WO1980001539A1 - Needle free injection device for injecting medicinal liquid materials - Google Patents

Abstract

The injection device comprises: an ejection chamber (31) with an ejection piston (50) extended by a rod (32), an intermediary chamber (23), passage means (19, 20, 33) between the ejection chamber and the intermediary chamber and between the intermediary chamber and a reserve for said material, a valve (15, 16), actuated by said rod, allowing the opening of the passage between the intermediary chamber and the ejection chamber during at least the final part of the backward motion of the ejection piston and to interrupt said passage during the final part of the ejection motion of the ejection piston, means to bring to depression conditions (24, 29) the ejection chamber with respect to the intermediary chamber during said final part of the backward motion of the ejection piston so as to provide the filling of said ejection chamber, a seat (6) intended to receive a reserve of said medicinal material and driving means (34, 35, 36) for operation of the ejection piston.

Description

Device for needle-free injection of liquid medicinal substances.

The present invention relates to a needle-less injection device for liquid medicinal substances. More specifically, the present invention relates to a jet injection device, intended for needle-free injection of medicinal substances by percutaneous route.

We know 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 a device for injection without needle allowing to act quickly.

A number of devices for injecting medicinal substances are already known, including 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 consisting of 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, to activate 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 drawback of not always ensuring sufficient accuracy of the volume ejected, since the transfer must be rapidly carried out from the bottle to the ejection chamber over a relatively large distance and by narrow passages. In addition, air bubbles often occur, which is an additional cause. ejected volume errors.

The present invention proposes to remedy these drawbacks and to provide an injection device allowing both 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 an injection device without a needle for liquid medicinal substances, 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 mobile rear wall is cons

-'-- ^> formed by an ejection piston extended in its posterior part by a rod, said ejection chamber being located at the anterior end of the dudir. body,

(b) an intermediate chamber,

(c) passage means for the medicinal substance between said reserve and said intermediate chamber,

(d) passage means for the medicinal substance between said intermediate chamber and said ejection chamber,

(E) a valve, controlled 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.

- (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.

WIPO (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 mean 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. In fact, if the piston rod slides freely, pratically 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 sealing 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 with it and drives it 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 medicinal substance may 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 controlled valve consists of a sleeve 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 bushing and the contact with the other stop allowing said rod to drive in its movement towards the front said bushing by 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 to constitute a needle and corresponding conical seat system, and the contact of said needle with said seat allows the rod driving said bush 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 of ejection passage, said valve allowing the fluids to pass only in the direction ejection. In this case, the intermediate chamber is formed by the passage means from the reserve of medicinal substance towards the cylindrical body of the injection head. 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 ejection chamber and the reserve) being then open, the medicinal substance passes into the ejection chamber under the action of atmospheric pressure.

- According to another embodiment, said means for depressurizing the ejection chamber relative to the intermediate chamber can comprise, on the one hand, a part, driven by the ejection piston rod, the backward movement during the return movement of the piston decreases the volume of the intermediate chamber and, conversely, forward movement during the ejection movement increases the volume of the intermediate chamber, and secondly, a second piloted valve for closing the passage between said intermediate chamber and said reserve during said backward movement and opening said passage during said forward movement.

In this embodiment the intermediate chamber is produced in the cylinder body and said relative depression between the ejection chamber and the intermediate chamber is created by the fact that the volume of the intermediate chamber decreases (and that the pressure y increases since the communication with the reserve is closed) while the volume of the ejection chamber increases, so that the drug substance passes from the intermediate chamber to the ejection chamber.

According to a particularly simple embodiment, said part making it possible to modify the volume of the intermediate chamber can be constituted by the socket

(constituting the first piloted valve) as defined above.

Said second piloted valve can be 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 the rod to drive in

^ JREA T its forward movement of said sleeve, and contact with the other stop allowing the rod to drive in its rearward movement said sleeve while interrupting the passage of the medicinal substance between said reserve and said chamber intermediate.

