Reusable motorized auto-injection device

Abstract

A reusable motorized auto-injection device comprises: a single motor; a motion conversion mechanism; a drive shaft configured to be driven by said motion conversion mechanism to move linearly; and a loading sleeve configured to receive a syringe containing a medication; wherein the motion conversion mechanism comprises an outer sleeve and an inner shaft disposed within the outer sleeve, wherein a thread is provided on one of the outer wall of the inner shaft and the inner wall of the outer sleeve, and an engagement element is provided on the other, and wherein the thread includes a first section and a second section having a continuous thread groove, the first section and the second section having different pitches, the engagement element being configured to be able to engage successively with respective thread groove of the first section and the second section in such a way that, when engaging with the thread groove of the first section, the drive shaft is moved linearly at a first, faster speed to realize rapid insertion of the needle of the syringe, and when engaging with the thread groove of the second section, the drive shaft moves linearly at a second, slower speed to realize a slow infusion of the medication of the syringe.

Description

REUSABLE MOTORIZED AUTO-INJECTION DEVICECROSS REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to Chinese Application No. 202311113120.8 entitled “Reusable Motorized Auto-Injection Device” filed August 31, 2023, the disclosure of which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates to an injection device for delivering a dose of a medication from a syringe, and in particular to a reusable motorized auto-injection device, such as an auto-injection pen.BACKGROUND OF THE INVENTION

[0003] Auto-injection devices such as auto-injection pens are widely used because they make medication injection easier and more convenient. Each time a medication is injected, a user simply opens the injection pen, loads a syringe or cartridge, and then activates a switch for automatic needle feeding and automatic infusion of the medication.

[0004] Typically, prior art auto-injection pens require independent implementation of both needle insertion and medication infusion motions. The two motions have different objects and different speeds, so two sets of motion mechanisms are typically required to realize the two motions for the needle and the medication, respectively. For example, two springs, or one spring and one motor, or two motors are used to realize the respective motions of the needle and the medication, respectively.

[0005] For example, CN110650761B discloses a self-injector comprising a plunger engaged with a stopper, a cannula surrounding the plunger, an insertion spring that biases the cannula with respect to the rear of the device, and a delivery spring that biases the plunger with respect to the cannula. The insertion spring is used to insert the needle into a patient and the delivery spring is used to infuse medication.

[0006] As another example, CN1665557A discloses a medical automatic medication delivery device having two motors. By operating a switching mechanism provided on the body, a first motor is activated to automatically cause an injection needle housed in the body to protrudefrom the body for carrying out feeding of the needle to the injection site, and then a second motor is activated to push the medication to infuse the medication into a patient.

[0007] The use of two sets of motion mechanisms results in a complex and bulky structure of the entire injection device and an increased risk of failure. In addition, the use of two motors increases the complexity of wiring and raises costs.SUMMARY OF THE INVENTION

[0008] Accordingly, it is an object of the present disclosure to provide a reusable motorized auto-injection device which is capable of solving at least one of the above technical problems existing in the prior art. In particular, the motorized auto-injection device of the present disclosure is capable of simplifying the structure, reducing the cost, and being easy to miniaturize.

[0009] The reusable motorized auto-injection device of the present disclosure uses a single motor to realize two motions of needle insertion and medication infusion. The speeds of the two motions are automatically realized by means of a motion conversion mechanism comprising two thread sections having different pitches, whereby during operation the device automatically switches from a thread section with a larger pitch to a thread section with a smaller pitch, thereby causing a drive shaft to move linearly at different speeds.

[0010] Further, the switching of the speed at which the drive shaft moves linearly combined with a loading sleeve achieves the switching of two moving objects simultaneously.

