A plunger that is detachable from the plunger head of a pump device

Abstract

The disposable reservoir has a PEM and includes a plunger head that is movable bidirectionally with the PEM between the proximal end and the distal end of the disposable reservoir. The PEM is configured to engage a plunger rod of the reusable portion of the drug delivery device. The disposable reservoir also includes a PRM that is configured to release the plunger rod from the PEM when the PEM is drawn into a storage position within the PRM. The plunger rod can be locked by the PEM and released from the PEM using a snap-fit function. Alternatively, the plunger rod can be locked by the PEM using a snap-fit function and released from the PEM using bayonet connection means. Alternatively, the plunger rod can be locked by the PEM and released from the PEM using bayonet connection means.

Description

Technical Field

[0001] The present invention generally relates to systems and methods for coupling a disposable portion (DP) (e.g., a liquid drug reservoir) of a drug delivery device (e.g., a pump device) to a reusable portion (RP) of the pump device. More particularly, the present invention relates to the design of a plunger rod and a plunger head that can releasably engage the plunger rod to the plunger head.

Background Art

[0002] Some liquid drug delivery systems are two-component systems that include a reusable part and a disposable part. The reusable part typically includes, among other things, an electric motor and a gear system driven by the electric motor. The disposable part typically includes a liquid drug reservoir and a gear-driven plunger or a stand-alone plunger, which is a means for discharging the liquid drug from the reservoir. In conventional drug delivery devices, the plunger means includes a plunger rod (also referred to as a lead screw or spindle) and a plunger head, and the plunger rod is an inseparable part from the plunger head. Further, such plunger means is generally inseparable from the reservoir itself, and using such plunger means has drawbacks. For example, the disposable reservoir is discarded after being used with a plunger rod and a plunger nut (a means for converting rotational motion into linear motion of the plunger rod), or other / additional drive elements. Such things are wasteful and uneconomical. Also, since the plunger rod (lead screw) is inside the disposable reservoir, the connection between the disposable reservoir and the reusable part often results in a decrease in the accuracy of the drug delivered due to the uncertainty of the exact position or orientation of the lead screw in the reservoir. Further, the assembly process of the disposable reservoir including the plunger rod is relatively complicated. Moreover, inseparably attaching the plunger rod to the disposable reservoir hinders stockpiling or distribution such as pre-filling the disposable reservoir with disposable items. Therefore, conventional disposable reservoirs are typically filled from vials only for a short time before being used. SUMMARY OF THE INVENTION

[0003] A pump device for delivering a medicament includes a disposable reservoir and a reusable portion removably connectable to the disposable reservoir. The disposable reservoir includes, among other things, a plunger head movable bidirectionally within the disposable reservoir between a proximal end of the disposable reservoir and a distal end of the disposable reservoir. The reusable portion includes, among other things, a plunger rod. When the disposable reservoir and the reusable portion are coupled to each other, the plunger rod and the plunger head are designed such that the plunger rod can be releasably locked within the plunger head so that the plunger rod moves linearly, optionally bidirectionally (back and forth), within the disposable reservoir together with the plunger head. The distal end of the disposable reservoir is an end of the reservoir that includes a discharge opening for filling the reservoir such that a liquid medicament can move within the reservoir and, for example, be discharged from the reservoir and delivered to a patient from a vial outside of the disposable reservoir. The proximal end of the disposable reservoir is an end of the reservoir opposite the distal end of the disposable reservoir. Thus, the plunger head is movable longitudinally (axially) within the disposable reservoir from the distal end of the reservoir towards the proximal end to fill the disposable reservoir with the medicament and from the proximal end of the reservoir towards the distal end to deliver the medicament from the reservoir to the patient.

[0004] The plunger head includes a concentric plunger engagement member (PEM) that is movable bidirectionally along with the plunger head between the proximal and distal ends of the disposable reservoir. The disposable reservoir further has a perforated plunger release member (PRM) that is concentrically fixed to the proximal end of the disposable reservoir. The plunger rod includes a distal end and is movable bidirectionally within the perforated PRM. When the disposable reservoir and the reusable portion are coupled together, the distal end of the plunger rod can be locked within the PEM, and the distal end of the plunger rod can be released from the PEM by the PRM. By functioning as discharge means and storage means, the PRM discharges the plunger rod from the PEM when the plunger rod pulls the PEM to a storage position within the PRM. The plunger rod can be locked within the PEM and released from the PEM by snap-fit connection means, or bayonet connection means, or a combination of snap-fit connection means and bayonet connection means. The snap-fit connection means can include an annular snap-fit function, or a cantilever snap-fit connection, or a combination of an annular snap-fit function and a cantilever snap-fit connection.

[0005] Configuration #1: Locking and releasing by snap-fit In some embodiments, by using snap-fit connection means, the plunger rod can be locked within the PEM and released from the PEM. The snap-fit connection means can include the distal end of the plunger rod, the PEM, and the PRM. The snap-fit connection is a non-reversible snap-fit connection, that is, once the plunger rod is locked within the PEM by snap-fit, or the plunger rod is locked to the PEM by snap-fit, the plunger rod can only be released from the PEM by using a "third party" (i.e., the PRM).

[0006] The distal end of the plunger rod includes an inlet tip (plunger interface) and an annular lock groove formed circumferentially at the distal end between the inlet tip and the remainder of the plunger rod. The PEM includes a ring-shaped base and elongated flexible arms extending annularly from the ring-shaped base and curving inwardly towards the central axis of the PEM, forming a flexible cap-like structure with an opening in the center. The structure like the flexible cap is designed to snap-fit into the annular lock groove of the plunger rod.

[0007] The PRM includes an external (outer) cylindrical body and a concentric internal (inner) hollow cylinder that can move the plunger rod bidirectionally, for example, by an electric motor included in a reusable part. The internal hollow cylinder concentric with the external cylindrical body defines an open annular channel therebetween for accommodating the PEM, and the internal hollow cylinder of the PRM is configured to deflect the elongated flexible arms of the PEM radially outward to release ("snap out") the plunger rod from the PEM when the PEM is drawn into a rest (accommodation) position within the open annular channel of the PRM by the plunger rod. The inlet tip of the plunger rod can be selected from the group consisting of a hemispherical tip, a conical tip, and a frustum.

[0008] Each of the elongated flexible arms of the PEM can include a proximal section extending from the ring-shaped base at an acute angle α (0° < α < 90°, for example, α = 80°) with respect to the plane of the ring-shaped base. Each of the elongated flexible arms of the PEM can further include a distal section extending continuously (and seamlessly) from the corresponding proximal section at an acute angle β (0° < β < α, for example, β = 60°) with respect to the ring-shaped base. The distal section of the elongated flexible arm is configured to snap-fit (lock) into the annular lock groove of the plunger rod when the inlet tip of the plunger rod is linearly pressed against the elongated flexible arm of the PEM.

[0009] The annular locking groove of the plunger rod includes an annular pulling shelf for pulling the PEM together with the plunger rod in the rear (refilling) direction by pulling the distal section of the elongated flexible arm when the plunger rod is retracted into the disposable reservoir. Further, the annular locking groove can include a conical surface for allowing the plunger rod to move in the forward (emptying) direction through the opening of the flexible cap-shaped structure until the inlet tip of the plunger rod contacts (abuts) the inner pushing surface of the plunger head. When the inlet tip of the plunger rod moves forward through the opening of the flexible cap-shaped structure, the elongated flexible arm is deflected radially outward by the inlet tip of the plunger rod. When the inlet tip passes through the opening of the flexible cap-shaped structure, the flexible cap-shaped structure is snap-fitted into the annular locking groove of the plunger rod, and the plunger rod is locked within the plunger engagement member (PEM). The inlet tip of the plunger rod may be provided with a curved inlet side to facilitate deflecting the elongated flexible arm radially outward.

[0010] The number of the elongated flexible arms may be 2n (n = 1, 2, 3,...), the elongated flexible arms may be of the same size and shape, and may be angularly equidistant from each other. That is, the elongated flexible arms may be angularly equidistantly dispersed around the longitudinal axis of the PEM. The number of the elongated flexible arms can be selected from the group consisting of, for example, four elongated flexible arms, six elongated flexible arms, and eight elongated flexible arms.

[0011] Configurations #2 and #3: Locking by snap fit / bayonet, unlocking by bayonet The distal end of the plunger rod can include an inlet tip portion that includes N fins that are angularly distributed about the longitudinal axis of the plunger rod and extend radially outward from that longitudinal axis, and segmented (individual, discontinuous) locking grooves formed circumferentially at the distal end between the N fins and the remainder of the plunger rod. The plunger engagement member (PEM) includes a hollow cylindrical member having an inner wall, and N ribs extending radially inward from the inner wall toward the longitudinal axis of the hollow cylindrical member and configured to lock each of the N fins. The PEM also includes S bayonet slots or grooves formed circumferentially in the hollow cylindrical member. The S bayonet slots are designed as a three-dimensional curve (helix) that surrounds the longitudinal axis of the hollow cylindrical member at a constant radial distance from the longitudinal axis. The helical slots are designed to allow rotational movement of the PEM up to the rotational angle required to lock the fins to the ribs of the PEM and / or (depending on the configuration) up to the rotational angle required to unlock the fins from the ribs of the PEM.

[0012] The PRM includes a hollow cylindrical body within which the plunger rod is movable, and S bayonet pins or other means of suitable shape extending radially inward from the inner wall of the hollow cylindrical body. The S bayonet pins are each engagable with the S bayonet slots of the PEM, whereby the PEM rotates relative to the fixed PRM.

[0013] N fins are aligned with N ribs respectively, as a result, locked by the N ribs, enabling a locking angular position for the plunger head to be retracted by the plunger rod, and between an unlocking angular position where the N fins are misaligned with the N ribs respectively and the plunger rod can be released from the plunger head when the PEM is linearly retracted into the rest (stowed) position within the PRM by the plunger rod, the PEM is rotatable relative to the PRM. Each of the S bayonet slots is designed such that when the PEM linearly moves within the rest (stowed) position in the PRM, the PEM can be rotated from the locking angular position to the unlocking angular position, and when the PEM linearly moves from the rest position in the PRM, the PEM can be rotated from the unlocking angular position to the locking angular position.

[0014] The step of rotating the PEM from the locking angular position to the unlocking angular position includes rotating the PEM clockwise (or counterclockwise) by the unlocking angle (γ), and the step of rotating the PEM from the unlocking angular position to the locking angular position includes rotating the PEM counterclockwise (or clockwise) by the locking angle (γ), where the value of the unlocking / locking angle (γ) is γ = 180° / N. For example, when N = 4, the value of the locking angle is γ = 180° / 4 = 45°. The value of N can be selected from the group consisting of N = 2, N = 3, N = 4, N = 5, and N = 6 (where N is the number of fins of the plunger rod and ribs of the PEM).

[0015] The distal end of the plunger rod also includes a push-in flange. The diameter of the push-in flange is larger than the inner diameter of the PEM's perforated cylindrical member, and when the plunger rod is moved forward within the disposable reservoir, the PEM can be pushed forward (i.e., in the direction of emptying the reservoir) together with the plunger rod. Each of the N fins of the plunger rod includes N retraction shelves, and when the PEM is in the locked angular position, the PEM is sandwiched between the push-in flange and the N retraction shelves, and when the plunger rod is retracted (pulled back) within the disposable reservoir, the PEM can move backward (in the direction of refilling the reservoir) integrally with the plunger rod. The inlet tip of the plunger rod may be shaped as a segmented hemispherical tip, a segmented conical tip, or a cross-shaped Phillips driver head.

