EP3484546A1

EP3484546A1 - Automatic injection device with reduced residual volume

Info

Publication number: EP3484546A1
Application number: EP17737317.2A
Authority: EP
Inventors: Pascal Dugand; Kevin Stamp
Original assignee: Nemera la Verpilliere SAS
Current assignee: Nemera la Verpilliere SAS
Priority date: 2016-07-15
Filing date: 2017-06-13
Publication date: 2019-05-22
Also published as: CN109475692B; FR3053894B1; CN109475692A; FR3053894A1; JP2019523116A; WO2018011480A1; JP7005613B2; US20200238010A1; US11224694B2

Abstract

Automatic injection device (22) comprising: - an injection syringe (24) equipped with a syringe body (26) and with a piston rod mounted movably in this syringe body (26) so as to cover an injection stroke, - a piston control member capable of changing between ■ a configuration in which it is in engagement with the piston rod and ■ a configuration in which it is disengaged from this piston rod, - means for moving the piston control member between its two configurations with respect to the piston rod. The means for moving the control member between its two configurations comprise a camway (110) carried by a disengagement member (92) and a cam carried by the control member. The disengagement member (92) is movable with respect to the piston rod and the syringe body (26) after the end of the injection stroke, in such a way as to cause the camway (110) to interact with the cam.

Description

Automatic injection device with reduced residual volume

The present invention relates to the field of automatic injection devices for liquid products, in particular pharmaceuticals.

An automatic injection device is used in particular in the medical field for the automatic administration of a liquid medicament requiring an injection. A device of this type makes it possible in particular for a person, for example suffering from rheumatoid arthritis, multiple sclerosis, diabetes or suffering anaphylactic shock in the event of allergy, to inject himself a dose of independently. Already known in the state of the art, in particular according to US8734402, an automatic injection device comprising an injection syringe provided with a body carrying an injection needle and a piston rod mounted movable in this body to traverse an injection stroke whose limit is defined by an abutment of the piston rod in the syringe body.

Usually, the automatic injection device comprises first and second telescopic parts inside which is housed the injection syringe.

The relative movement of the first and second telescopic parts controls the operation of the automatic injection device.

Thus, to operate the automatic injection device, a user grasps a proximal end of this automatic injection device and presses a distal end of this automatic injection device against his skin so as to cause a relative movement of the first and second telescopic parts in a shortening direction of the automatic injection device. This automatically causes, thanks to the triggering of elastic forces, a succession of operating steps, in particular the penetration of the injection needle into the skin of the user and the injection of the liquid product contained in the body of the user. syringe through the skin. After the injection, follows a step of retracting the needle inside one of the telescopic parts to avoid injury.

To achieve at least part of these operating steps, the automatic injection device described in US8734402 comprises, on the one hand, a piston control member capable of changing between:

a configuration engaged with the piston rod to push this piston rod, and

a disengaged configuration of this piston rod.

On the other hand, the automatic injection device comprises means for moving the control member relative to the piston rod between its engaged and disengaged configurations. These means of displacement of the control member comprise a cam track carried by a positioning control member which, during the injection stroke, is immobilized axially with the syringe body. This cam path cooperates, by relative movement during the injection stroke, with a cam carried by the control member.

It is observed that the position of the piston rod in the syringe body when the control member reaches its disengaged configuration is made inaccurate by the dimensional uncertainties of several of the elements of the automatic injection device. If the plunger rod is abutted in the syringe body before the control member reaches its disengaged configuration, the control member can no longer move to reach its disengaged configuration. The automatic injection device is then blocked inadvertently and the retraction of the injection needle does not take place.

To remedy this drawback, it is known to adapt the dimensions of the automatic injection device so that the piston rod is not abutted in the syringe body before the control member reaches its configuration. disengaged. However, in this case, when the control member reaches its disengaged configuration, the liquid contained in the body of the syringe is not totally injected.

The object of the invention is in particular to provide an automatic injection device in which the retraction of the injection needle operates reliably at the end of the injection stroke and in which the quantity of non-injected product is scaled down.

For this purpose, the subject of the invention is an automatic injection device comprising:

an injection syringe provided with a syringe body carrying an injection needle and a piston rod movably mounted in this syringe body for traversing an injection stroke whose limit is defined by an abutment of the piston rod in the syringe body,

a piston control member capable of changing between

o a configuration engaged with the piston rod to push this piston rod and

o a disengaged configuration of this piston rod,

means for displacing the piston control member with respect to the piston rod between its engaged and disengaged configurations,

characterized in that the means for moving the piston control member between its engaged and disengaged configurations comprises at least a first cam track carried by a disengaging member and a cam carried by the piston control member, the disengaging member being movable relative to the piston rod and to the syringe body after the piston rod has reached the end of the injection stroke, so as to cooperate the first cam path carried by the disengaging member with the cam carried by the control member of the piston.

