Injection device (adaptable device)

[0001] The present invention relates to an injection device of the type that houses the syringe, moves it, releases its contents, and then withdraws it automatically.

BACKGROUND ART [0002] Known injection devices are shown in WO 95/35126 and EP-A-0 516 473, usually using a drive spring and some kind of release mechanism that releases the syringe from the drive spring when its contents, such as it is presumed unloaded to allow it to be withdrawn by the return spring.

[0003] International Patent Application Publication No. 02/056947 discloses a syringe connector comprising an upper opening into which a syringe can be loaded, a first retaining element placed on one side of the opening, and a second retaining element placed on the other side of the opening. The first retaining element and the second retaining element abut against the forwardly facing abutting surface of the syringe collar on the syringe substantially symmetrically. The syringe connector further includes a cradle, at least one attachment member for abutting against the forwardly facing abutting surface of the syringe flange, as well as a carriage slidably disposed within the cradle. The cart includes a connector to form a detachable connection with the plunger or syringe plunger extension, as well as a drive element for the injection device. The connector includes a plurality of flexible gripping elements that are bent radially outward to engage the flange on the back of the plunger or syringe plunger extension when the carriage is moved forward within the syringe connector. The syringe connector may further include a connector at its rear to connect to the injector.

[0004] US Patent No. 5,520,653 discloses an adapter, comprising a syringe carrier, having a front end, a rear end, and a syringe holding channel, disposed between the front and rear ends of the carrier to connect at least to a portion of the syringe collar; attachment flanges near the posterior end of the carrier to detachably secure the carrier in a desired position relative to the front wall of the injection device head; a pusher mounted with the possibility of reciprocating movement inside the carrier, having a front end connected to the syringe plunger when the syringe is installed in the carrier; and a hole in the drive head connecting to a pair of slots in the drive head located near the rear end of the pusher to detachably fix the pusher in a desired position relative to the drive head of the injection device head. [0005] European Patent Application Publication No. 0482677 discloses a syringe adapter for a power injector equipped with hooking and gripping means for attaching to the gripping projection of the device on the syringe plunger mounting plate. The rear end of the adapter has a device handle protrusion, so that the syringe, after reducing its volume by the length of the adapter, can be used in a typical assisted injection device. [0006] Publication of European Patent Application No. 1618575 discloses an injection needle which is placed in the body of the device, which, after pressing the outer part of the body of the device for administration to the body area of ​​the patient to whom the drug solution is to be administered, is automatically discharged from the body of the device, so that the needle can be inserted into the body area, and the injection needle inserted into the body area is automatically placed in the body of the device, to remove the needle from the body. [0007] UK Patent Application Publication No. 2414402 discloses an injection device with a housing adapted to receive a syringe having an outlet nozzle, the housing having an indicator opening. The trigger and front drive are arranged so as to act on the syringe when the trigger is activated to move the syringe forward from the retracted position to the extended position, thereby discharging the contents of the syringe through the discharge nozzle.

[0008] International Patent Application Publication No. WO 2004054645 discloses an injection device that includes means for delaying syringe release until a predetermined time after actuation has elapsed.

[0009] In general, such injection devices require the use of a drive spring operating with a high force to reliably empty the syringe in the period prior to withdrawal of the syringe. When the drive spring is first released, the spring first engages the lumen in the syringe and then displaces the needle, then delivers the drug. The spring force is much higher than required for the initial stages, and the excess energy is released in the form of noise and vibration resulting from spring recoil.

[0010] The injection device may generally operate over a range of syringe fill volumes. When the fill volume is low, a significant clearance can be occupied, resulting in more noise and more recoil after starting.

[0011] It is therefore desirable to minimize noise and recoil so as not to frighten the patient in the case of a certain range of syringe filling volumes.

SUMMARY OF THE INVENTION [0012] The injection device of the present invention was designed with the above-mentioned and other problems in mind.

[0013] Accordingly and in accordance with the first aspect of the present invention, an injection device is provided which includes:

a housing adapted to be positioned in the center of a syringe having an outlet nozzle and a movable piston moving the syringe to remove the contents of the syringe through the outlet nozzle; a drive adapted to act upon the syringe when it is started, to move it forward from a retracted position in which the discharge nozzle is contained within the housing, to an extended position in which the discharge nozzle protrudes from the housing;

a drive clutch extending from the drive to the syringe dosing piston to transfer the drive motion to the piston, the device characterized in that the drive clutch includes a fixed length drive clutch and a replaceable drive clutch.