[0016] Configuration #2: Snap-fit connection, bayonet separation In some embodiments, the plunger rod is lockable within the PEM by using snap-fit connection means and releasable from the PEM by using bayonet connection means. In these embodiments, the PEM provides both snap-fit means for locking the plunger rod within the PEM and bayonet means for facilitating the release of the plunger rod from the PEM. The snap-fit connection means can include the snap-fit function of the distal end of the plunger rod and the PEM, and the bayonet release means can include the bayonet function of the same PEM and PRM. The snap-fit connection of these embodiments is also a non-reversible snap-fit connection. That is, when the plunger rod is locked within the PEM by snap-fitting the plunger rod to the PEM, or when the plunger rod is locked to the PEM by snap-fit, the plunger rod can only be released from the PEM by using the PRM.

[0017] The PEM is initially disposed at the distal end of the disposable reservoir and moves the plunger rod forward through the PRM within the disposable reservoir. The plunger rod can be locked within the PEM / locked by the PEM at the locking angular position. Thereby, the N fins of the plunger rod are snap-fitted respectively by the N ribs of the PEM. When the plunger rod is locked within the PEM / locked by the PEM, the PEM is pulled into the rest (storage) position within the PRM, thereby imparting a torsional movement to the PEM from the locking angular position to the release angular position with respect to the PRM, whereby the plunger rod can be released from the PEM.

[0018] To facilitate snap-fitting the N ribs of the PEM into the segmented locking grooves at the distal end of the plunger rod, the perforated cylindrical member of the PEM may be reversibly expandable radially outward by the N fins of the plunger rod pushing against the N rigid ribs, or the perforated cylindrical member of the PEM may be rigid (nonexpandable) and the N ribs may be reversibly compressible by the N fins, or the N ribs of the PEM may be reversibly compressible by the N fins of the plunger rod, or the perforated cylindrical member of the PEM may also be reversibly expandable radially outward.

[0019] Configuration 3: Connection and disconnection by bayonet In other embodiments, the PEM is initially housed at the release angular position within the PRM, in which case the plunger rod is locked within / by the PEM by linearly moving the plunger rod forward through the PRM, whereby the plunger rod linearly moves the PEM from the storage position within the PRM and simultaneously causes the PEM to torsionally move relative to the PRM, thereby rotating the PEM from the release angular position to the lock angular position. When the plunger rod is locked within / by the PEM, the plunger rod is released from the PEM by retracting the PEM to the rest (storage) position within the PRM, thereby causing the PEM to torsionally move relative to the PRM and rotate the PEM from the lock angular position to the release angular position. The bayonet connection in these embodiments is also a non-reversible connection, i.e., once the plunger rod is locked within / by the PEM, the plunger rod can only be released from the PEM by using the PRM.

[0020] According to another aspect of the invention, there is provided a disposable reservoir comprising a plunger engagement member (PEM) and a plunger release member (PRM) as shown in the associated drawings and described herein, and further provided is a plunger rod engageable with the PEM and releasable from the PEM by the PRM as shown in the associated drawings and described herein.

[0021] Disposable reservoir including PEM and PRM (Configuration #1, #2, #3) Also provided is a disposable reservoir releasably attachable to a reusable portion of a drug delivery device, the disposable reservoir including a plunger head. The plunger head includes a plunger engagement member (PEM) and is movable bidirectionally with the PEM between a proximal end and a distal end of the disposable reservoir, the PEM being configured to engage a plunger rod of the reusable portion of the drug delivery device. The disposable reservoir further includes a plunger release member (PRM) configured to release the plunger rod from the PEM when the PEM is drawn into a stowed position within the PRM.

[0022] The plunger rod can be moved forward through the PRM within the disposable reservoir until the plunger rod is snap-fitted by the PEM, the plunger rod being configured to be lockable by or within the PEM, and the plunger rod can be released from the PEM by drawing the PEM into the stowed position and the PRM deflecting (snapping out) the PEM to release the plunger rod from the PEM.

[0023] The PEM is initially disposed at the distal end of the disposable reservoir, and the plunger rod is initially lockable at a locked angular position by the PEM as the plunger rod is moved forward through the PRM within the disposable reservoir until the plunger rod is snap-fitted by the PEM. The plunger rod can be released from the PEM by drawing the PEM into the stowed position within the PRM and torsionally moving the PEM from the locked angular position to a released angular position relative to the PRM.

[0024] The PEM is initially housed within the PRM at the release angular position, and the plunger rod is locked by the PEM by moving the plunger rod forward through the PRM, whereby the plunger rod linearly moves the PEM from the housed position within the PRM, and simultaneously rotates the PEM from the release angular position to the locked angular position. By retracting the PEM into the housed position within the PRM, the plunger rod is released from the PEM and the PEM is rotated to return from the locked angular position to the release angular position.

Brief Description of the Drawings

[0025] The accompanying drawings show various exemplary embodiments and aspects, but these examples are not limiting. It will be understood that, for the sake of brevity and clarity of description, the elements shown in the figures referred to below are not necessarily drawn to scale. Also, where appropriate, reference numerals repeated among the figures indicate like, corresponding, or similar elements.

[0026] Figures 1A - 1C show a snap - fit lock of a plunger rod (150) within a plunger engagement member (140) according to an exemplary embodiment.

[0027] Figures 1D - 1G show a plunger head (130) according to an exemplary embodiment.

[0028] Figures 2A - 2D show a plunger rod (150) and a plunger engagement member (140) as part of a plunger head (130) according to an exemplary embodiment.

[0029] Figures 2E - 2F show an example of a 4 - arm plunger engagement member (140) according to an exemplary embodiment.

[0030] Figures 2G - 2I show an example of a 6 - arm plunger engagement member (140) according to an exemplary embodiment.

[0031] Figures 3A - 3C show an example of a plunger release member (190) according to an exemplary embodiment.

[0032] Figure 4 shows the position of the plunger engagement (140) relative to the plunger release member (190).

[0033] Figures 5A - 5B show how the plunger rod (150) is snap - fit unlocked from the plunger engagement member (140) by using the plunger release member (190) according to an exemplary embodiment.

[0034] Figures 6A - 6B show how the plunger rod (150) is unlocked from the plunger engagement member (140) when the disposable portion of the pump device is coupled (attached) to the reusable portion of the pump device.

[0035] Figure 7 shows an example of a plunger rod (700) according to some embodiments.

[0036] Figures 8A - 8B show an example of a plunger engagement member (810) according to some embodiments.

[0037] Figures 9A - 9B show an example of a plunger release member (900) according to some embodiments.

[0038] Figures 10A - 10B show the plunger rod (700) within the plunger engagement member (810) when the plunger engagement member (810) is in the storage position within the plunger release member (900) according to some embodiments.

[0039] Figure 10C shows the plunger rod (700) locked to the plunger engagement member (810) when the plunger engagement member (810) is away from the storage position of the plunger release member (900) according to some embodiments.

[0040] Figures 10D - 10E schematically show, respectively, a state where a plunger engagement member (1016) is in an unlocked (released) angular position with respect to a fin (1070) of a plunger rod, and a state where the plunger engagement member is in a locked angular position with respect to the fin (1070) of the plunger rod, according to an example of an embodiment.

[0041] Figures 11A - 11I show various operating stages of a pump device, such as coupling a disposable portion (1100) of the pump device to a reusable portion (1110) of the pump device and separating the disposable portion (1100) from the reusable portion (1110), according to an exemplary embodiment.

[0042] Figures 12A - 12M show various operating stages of a pump device, such as coupling a disposable portion (1200) of the pump device to a reusable portion (1210) of the pump device and separating the disposable portion (1200) from the reusable portion (1210), according to an exemplary embodiment.

[0043] Figures 13A - 13F show various positions of a plunger engagement member (1310) within a plunger release member (1330), according to an exemplary embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0044] In the following description, various embodiments of the present invention will be described in detail. However, the following description is not intended to limit the scope of the claims, but rather to exemplarily illustrate various principles of the present invention and various methods of implementing them.

[0045] The detailed description and the associated drawings generally disclose three configuration examples. (1) Configuration #1 includes a snap - fit connection mechanism for locking a plunger rod of a pump device within or by a plunger head of the pump device and releasing the plunger rod from the plunger head (see, for example, Figures 1A - 1G, 2A - 2I, 3A - 3C, 4, 5A - 5B, and 6A - 6B). (2) Configuration #2, like Configuration #1, includes a snap-fit connection mechanism for locking the plunger rod of the pump device within or by the plunger head of the pump device, and a bayonet mechanism for releasing the plunger rod from the plunger head (see, for example, FIGS. 7, 8A-8B, 9A-9B, 10A-10C, and 11A-11I). (3) Configuration #3 includes a bayonet mechanism for locking the plunger rod of the pump device within or by the plunger head of the pump device and for releasing (unlocking) the plunger rod from the plunger head (see, for example, FIGS. 7, 8A-8B, 9A-9B, 10A-10C, 12A-12M, and 13A-13F).

[0046] Common to the three configurations is that a plunger engagement member (PEM) is added to the plunger head of the pump device. This member is designed to engage and lock the distal end of the plunger rod of the pump device, and further, a fixed plunger release member (PRM) is added that is designed to unlock the distal end of the plunger rod from the plunger head. Common to Configurations #2 and #3 is the bayonet mechanism used to rotate the PEM relative to the PRM, which is used, for example, to unlock the plunger rod from the plunger head (Configuration #2) and to lock and unlock the plunger rod from the plunger head (Configuration #3). The bayonet mechanism used herein is not used in the conventional manner; that is, the bayonet pins and slots are not used as locking means, but rather are used only to rotate the PEM relative to the fixed PRM, and the rotation occurs from the "unlock" angular position to the "lock" angular position and back to the unlock angular position again (as described in connection with Configuration #3), or simply from the lock angular position to the unlock angular position (as described in connection with Configuration #2).

[0047] Figures 1A-1C schematically show cross-sectional views of a drug delivery device 106 (see FIG. 1C) according to an exemplary embodiment. The drug delivery device includes a reusable portion 110 and a disposable drug reservoir 120. The reusable portion 110 and the disposable drug reservoir 120 are releasably coupleable (122, 124) to each other using, for example, magnets (i.e., using magnetic attraction forces), snap-fit connectors, bayonet connectors, etc. For example, a permanent magnet can be fixedly embedded in the reusable portion 110 or the disposable drug reservoir 120, and a metal plate magnetically attracted to the magnet can be fixedly embedded in the other portion, such that when the reusable portion 110 and the disposable drug reservoir 120 approach each other, the permanent magnet magnetically attracts the metal plate.

[0048] The disposable reservoir 120 includes a plunger head 130 that is slidable bidirectionally along the axial direction of the reservoir 120. The plunger head 130 includes a plunger engagement member (PEM) 140. The reusable portion 110 includes a plunger rod 150. The plunger rod 150 includes a threaded portion 152 and an unthreaded distal end 160. The distal end 160 (of the plunger rod 150) and the plunger engagement member 140 are releasably engagable. The disposable reservoir 120 also includes a bottom cover 190, which has an opening at its center through which the plunger rod 150 is movable bidirectionally. (The bottom cover 190 is an axially symmetric object that functions as a plunger release member - PRM) As shown in FIGS. 1A-1C, the PRM 190 and the PEM 140 of the disposable reservoir 120 are separate elements, the PRM 190 is attached (fixedly attached) to the proximal end 126 of the reservoir 120, and the PEM 140 is slidable bidirectionally within the reservoir 120 between the proximal end 126 and the distal end 128 of the reservoir 120 (movable by the plunger rod 150 when coupled to the PEM 140).