Thus, when the piston control member moves from its configuration engaged with the piston rod to its disengaged configuration, the piston rod can be abutted in the syringe body before the control member reaches its configuration. disengaged, this without blocking the operation of the automatic injection device and prevent retraction of the injection needle. Indeed, the disengaging member (which is movable relative to the piston rod and the syringe body after the piston rod has reached the end of the injection stroke) allows to complete the body of disengaging its stroke to its disengaged configuration by cooperating the first cam path carried by the disengagement member with the cam carried by the control member.

According to other optional features corresponding to different embodiments of the automatic injection device:

the means for displacing the piston control member between its engaged and disengaged configurations further comprises a second cam path carried by a positioning control member which, during the injection stroke, is immobilized axially with the syringe body, this second cam path cooperating, by relative movement during the injection stroke, with the cam carried by the piston control member;

the disengaging member at least partially surrounds the positioning control member, the disengaging member and the positioning control member comprising means for immobilizing rotation between them provided with at least one groove and a additional tongue;

the rotational immobilization tongue is formed in the disengagement member, the first cam path delimiting one end of the tongue;

the automatic injection device comprises first and second telescopic parts whose relative displacement controls the operation of this automatic injection device, the disengaging member being integral with the first telescopic part, which is intended to be held by a user, and the positioning control member being secured to the second telescopic portion;

- The disengaging member is movable relative to the piston rod and the syringe body after the piston rod has reached the end of the injection stroke by elastic return means acting between the first and second parts. telescopic in the direction of an elongation of the automatic injection device; - The elastic return means comprise a plastic spring integrally with the second telescopic portion;

the automatic injection device comprises releasable means for locking the first and second telescopic parts during at least part of the injection stroke;

the automatic injection device comprises means for releasing the releasable locking means of the first and second telescopic parts carried by a thrust member axially integral with the piston control member during the injection stroke;

- The releasable locking means comprise at least one retractable pawl carried by the second telescopic portion and cooperating with a notch carried by the first telescopic portion;

- The release means of the releasable locking means of the first and second telescopic parts comprise a retractable ramp retractable pawl;

the automatic injection device comprises means for limiting the stroke between the first and second telescopic parts;

the means for limiting the stroke comprise a radial projection carried by the second telescopic part cooperating with an edge of a slot formed in the first telescopic part to limit the stroke between the first and second telescopic parts during the extension of the device automatic injection and two axial stops respectively carried by the first and second telescopic portions arranged to limit the stroke between the first and second telescopic parts during the shortening of the automatic injection device;

the automatic injection device comprises means for visually indicating the end of the injection stroke;

the visual indication means comprise a window formed through the first telescopic part and at least one visual indicator carried by the piston control member, this visual indicator being positioned in line with the window after the piston rod has reaches the end of the injection stroke.

The invention will be better understood on reading the description which follows, given solely by way of example and with reference to the appended drawings, in which:

FIG. 1 is a perspective view of an automatic injection device according to a first embodiment of the invention, in an initial configuration, preceding the operation of this automatic injection device;

FIG. 2 is a view similar to FIG. 1, the automatic injection device being shown without an outer casing forming a disengaging member;

- Figure 3 is a view similar to Figure 2, the automatic injection device being shown without a control member;

- Figures 4 and 5 are sectional views of the automatic injection device respectively according to the planes IV-IV and V-V of Figure 1;

- Figure 6 is a perspective view, in section along the plane IV-IV, of the outer casing of the automatic injection device shown in Figure 1;

FIG. 7 is a perspective view of a half-shell of the control member of the automatic injection device represented in FIG. 1;

FIG. 8 is a perspective view of a piston control member of the automatic injection device shown in FIG. 1;

FIG. 9 is a detailed view of the surrounded portion IX of the automatic injection device of FIG. 5 showing injection springs not shown in FIG. 5;

FIG. 10 is a perspective view, in section along an X-X plane of FIG. 16, of the automatic injection device represented in FIG. 1, in which the piston control member is in a disengaged configuration;

- Figures 11 and 12 including detailed views of the circled portion XI of Figure 1, in different operating configurations of the automatic injection device;

- Figures 13 to 17 are sectional views along the plane IV-IV of the automatic injection device shown in Figure 1 in different operating configurations of the automatic injection device;

FIGS. 18 to 21 are front views of an automatic injection device according to a second embodiment of the invention, comprising means for visually indicating the end of the injection stroke in different configurations. FIGS. 1 to 17 show an automatic injection device 22 for a liquid product, according to a first embodiment of the invention. More specifically, the automatic injection device 22 is a medical device for the automatic administration of a liquid medicament by injection. The automatic injection device 22 is of generally cylindrical shape along an axis X.