[0014] By changing the length of the replaceable drive clutch, noise and vibration arising from the activation of the device can be kept to a minimum for a given volume of content in the syringe.

[0015] Preferably, the replaceable drive clutch comprises a rigid member configured to connect with the dispensing piston and with a fixed length drive clutch.

[0016] The rigid element has a longitudinal axis.

[0017] Preferably, the amount of syringe content that is discharged outside during use determines the length of the replaceable drive clutch along its longitudinal axis. [0018] In general, the length of the replaceable drive clutch is inversely proportional to the size of the contents of the syringe. [0019] A replaceable release element is used, adapted to disengage the drive from the fixed length drive clutch after a predetermined piston movement.

[0020] Preferably, the replaceable release element is a constriction adapted to act on at least one arm connecting the fixed-length drive clutch to the drive and thus releases the drive from the fixed-length drive clutch.

[0021] Preferably, the constriction length defines a predetermined amount of piston movement.

[0022] In general, the length of the neck is inversely proportional to the size of the contents of the syringe.

[0023] According to a second aspect of the invention there is provided a method of making an injection device, comprising:

inserting a syringe having a plunger into the first subassembly;

inserting a replaceable drive clutch into the syringe to contact the plunger;

providing a second subassembly comprising a fixed length drive and drive clutch; and assembling the first subassembly and the second subassembly together, in which method, after assembly, the fixed length drive clutch and the replaceable drive clutch are in contact during use to transfer the drive motion to the piston.

[0024] Preferably, the replaceable element has a longitudinal axis and comprises a rigid element configured to engage the piston and the drive clutch.

[0025] In one embodiment of the present invention, an additional step of selecting a replaceable drive clutch according to its length, determined by the amount of syringe content, is used.

[0026] The next step of connecting the replaceable release element to the first subassembly was used before the assembly stage, in which the replaceable release element is adapted to actuate after a predetermined amount of piston movement a delay mechanism in the drive acting on a fixed length drive clutch.

[0027] Preferably, the replaceable release element is selected according to its length determined by the size of the contents of the syringe.

DESCRIPTION OF THE FIGURES [0028] In the following, the present invention will be described based on the attached drawings, in which:

Figure 1 is a cross-sectional view of an injection device according to the present invention; Fig. 2 shows an enlarged part of the injection device shown in Fig. 1;

Figure 3 is an exploded view of the injection device of the present invention;

Figure 4 is a perspective view of the components of the injection device of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS [0029] Figs. 1 to 4 show an injection device 100 having an injection device housing 112. The end of the housing 112 has an outlet opening 128 through which the end of the sleeve 119 can exit.

[0030] The housing 112 comprises a subcutaneous syringe of the usual type, comprising a syringe body 116, defining a reservoir and terminating at one end with a hypodermic needle 118, and at the other end with a flange 120. The syringe body 116 has a substantially constant diameter along the length of the reservoir and has a much smaller diameter near the tip of the syringe, terminated with a hypodermic needle. A drive clutch 134 operates through the syringe plug to discharge the contents of the syringe 114 through the needle 118. The drive clutch 134 limits the drug 124 to be administered within the reservoir formed by the syringe body 116. While the syringe shown in the figure is a hypodermic syringe, this is not a necessary solution. Transdermal injection syringes or ballistic dermal injection syringes may also be used with the injection device of the invention.

[0031] As shown, the syringe is placed in the syringe carrier 150. The syringe carrier 150 has a proximal end 151 through which the syringe needle 118 projects outward. The needle 118 is attached to the syringe body 116 via the needle subassembly 172, which has a reduced diameter. At the proximal end 151 of the syringe carrier 150, there is a smaller diameter portion 173 that supports the tip of the syringe 114 on the body 116. The syringe carrier 150 also has a pair of flexible projections 152. The pair of flexible projections 152 engage with a corresponding pair of locking holes on the return spring support 160 such that the syringe carrier 150 cannot move relative to the return spring support 160. The syringe carrier 150 also includes a bearing surface 153 near its second end against which the corresponding bearing surface of the return spring support 160 is pressed by the return spring 126. The return spring 126, via the spring return support 160 and the syringe carrier 150, pushes the syringe 114 from the extended position in which the needle 118 projects from the hole 128 in the housing 112 to the retracted position in which the needle 118 is inside the housing 112.