[0049] The recyclable portion 110 includes an electric motor-based drive system having an electric motor 170 and a gear system 180 driven or powered by the electric motor 170. The gear system 180 includes one or more gears and nuts. The nut is axially held and includes an external thread or profile that engages with the gears of the gear system 180. The internal thread of the nut engages with the threaded portion 152 of the plunger rod 150. The configuration of the gear system 180 is such that when the nut is rotated by the gear, the nut linearly moves the plunger rod 150 through the concentric hole of the PRM190 without rotating the plunger rod 150. (The same gear / nut configuration applies to all plunger rods operating according to any of the configurations disclosed herein, such as plunger rods 700, 1112, 1212, and 1300.) Using the gear system 180, the electric motor 170 can linearly and bidirectionally move the plunger rod 150 along the axial direction of the plunger rod, i.e., along the longitudinal axis 154 of the plunger rod. The plunger rod 150 and the plunger head 130 can be engaged via the PEM140 and can move integrally and bidirectionally within the disposable reservoir 120 when the disposable reservoir 120 and the recyclable portion 110 are coupled to each other and while the disposable reservoir 120 and the recyclable portion 110 are coupled to each other. Also, the plunger rod 150 and the plunger head 130 are releasable from each other so that the disposable reservoir 120 can be detached from the recyclable portion 110.

[0050] The disposable reservoir 120 can be filled with a liquid medicament from the vial 100. The vial 100 is within the vial adapter 102, and the vial adapter 102 is releasably connectable to the disposable reservoir 120 by a luer-type connector 104. Two sealing O-rings 132 and 134 prevent leakage of the liquid medicament from the reservoir 120.

[0051] Figure 1A shows the reusable portion 110 and the disposable reservoir 120 before they are coupled together, the plunger rod 150 in a "standby" state (fully retracted) housed within the reusable portion 110, and the plunger head 130 in a "standby" (i.e., reservoir pre-filled) state where the plunger head 130 is disposed at the distal end 128 of the reservoir 120. In Figure 1B, the reusable portion 110 and the disposable reservoir 120 are coupled together, but the plunger rod 150 remains in a "standby" state (fully retracted) housed within the reusable portion 110, and the plunger head 130 is also in a "standby" state. In Figure 1C, the plunger rod 150 has fully extended from the reusable portion 110 and is engaged with the PEM 140 at the distal end 128 of the reservoir 120, so the drug delivery device 106 is in a "ready" state. When the drug delivery device 106 is in a "ready" state, the plunger rod 150, and thus the plunger head 130, is retracted rearward (e.g., by an electric motor 170), filling the reservoir 120 with drug, and then advances forward again during treatment to empty the reservoir 120. ("Rearward" means moving the plunger head 130 in the direction from the distal end 128 towards the proximal end 126, i.e., the opposite direction of direction 136)

[0052] Generally, the plunger rod 150 and the PEM 140 can be releasably engaged, for example, by using a snap-fit connection mechanism, or a bayonet connection mechanism, or a combination of a snap-fit connection and a bayonet connection. The snap-fit connection mechanism can be, for example, an annular snap-fit connection function (including snap-fit chips or segmental lips), or a cantilever snap-fit connection function, or a combination of an annular snap-fit connection function and a cantilever snap-fit connection function, or can include them.

[0053] Configuration #1: Locking and Unlocking of the Plunger Rod by Snap-Fit Referring to FIGS. 1A-1G, the snap-fit connection includes a distal end 160 of the plunger rod 150 and a plunger engagement member (PEM) 140. FIGS. 1D-1G show the plunger head 130 without the PEM and O-rings 132 and 134. FIGS. 1D-1E and 1G show an internal receiving (“pushing-in”) concave surface 138 of the plunger head 130 (also shown in FIGS. 2B-2C).

[0054] Referring also to FIG. 2A, the distal end 160 of the plunger rod 150 includes an inlet tip 210 and an annular lock groove 220 formed circumferentially at the distal end 160 between the inlet tip 210 and the remaining portion of the plunger rod 150. The inlet tip 210 may have a convex shape, such as a hemispherical shape (as shown in FIGS. 2A, 2C, 2D) or other shapes. For example, the inlet tip 210 may be conical, or may be a frustum of a cone, a pyramid, or a frustum of a pyramid.

[0055] Figure 2B shows the PEM 140 before it is snap-fitted into the annular lock groove 220 of the plunger rod 150. Figure 2C is a three-dimensional cross-sectional view showing the PEM 140 snap-fitted into a predetermined position (i.e., the annular lock groove 220) within the plunger rod 150. Referring to Figure 2B, the PEM 140 includes a ring-shaped base 250 and a plurality of equally long flexible arms 260. The plurality of elongated flexible arms 260 extend circumferentially from the ring-shaped base 250 and are angularly equidistant from each other. The elongated flexible arms 260 extend at an acute angle from the ring-shaped base 250 and bend (converge) inwardly toward the central axis 142 of the plunger engagement member 140. In this way, the plurality of elongated flexible arms 260 form a flexible cap-shaped structure (e.g., as shown in Figures 2F-2H) having a central opening 144 at the apex, which is defined by a snap-fit lip that can be snap-fitted into the annular lock groove 220. Since the plunger engagement member 140 is concentrically fixed and embedded in the plunger head 130, the two objects can move integrally within the disposable reservoir 120 not only in the direction of emptying the reservoir (direction 124) but also in the opposite direction (i.e., the direction of filling the reservoir, which is the opposite of direction 124). Figure 2C shows the plunger rod 150 snap-fitted by the PEM 140.

[0056] Figure 2E shows a cross-sectional view of the four-arm PEM 140, and Figure 2F shows a three-dimensional view of the four-arm PEM 140. (As shown in other drawings and described herein, the PEM 140 can include a different number of elongated flexible arms) Referring to Figure 2E, each elongated flexible arm 260 includes a proximal section 262 that extends from the ring-shaped base 250 at an acute angle α with respect to the ring-shaped base 250 (where 0° < α < 90°, for example, α = 60°). Each elongated flexible arm 260 also includes a distal section 264 that extends continuously from the proximal section at a smaller acute angle β with respect to the ring-shaped base 250 (i.e., 0° < β < α, for example, β = 45°). The distal sections (264) of the plurality of elongated flexible arms 260, or the entire flexible arm, are configured (e.g., sized, shaped, material) such that the flexible arm is locked into the annular lock groove 220 of the plunger rod 150 and pulled toward the proximal end 126 of the disposable reservoir 120 by the plunger rod 150. Each elongated flexible arm 260 includes a pull surface or contact surface 266. Each pull surface 266 may be perpendicular to the central axis 142 of the plunger engagement member 140 in order to maximize the pull contact surface between the pull surface 266 and the annular pull shelf ("shoulder") 222 of the plunger rod 150 (see Figure 2D).

[0057] When the plunger rod 150 is retracted (e.g., pulled back) into the reservoir 120, the annular pull shelf 222 of the plunger rod 150 is moved rearward (backward) within the reservoir 120 in accordance with the movement of the plunger rod 150 by the pull surfaces 266 (one pull surface 266 for each flexible arm 260), thereby moving the plunger engagement member 140 and thus the plunger head 130. During this time, the elongated flexible arms 260 are snap (snap fit) into the annular lock grooves 220. For example, the plunger rod 150 can be controllably retracted within the reservoir 120 to fill the empty reservoir 120 with a drug or to release the plunger rod 150 from the plunger head 130 in preparation for detaching the disposable reservoir 120 from the reusable portion 110. The annular pull shelf 222 of the plunger rod 150 contacts the pull surface 266 of the elongated flexible arm 260 while the plunger rod 150 is retracted (moved rearward) within the reservoir 120, and then pulls the PEM 140 in accordance with the rearward (filling) movement of the plunger rod 150 by pulling the distal section 264 of the elongated flexible arm 260 with the plunger rod 150.

[0058] The annular lock groove 220 also includes a conical surface 230 (FIGS. 2A-2D). For example, until the inlet tip 210 of the plunger rod 150 contacts (seats or is received in) the inner receiving (“pushing”) concave surface 138 of the plunger head 130 (FIGS. 1D, 2B-2C), depending on the design specifications of the PEM 140 and the plunger 150, the conical surface 230 allows the distal end 160 of the plunger rod 150 to move further in the forward (emptying) direction 136 (FIG. 1A) through the flexible cap-shaped central opening 144. When the plunger rod 150 contacts the receiving concave surface 138 of the plunger head 130, the plunger rod 150 can push the plunger head 130 in the forward (emptying) direction, i.e., direction 136 (FIG. 1A). That is, when the flexible cap-shaped structure of the PEM 140 is snap-fitted into the annular lock groove 220 of the plunger rod 150, the inlet tip 210 of the plunger rod 150 pushes the receiving concave surface 138 of the plunger head 130, sliding the plunger head 130 in the forward (emptying direction 136) to discharge the drug from the reservoir. The receiving concave surface 138 is disposed at the center of the plunger head 130 (i.e., the concave surface 138 is on the axis 142, see FIG. 2B), and further, the concave profile of the receiving concave surface 138 exactly (or elastically) matches the convex profile of the inlet tip 210 of the plunger rod 150. The two mechanical features (i.e., the centrally disposed concave surface 138 and the complementary concave and convex profiles) help to avoid the generation of non-uniform mechanical stresses (e.g., bending, compression, and / or shear stresses) in the plunger head 130, the PEM 140, or the plunger rod 150 when the plunger rod 150 extends, i.e., moves in the emptying direction 136 (FIG. 1A).

[0059] When the inlet tip 210 of the plunger rod 150 moves forward (in the emptying direction 136, FIG. 1A) through the central opening 144 of the flexible cap-like structure (FIGS. 1B, 2B, 2E, 2F), the elongated flexible arm 260 can be reversibly deflected radially outward by the inlet tip 210 of the plunger rod 150. When the inlet tip 210 passes through the central opening 144 of the flexible cap-like structure, the flexible arm 260 can snap (snap fit) into the annular lock groove 220 of the plunger rod 150, preventing the plunger rod 150 from detaching from the PEM 140 when the plunger rod 150 is retracted (moved rearward) within the reservoir 120. To impart this function to the PEM 140, the diameter D3 of the opening 144 of the PEM 140 at rest (e.g., see FIGS. 2E, 2F) (i.e., when the flexible arm 260 is not deformed and is in the rest position or stress-free position) is smaller than the diameter D1 of the inlet tip 210 (see FIG. 2D) and is approximately the same as or larger than the diameter D2 of the "neck" of the annular lock groove 220 (FIG. 2D). Thus, to enable the plunger rod 150 to draw the PEM 140 (and thus the plunger head 130) when the plunger rod 150 is retracted rearward within the reservoir 120, the value of the diameter D3 satisfies the condition D3 < D1. (The value of the diameter D3 can further satisfy the condition D3 ≧ D2, but it may be slightly smaller than the diameter D2)

[0060] The inlet tip 210 of the plunger rod 150 includes a curved “inlet side” that allows the inlet tip 210 to bend the elongated flexible arm 260 radially outward away from the central axis 142 of the PEM 140 (FIGS. 1A, 2B). The diameters D4 and D5 of the PEM 140 (FIG. 2E) facilitate releasing the plunger rod 150 from the PEM 140, as will be further described below in connection with FIGS. 3A-3B, 4, and 5A-5B. Briefly, to bend the flexible arm 260 radially outward, the outer diameter D7 of the concentric cylindrical body 320 (FIGS. 3A, 4) is smaller than the inner diameter D5 of the ring-shaped base 250 of the PEM 140 and preferably larger than the diameter D4, where the cylindrical body 320 can bend the elongated flexible arm 260 by pushing against the proximal section 262. If the outer diameter D7 of the cylindrical body 320 is smaller than the diameter D4, the cylindrical body 320 can bend the elongated flexible arm 260 by pushing against the distal section 264.