[0011] A reusable motorized auto-injection device comprises: a housing; a single motor being housed within said housing; a motion conversion mechanism configured to convert a rotational motion of said motor into a linear movement; a drive shaft configured to be driven by said motion conversion mechanism to move linearly; and a loading sleeve configured to receive a syringe containing a medication, wherein said drive shaft is configured to be able to engage a stopper of said syringe so as to push said stopper, and wherein said motion conversion mechanism comprises an outer sleeve and an inner shaft disposed within said outer sleeve, a thread is provided on one of an outer wall of said inner shaft and an inner wall of said outer sleeve, an engagement element is provided on the other of said outer wall of said inner shaft and said inner wall of said outer sleeve, and wherein said thread comprise a first section and asecond section having a consecutive thread groove, said first section having a first pitch and said second section having a second pitch, said first pitch being greater than said second pitch, said engagement element being configured to be able to engage successively with the respective thread groove of said first section and said second section in such a way that, when engaging with the thread groove of said first section, said drive shaft is caused to move linearly at a first, faster speed, thereby realizing rapid insertion of the needle of said syringe; and when engaging with the thread groove of said second section, said drive shaft is linearly moved at a second, slower speed, thereby realizing a slow infusion of medication from said syringe. In this way, the auto-injection device according to this present disclosure automatically achieves the speeds of the aforementioned two motions by means of a motion conversion mechanism comprising two thread sections with different pitches.

[0012] Preferably, said engagement element is in the form of a protrusion or a tooth or a pin or a roller.

[0013] Preferably, there are two engagement elements opposed in a cross-section perpendicular to an axial direction of said drive shaft, and correspondingly, said thread has two opposed thread grooves extending helically in the axial direction.

[0014] Preferably, said two engagement elements are formed by a single pin extending radially through said inner shaft at one end of said inner shaft.

[0015] Preferably, an output shaft of said motor is connected to one of said outer sleeve and said inner shaft, and the other of said outer sleeve and said inner shaft is connected to said drive shaft.

[0016] Preferably, said thread is provided on the inner wall of said outer sleeve and said engagement element is provided on the end of said inner shaft.

[0017] Preferably, on an inner wall of said housing is provided a proximal stop which defines a most proximal position of said loading sleeve.

[0018] Preferably, said reusable motorized auto-injection device further comprises a distal stop provided distal to a distal end of said loading sleeve and spaced apart from said distal end, said distance determining a depth of insertion of a needle of said syringe.

[0019] Preferably, said reusable motorized auto-injection device further comprises a reset spring surrounding said loading sleeve, one end of said reset spring resting against said distalstop and the other end resting against an outwardly extending proximal protrusion of said loading sleeve. This allows the reset spring to reset the loading sleeve for re-use after the infusion is finished.

[0020] Preferably, said distal stop comprises a U-shaped body with a bottom wall being formed with a through hole for free passage of said syringe. In this way, the rapid linear movement of the drive shaft when the motor is operating in the first mode is able to move both the loading sleeve and the syringe as a whole (overcoming the biasing force of the reset spring), thereby driving the needle of the syringe rapidly into the patient.

[0021] Preferably, a tab for the user's finger to pinch is formed at a distal end of each of two sidewalls of said U-shaped body, said tab being configured to be able to move along a slit in said housing in order to adjust said distance. This allows the user to flexibly adjust the depth of insertion of the needle according to the different requirements of the medication infusion as well as the different sites of infusion.

[0022] Preferably, said distal stop further comprises a pawl or outer tooth formed on each of said two sidewalls of said U-shaped body and a plurality of inner teeth disposed opposite to said pawl or outer tooth, said pawl or outer tooth being configured to selectively engage a corresponding tooth of said plurality of inner teeth in order to fix said distance.

[0023] Preferably, said plurality of inner teeth are formed on an inner wall of said housing.

[0024] Preferably, said drive shaft is provided with a slider, said slider configured to non- rotationally, linearly move said drive shaft.

[0025] Preferably, said slider is configured to move along a linear track, said linear track being provided within said housing.

[0026] Preferably, in addition to said motor, said motion conversion mechanism, said drive shaft, and said loading sleeve can be also housed within said housing, thereby forming an integrated structure.

[0027] The present disclosure uses a dual pitch motion conversion mechanism that allows for achieving the requirement of rapid needle insertion and subsequent slow infusion. This concept allows for much simpler manufacture of an auto-injection device. The main advantage of the reusable motorized auto -injection device of the present disclosure over the prior art is that there is only one set of mechanical drive mechanism, i.e., the drive shaft and the motor circuit.Having only one set of drive mechanism improves the reliability and reduces the cost of the auto-injection device.

[0028] The reusable motorized auto-injection device of the present disclosure can be applied to many auto-injection devices, such as Epipen, BD Physioect™ disposable autoinjector, Aria smart autoinjector, and so on.