For example, - the middle part of said rod and the second piloted valve ^" 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 second valve piloted towards the rear while closing the passage for the medicinal substance between said reserve and said intermediate chamber.

In a particularly advantageous manner, the rod may carry on its central part a double needle capable of alternately placing the reserve in communication with the intermediate chamber or the intermediate chamber with the ejection chamber, said rod being capable of sliding in the assembly formed by the two flaps controlled with a small clearance to be able to pass from the position where it opens the communication between the reserve and the intermediate chamber to the position in which it closes this communication and on the contrary opens the communication between the intermediate chamber and the chamber 'ejection. - The front part of the cylinder body, comprising the ejection chamber, the ejection piston and its rod, the intermediate chamber, the controlled valve (s) and the seat for the reserve of medicinal substance, constitutes a head d 'removable injection can be coupled with said motor means, or uncoupled.

The coupling and uncoupling of the injection head with the motor means can be carried out using additional quick coupling means such as for example a coupling spout and a corresponding groove, or a ball snap in a corresponding circular groove, and / or a threaded ring and a corresponding male thread,

OMFI 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 forwards, said device comprises means for coupling said rod with said piston of weapons.

According to a particular embodiment, the arming piston has a front extension, and the rear end of the rod of the ejection piston and the front end of said extension include complementary means for quick attachment 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 fluid under .. pressure. Such an arrangement notably makes it possible to considerably simplify the trigger and trigger mechanism po _. ur the actuation of the device.

- Said cocking piston has a rear extension constituted by a rod provided with at least one mark, said marks becoming alternately visible as the cocking piston moves back. The operator can thus adjust the recoil of the weapon piston and therefore the volume of drug substance to be injected. Indeed, as long as he does not see the chosen benchmark 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 the said means for supplying said pressurized liquid include a piston pump and a conduit connecting said pump to the arming chamber.

Said piston pump can be actuated in any manner (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. by means ^" of reception 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, as mentioned above.

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 by 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.

WIPO These means for regulating the volume of the pressurized fluid 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 discovered towards the end. of the return stroke of the main piston and, in the event of a 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 armament chamber. 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 spring compri¬ mé 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, thanks to which said spring projects forwards said arming piston 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 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 insuf¬ fisante dose introduced into the ejection chamber.

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

OI.IFI 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 sectional view of the front part of an injection head of a device according to the invention,

FIG. 2 represents a schematic view in partial section of said device showing more particularly an actuation device according to the invention,

FIG. 3 represents a sectional view of the device for actuating a hydraulic pump which can supply the device, FIG. 4 represents a view of an improved hydraulic pump which can supply the device,

- Figure 5 shows a schematic view in partial section of another embodiment of an injection head according to the invention, - and Figure 6 shows a schematic sectional view of another embodiment of an action system for the device of the invention.

The device shown is in the form of an automatic injection gun intended for collective vaccination. It comprises a generally cylindrical body 1 on which is fixed a handle 2. The rear part of the body 1 and the handle 2 are occu¬ pated by the actuation mechanism intended to allow a rapid advance movement for ejection and mo ^'uve- lies back in position after the ejection.

In the front part of the body 1 is housed an interchangeable assembly which comprises in particular a bush 3 capable of being held in position by a nut 4 screwed onto the front end of the body 1. The bush 3 supports a support towards its rear end of bottle 5 extending radially and having a seat 6 intended to receive the end of an inverted bottle. In the middle of the seat 6 is placed a double needle 7 intended to pierce the bottle, this double needle leading on the one hand to a conduit 8 directed towards the sleeve 3 and on the other hand to an outlet in the open air 9. In order to allow the fitting of the socket 3 with the part 5, the body 1 is provided at its front part with a longitudinal slot 10 allowing the passage of the lower part of the part 5.