[0061] The number of elongated flexible arms 260 that the PEM 140 can include is 2n (n = 1, 2, 3, ···, etc.). The elongated flexible arms 260 are equal in size and shape and are angularly equidistant from each other on the ring-shaped base 250. The plunger engagement member (PEM) 140 includes, for example, four flexible arms, six flexible arms, eight flexible arms, etc. (the number of flexible arms can be otherwise. For example, the PEM may include an odd number of elongated flexible arms such as three flexible arms, five flexible arms, etc.)

[0062] Referring to FIG. 2C (example), the snap-fit connection mechanism including the PEM 140 and the distal end 160 of the plunger rod 150 does not have a "pull-in side" provided at the distal end 160, and the distal end 160 can "by itself", that is, "slide away from the PEM 140 by itself" and separate from the PEM 140 (release), which means it is irreversible (if the plunger head 160 of the plunger rod 150 includes a pull-in side, the plunger rod 150 cannot pull the PEM 140, and thus the plunger head 130 backward to fill the reservoir 120 with the drug). Nevertheless, the plunger rod 150 can be released from the PEM 140 by using the plunger release member (PRM) 190 of the disposable reservoir 120 as an auxiliary (discharge) member. (The PRM 190 is mechanically separated from the PEM 140 and functions independently). The snap-fit release function required to release (separate) the plunger rod 150 from the PEM 140 is imparted to the PRM 190 in the manner shown in FIGS. 3A - 3C described below. (The PRM 190 ("snap-out" element, or ring) is shown in FIGS. 1A - 1C, FIGS. 3A - 3B, FIG. 4, FIGS. 5A - 5B, and FIGS. 6A - 6B).

[0063] FIGS. 2E and 2F show an example of a plunger engagement member (PEM) including four elongated flexible arms 260. FIGS. 2G - 2I show a PEM including six elongated flexible arms 260. However, it is also possible to use a number of elongated flexible arms other than four or six. The number of flexible arms of the PEM depends on one or more of the following parameters. (1) Electrical parameters of the pump device (2) Electrical parameters of the power source (e.g., battery) supplying power to the pump device (3) Mechanical parameters of the flexible arms (4) Mechanical friction between the plunger head and the cylindrical body of the disposable reservoir in which the plunger head moves.

[0064] The electrical parameters of the pump device may be, for example, the electrical energy required for a motor (e.g., motor 170, FIG. 1A) to drive a plunger rod (e.g., plunger rod 150) around a predetermined number of times. The electrical parameters of the power source may be, for example, the total electrical energy capacity of the power source, or battery efficiency. The mechanical parameters of the flexible arm may be the ability of the flexible arm to bend (flex) radially outward to at least a desired distance and a desired number of times without losing its bending ability, or may be related thereto. Further, or alternatively, the mechanical parameters of the flexible arm may be the ease of bending of the flexible arm, or may be related thereto. Further, or alternatively, the mechanical parameters of the flexible arm may be the size, shape, and material of the flexible arm, or may be related thereto. As an example, the harder the flexible arm, the fewer the number of flexible arms that can be used to prevent an excessive load on the motor. The more easily the flexible arm bends (flexes), the greater the number that can be used. As another example, the larger the electrical capacity of the power source (e.g., battery), the greater the number of flexible arms that can be used.

[0065] Figure 3A shows a cross-sectional view of the PRM190, and Figure 3B shows the three-dimensional shape of the PRM190. The PRM190 includes an outer cylindrical body 310 and a hollow cylindrical body 320. The inner diameter of the cylindrical body 310 is D6. The outer diameter of the cylindrical body 320 is D7, and D7 < D6. The cylindrical body 320 has a hole 330 through which the plunger rod 150 can move freely. The cylindrical body 320 has a flange 312. The flange 312 protrudes outward from the cylindrical body 310, surrounds the cylindrical body 310, and forms an "L"-shaped object around the axis 142, enabling the PRM190 to be fixed to the proximal end 126 of the reservoir 120. The cylindrical bodies 310 and 320 are interconnected by an annular base 340. The annular base 340 protrudes outward from the cylindrical body 320, surrounds the cylindrical body 320, and forms an "L"-shaped object around the axis 142. The inner wall 350 of the cylindrical body 310, the outer wall 360 of the cylindrical body 320, and the annular base 340 form an open annular channel ("OAC") 370 around the cylindrical body 320 and the axis 142. The open annular channel (OAC) 370 provides a docking station configured to receive (accommodate) the PEM140 while and after the plunger rod 150 is pulled away from the PEM140.

[0066] When the motor 170 (Figure 1) has fully retracted the plunger rod 150 into the reservoir 120 and the ring-shaped base 250 of the PEM140 moves to the rest (accommodation) position within the OAC 370, the cylindrical body 320 is configured to bend the elongated flexible arm 260 radially outward to release the plunger rod 150 from the flexible cap-like structure of the PEM140. The open annular channel 370 is configured to receive (accommodate) a portion of the plunger head 130, the ring-shaped base 250 of the PEM140, and a portion of the elongated flexible arm 260. The length L (Figure 3B) of the cylindrical body 320 is a design parameter used to determine the first contact point on the flexible arm 260 where the concentric cylindrical body 320 of the PRM190 contacts when the PEM140 moves to the accommodation position within the PRM190.

[0067] Releasing the plunger rod 150 from the PEM 140 As described herein, the diameter DI (FIG. 2D) of the inlet tip 210 of the plunger rod 150 is larger than the diameter D3 (FIGS. 2E-2F) of the opening 144 of the plunger engagement member (PEM) 140 in a stress-free (unbent) state, allowing the inlet tip 210 of the plunger rod 150 to radially outwardly deflect the flexible arm 260 of the PEM 140, after which the flexible arm 260 resumes (returns to) its previous (initial, rest, unbent) state and snap-fits into the annular lock groove 220 of the plunger rod 150.

[0068] The PRM190 is fixed within the reservoir 120, while the PEM140 is axially (longitudinally) bidirectionally movable within the reservoir 120 between the proximal end 126 and the distal end 128 of the reservoir. Referring to FIG. 4, when the PEM140 is moved rearward (drawn in the direction 410) along the axis 142 (which is also the longitudinal axis of the reservoir 120) by the plunger rod 150, the PEM140 moves towards a storage position within the open annular channel (OAC) 370. While the PEM140 is moving towards the storage position within the OAC 370, the circular tip 322 of the cylindrical body 320 contacts the inner wall of the proximal section 262 of the PEM140 at a deflection engagement point, such as the deflection engagement point 420 of the intermediate section of the proximal section 262 (i.e., the deflection engagement point within each proximal section 262). Further moving the PEM140 in this direction (direction 410) causes the circular tip 322 of the cylindrical body 320 (FIGS. 3C and 4) to deflect each proximal section 262 of each flexible arm 260, and thus each of the elongated flexible arms 260, radially outward. The greater the outward deflection 430 of the flexible arm 260, the greater the value of the diameter D3 of the opening 144 (FIGS. 2F and 2H). The plunger rod 150 is releasable from the PEM140 when the value of D3 is greater (larger) than D1, where D1 is the diameter of the inlet tip 210 of the plunger rod 150. Depending on the design specifications of the PEM140 and the PRM190, the maximum radially outward deflection 430 of the flexible arm 260 occurs when the PEM140 is fully or partially (depending on the design specifications) in the storage position within the PRM190. Thus, when the PEM140 is housed within the PRM190, i.e., when the PEM140 is within the open annular channel (OAC) 370 within the PRM190, the PEM140 and the PRM190 are designed such that the condition D3 > D1 is satisfied.

[0069] Figures 5A and 5B are two-dimensional and three-dimensional cross-sectional views, respectively, of the PEM140 (and plunger head 130) in the storage position within the PRM190, which functions as a docking station for the PEM140 and the plunger head 130. When the PEM140 (along with the plunger head 130) is in the storage position within the PRM190, the deflection of the flexible arm 260 of the PEM140 is at a maximum (D3 > D1), and the plunger rod 150 can be easily released (pulled away or disconnected) from the PEM140, and thus the plunger head 130, for example, by the motor 170 (Figure 1A).

[0070] Figure 6A shows a pump device 600 with a disposable reservoir 120 still coupled to the reusable portion 110. The plunger engagement member (PEM) 140 is being received by the plunger release member (190) which functions as a docking station. Referring to Figure 6A, the inlet tip 210 of the plunger rod 150 is snap-fitted by the PEM140, thereby preventing the plunger rod 150 from being released from the PEM140 by the motor 170, and thus preventing the disposable reservoir 120 from being disconnected from the reusable portion 110 (in order to disconnect the disposable reservoir 120 from the reusable component 110, the plunger rod 150 must first be released from the plunger head 130, i.e., the PEM140). The motor 170, as shown in Figure 6A, can further retract the plunger rod 150 in direction 610 by a distance 620 and receive the PEM140 into the PRM190 (docking station).

[0071] Figure 6B shows a pump device 600 where the disposable reservoir 120 is still coupled to the reusable portion 110, but the PEM 140 is housed in the docking station (PRM 190). Referring to Figure 6B, the inlet tip 210 of the plunger rod 150 is no longer snap-fitted by the PEM 140. By moving the disposable reservoir 120 (e.g., manually) in the direction of 630 away from the reusable portion 110 to disconnect the disposable reservoir 120 from the reusable portion 110, the plunger rod 150 can be released from the PEM 140. Thus, when the PEM 140 is housed in the PRM 190 by the motor 170, the plunger rod 150 is automatically discharged from the PEM 140. Thus, the PRM 190 functions as both a discharging means and a housing means, and when the plunger rod 150 pulls the PEM 140 to the housing position of the PRM 190, the plunger rod 150 is discharged from the PEM 140. (The discharge of the plunger rod 150 from the PEM 140 is clearly shown in Figures 5A - 5B).

[0072] Features common to Configuration #2 and #3 Configurations #2 and #3 use bayonet connection means. As described herein, the difference between Configuration #2 and Configuration #3 is that in Configuration #2, the plunger rod can be locked (held) to the plunger engagement member (PEM) using a snap-fit function and released from the PEM using a bayonet function, whereas in Configuration #3, the plunger rod can be locked (held) to the PEM and released from the PEM using a bayonet function.

[0073] In some embodiments, the distal end of the plunger rod includes an inlet tip having N equally spaced angle-spaced fins extending radially outward from the longitudinal axis of the plunger rod. The distal end of the plunger rod also includes a segmented circumferential locking groove formed circumferentially at the distal end by the N fins between the N fins and the rest of the plunger rod.

[0074] FIG. 7 shows an example of a plunger rod 700 according to some embodiments, FIGS. 8A-8B show an example of a plunger head 800 including an example of a plunger engagement member (PEM) 810 according to some embodiments, and FIGS. 9A-9B show an example of a plunger release member (PRM) 900 according to some embodiments. The PEM 810 and the PRM 900 together constitute a mechanism. The PEM 810 is generally a cylindrical male object with circumferential bayonet slots or grooves, and the PRM 900 is generally a cylindrical female object with radial bayonet pins inside, and the two objects are designed to be coupled and separated from each other by a twisting operation.

[0075] The bayonet slots (or grooves) are formed circumferentially in the perforated cylindrical member 840 of the PEM 800. The bayonet slots are designed as a three-dimensional curve (helix) that surrounds the longitudinal axis 830 of the perforated cylindrical member at a constant radial distance from the longitudinal axis 830. The helical slots (e.g., slot 850) are designed such that the rotational (twisting) movement around the longitudinal axis 830 of the PEM 800 allows the rotational angle required to lock the fins (e.g., fins 724) within the PEM 800 and / or (depending on the configuration) the rotational angle required to release the lock of the fins from the PEM.