[0029] Other purposes, features, and details of the present disclosure may be more fully understood with reference to the following detailed description of exemplary embodiments and in conjunction with the accompanying drawings and in accordance with the accompanying claims.

[0030] A person skilled in the art will understand advantages of corresponding embodiments and various additional embodiments by reading the following detailed description of the corresponding embodiments with reference to the drawings as listed below. In addition, features in the drawings discussed below are not necessarily drawn to scale. Sizes of the features and elements in the drawings may be appropriately enlarged or reduced to more clearly illustrate the embodiments of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present disclosure is further described below in connection with the accompanying drawings and embodiments, wherein the same reference marks refer to similar or identical elements throughout the accompanying drawings and their description.

[0032] FIG. 1A is a three-dimensional view of a reusable motorized auto-injection device according to an embodiment of the present disclosure, wherein a top cover is removed.

[0033] FIG. IB is a top view of a reusable motorized auto-injection device according to the embodiment of the present disclosure, wherein the top cover is removed.

[0034] FIG. 2 is a detail view of a portion of a reusable motorized auto-injection device according to an embodiment of the present disclosure, showing in particular a motor, an outer sleeve, an inner shaft, a slider, and a portion of a drive shaft.

[0035] FIG. 3 is a schematic view of an exemplary syringe that may be loaded into a reusable motorized auto-injection device of the present disclosure.

[0036] FIG. 4 is a partially enlarged view of a reusable motorized auto-injection device according to an embodiment of the present disclosure, showing in particular the slider, the drive shaft, the loading sleeve, the reset spring, the distal stop, and the syringe.

[0037] FIG. 5 is a perspective view of an outer sleeve with internal threads of a reusable motorized auto-injection device according to an embodiment of the present disclosure.

[0038] FIG. 6 is a three-dimensional view of an inner shaft of a reusable motorized autoinjection device according to an embodiment of the present disclosure.DESCRIPTION OF THE INVENTION

[0039] Various illustrative embodiments of the present disclosure are described below. In this description, for the sake of explanation only, various systems, structures and devices are schematically depicted in the drawings, but all the features of actual systems, structures and devices are not described. For example, well-known functions or structures are not described in detail to avoid unnecessary details to obscure the present disclosure. Of course, it should be understood that in any practical application, many specific implementation decisions need to be made to achieve the specific goals of the developer or user, and the system-related and industry-related restrictions need to be observed. These specific goals may vary with actual applications. In addition, it should be understood that although such specific implementation decisions are complicated and time-consuming, this is a routine task for those of ordinary skill in the art who benefit from the present application.

[0040] The terms and phrases used herein should be understood and interpreted as having a meaning consistent with the understanding of those terms and phrases by those skilled in the relevant art. The consistent usage of terms or phrases herein is not intended to imply a specific definition of the term or phrase, that is, a definition that differs from the ordinary and customary meanings understood by those skilled in the art. For terms or phrases intended to have a special meaning, that is, meanings different from those understood by the skilled person, this special meanings will be clearly listed in the description by definition, giving special meanings to the term or phrase directly and unambiguously.

[0041] Unless the content requires, throughout the following description and claims, the words "comprising" and its variations, such as "including", will be interpreted in an open and inclusive sense, that is, as "comprising but not limited to".

[0042] In the description of this disclosure, singular forms of "a", “an”, and "the" include plural objects of discussion, unless the context clearly indicates to the contrary; an individually existing feature without quantity limitations can explicitly or implicitly include one or more of such feature. The meaning of "a plurality of" refers to two or more, unless otherwise specified.

[0043] In the present disclosure, the terms "first", "second", and the like are used for descriptive purposes only and cannot be construed as indicating relative importance or indicating the number of technical features. Therefore, similar to features that appear separately without quantity limitations, features that are limited to "first", "second", etc. can explicitly or implicitly include one or more of the features.

[0044] In the present disclosure, unless otherwise clearly specified and defined, such terms as "mounted", "connected", "coupled", "connected", "fixed", and so on should be understood in a broad sense. For example, it can be a fixed connection, or a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or be indirectly connected via an intermediate medium; or it can be an internal communication between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present disclosure according to specific situations.

[0045] In the present disclosure, for convenience of description, the operator (for example, a physician) is used as a reference object, and the side close to the operator is called "proximal", and the side away from the operator is called "distal".