The automatic injection device 22 is provided with an injection syringe 24 (visible in particular in FIGS. 4 and 5) comprising a substantially tubular syringe body 26 of X axis carrying at one of its ends a needle of Injection 28. The other end of the syringe body 26 is provided with a flange 29. A piston 30, of generally cylindrical shape, is slidably mounted in the syringe body 26 and allows the injection of a liquid product contained therein in the syringe body 26. When the piston 30 moves in the direction of the injection needle 28 it goes through an injection stroke during which the liquid contained in the injection syringe 24 is ejected by the injection needle 28. This stroke is limited by a wall of injection bottom 32 of the syringe body 26 forming an end stop of the stroke of the piston 30 in the syringe body 26. An initial position of the piston 30 is defined according to the amount of liquid that is to be injected. Before mounting the automatic injection device 22, after filling the injection syringe 24, the piston 30 is put in place at the initial position. The maximum injection stroke that the piston 30 can travel thus extends from the initial position of the piston 30 to a limit defined by the abutment of the piston 30 against the bottom wall 32 of the syringe body 26.

In this example, the injection syringe 24 is a pre-filled glass syringe with a stuck needle having a capacity of 1 ml (milliliter). Note that the syringe body 26 defines a maximum volume of liquid capacity, but it is possible to fill only partially, choosing an initial position of the piston 30 adapted.

To perform an injection, the patient grasps the automatic injection device 22 at one end and applies the other end of this automatic injection device 22 against his skin. A succession of movements of different organs of the automatic injection device 22 automatically driven then causes the insertion of the injection needle 28 in the skin of the patient and then the injection of the contents of the syringe body 26 through the needle 28. After the injection, the injection needle 28 retracts into the device 22.

In the following, a component of the automatic injection device 22 close to the patient's hand during the operation of the automatic injection device 22 and distal an element of the automatic injection device 22 remote from the hand will be referred to as proximal. of the patient. Therefore, the end of the automatic injection device 22 that the patient applies against his skin is a distal end of the automatic injection device 22 and the injection needle 28 is carried by a distal end of the syringe body 26.

When not in use, the automatic injection device 22 may be provided with a protective cap (not visible in the figures) of the RNS (Rigid Needle Shield) type, comprising an inner plug soft rubber intended to receive the end of the injection needle 28 and to seal it. The inner cap is surrounded by a shell of rigid plastic material conferring good mechanical strength to the inner cap. This protective cap is fixedly mounted in a withdrawal member (not shown in the figures) intended to be handled by the user when removing the protective cap. This removal body covers the distal portion of the automatic injection device 22 when mounted on the automatic injection device 22.

As can be seen for example in Figures 3 to 5, the injection syringe 24 is positioned within a syringe holder 34 of generally tubular X-axis open on both sides. The injection syringe 24 is immobilized inside the syringe holder 34 in particular by elastomer elements 36 (visible in particular in FIGS. 13 to 17) connected to the syringe holder 34 and in contact with the syringe body 26 of the syringe. such that the injection syringe 24 is immobilized axially by adhesion. Two viewing windows 40 (visible in particular in FIGS. 1 to 2) are arranged facing each other in the syringe holder 34. Each viewing window 40 is of elongated shape, extends substantially in the direction of the X axis and makes the injection syringe 24 visible through the syringe holder 34.

The syringe holder 34 is slidably mounted in a generally tubular, X-axis positioning control member 42, which positioning control member 42 is substantially longer than the syringe holder 34. The positioning 42 comprises two half-shells 44a, 44b generally semi-cylindrical, an end sleeve 46 and a retaining ring 47. The various elements 44a, 44b, 46 and 47 of the positioning control member 42 are immobilized by compared to others. The end sleeve 46 forms the distal portion of the positioning control member 42. It is the distal surface 48, the most distal of the end sleeve 46, which is intended to be applied against the skin of the patient. The retaining ring 47 has a generally annular shape and is housed in the distal portion of the positioning control member 42. One function of the end sleeve 46 is to protect the injection needle 28 against unintended contact with an element of its environment when the automatic injection device 22 is not used. Indeed, during the insertion of the injection needle 28 into the skin of the patient, the injection syringe 24 moves axially with respect to the positioning control member 42 so that the needle Injection 28 becomes protruding with respect to the distal surface 48 of the end sleeve 46. After completion of the injection, the injection syringe 24 axially retracts into the automatic injection device 22 so that the injection needle 28 is no longer protruding from the distal surface 48. Thus, before and after the operation of the automatic injection device 22, the injection needle 28 is not protruding from the control 42.