[0032] The syringe carrier 150 has a shield 154 into which the syringe 114 can be inserted from the distal end side 170. The syringe 114 is provided with a protective sleeve (not shown). If the syringe were to break or fall apart, the sheath 154 that surrounds the syringe 114 along its length would hold the pieces of the syringe and reduce the likelihood of them escaping from the injection device 110.

[0033] The housing is further provided with a resilient latching member 161 which is pushed into a position in which it engages with the locking surface 163 on the return spring support 160. Before engaging with the locking surface 163, the latch member 161 also slides through the latch hole 165 in the sleeve 119. The latch member 161 has an inclined surface 167 on which the edge of the latch hole 165 acts by means of a cam acting on the cam follower.

[0034] The housing also includes an actuator and a drive, which here is in the form of a drive compression spring 130. The drive from the drive spring 130 is transmitted by a multi-part drive to the syringe plunger 114 to move the syringe from the retracted position to the extended position and release its contents through the needle 118. The drive accomplishes this task by acting directly on drug 124 and syringe 114. The static friction between the drive clutch 134 and the syringe body 116 initially ensures that they move together until the return spring 126 reaches the minimum length or the syringe body 116 encounters another obstacle (not shown) that will delay its movement.

[0035] The multi-part drive between the drive spring 130 and the syringe 114 consists of three main components. The drive sleeve 131 receives drive from the drive spring 130 and transfers it to the drive element 132. This, in turn, transfers power to the 134 drive clutch, which has already been mentioned here. [0036] The drive member 132 includes a hollow stem 140, the inner cavity of which forms a collection chamber 142 connecting to the channel 144, which extends from the collection chamber through the end of the stem 140. The drive clutch 134 includes a blind hole 146 that is open at one end in order to receive the stem 140 and closed at the other end. As can be seen, the opening 146 and the stem 140 form a fluid reservoir 148 in which a damping fluid is contained.

[0037] The drain 214 is located on the housing 112 away from the outlet opening 128. The trigger, when activated, serves to separate the drive sleeve 131 from the housing 112, enabling it to move relative to the housing 112 under the influence of the drive spring 130. Operation of the device is explained below. [0038] Initially, the spring return carrier 152 and, as a result, the syringe carrier 150 and the syringe 114 were prevented from movement by means of the elastic latch member 161. By moving the sleeve 119 toward the inside of the housing 112, the edge of the latch opening 165 is brought into contact with the inclined surface 167 of the latch member 161, which causes the latch member 161 to move outwardly, and thus detaches from the return spring support 160. When the latch member 161 is detached from the locking surface 163, the syringe will be able to move freely.

[0039] The actuator is then pressed and the drive spring 130 is released. The drive spring 130 moves the drive sleeve 131, the drive sleeve 131 moves the drive member 132 and the drive member 132 moves the drive clutch 134. The drive clutch 134 moves, and due to static friction and hydrostatic forces acting through the drug 124 to be administered, moves the syringe body 114 against the action of the return spring 126. The syringe body 114 moves the syringe carrier 150, which in turn moves the support of the return spring 160 and compresses the return spring 126. The hypodermic needle 118 extends from the outlet opening 128 of the housing 112. This continues until the return spring 126 reaches the smallest size or the syringe body 116 encounters another obstacle (not shown) that delays its movement. Because static friction between the clutch

134 drive and the syringe body 116 and the hydrostatic forces acting through the drug 124 intended for administration are not sufficient to counteract the total drive force generated by the drive spring 130, at this point the drive clutch 134 begins to move within the syringe body 116 and drug 124 begins to be released . The dynamic friction between the drive clutch 134 and the syringe body 116 and the hydrostatic and hydrodynamic forces now acting through the drug 124 to be administered are, however, sufficient to keep the return spring 126 compressed, so that the hypodermic needle 118 remains extended. [0040] Before the drive clutch 134 reaches the end of its movement within the syringe body 116, therefore, before the contents of the syringe are completely released, the flexible latch arms connecting the first and the drive clutch 132, 134 reach the removable release member 155 connected to the distal end of the syringe carrier 150 . [0041] The removable release member 155 is essentially a constriction that moves the flexible latch arms to a position in which they no longer connect the drive member 132 to the drive clutch 134. When this happens, the drive member 132 no longer acts on the drive clutch 134, which allows the drive element 132 to move relative to the drive clutch 134. Because the damping fluid is contained within the reservoir 148 formed between the end of the drive member 132 and the blind hole 146 in the drive clutch 134, the volume of the tank 146 will tend to decrease as the drive element 132 moves relative to the drive clutch 134 when the spring is first applied 130 drive. When the reservoir 148 collapses, the damping fluid is forced through the channel 144 into the collection chamber 142. Thus, when the flexible latch arms are released, some of the force exerted by the drive spring 130 will act on the damping fluid, causing it to flow through the constriction formed by the channel 144; the remainder acts hydrostatically through the fluid and through the friction between the first and drive clutch 132, 134 and thus through drive clutch 134. Accordingly, the drive clutch 134 continues to move within the syringe body 116 and drug 124 is still released. Losses associated with the flow of damping fluid do not weaken the force acting on the syringe body to a large extent. Thus, the return spring 126 remains compressed and the hypodermic needle remains extended.