[0046] FIGS. 1A and IB generally illustrate a reusable motorized auto-injection device according to an embodiment of the present disclosure. The reusable motorized auto-injection device includes a housing 1, a motor 2 housed in the housing 1, a motion conversion mechanism 4, a drive shaft 6, and a loading sleeve 7. The motor 2 is powered by a power source 3. The power source 3 may be a battery, such as a non-rechargeable battery or a rechargeable battery, or it may be an AC / DC converter, such as a power adapter.

[0047] The motion conversion mechanism 4 is configured to convert a rotational motion of the motor 2 into a linear movement of the drive shaft 6. In operation, the motor 2 drives the motion conversion mechanism 4, and the motion conversion mechanism 4 in turn drives the drive shaft 6 for linear movement. The loading sleeve 7 is configured to receive a syringe 10. The drive shaft 6 pushes a stopper of the syringe 10.

[0048] In this embodiment, the housing 1 comprises a first housing portion la and a second housing portion lb, each with a top cover (not shown in the figures). As shown, the motor 2, the motion conversion mechanism 4, and the drive shaft 6 may be provided in the first housing portion la and the loading sleeve 7 may be provided in the second housing portion lb. The first housing portion la and the second housing portion lb may be removably attached together, e.g., by means of a snap connection, a threaded connection, etc., in order to open the housing 1 and load the syringe 10 into the loading sleeve 7. In the embodiment shown, the housing 1 has a substantially square cross-section, but any other shape of cross-section is possible, such as rectangular, circular, oval, and so on. The housing 1 can be made of any suitable material, such as plastic.

[0049] A button type or pushing type switch (not shown) may be provided on the housing 1 for initiating or activating the auto-injection device, for automatically and sequentially carrying out two motions: needle insertion and medication infusion.

[0050] In addition to the motor 2, other components such as the motion conversion mechanism 4, the drive shaft 6, and the loading sleeve 7 can be also housed in the housing 1, thereby making it possible to form an integrated structure.

[0051] In an example, the motor 2 may be a micro DC motor integrated with a reduction mechanism, such as a Bringsmart™ micro motor with a rated voltage of 6 V and a rated speed of 30 rpm. Other types of motors are also possible.

[0052] As shown in FIG. 2, the motion conversion mechanism 4 comprises an outer sleeve 41 and an inner shaft 42 disposed within the outer sleeve 41. In the example shown, the outer sleeve 41 is provided with a thread (one or more) on the inner wall or inner surface thereof, as shown in FIG. 5; and the inner shaft 42 is unthreaded but is provided with a engagement element 43 (one or more) on the outer wall or outer surface thereof, which may be disposed atthe end of the inner shaft 42, as shown in FIG. 6. As shown in FIG. 6. The engagement element 43 is configured to engage with said thread, i.e. to engage in the thread groove of said thread.

[0053] As shown in FIG. 5, the thread of the outer sleeve 41 comprises a first section 44 and a second section 46, the first section 44 having a first pitch Pl and the second section 46 having a second pitch P2, wherein said first pitch Pl is greater than said second pitch P2. The ratio between the first pitch Pl and the second pitch P2 may be, for example, from 2:1 to 4:1, preferably from 2.5:1 to 3:1. The manufacturer can flexibly set the ratio according to different requirements for medication infusion, different infusion sites, and the like. The engagement element 43 on the inner shaft 42 is configured to be able to engage successively with the respective thread of the first section 44 and the second section 46, which, when engaging with the thread of the first section 44, enables the drive shaft 6 to move linearly at a first, faster speed, and the drive shaft 6 pushes distally the syringe 10 and the loading sleeve 7 as a whole against the biasing force of the reset spring 8 (as will be explained in more detail hereinafter), thereby achieving rapid insertion of the needle of the syringe 10; and, when engaging with the thread of the second section 46, enables the drive shaft 6 to move linearly at a second, slower speed, the drive shaft 6 pushes the stopper of the syringe 10 to move within the barrel of the syringe 10, thereby achieving a slow infusion of the medication of the syringe 10. Although the first section 44 and the second section 46 have different pitches, the thread grooves of the first section 44 and the thread grooves of the second section 46 are continuous with each other so as to allow for a continuous and smooth transition of the engagement element 43 when switching from engagement with the thread of the first section 44 to engagement with the thread of the second section 46.