The syringe holder 34 and the positioning control member 42 comprise means for guiding and limiting the stroke between them, comprising in particular:

an internal shoulder 50 of the end sleeve 46 intended to stop the axial movement of the syringe holder 34 relative to the positioning control member 42 in the proximal to distal direction cooperating with a distal surface 52 of the syringe holder 34;

radial lugs 54 (visible in particular in FIG. 5) carried by the syringe holder 34 cooperating with axial notches 56 of the end sleeve

46 to prevent X-axis rotation of the syringe holder 34 relative to the positioning control member 42.

Thus, the only degree of freedom of the syringe holder 34 with respect to the positioning control member 42 is the X-axis translation.

The injection syringe 24 comprises a piston rod 58 kinematically connected to the axial movement of the piston 30, and thus movable in the syringe body 26. The piston rod 58 has a generally cylindrical shape of axis X. The distal end the piston rod 58 cooperates axially with the proximal end of the piston 30. Alternatively, the piston rod 58 and the piston 30 can be screwed to each other. As the piston rod 58 and the piston 30 are kinematically connected in their axial movement these two members travel together the injection stroke.

FIG. 8 shows a piston control member 64 of generally tubular shape with an X axis. The piston control member 64 is slidably mounted in the positioning control member 42. piston 64 cooperates with the proximal portion of the piston rod 58 so that the piston control member 64 is able to change angularly with respect to the piston rod 58 between:

a configuration engaged with the piston rod 58 to push this piston rod 58 and

a disengaged configuration of this piston rod 58.

The piston rod 58 is provided at its proximal end with a proximal shoulder 66 on which four radial projections 68 are provided. The piston control member 64 is provided with an inner shoulder 70 in which four axial grooves 72 are provided. The outer contour defined by the proximal shoulder 66 and the four radial projections 68 of the piston rod 58 has a shape complementary to the inner contour defined by the inner shoulder 70 and the four grooves 72 of the piston control member 64 Thus, when the four radial projections 68 are angularly offset from the four axial grooves 72, the piston controller 64 is in its configuration engaged with the piston rod 58. In the configuration engaged with the piston rod 58, the four radial projections 68 cooperate with the inner shoulder 70 and the piston control member 64 is adapted to push the piston 30 towards the distal end of the positioning control member 42. When the four projections radial 68 and the four axial grooves 72 are vis-à-vis, as can be seen in Figure 10, then the piston controller 64 is in a disengaged configuration. In the disengaged configuration, the radial projections 68 may engage axial grooves 72. When the piston control member 64 and the piston rod 58 move axially, the piston rod 58 can then retract into the piston control member 64.

The automatic injection device 22 also comprises a needle control member 74 of generally tubular shape. The needle control member 74 is slidably mounted in the positioning control member 42. The proximal portion of the needle control member 74 is provided with a proximal surface 76 cooperating axially with a distal surface 78 of the distal portion of the piston control member 64. Thus, the needle control member 74 and the piston controller 64 are kinematically connected in their axial movements. The needle control member 74 cooperates with the distal portion of the syringe holder 34 such that the needle control member 74 is capable of angularly moving relative to the syringe holder 34 between:

a configuration engaged with the syringe holder 34 to push this syringe holder 34 and

a disengaged configuration of this syringe support 34.

As illustrated in particular in Figures 4, 5 and 13, the syringe holder 34 is provided at its proximal end with a contact surface 80 adapted to cooperate with two axial abutment surfaces 82 carried by two internal radial projections 84 of the needle control member 74. Two grooves 86 are provided in the contact surface 80 of the syringe holder 34. These grooves 86 allow, when aligned with the axial stops 82 of the needle control member 74 the passage of these axial stops 82 through the contact surface 80 of the syringe holder 34. Thus, when the internal radial projections 84 of the needle control member 74 are angularly offset relative to the grooves 86 of the syringe holder 34 the needle control member 74 is in its configuration engaged with the syringe holder 34 to push this syringe holder 34. In this configuration the axial stops 82 cooperate with the conical surface. 80 of the syringe holder 34 and the needle control member 74 is able to push the syringe holder 34 into the distal end of the positioning control member 42. When the internal radial projections 84 of the needle control member 74 is aligned with the grooves 86 of the syringe holder 34, the needle control member 74 is in a disengaged configuration of the syringe holder 34. In the disengaged configuration, the internal radial projections 84 can engage in the grooves 86. When the organ of Needle control 74 and syringe holder 34 move axially together, needle control member 74 can then advance around syringe holder 34 without pushing it.