The part 3 has in its center a bore in which can slide a cylindrical sliding part 11 ending at its rear end, beyond the rear extremity of the part 3 by a flange 12 sliding in the bore of the body 1 then by an extension 13 having a circular groove. In the part 11 is screwed the rear end of a rod 14 having towards its middle part a conical flare or rear needle 15 immediately followed by a conical flare or front needle 16. On the rod 14 and in the bore of the sleeve 3 is slidably mounted a sleeve 17 provided with a central narrowing so as to leave between it and the wall of the sleeve 3 an annular slot 18 into which opens a channel 19 formed in said sleeve and connected to the passage 8. Furthermore, the rod 14 in the part which substantially corresponds to the front half of the part 17 is reduced in diameter to leave between it and the said part a passage or an annular slot 20 which points towards the rear face. of the needle 15 and which is in communication with the slot 18 by radial passages 21 pra _. ticked in part 17. In addition, the anterior end of this part 17 has the shape of a frustoconical seat 22 capable of cooperating with the rear needle 15.

At this level, the orifice made in the part 3 is widened to form an intermediate chamber 23 in which the posterior end 24 of a dou ± ^" i ^ S \ ËA _ can move.

WIPO 29. It can be seen that the rear end 24 also has a corresponding seat of conical shape with regard to the front needle 16.

A socket 26 secured to the front end of the socket 3 forms the side wall of the ejection chamber This socket 26 is closed at its front end by an ejection head 27 provided at its center with the end of ejection passage 28.

In the bore of the sleeve 26, the sleeve 29 slides with friction with the front end 30 behind the ejection chamber 31, the front limit of which is formed by the rear wall of the part 27.

In said sleeve 29 slides without friction the front extension 32 of the rod 14, extension provided in its center with a passage 33 communicating freely with the chamber 31 and which is also capable of being placed in communication with the chamber 23 when the position of the needle 16 is suitable.

The assembly thus contained in the socket 3, or carried by the latter can thus be easily separated from the body by simple unscrewing of the nut 4 and extraction towards the front.

With reference to FIG. 2, the motor means, housed at the rear of the body 1, comprise a powerful spring 34 bearing on a fixed part 35 secured to the body 1 and on a sliding part 36 including an anteriorly extended 37 carries radial balls 38 sol¬ licit inwardly by suitable elastic means. These balls 38 penetrate into the groove of the posterior extension 13 of the sliding sleeve 11. The front end of the extension 37 is ap¬ plicated against the rear face of the flange 12, this in order to be able to directly transmit the thrust of the spring to said flange 12 and therefore to the part 11 and to the rod 14, while during the backward movement, which requires only a reduced force, the drive of the part 11 and the

WIPO the rod 14 is effected by means of the balls 38.

The part 36 is integral with a long rod 39 sliding in the part 35 and carrying a return piston 40 towards its rear end. In front of the piston 40, a chamber 41 is arranged, the front face of which is limited by a part 42 integral with the part 35. This part 42 comprises an annular slot 43 into which opens a conduit 44 connected by a flexible pipe 45 to any motor device, for example a pedal pump. The retention of the part 36, despite the spring thrust when the device is armed, - is ensured by a detent device comprising the detent itself 46 and intermediate parts leading to a lever 47 provided with a hooking spout 48. This spout 48 is capable, when the part 36 is called back toward the rear against the thrust of the spring, to come into place against the front face 49 of the part 36 to maintain the latter immobilized until the support on the trigger, releasing the spout A3, then releases the spring and the part 38, the rod 39 and the rod 14.

The operation is as follows:

The device being in its end of injection position shown in the drawing, the operator actuates the fluid pump and the pressurized fluid is addressed by the conduit 45 and the passage 44 to the chamber 41 so that it repels the piston 40 towards the rear which carries with it the rod 39 and the part 36 which compresses the spring 34 until the front face 49 of the part 36 is hooked by the spout 48. This same return movement causes the rear part 11 and rod 14, part 17 remaining for its part immobile during the very beginning of this return movement due to the friction against the part 3. However, quickly the space between the seat 22 and the rear needle 15 is canceled and the continuation of the rearward movement then drives the part 17 also towards the rear, the communication between the passages 8, 19 and the chamber 23 then being interrupted.