[0042] After some time, the drive clutch 134 ends to move within the syringe body 116 and cannot move further. At this point, the contents of the syringe 114 are completely released, and the force exerted by the drive spring 130 acts to hold the drive clutch 134 in its final position and still causing the flow of damping fluid through the channel 144, which allows the drive element 132 to continue its movement.

[0043] Before the fluid reservoir 148 is emptied, the flexible latch arms connecting the drive sleeve 131 to the drive element 132 reach another constriction within the housing 112. The constriction moves the flexible latch arms so that they stop connecting the drive sleeve 131 to the drive element 132. When this happens, the drive sleeve 131 will no longer act on the drive member 132, allowing them to move relative to each other. At this point, the forces generated by the drive spring 130 are no longer transferred to the syringe 114. The only force exerted on the syringe will be the return force of the return spring 126, which acts at the end of the syringe 114 closest to the needle 118 through the spring support 160 and the syringe carrier 150. As a result, the syringe is returned to its retracted position and the injection cycle is completed.

[0044] As seen in Figure 3, drive clutch 134 includes a fixed length drive clutch 134a and a replaceable drive clutch 134b. The length of the replaceable drive clutch 134b can be changed by replacing it with another replaceable drive clutch. The replaceable drive clutch 134b includes a cap 234 at its end adjacent the fixed length drive clutch 134a to receive a projection 235 on the fixed length clutch 134b.

[0045] By changing the overall length of the drive clutch 134 as a result of changing the length of the replaceable drive clutch 134a, the initial start position (before trigger actuation) of the proximal end 240 (ends closest to the needle 118 of the outlet syringe 114) of the drive clutch 134 can be changed. Accordingly, the proximal end 240 may be arranged such that the initial start position is as close as possible to the syringe content - that is, the initial volume of the syringe 114 may substantially correspond to the volume of the contents of the syringe. In this way, the clearance to be taken when the drive 130 is released for the first time can be kept to a minimum, thereby reducing noise and recoil in the device

110 for injection.

[0046] Therefore, less fluid in the syringe requires a longer replaceable drive clutch 134a.

[0047] Because the length of the drive clutch 134 is variable, it follows that the point at which the flexible latch arms no longer connect the drive member 132 to the drive clutch should be differentiated to ensure that the contents of the syringe can be completely released. This is done by changing the length of the removable release element 155.

[0048] The longer the drive clutch 134, the longer the removable release member 155 should be.

[0049] The removable release member 155 is provided with flexible arms 271 for connecting the replaceable release member 155 to the syringe carrier 150 at the notches 281 on the syringe carrier 150.

[0050] As shown in Figure 4, the injection device 100 can be assembled using two components to facilitate the manufacturing process.

[0051] The first subassembly 210 includes a syringe 114, syringe carrier 150, a replaceable drive clutch 134b, and a replaceable release member 155.

[0052] The second subassembly 220 includes a housing 112 and drive members and actuators of the injection device 110, including a fixed length drive clutch 134a. [0053] In this way, the decision on the amount of content to be introduced into the syringe can be made regardless of the design of the drive components (which is difficult to assemble), since the length of the replaceable drive clutch 134b and the replaceable release element 155 can be changed immediately prior to final assembly of the entire injection devices 110 by joining the first subassembly 210 and the second subassembly 220.

[0054] It should of course be understood that the present invention has been described above by way of example only and that detailed modifications may be made without departing from the scope of the present invention.

25273 / EP / 15

EP1896096