[0076] Referring to FIG. 8A, the PEM 810 is fixedly embedded or attached to the tip section 890 of the plunger head 800 or is manufactured as part of the plunger head 800 (e.g., using plastic injection molding). Thereby, the two different objects (PEM, plunger head) can move integrally in the disposable reservoir not only in the discharge direction of the reservoir but also in the opposite direction (i.e., the filling direction of the reservoir).

[0077] The plunger rod 700, the plunger head 800, and the PRM 900 can be used in at least two configurations (i.e., Configuration #2 and #3) described herein. In Configuration #2, the plunger rod 700 can engage with the PEM 810 by using a snap-fit connection and can be detached (released) from the PEM 810 by using a bayonet mechanism that includes a number of helical bayonet slots S and the same number of bayonet radial pins that can be inserted into the bayonet slots and are slidable within the bayonet slots. The bayonet slots are designed as a three-dimensional curve (helix) that surrounds the longitudinal axis of the PEM's perforated cylindrical member at a constant radial distance from the longitudinal axis. The helical slots of the PEM are designed such that, by the slots, the PEM can rotate about the longitudinal axis by the rotation angle required to lock the fins to the PEM and / or (depending on the configuration) the rotation angle required to unlock the fins from the PEM. In Configuration #3, the plunger rod 700 can engage (lock) with the PEM 810 by using a bayonet mechanism and can be detached (released) from the PEM 810 by using the bayonet mechanism.

[0078] Referring to FIG. 7, the plunger rod 700 includes a distal end 710 having an inlet tip 720. By way of example, the inlet tip 720 includes four fins 722, 724, 726, and 728 arranged at equally spaced angles. (The inlet tip 720 can include N fins arranged at any suitable angle.) The fins 722, 724, 726, and 728 extend radially outward (away) from the longitudinal axis 730 of the plunger rod 700. The distal end 710 of the plunger rod 700 also includes a segmented lock groove 740 formed circumferentially at the distal end 710 between the fins 722, 724, 726, 728 and the conical surface 770. The circumferential lock groove 740 is segmented by the fins 722, 724, 726, 728 which are circumferentially spaced by a plurality of recesses, and two adjacent fins are spaced (separated) by a recess. For example, fins 724 and 726 are adjacent fins, extend radially outward from the longitudinal axis 730, and are spaced by a recess 750. (For comparison, the circumferential lock grooves 220 in FIGS. 2A and 2D are continuous grooves.)

[0079] The fins 722, 724, 726, 728 and the recesses therebetween form a cross-shaped object similar to the head of a plus driver. The inlet tip 720 is generally shaped as a segmented hemispherical tip, a segmented conical tip, or the head of a cross-shaped plus driver. Each of the exemplary fins 722, 724, 726, and 728 has a curved "inlet side" for imparting the snap-fit function referred to herein in connection with Configuration #2 to those fins. In Configuration #3, the fins do not require a curved inlet side for engaging the PEM or for releasing the fins from the PEM. Thus, in Configuration #3, each fin can have a curved inlet side, but in that configuration the curved inlet side is of little or no use since the snap-fit biasing function is not required.

[0080] Referring to FIGS. 8A-8B, the plunger engagement member (PEM) 810 includes a perforated cylindrical member 840 having an inner wall 812 and four ribs 820. The ribs 820 extend radially inward from the inner wall 812 of the PEM 810 toward the longitudinal axis 830 of the plunger head 800. The ribs 820 are angularly spaced or distributed equidistantly around the inner wall 812 of the PEM 810 about the longitudinal axis 830 of the plunger head 800 (and the cylindrical body 840). The ribs 820 have the same number (four in this example) of recesses spaced alternately so that two adjacent ribs 820 are each spaced by one recess. (The PEM may include N ribs such as the ribs 820, and accordingly, the number N of recesses may be the same.)

[0081] The ribs 820 of the PEM 810 are designed to lock the fins 722, 724, 726, and 728 of the plunger rod 700, respectively. Locking of the fins 722, 724, 726, and 728 by the ribs 820 may be effected by rotating the plunger head 800 (and thus the PEM 810) about its longitudinal axis 830 from a "release" position where the fins 722, 724, 726, and 728 freely pass through the recesses between the ribs 820 to a "lock" position where the ribs 820 of the PEM 810 are aligned with the fins 722, 724, 726, and 728 so as to lock or hold the fins, respectively, by snap-fitting the distal end 710 of the plunger rod 700 by the PEM 810 according to Configuration #2 or by inserting the plunger rod 700 into the PEM 810 according to Configuration #3.

[0082] The PEM810 also includes four bayonet slots 850, 860, 870, and 880. The bayonet slots 850, 860, 870, and 880 are formed on the outer periphery of the cylindrical body 840 and are generally arranged as helical slots. In the example of the PEM shown in FIGS. 8A-8B, each bayonet slot spirally rotates counterclockwise around the longitudinal axis 830 of the PEM810 towards the axial leading section 890 of the plunger head 800. The PEM810 is the axial subsequent section of the plunger head 800. (The "leading section 890" is the section of the plunger head 800 that is generally forward of the tip 720 of the plunger rod 700 when the plunger rod 700 is coupled to the PEM810 and moves the plunger head 800 to discharge the drug from the disposable reservoir. The "subsequent section 810" is the PEM section that is generally rearward of the tip 720 of the plunger rod 700 when the plunger rod 700 is coupled to the PEM810 and moves the plunger head 800 forward to discharge the drug from the disposable reservoir.)

[0083] Each bayonet slot has an entry point at the proximal end / rear end 892 (FIG. 8B) of the PEM810 and an end point at the distal end / tip 894 (FIG. 8B) of the PEM810, and each bayonet slot curves around the axis 830 between the entry point and the end point. For example, the bayonet slot 850 has an entry point 852 at the rear end 892 of the PEM810 and an end point 854 at the tip 894 of the PEM810. Similarly, the bayonet slot 860 has an entry point 862 (FIG. 8B) at the rear end 892 of the PEM810 and an end point (not shown in FIGS. 8A-8B) at the tip 894 of the PEM810. Similarly, the bayonet slot 870 has an entry point (not shown in FIGS. 8A-8B) at the rear end 892 of the PEM810 and an end point (not shown in FIGS. 8A-8B) at the tip 894 of the PEM810. Similarly, the bayonet slot 880 has an entry point 882 at the rear end 892 of the PEM810 and an end point 884 at the tip 894 of the PEM810.

[0084] Referring to FIGS. 9A - 9B, the plunger release member (PRM) 900 includes a hollow cylindrical body 910 having a hole 920. The cylindrical body 910 also includes an external flange (ledge) 930. The ledge 930 projects radially outward in the circumferential direction from the cylindrical body 910, surrounds the cylindrical body 910, and forms an "L"-shaped object around the longitudinal axis 940 of the cylindrical body 910. By means of the "L"-shaped object, the PRM 900 can be fixed (attached) to the proximal end 126 of the reservoir 120. The cylindrical body 910 also includes an internal flange (ledge) 950. The ledge 950 projects circularly inward from the inner wall 952 of the cylindrical body 910 toward the longitudinal axis 940 of the cylindrical body 910. The diameter of the ledge 950 is D8 (see FIG. 10A).

[0085] The cylindrical body 910 also includes four bayonet radial pins 960, 970, 980, and 990, the number (4) of which corresponds to the four bayonet slots 850, 860, 870, and 880. The bayonet pins 960, 970, 980, and 990 are configured to enter the bayonet slots 850, 860, 870, and 880, respectively, through the entry points of the bayonet slots. For example, the bayonet pin 960 can enter the bayonet slot 850 through the entry point 852, the bayonet pin 970 can enter the bayonet slot 860 through the entry point 862, the bayonet pin 980 can enter the bayonet slot 870 through the entry point, and the bayonet pin 990 can enter the bayonet slot 880 through the entry point 882.

[0086] A bayonet connector is generally a connector in which one part of the connector can move linearly relative to the other part by rotating one part of the connector relative to the other part. To enable this function, one part of the bayonet connector includes a helical slot, and the other part of the bayonet connector includes a guide pin. When the helical slot is pressed linearly against the guide pin, one part of the connector makes a rotational movement relative to the other part. Returning again to FIGS. 8A-B and 9A-9B, due to the helical design of the bayonet slots 850, 860, 870 and 880 (in combination with the bayonet pins 960, 970, 980 and 990), when the PEM810 engages with the PRM900 and moves linearly relative to the PRM900 by the plunger rod 700, the PEM810, and thus the entire plunger head 800, can be rotated around the vertical axis 830. For example, when the PEM810 and the PRM190 are engaged, to rotate the PEM810 relative to the PRM190, when the plunger rod 700 is released from the PEM810, the PEM810 is pushed linearly into the PRM900 (Configuration #2), or the PEM810 is linearly separated from (removed from) the PRM900 and the plunger rod 700 is locked to the PEM810 (Configuration #3).

[0087] In Configuration #2, the plunger rod 700 can engage with the PEM810 using a snap-fit connection (thus eliminating the need for any part to rotate relative to other parts), and can be released from the PEM810 by rotating the PEM910 in the "release" direction to disengage the distal end 710 of the plunger rod 700 from the rib 820 of the PEM810. In Configuration #3, the PEM810 can rotate in the "lock" direction to engage the plunger rod 700 with the PEM810, with all fins of the plunger rod 700 being locked by the respective ribs 820 of the PEM810), and can be released from the PEM810 by rotating in the "release" direction.

[0088] In both Configurations #2 and #3, rotating the PEM810 in the "release" direction is effected by axially pulling the PEM810 rearward by the plunger rod 700, during which process the bayonet slots 850, 860, 870, and 880 are each guided to rotate by the bayonet pins 960, 970, 980, and 990 of the PRM900 to the "release" angular position. In Configuration #3, rotating the PEM810 in the "lock" direction (i.e., the direction opposite to the "release" direction) is effected by axially pushing the PEM810 forward by the plunger rod 700, during which process the bayonet slots 850, 860, 870, and 880 are each guided to rotate by the bayonet pins of the PRM900 to the "lock" angular position.

[0089] As described herein, the PRM900 is fixedly attached to the end point 126 of the reservoir 120, which means that the PRM900 is stationary within the reservoir 120. In FIGS. 8A and 9A, after the bayonet pins 960, 970, 980, 990 enter the bayonet slots 850, 860, 870, 880 through their respective entry points, the PEM810 can be linearly (axially) pushed in a first direction by the plunger rod 700 (i.e., to facilitate pulling the plunger rod 700 away from the PEM810 in accordance with Configuration #2), thereby rotating the PEM810 from a locked angular position where each of the four ribs 820 locks one of the fins 722, 724, 726, 728, to a release (unlock) angular position where none of the fins 722, 724, 726, 728 are locked by the ribs, and thus the plunger rod 700 can be removed from the PEM.

[0090] When bayonet pins 960, 970, 980, and 990 are respectively within bayonet slots 850, 860, 870, and 880, PEM 810 is pushed in the second direction, the longitudinal (axial) direction, by plunger rod 700 (i.e., in order to facilitate the engagement of plunger rod 700 and PEM 810 according to Configuration #3), and PEM 810 can be rotated from a release angular position where the fins of the plunger rod are not locked by rib 820 to a locked angular position where all of fins 722, 724, 726, and 728 are respectively locked by rib 820. Next, as described herein in connection with Configuration #2, fins 722, 724, 726, and 728 can be released from rib 820 by rotating PEM 810 (along with the bayonet pins) in the opposite direction (i.e., the first direction) by plunger rod 700.