Likewise during the initial part of this return movement, the sleeve 29 remains stationary because of the friction between the part 26 but is soon drawn back 5 by the anterior end forming a stop of the extension 32 which for this purpose perforated nut 50. This small offset between the start of the return movement of the rod 14 and the start of the return movement of the sleeve 29 makes it possible to move the front needle backwards

1016 away from the seat 25 which releases the communication between the chamber 23 and the injection chamber 31 through the passage 33. The volume of the chamber 23 narrows by the movement of the piston 24 towards the rear, the substance liquid drug is repressed by the passage

1533 towards the chamber 31 which it fills while the latter increases in volume. At the end of the return movement, the volume of the chamber 23 is minimum and the volume of the injection chamber 31 is maximum, the medicamentous substance having passed from one to the other.

When the user presses the trigger 46 and releases the part 36, the assembly which has retreated (39,36,11,14,32) is suddenly thrown forward. During the first part of the forward ejection movement, the part 17 remains stationary due to friction until it is driven by the part 11 which has come into contact with it. In this position, the passage between the needle 15 and the seat 22 is open and the liquid coming from the source or the bottle of medicinal substance is sucked by the needle 7, the channel 8, the passage 19, 0 the slot 18, the passage 20 and the chamber 23 which increases in volume. Similarly, during the very beginning of the advance movement, the sleeve 29 remains stationary until the needle 16 has traversed the short interval which separates it from the seat 25. From this moment the commu - 5 connection between the chamber 31 'and the chamber 23 is interrupted and the chamber 31 which rapidly decreases in volume sees its pressure increase suddenly and the liquid is ejected through nozzle 28.

The device thus described has great simplicity of manufacture and use. It can be sterilized by extraction prior together with the rapid binding to beads to undergo a tempering or otherwise sterilization can be performed by mounting the ai¬ guille 7 ^and the seat 6 years a liquid bottle disinfecting and by carrying out some projections of this liquid.

If it is desired to compensate for a possible variation in volume originating for example from a modification of the flexible condui¬ your it suffices to modify in a corresponding manner the volume of the chamber 41 by adjusting the position of the piston 40, this by turning more or less the nut 60 screwed to the rear of the rod 39 and forming a shoulder receiving the rear end of the piston 40.

Referring to Figure 3, one sees a device ac¬ tioning pedal of a pump, this device ¹ action¬ ment having a body 51 on which is mounted a pivot 52 around which is rotated a pedal 53. This pedal is extended by a small lever arm 54 capable of pressing on a plunger 55 capable of transmitting its movement to the rod 56 of a piston 57 penetrating into a pump cylinder 58, said pump being for example detachably mounted on an extension 59 of the body 51, said extension 59 having a hori¬ zontal section shaped ^'horseshoe being provided with an upper flange for receiving and retaining the body of the pump cylinder.

Reference is made to FIG. 4. In the variant of the pump shown, the interior of the cylinder 58a of the pump forms la. chamber in which the action 57a piston 57a moves, via 56, for example by means of a pedal (not shown) similar to that of FIG. 3. A single conduit 45a. walks towards the device. To cylinder 58a. is attached a compensation cylinder 61 communicating with the cylinder 58a_ by a thin transverse passage 62. In the cylinder 61 can slide a secondary piston biased 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 off the passage 62. the liquid is then expelled through duct 45a_ _... When returning the piston 57a_, if there is a loss of liquid (eg due to a microleakage, or a deformation of the flexible conduits), liquid is ^lυ then fed from the cylinder 61 to the cylinder 58a to compensate for 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 a perfect adaptation to 15 volume changes caused either by mechanical deformations or ^'by changes in temperature.

We now refer to Figure 5.