[0054] The engagement element 43 is in the form of a protrusion or a tooth or a pin (as shown in FIG. 6) or a roller. In particular, in the example shown in FIG. 6, the engagement element 43 is two engagement elements (in the form of pins, as shown) opposed in a cross-section perpendicular to an axial direction of the drive shaft 6. Preferably, said two engagement elements are formed by two ends of a single pin extending radially through the inner shaft 42 at one end of the inner shaft 42. Accordingly, the thread on the inner wall of the outer sleeve 41 has two opposing thread grooves 45, 47 extending helically in the axial direction, as shown in FIG. 5. That is, the thread of both the first section 44 and the second section 46 is a double-start thread. Of course, as described above, the corresponding thread grooves of the doublestart thread in the first section 44 and the second section 46 are continuous in order to enable a continuous and smooth transition of the two engagement elements from engagement with the double-start thread in the first section 44 to engagement with the double-start thread in the second section 46. The "double-start thread" herein refers to a thread formed by two helical lines equally spaced along an axial direction, or in the case of a plurality of threads, it is referred to as a "multi-start thread". A thread formed along one helical line is called as a "single-start thread".

[0055] The above configurations of a thread and an engagement element are only examples. Alternatively, an opposite configuration is possible, wherein the inner wall of the outer sleeve is provided with an engagement element and the outer wall of the inner shaft is provided with a corresponding thread having a first section and a second section with different pitches. The other features described above can be applied accordingly to this opposite configuration. Furthermore, the number of consecutive threads (here the number of helical lines; it can be at least one) and the number of corresponding engagement elements (it can be at least one) is not limited.

[0056] In the example shown in FIG. 5, the outer sleeve 41 is further provided with a bore 40 for engaging an output shaft 21 of the motor 2. Accordingly, the inner shaft 42 is attached to the drive shaft 6, as shown in FIG. 6. The inner shaft 42 and the drive shaft 6 may be separately manufactured and then attached together, or they may be integrally formed. In this way, the outer sleeve 41 is a driving element and the inner shaft 42 is a driven element. This is merely an example herein. Alternative opposite configuration is also possible, wherein the outer sleeve is attached to the drive shaft 6 and the inner shaft is attached to the output shaft 21 of the motor 2, such that the inner shaft is a driving element and the outer sleeve is a driven element.

[0057] The drive shaft 6 is further provided with a slider 5 configured to non-rotationally, linearly move the drive shaft 6. The inner shaft 42 and the drive shaft 6 may be attached together via this slider 5. In the case where the inner shaft 42 is integrally formed with the drive shaft 6, the slider 5 is provided with a hole so as to be provided over them, preferably at the intersection of the inner shaft and the drive shaft. The housing 1 is provided with a linear track 17 alongwhich the slider 5 can move linearly. In the embodiment shown in FIGS. 1A and IB, the linear track 17 is formed within both the first housing portion la and the second housing portion lb.

[0058] The syringe 10 may be a cartridge containing a medication. In one example, as shown in FIG. 3, the syringe 10 includes a barrel 103, a distal needle 102, and a stopper (not shown) disposed in the barrel 103. Thus, such a syringe may also be referred to as a "pen needle". The syringe is provided with a lug or protrusion 101 at an end opposite to the needle 102, which rests on a corresponding lug or protrusion 701 at the proximal end of the loading sleeve 7 when the syringe 10 is inserted into the loading sleeve 7, whereby when the stopper of syringe 10 is pushed by the drive shaft 6, due to the faster linear movement speed of the drive shaft 6 during needle insertion, the plug of syringe 10 will transmit the thrust of the drive shaft 6 to the syringe 103 and thus push the loading sleeve 7, allowing the syringe 10 and the loading sleeve 7 together to advance. In attaching the first housing portion la and the second housing portion lb together, the stopper of the syringe 10 is configured to be abutted against by the distal end of the drive shaft 6.

[0059] It should be noted that although the term "syringe" is used herein for the sake of clarity and consistency, the term is not intended to be limiting. In some arrangements, for example, the syringe may be a pen needle or a cartridge (which may, by way of example, be arranged to receive a disposable injection needle) or other medication container. In some arrangements, the syringe / pen needle / cartridge / medication container may form an integrated piece with the injection device (or part thereof).