The needle control member 74 is provided with a cam 88 cooperating with a needle control cam path 90 formed in the positioning control member 42. This needle control cam path 90 is for rotating the needle control member 74 so that when the syringe holder 34, pushed by the needle control member 74, reaches the end of its axial insertion movement of the needle 28, the needle control member 74 reaches, by rotation, its disengagement configuration of the syringe holder 34.

Note that the automatic injection device 22 comprises first and second telescopic parts whose relative displacement controls the operation of this automatic injection device 22. Indeed, the positioning control member 42 forms the second telescopic portion mounted sliding in an outer casing 92 forming the first telescopic part. The outer casing 92 partially surrounds the positioning control member 42 and is intended to be held by the user. The outer housing 92 has a generally tubular X-axis shape partially closed at its proximal end. As the outer housing 92 moves toward the proximal portion of the control member 42, the total length of the automatic injection device 22 increases. This direction of elongation direction displacement of the automatic injection device 22 is qualified. On the contrary, when the outer casing 92 moves towards the distal portion of the positioning control member 42, the total length of the injection device automatic 22 decreases. This direction of shortening direction of the automatic injection device 22 is qualified. Stroke limiting means between the outer casing 92 and the positioning control member 42 comprise:

two radial projections 94 carried by the retaining ring 47 of the positioning control member 42 intended to cooperate with edges 96 of openings 98 (visible in particular in FIG. 1) formed in the outer casing 92 to limit the stroke of the positioning control member 42 during the extension of the automatic injection device 22;

two axial stops 100, 102 respectively carried by the positioning control member 42 and the outer casing 92 arranged so as to limit the stroke between the positioning control member 42 and the outer casing 92 during the shortening of the device automatic injection 22;

grooves 104 (visible in FIGS. 2 and 7) formed in the positioning control member 42 and tongues 106 carried by the surface inside the outer casing 92 cooperating so as to immobilize the outer casing 92 in rotation relative to the positioning control member 42. The outer casing 92 forms a disengaging member 92 carrying a first cam path 110 intended to cooperate with a cam 112 carried by the piston control member 64. This first cam path 110 is formed by the edge 110 of a window 114 which defines the end of one of the tabs 106. The first cam path 110 and the cam 112 of the piston controller 64 forms means for moving the piston controller 64 relative to the piston rod 58 between its engaged and disengaged configurations. The first cam path 110 is inclined with respect to the X axis so that when the first cam path 110 and the cam 112 of the piston controller 64 cooperate and the piston controller 64 moves to the distal portion of the piston controller 64, the piston controller 64 rotates relative to the piston rod 58.

A second cam path 116 is provided in the positioning control member 42. Like the first cam path 110, this second cam path 116 is inclined with respect to the X axis so that when the second cam path 116 cam path 116 and cam 112 of the piston controller 64 cooperate and as the piston controller 64 moves toward the distal portion of the positioning control member 42, the control member of piston 64 rotates relative to the piston rod 58. The inclination and the position of this second cam path 116 are such that when the piston 30 and the piston rod 28 abut in the bottom wall 32 of the syringe 24, the piston control member 64 does not reach its disengagement configuration by cooperating with the second cam path 116. In order for the piston control member 64 to reach its disengaging configuration, it is necessary to that the first cam path 110 cooperates with the org piston control pin 64 to drive it to its disengagement configuration. This cooperation between the first cam path 110 and the piston control member 64 takes place after the end of the injection, that is after the piston 30 and the piston rod 58 have reached the end. of the injection stroke.

The positioning control member 42 is provided with releasable locking means of the positioning control member 42 and the outer casing 92 during at least part of the injection stroke. These releasable locking means comprising two retractable pawls 118 (visible in particular in Figures 13 to 17), positioned on either side of the positioning control member 42 on each of the two half-shells 44a and 44b, for cooperate with four notches 120 formed by four holes 120 formed in the outer housing 92. The four holes 120 are grouped in pairs so that each retractable pawl 118 is able to cooperate with two notches 120. Two notches 120 cooperating with the same retractable pawl 118 are aligned in the direction of the axis X. The retractable catches 118 retractable are formed by flip-flops pivoting between:

a release configuration, in which the distal end of the retractable pawls 118 is not protruding with respect to the positioning control member 42, and

a locking configuration in which the distal end of the retractable pawls 118 protrudes outwardly from the positioning control member 42 and a proximal end of the retractable pawls 118 protrudes inwardly of the control member of the positioning 42.