The injection head shown has a 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 5 of the piston is fixed a screw 70 whose head forms a stop and has radial notches such as 71. The front part the piston can slide in the bore of the piloted valve 72 whose front end has a recess for the housing of the screw head 70. The rear end wall 73 of the piloted valve 72 forms a seat for the needle 69. at the front end of the body 65 is screwed a bushing 74 containing a valve 75 driven by a spring 76, said valve passing fluid (air, liquid) only in the ⁵ ejection. The front end of the screw head 70 and the rear end of the socket 74 and of the valve 75 define an ejection chamber 77. At the front end

_______ the sleeve 74 is fixed by screwing an injection nozzle fitted with a filter 79 and comprising a fine passage 80.

The body 65 is surmounted by a seat 81 for the reserve of medicinal substance (such as an inverted bottle). FIG. 5 shows 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 here plays the role of the intermediate chamber mentioned in the description of the present application. A filter seal 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 comprises a hooking spout 88 and is surrounded by a ring 89 internally threaded.

Reference is now made to FIG. 6, which describes the actuation system on which the removable injection head shown in FIG. 5 can be mounted. This actuation device comprises a cylindrical body 90 extended by a handle or butt 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 made by the 'through a non-return ball valve 98, main¬ held by a spring 99, the movement in the return direction can be effected by pressing 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. 5, 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 reference 111.

The hose 97 is connected to a hydraulic pump, not shown. To set up the injection head shown in Figure 5 on the actuating device shown in Figure 6, 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 included enclosed device is as follows. in Figures 5 and 6, there is shown 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 of the central passage from the rear end 112 of the sleeve 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 medicinally lying substance between the conduit 87 and the conduit formed along the rod 67 thanks to the flat surface 68. When the piston 66 continues its recoil movement the screw head 71 abuts against the recess bottom formed at the front end of the part 72 which is then driven in the same recoil movement as the piston 66. Due to this recoil the volume of the chamber 77 increases, but the valve 75 does not allow 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 provided with a medicinal substance before the start of operation, said medicinal substance will flow, due to this depression, - via conduit 87, the passage formed between the walls 73 and 69 which are spaced apart from one another, the flat 68 and the notches 71, and will fill the chamber 77. After completion of the backward movement of the movable assembly, the operator pulls the trigger 101 via the pusher 100 pushes the ball 98 to the right, which ^'allows the return of the oil under pressure contained in the chamber 94 and in the ^' conduit 96 towards 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 suddenly thrown forward. At the beginning 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 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 the valve 75 back, allowing the substance to pass drug contained in the chamber 77. ans the ejection nozzle 78. Finally the liquid substance is ejected in a powerful jet by the end passage 80.

The devices of FIGS. 5 and 6 present the advantages of the devices of FIGS. 1 and 2. They also have the advantage of simpler manufacture, assembly and disassembly.