[0091] In Configuration #2, the cylindrical member 840 of PEM810 is reversibly expandable (and / or the ribs 820 are reversibly compressible), and when the plunger rod 700 moves linearly within PEM800 (e.g., by the motor 170), engagement between the plunger rod and PEM810 is enabled by snap-fitting N ribs into the segmented lock grooves 740 of the plunger rod 700. In this configuration, the plunger rod 700 can be released from PEM800 by rotating PEM800 about its axis (830) from the "lock" ("snap-fit") position to the "release" position. In Configuration #3, PEM800 (including the cylindrical member 840 and the ribs 820) is made of a rigid (nonexpandable) material, and locking of N fins (e.g., the four fins shown in FIG. 7) by N ribs (e.g., the four ribs shown in FIG. 8A) is performed by rotating PEM800 about the longitudinal axis 830 in a first direction (e.g., counterclockwise) with respect to the inlet tip 720 of the plunger rod 700 until each of the fins 722, 724, 726, and 728 reaches the "lock" position where it is locked by one of the ribs 820. In this configuration, the plunger rod 700 can be released from PEM800 by rotating PEM800 about its axis (830) in the opposite direction (e.g., clockwise) from the "lock" position to the "release" position.

[0092] The fins, ribs, and recesses formed by the ribs are configured such that the plunger rod 700 can move from a lock angular position where the fins are aligned with and locked by the ribs, enabling the PEM800 (and thus the plunger head) to move rearward in accordance with the rearward movement of the plunger rod 700, to an unlock (release) angular position where the fins are aligned with the recesses and the inlet tip 720 of the plunger rod 700 can be released from the PEM800, and thus from the plunger head.

[0093] Referring to FIGS. 7 and 10A, the distal end 710 of the plunger rod 700 includes a push flange 760. The flange (shelf) 950 of the PRM 900 (FIGS. 9A-9B) has an inner diameter D8, the flange 760 of the plunger rod 700 has an outer diameter D9, and the PEM 810 has an inner diameter DI0. The values of D8, D9, and DI0 are selected such that DI0 < D9 < D8. When the plunger rod 700 moves axially in the direction 1010 (e.g., by the motor 170) (at this stage, the PEM 810 does not move), the inlet tip 720 of the plunger rod 700 passes through the inner flange (shelf) 950 of the PRM 900 and then through the cylindrical member 840 of the PEM 810 until the flange 760 contacts (abuts) the cylindrical member 840 of the PEM 810 at 1020 and moves linearly (axially). From this point, when the plunger rod 700 moves further linearly in the 1010 direction, the PEM 810 also begins to move in the same direction (the 1010 direction). The bayonet slots and pins are designed such that the linear displacement of the PEM 810 (and thus the entire plunger head 800) in the 1010 direction is converted into a rotational movement (1030) about the axis (axis 830) of the PEM 810. When the PEM 810 is pushed further linearly, the PEM 810 continues to rotate about the axis 830 until the bayonet slots move away from the respective fixed bayonet pins.

[0094] Since the diameter D9 of the flange 760 is larger than the inner diameter D10 of the cylindrical member 840, when the plunger rod 700 is moved forward in the reservoir 1020 by the motor 170, the flange 760 can push the PEM810 (a part of the plunger head) together with the plunger rod 700 in the forward (emptying) direction 1010. In both Configuration #2 and Configuration #3, when the plunger rod 700 is locked to the PEM810, the PEM810 is firmly sandwiched between the pushing flange 760 of the plunger rod 700 and the retracting shelf of the fins 720, and can move bidirectionally in the reservoir 2020 integrally with the plunger rod 700, move in the direction 1010 to empty the reservoir 120, and move in the opposite direction to fill the reservoir 120.

[0095] Figure 10B shows the initial state in which the fins 722, 724, 726, and 728 of the plunger rod 700 are unlocked by the ribs 820 and the plunger rod 700 can be retracted from the PEM810 by linearly moving the plunger rod. For example, the fin 722 can freely move bidirectionally in the recess 1040 formed by the ribs 820 / 1 and 820 / 2. Similarly, the fin 728 can freely move bidirectionally in the recess 1050 formed by the ribs 820 / 4 and 820 / 1. Figure 10C shows the final angular state in which the bayonet slots are separated (moved away) from the respective fixed bayonet pins, the PEM810 rotates with respect to the fins 722, 724, 726, and 728 of the plunger rod 700, and the fins 722, 724, 726, and 728 are locked by the ribs 820 of the PEM800 at their respective angular positions.

[0096] Figure 10D schematically shows an exemplary initial angular position (γ) of an exemplary PEM1060 relative to fins of an exemplary plunger rod. As an example, PEM1060 includes four ribs (1062, 1064, 1066, and 1068), and thus, the plunger rod includes four fins 1070. The initial angular position (angle γ) of PEM1060 relative to the plunger rod (and thus, the fins 1070) is referred to herein as the "unlock angular position" or the "release angular position". This is because neither of the fins 1070 is locked by the ribs of the PEM, and thus, at this angular position of PEM1060 relative to the plunger rod, the fins 1070 are retractable from the PEM1060. The value of the angle δ between two adjacent ribs is constant, but the value of the angle γ between a rib and an adjacent fin varies according to the linear (axial) distance that the plunger rod (and thus, the PEM) moves. The value of δ is determined by the number (r) of ribs of the PEM and can be calculated as follows: δ = 360° / r. In the example shown in Figure 10D, the number of ribs is four (r = 4), and δ = 360° / 4 = 90°. The value of γ can be calculated as follows: γ = δ / 2. Continuing with the above example, γ = δ / 2 = 90° / 2 = 45°.

[0097] Figure 10E schematically shows PEM 1060 after it has rotated counterclockwise (CCW) by an angle γ = 45° from the unlock / liberation angular position shown in Figure 10D (corresponding to the unlock / release angular position shown in Figure 10B) to the lock angular position (corresponding to the lock angular position shown in Figure 10C) where each fin 1070 is locked by the corresponding rib, by the plunger rod 700 pushing PEM 1060 linearly. For example, fin 1072 is fixed by rib 1068. (The four "black and white" dotted line patterns shown in Figure 10E, for example, the black and white dotted line pattern 1080, each show the distal region of the fin that overlaps, i.e., contacts, the distal region of the rib. In Figure 10D, the fin and the rib do not overlap.) Figures 10B, 10C, and 10D show a fin structure including four fins and the resulting rib structure including four ribs. However, the fin structure of the plunger rod can include less than four fins (e.g., three fins) or more than four fins (e.g., five fins), and the rib structure has the same number of ribs.

[0098] Figures 11A - 11I show the steps of operating the pump device according to Configuration #2. Figure 11A shows the disposable portion (reservoir) 1100 of the pump device before it is coupled to the reusable portion 1110 of the pump device. Reservoir 1100 includes a plunger head 1102 that is movable bidirectionally within reservoir 1100. Plunger head 1102 is configured as a snap - fit connection (lock) mechanism or includes a plunger engagement member (PEM) 1104 having a snap - fit connection (lock) mechanism.

[0099] The disposable portion (reservoir) 1100 also includes a plunger release member (PRM) 1106 fixed within the disposable portion 1100. That is, the PRM 1106 is attached so as to be fixed to the proximal end of the disposable portion 1100 and cannot move relative to the disposable portion 1100. The reusable portion 1110 of the pump device includes, among other things, a plunger rod 1112 and an electric motor 1114 for linearly moving the plunger rod 1112 bidirectionally. The plunger rod 1112 includes a distal end 1116 having a flange and a plurality of fins, similar to the distal end 710 of the plunger rod 700. The PRM 1106 includes bayonet pins. (Two bayonet pins of the PRM 1106 are shown at 1108) The disposable portion 1100 is coupled to the medical vial 1120 via a vial adapter 1130. To initiate operation of the pump device, the disposable portion 1100 is moved (1118) towards the reusable portion 1110 and, for example, magnetically coupled to it.

[0100] Initially (e.g., before the disposable portion and the reusable portion are coupled), the plunger rod 1112 is housed (fully retracted) within the reusable portion 1110. As shown in FIG. 11B, when the disposable portion 1100 is coupled to the reusable portion 1110, the electric motor 1114 is controlled to operate and move the plunger rod 1112 forward in the direction 1111 (extend) to engage the plunger rod 1112 with the PEM 1104 (and thus the plunger head 1102). To engage the plunger rod 1112 with the PEM 1104, the ribs of the PEM 1104 are snap-fitted into the fins of the distal end 1116 of the plunger rod 1112 such that the ribs of the PEM 1104 lock the respective fins of the plunger rod 1112.

[0101] Referring to Configuration #2, the PEM (e.g., PEM 1104) may initially be disposed at the distal end of the reservoir, as shown, for example, in FIGS. 11A - 11C. However, the PEM may initially be within the reservoir at any intermediate position between the PRM (e.g., PRM 1106) and the distal end of the reservoir. If the PEM is initially disposed at an intermediate position between the PRM and the distal end of the reservoir, it may be necessary to push the PEM, i.e., the plunger head, to the distal end of the reservoir with the plunger rod so that the distal end of the plunger rod (e.g., distal end 1116) is properly snap - fitted by the PEM.

[0102] FIG. 11C shows a state where the distal end 1116 of the plunger rod 1112 is fully extended and snap - fitted and locked by the PEM 1104. (FIG. 11D shows the fins of the plunger rod 1112 at a locked - angle position where the fins of the plunger rod 1112 are locked by the ribs of the PEM 1104) At this stage, the electric motor 1114 is controllably actuated to pull the plunger rod 1112 rearward in the direction of 1113. Since the fins of the plunger rod 1112 are locked by the ribs of the PEM 1104, when the plunger rod 1112 is pulled in, the plunger head 1102 moves with the plunger rod 1112, creating a suction force in the reservoir 1100 to fill the reservoir 1100 with the drug. (FIG. 11E shows the reservoir 1100 filled with the drug)

[0103] Referring to FIG. 11E, the PEM 1104 is drawn into the reservoir 1100 only from the distal end of the reservoir 1100 to the point where the bayonet pins 1140 (FIG. 11B) of the PRM 1106 respectively abut the inlet points of the slots of the PEM 1104. Beyond the abutting point (retreated by the plunger rod 1112), if the PEM 1104 is drawn, for example, to the storage position of the PEM 1104 within the PRM 1106, the bayonet pins 1140 of the PRM 1106, together with the bayonet slots of the PEM 1104, rotate the PEM 1104 about its axis from the locked angular position shown in FIG. 11D to the unlocked (released) angular position shown in FIG. 11H, which is not desirable at this stage. At this stage, the electric motor 1114 (FIG. 11A) is controllably operated to linearly (axially) move (extend) the plunger rod 1112 in the direction of 1115, for example, to empty the reservoir 1100 by delivering the drug from the reservoir 1100 to the injection site of the patient. When the plunger rod 1112 moves linearly forward in the direction of 1115 (e.g., by the electric motor 1114), the flange 1150 of the plunger rod 1112 pushes the PEM 1104 in the same direction, delivering the drug in the reservoir 1100 to the person in need.

[0104] FIG. 11F shows a state where the reservoir 1100 is empty and the plunger rod 1112 is fully extended. At this stage, the electric motor 1114 is controllably actuated to linearly retract the plunger rod 1112 in the direction of 1117, releasing the plunger rod 1112 from the PEM 1104 (and thus the plunger head 1102). To release the plunger rod 1112 from the PEM 1104, the plunger rod 1112 is fully retracted into the reservoir 1100 (in contrast to the partial retraction of the plunger rod in FIG. 11E), enabling the PEM 1104 to engage with the PRM 1108, and the bayonet pins 1140 and bayonet slots of the PEM 1104 rotate the PEM 1104 from the locked angular position to the unlocked (released) angular position, during which the PEM 1104 linearly moves in the direction of 1117 by the plunger rod 1112.