When in their blocking configuration, the retractable pawls 118 are able to cooperate with the notches 120. When a retractable pawl 118 cooperates with a catch 120, the positioning control member 42 can not move towards the notch. distal end of the outer housing 92 relative to the outer housing 92 but can still move in the opposite direction. The automatic injection device 22 also comprises means for releasing the releasable blocking means 118, 120 carried by a thrust member. This thrust member is formed by the needle control member 74. The thrust member comprises a retraction ramp adapted to cooperate with the proximal end of the retractable pawls 118 so that the retractable pawls 118 are locked in their liberation position. The needle control member 74 cooperates axially with the pawls 118 during axial movement of the needle control member 74 in the positioning control member 42. When the needle control member 74 does not cooperate with the retractable pawls 118, the retractable pawls 118 are not locked in their release position and are biased to their locking position.

The automatic injection device 22 is provided with elastic return means acting between the outer casing 92 and the positioning control member 42. These elastic return means comprise two return springs 122, visible only in FIG. 9, positioned between spring supports 124 of the outer housing 92 and bearing surfaces 126 of the positioning control member 42. The return springs 122 are metal compression springs 122, acting in the direction of an elongation of the automatic injection device 22. The spring supports 124 are axial protuberances located within the proximal portion of the outer housing 92. The bearing surfaces 126 of the positioning control member 42 are distal surfaces of the 42. In a variant, it is possible to replace these metal springs 122 by plastic springs made of material with the positioning control member 42.

An injection spring 128, visible only in FIG. 9, is positioned in the proximal end of the positioning control member 42. The injection spring 128 acts axially between the positioning control member 42 and the piston control member 64, so as to push the control member piston 64 to the distal portion of the positioning control member 42. The piston control member 64 carries at its proximal end two release tongues 130 of the injection spring 128. The release tongues 130 are intended for cooperate with an orifice 132 of the retaining ring 47 so as to axially immobilize the positioning control member 42 and the piston control member 64. The release tongues 130 are provided with ramps 134 (visible in particular in the figure 8) adapted to cooperate with release surfaces 136 of the outer casing 92.

A retraction spring (not shown in the figures) is positioned between the end sleeve 46 and the syringe holder 34. The retraction spring is a compression spring whose one end is supported on an internal shoulder 138 of the sleeve. 46 end and the other end is supported on a shoulder 140 of the syringe holder 34. This retraction spring pushes the syringe holder 34 in the direction of the retraction movement of the syringe holder 34 in the control body of the syringe 34 This retraction movement is a movement of the syringe holder 34 towards the proximal end of the positioning control member 42. The various stages of operation of the automatic injection device 22 will be described below.

To operate the automatic injection device 22, it is necessary, in a first step, to remove the withdrawal member and the protective cap from the distal portion of the automatic injection device 22. The automatic injection device 22 is then in the configuration shown in Figure 1, which we qualify as initial configuration. Then, the user grasps the automatic injection device 22 through the outer housing 92 and applies the distal surface 48 of the end sleeve 46 against his skin where the injection of the liquid contained in the syringe body 26 is desired.

Then, during an unlocking step, the user applies an axial force towards the distal portion of the automatic injection device 22, on the outer casing 92. Thus, the outer casing 92 moves axially toward the distal portion of the casing. the positioning control member 42. This displacement causes the cooperation of the ramps 134 of the release tabs 130 with the release surfaces 136 of the outer casing 92. The release tabs 136 are then deformed inwards and no longer immobilize. axially the piston control member 64 with the positioning control member 42. During this step, the retractable pawls 118 pass from a configuration in which they cooperate with the two most distal notches 120 of the outer casing 92 to a configuration in which they cooperate with the two most proximal retractable catches 118 of the outer casing 92. The outer casing 92 is then immobilized in the direction of elongation of the automatic injection device 22. automatic injection 22 then reaches the configuration shown in FIG. 13, in which the piston control member 64 is free to move axially toward the distal portion of the positioning control member 42 and the two axial stops 100 and 102 carried by the positioning control member 42 and the outer housing cooperate 92.