[0060] In the example shown in FIG. 2, when activating the auto-injection device, the motor 2 rotates and its output shaft 21 drives the outer sleeve 41 to rotate, thereby driving the engagement element 43 to move along the thread groove(s). The engagement element 43 is initially engaged in the thread groove of the first section 44, and since the pitch Pl of the first section 44 is larger, the linear displacement generated by one revolution of the movement of the engagement element 43 along the thread groove is larger, thereby driving the drive shaft 6 to move linearly at a first, faster speed, thereby realizing the rapid insertion of the needle of the syringe 10. When the insertion action of the needle is finished, the engagement element then engages in the thread groove of the second section 46, and since the pitch P2 of the second section 46 is smaller, the linear displacement generated by one revolution of the movement ofthe engagement element 43 along the thread groove is smaller, thereby pushing the drive shaft 6 to move linearly at a second, slower speed, thereby realizing a slow infusion of the medication of the syringe 10. In this way, an axial length of the first section 44 or an axial distance that the engagement element 43 moves along the thread groove of the first section 44 corresponds substantially to a distance that the needle 102 of the syringe 10 moves rapidly (i.e., is inserted), and an axial length of the second section 46 or an axial distance that the engagement element 43 moves along the thread groove of the second section 46 corresponds substantially to a distance that the stopper of the syringe 10 moves slowly (i.e., infuses the medication). The term "axial" herein refers to an axial direction of the drive shaft 6 or an axial direction of the outer sleeve or the inner shaft.

[0061] The loading sleeve 7 is provided in the second housing portion lb, which is configured to be able to be moved distally under the thrust action of the drive shaft 6. A distal stop 9 is further provided in the second housing portion lb, which distal stop may be in the form of an inwardly extending protrusion or a baffle, or may be in the form shown in FIGS. 1A, IB, or 4. The distal stop 9 defines the maximum position at which the loading sleeve 7 can move distally, preventing the needle from moving further distally during medication infusion. Accordingly, a proximal stop 15 (e.g., in the form of an inwardly extending protrusion or a baffle) is provided at the proximal end of the second housing portion lb, which proximal stop 15 defines the most proximal position (i.e., the initial position) of the loading sleeve 7, i.e., defines the furthest position to which the loading sleeve 7 moves proximally during reset.

[0062] Referring in particular to FIG. 4, a reset spring 8 is provided around the loading sleeve 7. One end of the reset spring 8 rests against the distal stop 9 and the other end rests against an outwardly extending lug or protrusion 701 of the loading sleeve 7. The reset spring 8 biases the loading sleeve 7 towards the proximal stop 15. During the rapid linear movement of the drive shaft 6 at the first speed, because the liquid medication inside the syringe 10 is incompressible and the medication is discharged very slowly through the needle 102, the medication does not have time to be discharged (the duration of the rapid linear movement of the drive shaft 6 is very short, typically less than or equal to 1 second), and thus the thrust of the drive shaft 6 is transmitted via the stopper of the syringe 10 to the entire syringe, thereby moving the entire syringe 10 and consequently the loading sleeve 7 together against the biasing force of the resetspring 8, and thereby driving the needle 102 of the syringe 10 to be inserted quickly into a patient . After the infusion is finished, the reset spring 8 may bias the loading sleeve 7 proximally to reset the loading sleeve 7 for re-use.

[0063] The maximum distance that the loading sleeve 7 can be moved distally from its initial position corresponds to the insertion depth of the needle 102. Thus, adjusting this distance can adjust the insertion depth of the needle. In an example, the position of the distal stop 9 is configured to be adjustable, thereby forming a depth adjuster that is provided distal to the distal end of the loading sleeve 7 and spaced apart from the distal end by a distance D that determines the depth of insertion of the needle 102 of the syringe 10. This provides the user with the flexibility to adjust the depth of insertion of the needle according to the different requirements of the medication infusion as well as the different sites of infusion.

[0064] In the embodiment shown, see FIG. 4, said depth adjuster comprises a U-shaped body 902, with a through-hole formed in the bottom wall of said U-shaped body for free passage of the syringe 10. At the proximal end of each of two sidewalls of the U-shaped body 902 is formed a tab 901 for pinching by the user's fingers, said tab 901 being configured to be able to move along a slit in the housing 1 (specifically the second housing part lb) in order to adjust said distance D.