WIPO

Claims

EVENDICATIONS 1. A needle-less injection device for liquid medicinal substances, characterized in that it comprises, in a cylinder body, (a) an ejection chamber whose anterior wall communicates with the outside, by means of an end ejection passage, the movable rear wall of which is formed by an ejection piston extended in its rear part by a rod, said ejection chamber being located at the anterior end of said body, (b) an intermediate chamber, (c) passage means for the lying substance between said reserve and said intermediate chamber, (d) passage means for the lying 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, (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, (g) on said cylinder body a seat 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 consists of 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 sleeve and the contact with the other stop allowing said rod to lead in its movement _. forward said socket while interrupting the passage of said drug substance between said intermediate chamber and said ejection chamber. 3. Device according to any one of claims 1 10 and 2, characterized in that said means for placing the ejection chamber under vacuum with respect to said intermediate chamber consist of a valve located between the ejection chamber and said end of ejection passage, said valve allowing the fluids 5 to 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 rod ^" ejection piston and the rear part of said sleeve have a shape capable of constituting 0 a system of needle and corresponding conical seat, and that the contact of said needle with said seat allows the rod to drive said socket forward while closing the passage for the medicamentous substance between said intermediate chamber and said chamber 5 ejection. 5. Device according to any one of claims 1, 2 and 4, characterized in that said means for placing the ejection chamber under vacuum with respect to .the intermediate chamber comprises, on the one hand, 0 a part, driven by the piston rod of ejec¬ tion, whose displacement backwards during the return movement of the piston decreases the volume of the intermediate chamber and conversely moving forward during the ejection movement increases the volume of the _) tr ^J intermediate chamber, and on the other hand, __- .- _^ CY.PI \ / ^' m. ^{Wii U} a second piloted valve making it possible to close the passage between said intermediate chamber and said reserve during said backward movement and to open said passage during said forward movement. 6. Device according to claim 5, characterized in that the said part making it possible to modify the volume of the intermediate chamber consists of the bush as defined in claim 2. 7. Device according to any one of claims 5 and 6, characterized in that said second piloted valve is constituted by a sleeve in which the rod of the ejection piston can slide freely between two stops, contact with one stops allowing the rod to drive in its forward movement said bushing, and contact with the other stop allowing the rod to drive in its rearward movement said bushing while interrupting the passage of the drug substance between said reserve and said intermediate chamber. 8- Device according to claim 7, characterized in that the middle part of said rod and said second piloted valve have a shape capable of constituting a needle system and corresponding conical seat, and that the contact of said needle with said seat allows to the rod to drive said second valve piloted towards the rear while closing the passage for the mediate substance between said reserve and said intermediate chamber. 9. Device according to any one of the preceding claims, characterized in that the anterior part of the cylinder body, comprising the ejection chamber, the ejection piston and its rod, the intermediate chamber, the or the piloted valves and the seat for the reserve of medicinal substance, constitutes a removable injection head which can be coupled with said motor means, or uncoupled. -24- 10. Device according to any one of the preceding claims, characterized in that the said motor means comprise a spring, an arming piston sliding in an arming chamber, means for bringing a fluid under pressure into the said chamber. ar¬ ment, so as to move said arming piston rearward by compressing the spring, means for main¬ hold said spring in the compressed position, and means for releasing said spring so as to project said arming piston forward, and in that it comprises means for coupling said rod with said cocking piston. 11. Device according to any one of claims 9 and 10, characterized in that the cocking piston has a front extension, and in that the rear end of the rod of the ejection piston and / or body of said injection head, and the front end of said extension comprise complementary quick coupling means allowing coupling and uncoupling of said rod and / or said injection head 12. Device according to claim 11, characterized by the fact that said complementary means consist of a hooking spout and a groove, or by a ball-bearing enclosure in a circular groove, and / or by a threaded ring and a corresponding male thread. 13. Device according to claim 10, characterized in that said means for holding said compressed spring comprise a non-return valve of the fluid , under pressure, and that said means for releasing said spring comprise a lever capable of being actuated manually and of acting on said non-return valve to allow the return of the fluid under pressure. 14. Device according to any one of claims 10 and 13, characterized in that said cocking piston comprises a rear extension constituted by a rod provided with at least one mark, said marks becoming in turn visible at measure that the piston of arms goes back. 15. Device according to any one of claims 10 to 14, characterized in that said pressurized fluid is a liquid and that said means for bringing said pressurized liquid comprise a piston pump and a conduit connecting said pump to the chamber of weapons. 16. Device according to claim 15, 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 liquid under pressure, and connected to the main chamber by a narrow passage, said compensation chamber being constantly under the pressure of a secondary piston biased by a spring, said narrow passage opening into the main chamber a short distance from the rest position of the main piston. 17. Device according to claim 10, characterized in that said cocking piston is traversed by a rod whose 1'end 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 arming chamber. 18. Device according to any one of claims 10 and 17, characterized in that said means for holding said compressed spring comprise a spout per¬ putting to immobilize by hooking an anterior extension of the cocking piston, and that said means to release said spring comprise a lever or a catch allowing you to unhook said spout, whereby said spring projects said cocking piston forward which in turn actuates the ejection piston while forcing the fluid out of the armament chamber.