[0105] Figure 11G shows the plunger rod 1112 fully retracted within the reservoir 1100, at which position the PEM 1104 is fully housed within the PRM 1106. Figure 11H shows the rib of the PEM 1104 at the unlocking angular position where the plunger rod 1112 (Figure 11D) can be released from the PEM 1104. At this stage, the plunger rod 1112 is fully retracted within the reusable portion 1110 by the electric motor, and the disposable portion 1100 is detached (disconnected) from the reusable portion 1110. Figure 11I shows the plunger rod 1112 fully retracted (fully housed) within the reusable portion 1110, the PEM 1104 fully housed within the PRM 1106, and the reusable portion 1110 detached from the disposable portion 1100. Thus, when the PEM 1104 is housed in the PRM 1106 by the motor 1114, the plunger rod 1112 is automatically discharged from the PEM 1104. Therefore, the PRM 1106 serves both as a discharging means and a housing means, and when the plunger rod 1112 pulls the PEM 1104 to the housing position of the PRM 1106, the PRM 1106 discharges the plunger rod 1112 from the PEM 1104. (To discharge the plunger rod 1112 from the PEM 1104, the PEM 1104 is rotated vertically with respect to the plunger rod 1112)

[0106] Figures 12A - 12M show the steps of operating the pump device according to Configuration #3. Figure 12A shows the disposable portion (reservoir) 1200 of the pump device before being coupled to the reusable portion 1210 of the pump device. The reservoir 1200 includes a plunger head 1202 that is movable bidirectionally within the reservoir 1200. The plunger head 1202 includes a plunger engagement member (PEM) 1204 configured as a bayonet connection mechanism or having a bayonet connection mechanism.

[0107] The disposable portion (reservoir) 1200 includes a plunger release member (PRM) 1206 fixed within the disposable portion 1200. That is, the PRM 1206 is fixedly attached to the proximal end of the disposable portion 1200 and cannot move relative to the disposable portion 1200. The reusable portion 1210 of the pump device includes, among other things, a plunger rod 1212 and an electric motor 1214 for linearly moving the plunger rod 1212 bidirectionally. The plunger rod 1212 includes a distal end 1216 having a push flange and a plurality of fins, similar to the distal end 710 of the plunger rod 700. The PRM 1206 includes bayonet pins. (The bayonet pins of the PRM 1206 are shown at 1208 in FIGS. 12G and 12J) To initiate operation of the pump device, the disposable portion 1200 is moved in the direction 1218 towards the reusable portion 1210 and magnetically coupled, for example. Initially (e.g., before the disposable portion 1200 and the reusable portion 1210 are coupled), the plunger rod 1212 is housed (fully retracted) within the reusable portion 1210 and the PEM 1204 is fully housed within the PRM 1206.

[0108] As shown in FIG. 12B, when the disposable portion 1200 is coupled to the reusable portion 1210, the electric motor 1214 is controllably operated to move (extend) the plunger rod 1212 forward in the direction 1211 and engage the distal end 1216 of the plunger rod 1212 with the PEM 1204 (and thus the plunger head 1202). To engage the distal end 1216 of the plunger rod 1212 with the PEM 1204, it can be accomplished by using a bayonet mechanism that can rotate the ribs of the PEM 1204 from an unlocked angular position to a locked angular position relative to the fins of the distal end 1216 of the plunger rod 1212, at which locked angular position the ribs of the PEM 1204 lock the fins of the plunger rod 1212, respectively.

[0109] In Configuration #3, for example, as shown in FIGS. 12A-C, the PEM 1204 is initially positioned (stored) at the proximal end of the reservoir 1200, and the bayonet pins of the PRM 1206 are already seated (occupied) in the helical bayonet slots of the PEM 1204 respectively. When the PEM 1204 moves linearly from its initial (stored) position, the bayonet mechanism, i.e., the slots of the PEM 1204 together with the pins 1208 of the PRM 1206 (FIGS. 12G and 12J), rotates the PEM 1204 from the unlocked angular position to the locked angular position.

[0110] FIG. 12C shows the distal end 1216 of the plunger rod 1212 within the PEM 1204 in the pre-locked state before the PEM 1204 is pressed against the bayonet pin 1208 and rotates to the locked angular position. FIG. 12D shows the state where the distal end 1216 of the plunger rod 1212 (and thus the fins of the plunger rod 1212) remains unlocked by the ribs of the PEM 1204.

[0111] FIG. 12E shows the state where the PEM 1204 has moved linearly by a distance 1201 from the storage position of the PRM 1206 (by the electric motor 1214), and as a result, has rotated from the unlocked angular position to the locked angular position. At the locked angular position, as shown in FIG. 12F, the fins of the plunger rod 1212 are locked by the ribs of the PEM 1204 respectively. At this stage, the electric motor 1214 is controllably operated to further move the plunger rod 1212 forward in the direction 1213 to suck the drug from the drug vial and prepare to fill the reservoir 1200 with the drug.

[0112] Figure 12G shows the PEM 1204 at the distal end of the reservoir 1200 and the vial 1220 coupled to the reservoir 1200 via a vial adapter. At this stage, since the fins of the plunger rod 1212 are locked by the ribs of the PEM 1204, when the plunger rod 1212 is pulled in the direction 1215, the plunger head 1202 moves in the direction 1215 together with the plunger rod 1212. When the plunger head 1202 is moved in the direction 1215, a suction force is generated in the reservoir 1200 and the reservoir 1200 is filled with the drug. (Figure 12H shows the reservoir 1200 filled with the drug.)

[0113] Referring to Figure 12H, the PEM 1204 is drawn into the reservoir 1200 from the distal end of the reservoir 1200 to the point where the bayonet pins of the PRM 1206 abut against the entrance points of the slots of the PEM 1204 respectively (retracted by the plunger rod 1212). (At this point, the reservoir 1200 is filled with the drug.) Beyond the abutting point, if the PEM 1204 is further drawn, for example, to the storage position of the PEM 1204 in the PRM 1206, the bayonet pins 1208 of the PRM 1206 rotate the PEM 1204 about its axis from the locked angular position shown in Figure 12F to the unlocked position shown in Figure 12L together with the slots of the PEM 1204, but this is not desirable at this stage. At this stage, the electric motor 1214 is controllably operated to linearly (axially) move (extend) the plunger rod 1212 in the direction 1217 as shown in Figure 12I, for example, to empty the reservoir 1200 by delivering the drug from the reservoir 1200 to the injection site of the patient. When the plunger rod 1212 moves linearly forward in the direction 1217 (e.g., by the electric motor 1214), the flange 1230 of the plunger rod 1212 pushes the PEM 1204 in the same direction to deliver the drug in the reservoir 1200 to the required person.

[0114] Figure 12J shows the state where the reservoir 1200 is empty and the plunger rod 1212 is fully extended. At this stage, the electric motor is controllably operated to linearly retract the plunger rod 1212 in the direction of 1219, releasing the distal end 1216 of the plunger rod 1212 from the PEM 1204 (and thus the plunger head 1202). To release the distal end 1216 of the plunger rod 1212 from the PEM 1204, the plunger rod 1212 is fully retracted into the reservoir 1200 (in contrast to the partial retraction of the plunger rod 1212 in Figure 12H), re - engaging the PEM 1204 with the PRM 1206, and the bayonet pins 1208 and bayonet slots within the PEM 1204 rotate the PEM 1204 from the locked angular position to the unlocked (released) angular position, during which the PEM 1204 is linearly moved in the direction 1219 by the plunger rod 1212.

[0115] Figure 12K shows the plunger rod 1212 fully retracted into the reservoir 1200, and Figure 12L shows the plunger rod 1212 released from the ribs of the PEM 1204 after rotating the PEM 1204 (with respect to the plunger rod) to the unlocked angular position where the plunger rod 1212 is released from the PEM 1204. At this stage, as shown in Figure 12M, the plunger rod 1212 is fully retracted by the electric motor and stored in the reusable portion 1210, and the disposable portion 1200 is separated (the connection is severed) from the reusable portion 1210. Thus, when the PEM 1204 is stored in the PRM 1206 by the motor 1214, the plunger rod 1212 is automatically discharged from the PEM 1204, similar to that described in relation to Figure 11G.

[0116] Figure 12K shows the plunger rod 2112 fully retracted into the reservoir 1200, at which position the PEM 1204 is fully housed within the PRM 1206. Figure 12L shows the four ribs of the PEM 1204 at the unlocking angular position where the plunger rod 1212 can be released from the PEM 1204. At this stage, the plunger rod 1212 is fully retracted by the electric motor and housed within the reusable portion 1210, and the disposable portion 1200 is detached (disconnected) from the reusable portion 1210. Figure 12M shows the plunger rod 1212 fully retracted (fully housed) within the reusable portion 1210, the PEM 1204 fully housed within the PRM 1206, and the disposable portion (reservoir) 1200 detached from the reusable portion 1210.

[0117] Figures 13A - 13F show how a bayonet function is used to lock the plunger rod 1300 to the plunger engaging member (PEM) 1310 of the plunger head 1320 according to Configuration #3. Figure 13A is a cross - sectional view showing the PEM 1310 in the storage position of the plunger release member (PRM) 1330. As described herein in connection with Configurations #2 and #3, when the PEM is in the storage position of the PRM, the PEM is in the unlocking (releasing) angular position, which means that the plunger rod is not yet locked by the PEM. Further, when the PEM is in the storage position within the PRM, each bayonet pin of the PRM is located at the end point of each bayonet slot within the PEM.

[0118] Referring to Figure 13A, the bayonet pin 1340 of the PRM 1330 is located at the end point of the bayonet slot 1350 of the PEM 1310 (the end points of the bayonet slot 1350 are more clearly shown at 1370 in Figure 13C). At this stage, the bayonet pins (such as pin 1340) are at the position farthest from the entry point of each bayonet slot. Figure 13B shows a cross - section of a 3 - dimensional assembly including the plunger rod 1300, the PEM 1310, and the PRM 1330.

[0119] When the plunger rod 1300 is linearly moved in the direction 1360, for example, by an electric motor (FIG. 13B), the flange 1302 of the plunger rod 1300 pushes the PEM 1310 in the same direction (1360), and as a result, rotates the PEM 1310 in the counterclockwise (CCW) direction 1380 (FIG. 13C). When the PEM 1310 starts to rotate in the CCW direction, the endpoints of the bayonet slots move away from the bayonet pins respectively, and as the PEM 1310 continues to rotate in the CCW direction (1380), the distance between the endpoint of each slot and the respective bayonet pin increases. FIG. 13C shows the PEM 1310 in an intermediate state where the bayonet pins have risen to about half of the bayonet slots. As an example, FIG. 13C shows the bayonet pin 1340 in an intermediate state where the bayonet pin 1340 has risen to about half of the bayonet slot 1350. FIG. 13D shows the assembly of FIG. 13C from another perspective and shows an additional bayonet pin (pin 1390) that has risen to about half of the corresponding bayonet slot (slot 1392), similar to the bayonet pin 1340.

[0120] When the plunger rod 1300 continues to move linearly in the direction 1360, its flange 1302 continues to push the PEM 1310 in the same direction. As a result of the linear (axial) movement of the PEM 1310, the pins of the PRM 1330 continue to rotate the PEM 1310 in the CCW direction until the PEM 1310 reaches the locked angular position. When the PEM 1310 reaches the locked angular position, for example, as shown in FIG. 12F, the fins of the plunger rod 1300 are locked by the ribs of the PEM 1310 respectively (FIG. 12F shows the state where the PEM 1204 is in the locked angular position and the fins of the plunger rod 1212 are locked by the ribs of the PEM 1204 respectively).