[0065] Said depth adjuster further comprises a pawl or outer tooth 903 formed on each of the two sidewalls of the U-shaped body 902 and a plurality of inner teeth 904 disposed opposite to said pawl or outer tooth 903, said pawl or outer tooth 903 being configured to selectively engage a corresponding tooth of said plurality of inner teeth 904 so as to fix said distance D. Optionally, said plurality of inner teeth 904 are formed in the inner wall of the housing 1 (specifically the second housing part lb). During operation, the tabs 901 are pressed towards each other to cause the pawl or outer teeth 903 to disengage with the corresponding inner tooth of the plurality of inner teeth 904, thereby enabling the tabs 901 to move along the slit to adjust the distance D; when the distance D is adjusted to a desired value, the tabs 901 are released and relatively away from each other to engage the pawl or outer tooth 903 with the corresponding inner tooth of the plurality of inner teeth 904 once again, thereby fixing the U-shaped body 901 and thus fixing the distance at the desired value.

[0066] In use, the user opens the housing 1 by detaching the second housing part lb from the first housing part la, and then loads the syringe 10 into the loading sleeve 7 so that the protrusion 101 of the syringe 10 rests on the corresponding protrusion 701 of the loading sleeve 7, and then attaches the first housing portion la and the second housing portion lb. Next, the user aligns the distal end of the entire injection device at the injection site and triggers the switch. The motor 2 rotates to drive the outer sleeve 41 to rotate, and the engagement element 43 on the inner shaft 42 first engages in the thread groove of the first section 44 and moves along the thread groove of the first section 44 (having a larger first pitch Pl) and therefore the inner shaft 42 drives said drive shaft 6 at a faster speed in a rapid linear movement. Under the thrust action of the drive shaft 6, the syringe 10 and the loading sleeve 7 instantaneously move together, thereby inserting the needle into the injection site. When the distal end of the loading sleeve 7 contacts the distal stop 9 or the bottom wall of the U-shaped body of the depth regulator, it is no longer moved further distally, thus completing the rapid insertion of the needle. Immediately thereafter, the engagement element 43 on the inner shaft 42 engages in the thread groove of the second section 46 and moves along the thread groove of this second section 46 (having a smaller second pitch P2) and thus the inner shaft 42 drives said drive shaft 6 at a slower speed in a slow linear movement. At this point, the loading sleeve 7 is prevented from further moving distally and the proximal protrusion 101 of the syringe 10 rests against the proximal protrusion 701 of the loading sleeve 7, so that the barrel 103 of the syringe 10 cannot move further distally either; at this point, the stopper of the syringe 10 can be further moved distally by the thrust action of the drive shaft 6, so that the medication is slowly infused into the patient. When the infusion is finished, the drive shaft 6 can be restored to the initial position by reversing the motor 2, while the loading sleeve 7 is also restored to the initial position under the biasing action of the reset spring 8.

[0067] The present disclosure uses a dual pitch motion conversion mechanism that allows for achieving the requirement of rapid needle insertion and subsequent slow infusion. This conception allows for much simpler manufacture of the auto-injection device. The main advantage of the reusable motorized auto-injection device of the present disclosure over the prior art is that there is only one set of mechanical drive mechanism, i.e., the drive shaft andthe motor circuit. Having only one set of drive mechanism improves the reliability and compactness of the auto-injection device and reduces the cost.

[0068] The reusable motorized auto-injection device of the present disclosure may be applicable to many auto-injection devices, such as Epipen, BD Physioect™ disposable autoinjector, Aria smart autoinjector, and so on.

[0069] The present disclosure may include any feature or combination of features or a generalization thereof implicitly or explicitly disclosed herein, without limiting the scope of any of the limitations enumerated above. Any of the relevant components, features and / or structural arrangements described herein may be combined in any suitable manner.

[0070] The particular embodiments disclosed above are merely exemplary, and it will be apparent to those skilled in the art who benefit from the teachings herein that the present disclosure may be modified and implemented in different but equivalent ways. For example, the method steps described above may be performed in a different order. Furthermore, there is no limitation on the details of the constructions or designs illustrated herein, except as set forth in the following claims. It is therefore apparent that changes and modifications may be made to specific embodiments of the above disclosure, and all such variations are considered to fall within the scope and spirit of the present disclosure. Accordingly, the protection sought herein is set forth in the appended claims.