Following this unlocking step, an insertion step takes place. The injection spring 128 axially drives the needle control members 74 and piston 64 to the distal portion of the positioning control member 42. As the needle control member 74 is in the engagement configuration the syringe holder 34, it cooperates axially with the syringe holder 34 and displaces the latter so that the injection needle 28 becomes protruding with respect to the distal surface 48 of the end sleeve 46 and is inserted into the skin of the patient. During this step, the cam 88 of the needle control member 74 cooperates with the needle control cam path 90 so that the needle control member 74 rotates relative to the syringe holder 34. until it disengages from the syringe holder 34. In the same manner, the cam 112 of the piston controller 64 cooperates with the second cam path 116 so that the piston controller 64 rotates relative to the piston rod 58. However the piston control member 64 does not reach its disengagement configuration of the piston rod 58. At the end of this step, the automatic injection device 22 is in the configuration shown in Fig. 14, wherein the piston controller 64 is in its configuration engaged with the piston rod 64, the needle control member 74 is in its disengaged configuration and the internal shoulder 50 of the end sleeve 46 cooperates with the Distal interface 52 of the syringe holder 34. In this configuration, the injection needle 28 is inserted into the skin of the patient.

Following this insertion step, an injection step takes place. The injection spring 128 continues to urge the needle control members 74 and piston 64 axially toward the distal portion of the positioning control member 42, however, the needle control member 74 no longer cooperates. axially with the syringe holder 34. The piston control member 64 being in configuration engaged with the piston rod 58, it cooperates axially with the piston rod 48 and pushes the latter so that it travels its course. injection. The pharmaceutical liquid is then injected into the patient's body. During this step, the cam 112 of the piston control member 64 continues to cooperate with the second cam path 116, by relative movement, but does not reach its disengagement configuration of the piston rod 58. During this step, the needle control member 74 cooperates with the proximal end of the retractable pawls 118 and locks them in their release configuration. . When the retractable pawls 118 are in the release configuration, the outer casing 92 is again able to move axially towards the distal end of the positioning control member 42. At the end of this step, the injection device 22 is in the configuration shown in FIG. 15, in which the piston 30 and the piston rod 58 abut against the bottom wall 32 of the syringe body 26, the piston control member 64 is in the configuration taken with the piston rod 58 and the retractable pawls 118 of the positioning control member 42 are in the release configuration.

Following this injection step, a step of triggering the retraction takes place. To trigger the retraction of the injection needle 28, it is necessary that the first cam path 110, carried by the outer housing 92, cooperates with the cam 112 of the piston control member 64. For this cooperation takes place, the user must release the axial force exerted on the outer casing 92 so that the return spring 122 moves the outer casing 92 in the direction of elongation of the automatic injection device 22 It should be noted that during this step, the release member 92 is movable relative to the piston rod 58 and to the syringe body 26. During this movement, the first cam path 110 cooperates with the cam 112 of the piston control member 64 which causes a rotation of the piston control member 64 relative to the piston rod 58 to its disengaged configuration of the piston rod 58. At the end of this step , the automatic injection device 22 is in the 16, in which the piston control member 64 is in its disengaged configuration of the piston rod 58 and the radial projections 94 of the retaining ring 47 cooperate with the edges 96 of the lights 98 formed in the outer casing 92.

Following this step of triggering the retraction, a retraction step takes place. Since the piston control member 64 is in a disengaged configuration of the piston rod 58, the latter is free to move axially towards the proximal portion of the automatic injection device 22. The retraction spring is then free to push the piston. syringe support 34 to the proximal portion of the positioning control member 42. Thus, the injection needle 28 retracts into the positioning control member 42 so that it no longer protrudes from the the distal surface of the end sleeve 46. At the end of this step, the automatic injection device 22 is in the configuration shown in FIG. 17, in which the injection needle 28 is not projecting from the position control member 42. When the device automatic injection 22 is in this configuration, its operation is complete. The patient can then move the automatic injection device 22 away from his skin.

The following will be described, with reference to FIGS. 18 to 21, an automatic injection device 22 according to a second embodiment of the invention. In this case, elements similar to those of the preceding figures are designated by identical references.

In this embodiment, the piston controller 64 is provided with visual indication means 138 and 140 of the end of the injection stroke (visible in FIGS. 20 and 21). These indication means 138, 140 comprise two printed indications 138, 140 on the piston control member 64. These printed indications 138, 140 are made visible when they are positioned at the right of a window 142 formed through the housing. 92. A first indication 138 is an indication of the end of the injection stroke. It is visible during the step of triggering the retraction. The second indication 140 is an indication of the end of operation of the automatic injection device 22. It is visible after the step of retraction of the injection needle 28.

The invention is not limited to the embodiments presented and other embodiments will become apparent to those skilled in the art. In particular, it is possible to position the disengaging member on an element other than the outer casing and the inclination of the cam path could be eliminated and compensated by a different shape of the first cam path.

