, 71) for the drug substance between said intermediate chamber and said ejection chamber,  (E) a valve (72), piloted by said rod, allowing to open the passage between the intermediate chamber and the ejection chamber during at least the final part of the return movement of the ejection piston and to interrupt said passage during the final part of the ejection movement of the ejection piston, and  (f) means (75, 76) for depressurizing the ejection chamber with respect to the intermediate chamber during said final part of the return movement of the ejection piston, so as to fill said chamber ejection, and by the fact that it includes:  (g) on said cylinder body a seat (81) intended to receive a reserve of said medicinal substance, and (h) motor means actuating the ejection piston. 2. Device according to claim 1, characterized in that said piloted valve (72) consists of a sleeve in which the rod (67) of the ejection piston can slide freely between two stops, contact with one of the stops allowing said rod to drive said sleeve in its return movement and contact with the other stop allowing said rod to drive said sleeve in its forward movement while interrupting the passage of said drug substance between said intermediate chamber (85) and said ejection chamber (77) #.  3. Device according to any one of claims 1 and 2, characterized in that said means for placing # 4 # n4319 vacuum the ejection chamber relative to said intermediate chamber are constituted by a valve (75) located between the ejection chamber and said end ejection passage, (80) said valve letting the fluids pass only in the direction of ejection.  4. Device according to any one of claims 2 and 3, characterized in that the middle part of said ejection piston rod and the rear part of said sleeve have a shape capable of constituting a needle system (69) and corresponding conical seat, (73) and that the contact of said needle with said seat allows the rod (66) to drive said sleeve (72) forward while closing the passage for the drug substance between said intermediate chamber (85) and said ejection chamber (77).  5. Device according to any one of the preceding claims, characterized in that the front part of the cylinder body (65) comprising the ejection chamber, (77) the ejection piston (67) and its rod, the intermediate chamber (85) the piloted valve or valves (72) and the seat (81) for the reserve of medicinal substance, constitutes a removable injection head which can be coupled with said motor means, or uncoupled.  6. Device according to any one of the preceding claims, characterized in that the said motor means comprise a spring, (107) an arming piston (91) sliding in an arming chamber, (94) means (96 , 97) for bringing a pressurized fluid into said cocking chamber, so as to move said cocking piston backwards by compressing the spring, means (98, 99) for holding said spring in the compressed position, and means (100, 101) for releasing said spring so as to project said cocking piston forwards, and by the fact that it comprises means (102) for coupling  said rod (66) with said cocking piston (91). 7. Device according to any one of claims 5 and 6, characterized in that the cocking piston (91) has a front extension, (92) and in that the rear end of the piston rod d ejection (61) and / or of the body of said injection head, and the front end of said extension (92) comprise complementary quick coupling means allowing the coupling and uncoupling of said rod and / or said injection head.  8. Device according to claim 7, characterized in that said complementary means are constituted by a hooking spout and a groove, or by a snap-on ball in a circular groove, and / or by a threaded ring and a male thread corresponding.  9. Device according to claim 6, characterized in that said means for holding said compressed spring comprise a non-return valve (98) of the pressurized fluid, and that said means for releasing said spring comprise a lever (101) capable of being actuated manually and of acting on said non-return valve to allow the return of the pressurized fluid.  10. Device according to any one of claims 6 and 9, characterized in that said cocking piston (91) comprises a posterior extension constituted by a rod (93) provided with at least one mark, (III) said marks becoming visible in turn as the cocking piston moves back. 11. Device according to any one of claims 6 to 10, characterized in that said pressurized fluid is a liquid and that said means for supplying said pressurized liquid comprise a piston pump and a conduit (97) connecting said pump to the arming chamber (94).  12. Device according to claim 11, characterized in that said piston pump comprises, next to the main chamber of the pump body, regulating means comprising a compensation chamber filled, like the main chamber, with said pressurized liquid , and connected to the main chamber by a narrow passage, (62) said compensation chamber being constantly under the pressure of a secondary piston (63) biased by a spring, (64) said narrow passage opening into the main chamber at low distance from the main piston rest position (57a). 13. Device according to claim 6, characterized in that said cocking piston (91) is crossed by a rod whose rear end carries a nut forming a shoulder for the rear end of the cocking piston, such so that the operation of said nut makes it possible to adjust the volume of the arming chamber.  14. Device according to any one of claims 6 and 13, characterized in that said means for holding said compressed spring comprise a spout making it possible to immobilize by hooking an anterior extension of the cocking piston, and that said means for releasing said spring comprise a lever or a trigger making it possible to unhook said spout, whereby said spring projects said arming piston forward which in turn actuates the ejection piston while forcing the fluid out of the armament.