[0121] Figure 13E shows the state where PEM1310 (and thus the entire plunger head 1320) is in the locked angular position, with the bayonet pins of PRM1320 respectively disposed at the entry points of the bayonet slots of PEM1310 and in a state of emerging from the bayonet slots. As an example, the bayonet pin 1340 is disposed at the entry point 1352 of the bayonet slot 1360. When PEM1310 reaches the locked angular position, PEM1310 further moves in the 1360 direction, and PEM1310 moves linearly to the distal end of the reservoir without further rotating in the CCW direction or the clockwise (CW) direction. (When PEM1310 moves between the proximal end and the distal end of the reservoir, PEM1310 does not rotate in either direction (counterclockwise or clockwise) and maintains the locked angular position.)

[0122] Regarding Configurations #2 and #3, the number of bayonet pins and bayonet slots is not limited to a specific number (e.g., 2, 3, or 4), and since the number of bayonet pins is the same as the number of bayonet slots, one bayonet pin is associated with each specific bayonet slot, and vice versa.

[0123] According to some embodiments, the disposable reservoir contains levodopa or carbidopa, or a combination of levodopa and carbidopa.

[0124] The advantages of the disposable part (reservoir) of the present invention including PEM and PRM compared to the conventional disposable part (reservoir) are at least as follows. 1. Reduction of the cost of goods sold (COGS) related to the disposable part (reservoir) of the pump device. 2. The number of parts embedded in or included in the disposable part (reservoir) is small. 3. Improvement of the sustainability of the product. 4. Since the lead screw (plunger rod) is part of the reusable part of the pump device, the accuracy of the propulsion system is improved, and it can be operated with higher precision, smaller size, or stricter tolerances. 5. Instead of an oval syringe or syringes of other shapes, a round syringe can be designed. 6. Simplification of the assembly process of the disposable part (reservoir). 7. Support for the prefilled reservoir concept. 8. Improvement in the accuracy of lead screw positioning and position monitoring. 9. Efficiency improvement of occlusion control by strengthening the position control of the lead screw (plunger rod). 10. Improvement of the concept of the drug delivery system.

[0125] The articles "a" and "an" are used herein to refer to one or more than one (e.g., at least one) of the grammatical article's objects, depending on the context. By way of example, depending on the context, an element may mean one element or a plurality of elements. The term "comprising" is used herein to mean "including but not limited to" and is used interchangeably. The terms "or" and "and" are used herein to mean "and / or" and are used interchangeably, unless the context clearly indicates otherwise. The term "such as" is used herein to mean "such as but not limited to" and is used interchangeably.

[0126] Having thus described embodiments of the present invention, it will be apparent to those skilled in the art that modifications to the disclosed embodiments are within the scope of the present invention. Accordingly, alternative embodiments include functionally equivalent objects / articles. For example, the PEM and / or PRM and / or plunger rod may have a design different from that shown in the drawings (e.g., different shape, size, and / or material). Features of a particular embodiment may be used in other embodiments shown herein. The present disclosure has been described in connection with a pump device that includes a disposable reservoir and a reusable portion. However, the present disclosure may be relevant to other types of "two-component" devices, pumps, syringes, therapeutic agent dispensing devices, etc. (e.g., implemented by, used with, or potentially used in these). Accordingly, the scope of the following claims is not limited by the disclosure herein.

Claims

1. A pump device for delivering drugs, It comprises a disposable reservoir and a reusable part having a plunger rod, The disposable reservoir has a plunger head that is movable bidirectionally within the disposable reservoir between the proximal end and the distal end of the disposable reservoir. The plunger rod and the plunger head are connected to the disposable reservoir. When the reusable parts are connected to each other, the plunger rod is configured to be releasably lockable within the plunger head. A pump device for delivering medication.

2. The plunger head is equipped with a concentric plunger engaging member (PEM), The PEM is bidirectionally movable together with the plunger head between the proximal and distal ends of the disposable reservoir, the disposable reservoir further comprises a perforated plunger release member (PRM), the PRM is concentrically and fixedly attached to the proximal end of the disposable reservoir, the plunger rod has a distal end and is bidirectionally movable through the perforated PRM, and when the disposable reservoir and the reusable component are coupled together, the distal end of the plunger rod is lockable within the PEM and can be released from the PEM by the PRM. The pump device according to claim 1.

3. The plunger rod can be locked to and released from the PEM by using a snap-fit ​​connection means, a bayonet connection means, or a combination of a snap-fit ​​connection means and a bayonet connection means. The snap-fit ​​connection means includes an annular snap-fit ​​function, a cantilever snap-fit ​​connection function, or a combination of an annular snap-fit ​​function and a cantilever snap-fit ​​connection function. The snap-fit ​​connecting means includes the distal end of the plunger rod, the PEM and the PRM, The distal end of the plunger rod comprises an inlet tip and an annular lock groove formed circumferentially at the distal end between the inlet tip and the rest of the plunger rod, the PEM comprises a ring-shaped base and a flexible arm extending annularly from the ring-shaped base and curving inward toward the central axis of the PEM to form a flexible cap-like structure having an opening, the flexible cap-like structure is snap-fittable into the annular lock groove of the plunger rod, The PRM comprises an outer cylindrical body on which the plunger rod is movable and a concentric inner hollow cylindrical body, the outer cylindrical body and the concentric inner hollow cylindrical body define an open annular channel between them, and the inner hollow cylindrical body is configured to deflect the flexible arm of the PEM radially outward and release ("snap out") the plunger rod from the PEM when the PEM is retracted by the plunger rod into a storage position within the open annular channel. The pump device according to claim 2.

4. When the inlet tip of the plunger rod moves forward through the opening of the flexible cap-shaped structure, the flexible arm is deflected radially outward, and when the inlet tip passes through the opening of the flexible cap-shaped structure, the flexible cap-shaped structure snaps into the annular lock groove, and the plunger rod is locked within the plunger engaging member (PEM). The pump device according to claim 3.

5. The snap-fit ​​connection means is an irreversible snap-fit ​​connection. The pump device according to claim 3.

6. The distal end of the plunger rod is The inlet tip includes N fins distributed at an angle around the vertical axis of the plunger rod and extending radially outward from the vertical axis of the plunger rod, The distal end between the N fins and the rest of the plunger rod is provided with segmented (individual, discontinuous) locking grooves formed circumferentially, The plunger engaging member (PEM) is A perforated cylindrical member having an inner wall, and N ribs extending radially inward from the inner wall toward the longitudinal axis of the perforated cylindrical member, each configured to lock the N fins, The perforated cylindrical member comprises S bayonet slots formed in the circumferential direction, The pump device according to claim 2.

7. Each of the S bayonet slots is designed as a helix surrounding the vertical axis of the perforated cylindrical member at a constant distance from the vertical axis, and the bayonet slots allow the PEM to rotate around the vertical axis of the perforated cylindrical member at a rotation angle suitable for locking the N fins with the N ribs and unlocking the N fins from the N ribs. The pump device according to claim 6.

8. The PRM comprises a hollow cylindrical body on which the plunger rod is movable, and S bayonet pins extending radially inward from the inner wall of the hollow cylindrical body, each of the S bayonet pins being able to engage with the S bayonet slots of the PEM, thereby rotating the PEM relative to the PRM. The pump device according to claim 6.

9. The PEM is, with respect to the PRM, Each of the N fins is aligned with the N ribs, and is locked by the N ribs to a locking angle position that allows the plunger rod to retract the plunger head. The N fins are not aligned with the N ribs, and when the PEM is linearly retracted by the plunger rod into the storage position within the PRM, the plunger rod is rotatable between a release angle position that allows it to be released from the plunger head. Each of the S bayonet slots is designed to allow the PEM to rotate from the locked angle position to the released angle position when the PEM is moved linearly to its storage position within the PRM, and to allow the PEM to rotate from the released angle position to the locked angle position when the PEM moves linearly away from its storage position within the PRM. The pump device according to claim 8.

10. The step of rotating the PEM from the locked angle position to the released angle position includes rotating the PEM clockwise (or counterclockwise) by the released angle (γ), and the step of rotating the PEM from the released angle position to the locked angle position includes rotating the PEM in the opposite direction (counterclockwise or clockwise) by the locked angle (γ), and the value of the released / locked angle (γ) is γ = 180° / N. The value of N is selected from the group consisting of N=2, N=3, N=4, N=5, and N=6. The pump device according to claim 9.

11. The distal end of the plunger rod is further provided with a push-in flange, the diameter of which is greater than the inner diameter of the perforated cylindrical member, and when the plunger rod moves forward in the disposable reservoir, the push-in flange can push the PEM forward together with the plunger rod. The N fins are equipped with N retractable shelves, and in the locked angle position, the PEM is sandwiched between the push-in flange and the N retractable shelves, and when the plunger rod is retracted into the disposable reservoir, the PEM is movable rearward with the plunger rod. The pump device according to claim 9.

12. The aforementioned entrance tip is shaped as a segmented hemispherical tip, a segmented conical tip, or a cross-shaped Phillips screwdriver head. The pump device according to claim 6.

13. The PEM is initially positioned at the distal end of the disposable reservoir, and the plunger rod can be locked in the locked angle position by the PEM by moving the plunger rod forward through the PRM within the disposable reservoir until the N fins of the plunger rod snap into place by the N ribs of the PEM, and the plunger rod can be released from the PEM by retracting the PEM into its storage position within the PRM and twisting the PEM relative to the PRM from the locked angle position to the released angle position. The pump device according to claim 9.

14. The perforated cylindrical member of the PEM is reversibly expandable by the N fins of the plunger rod, thereby facilitating the snap-fitting of the N ribs of the PEM into the segmented lock grooves at the distal end of the plunger rod. The pump device according to claim 13.

15. The N ribs of the PEM are reversibly compressible by the N fins, thereby facilitating the snap-fitting of the N ribs of the PEM into the segmented lock grooves at the distal end of the plunger rod. The pump device according to claim 13.

16. The PEM is initially in a retracted position within the PRM at the release angle position, and the plunger rod can be locked by the PEM by moving the plunger rod forward through the PRM, and when the plunger rod linearly separates the PEM from the retracted position within the PRM, the PEM is rotated from the release angle position to the lock angle position, and the PEM can be released from the PEM by pulling the PEM back to the retracted position within the PRM and rotating the PEM from the lock angle position to the release angle position. The pump device according to claim 9.

17. The disposable reservoir has a plunger head, the plunger head is equipped with a plunger engagement member (PEM), which is bidirectionally movable together with the PEM between the proximal end and the distal end of the disposable reservoir, and the PEM is configured to engage with the plunger rod of the reusable portion of the drug delivery device. The disposable reservoir further includes a plunger release member (PRM) fixedly attached to the proximal end of the disposable reservoir, and the PRM is configured to release the plunger rod from the PRM when the PRM moves to a storage position within the PRM by the plunger rod. The pump device according to claim 1.

18. The plunger rod is lockable by or within the PEM by moving the plunger rod forward through the PRM within the disposable reservoir until the plunger rod snaps into place with the flexible arm of the PEM, and the plunger rod is releasable from the PEM by deflecting the flexible arm of the PEM and retracting the PEM into a storage position that releases the plunger rod from the PEM. The pump device according to claim 17.

19. The PEM is initially positioned at the distal end of the disposable reservoir, and the plunger rod is initially lockable in the locked position by the PEM by moving the plunger rod forward through the PRM within the disposable reservoir until the plunger rod snaps into the PEM, and the plunger rod is released from the PEM by moving the PEM to its storage position within the PRM, thereby twisting the PEM relative to the PRM from the locked position to the released position. The pump device according to claim 17.

20. The PEM is initially housed in the open angle position within the PRM, and the plunger rod can be locked by the PEM by moving the plunger rod forward through the PRM, and when the plunger rod moves the PEM linearly from the housed position within the PRM, the PEM is simultaneously rotated from the open angle position to the locked angle position, the PEM is returned to the housed position within the PRM, and the plunger rod can be released from the PEM by rotating the PEM from the locked angle position to the open angle position. The pump device according to claim 17.

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