Claims

1. Automatic injection device (22) comprising:

an injection syringe (24) provided with a syringe body (26) carrying an injection needle (28) and a piston rod (58) movably mounted in said syringe body (26) to traverse a injection stroke, a limit of which is defined by an abutment of the piston rod (58) in the syringe body (26), a piston control member (64) capable of changing between:

a configuration engaged with the piston rod (58) to push the piston rod (58), and

o a disengaged configuration of this piston rod (58),

means for moving the piston control member (64) relative to the piston rod (58) between its engaged and disengaged configurations,

characterized in that the means for moving the piston control member (64) between its engaged and disengaged configurations comprises at least a first cam path (110) carried by a disengaging member (92) and a cam ( 112) carried by the piston control member (64), the disengaging member (92) being movable relative to the piston rod (58) and the syringe body (26) after the piston rod ( 58) has reached the end of the injection stroke, so as to cooperate the first cam path (110) carried by the disengagement member (92) with the cam (112) carried by the control member of piston (64).

The automatic injection device (22) of claim 1, wherein the means for moving the piston controller (64) between its engaged and disengaged configurations further comprises a second cam path (116). carried by a positioning control member (42) which, during the injection stroke, is immobilized axially with the syringe body (26), this second cam path (116) cooperating, by relative movement during the stroke of injection, with the cam (112) carried by the piston control member (64).

3. Automatic injection device (22) according to claim 2, wherein the release member (92) at least partially surrounds the positioning control member (42), the disengagement member (92) and the positioning control member (42) comprising means for immobilizing rotation between them provided with at least one groove (104) and a tab (106) complementary.

An automatic injection device (22) according to claim 3, wherein the rotational immobilization tongue (106) is formed in the disengaging member (92), the first cam path (110) delimiting one end of the tongue (106).

An automatic injection device (22) according to any of claims 2 to 4, comprising first (92) and second telescopic portions

(42) whose relative movement controls the operation of this automatic injection device (22), the disengaging member (92) being integral with the first telescopic part (92), which is intended to be held by a user, and the positioning control member (42) being integral with the second telescopic portion (42).

The automatic injection device (22) according to claim 5, wherein the disengaging member (92) is movable relative to the piston rod (58) and the syringe barrel (26) after the rod piston (58) has reached the end of the injection stroke by elastic return means (122) acting between the first (92) and second (42) telescopic portions in the direction of an elongation of the injection device automatic (22).

The automatic injection device (22) according to claim 6, wherein the elastic return means (122) comprises a plastic spring integrally formed with the second telescopic portion (42).

An automatic injection device (22) according to any one of claims 5 to 7, comprising releasable locking means (118, 120) of the first and second telescopic portions (42, 92) during at least a portion of the injection stroke.

9. Automatic injection device (22) according to claim 8, comprising means for releasing the releasable locking means (118, 120) of the first and second telescopic parts (42, 92) carried by a thrust member (74). axially secured to the piston control member (64) during the injection stroke.

An automatic injection device (22) according to claim 8 or 9, wherein the releasable locking means (118, 120) comprise at least one retractable pawl (118) carried by the second telescopic portion (42) and cooperating with a notch (120) carried by the first telescopic portion (92).

1 1. Automatic injection device (22) according to claims 9 and 10 taken together, wherein the release means of the releasable locking means (118, 120) of the first and second telescopic portions (42, 92) comprise a retraction ramp retractable ratchet (118).

An automatic injection device (22) according to any one of claims 5 to 11, including stroke limiting means (94, 96, 100, 102) between the first and second telescopic portions (42, 92). .

13. Automatic injection device (22) according to the preceding claim wherein the stroke limiting means (94, 96, 100, 102) comprise a radial projection (94) carried by the second telescopic portion (42) cooperating with an edge (96) of a lumen (98) in the first telescopic portion (92) for limiting the stroke between the first and second telescopic portions (42, 92) during elongation of the automatic injection device (22); ) and two axial stops (100, 102) carried respectively by the first and second telescopic portions (42, 92) arranged to limit the stroke between the first and second telescopic portions (42, 92) during the shortening of the device. automatic injection (22).

14. Automatic injection device (22) according to any one of the preceding claims, comprising means for visual indication (138, 142) of the injection end of stroke.

The automatic injection device (22) according to claims 5 and 14 taken together, wherein the visual indication means (138, 142) comprises a window (142) formed through the first telescopic portion (92) and at minus a visual indicator (138) carried by the piston control member (64), which visual indicator (138) is positioned to the right of the window (142) after the piston rod (58) has reached the end of the the injection stroke.