Claims

THE INVENTION CLAIMED IS1. A reusable motorized auto-injection device comprising: a housing; a single motor, said motor being housed within said housing; a drive shaft, said drive shaft configured to move linearly driven by said motor; a motion conversion mechanism configured to convert a rotational motion of said motor into a linear movement; a drive shaft configured to be driven by said motion conversion mechanism to move linearly; and a loading sleeve configured to receive a syringe containing a medication, wherein said drive shaft is configured to be able to engage a stopper of said syringe so as to push said stopper, wherein said motion conversion mechanism comprises an outer sleeve and an inner shaft disposed within said outer sleeve, a thread is provided on one of an outer wall of said inner shaft and an inner wall of said outer sleeve, an engagement element is provided on the other of said outer wall of said inner shaft and said inner wall of said outer sleeve, and wherein said thread comprise a first section and a second section having a consecutive thread groove, said first section having a first pitch and said second section having a second pitch, said first pitch being greater than said second pitch, said engagement element being configured to be able to engage successively with the respective thread groove of said first section and said second section in such a way that, when engaging with the thread groove of said first section, said drive shaft is caused to move linearly at a first, faster speed, thereby realizing rapid insertion of the needle of said syringe; and when engaging with the thread groove of said second section, said drive shaft is linearly moved at a second, slower speed, thereby realizing a slow infusion of medication from said syringe.

2. A reusable motorized auto-injection device according to claim 1, characterized in that said engagement element is in the form of a protrusion or a tooth or a pin or a roller.

3. A reusable motorized auto-injection device according to claim 1, characterized in that there are two engagement elements opposed in a cross-section perpendicular to an axial direction of said drive shaft, and correspondingly, said thread has two opposed thread grooves extending helically in the axial direction.

4. A reusable motorized auto-injection device according to claim 3, characterized in that said two engagement elements are formed by a single pin extending radially through said inner shaft at one end of said inner shaft.

5. A reusable motorized auto-injection device according to claim 1, characterized in that an output shaft of said motor is connected to one of said outer sleeve and said inner shaft, and the other of said outer sleeve and said inner shaft is connected to said drive shaft.

6. A reusable motorized auto-injection device according to claim 1, characterized in that said thread is provided on the inner wall of said outer sleeve and said engagement element is provided on the end of said inner shaft.

7. A reusable motorized auto-injection device according to claim 1, characterized in that a proximal stop is provided with on the inner wall of said housing, which proximal stop defines a most proximal position of said loading sleeve.

8. A reusable motorized auto-injection device according to claim 1, characterized in that said reusable motorized auto-injection device further comprises a distal stop provided distal to a distal end of said loading sleeve and spaced apart from said distal end by a distance, said distance determining a depth of insertion of a needle of said syringe.

9. A reusable motorized auto-injection device according to claim 8, characterized in that said reusable motorized auto-injection device further comprises a reset spring surrounding said loading sleeve, one end of said reset spring resting against said distalstop and the other end resting against an outwardly extending proximal protrusion of said loading sleeve.

10. A reusable motorized auto-injection device according to claim 8, characterized in that said distal stop comprises a U-shaped body with a bottom wall being formed with a through hole for free passage of said syringe.

11. A reusable motorized auto-injection device according to claim 8, characterized in that said distal stop comprises a U-shaped body with a tab for a user's finger to pinch formed at a distal end of each of said two sidewalls of said U-shaped body, said tab configured to be capable of being moved along a slit in said housing so as to adjust said distance.

12. A reusable motorized auto-injection device according to claim 10 or 11, characterized in that said distal stop further comprises a pawl or outer tooth formed in each of said two sidewalls of said U-shaped body and a plurality of inner teeth disposed opposite to said pawl or outer tooth, said pawl or outer tooth configured to selectively engage a corresponding one of said plurality of inner teeth so as to fix said distance .

13. A reusable motorized auto-injection device according to claim 12, characterized in that said plurality of inner teeth are formed on an inner wall of said housing.

14. A reusable motorized auto-injection device according to claim 1, characterized in that said drive shaft is provided with a slider, said slider being configured to non-rotationally, linearly move said drive shaft.

15. A reusable motorized auto-injection device according to claim 14, characterized in that said slider is configured to move along a linear track, said linear track being provided within said housing.

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