Medical syringe metering pump with an interlock

Abstract

A metering pump for a medical injector includes a housing, a sleeve at least partially received within the housing, a piston at least partially received within the sleeve, and an interlock. The piston has a first position in which the chamber has a first volume and a second position in which the chamber has a second volume, the first volume being greater than the second volume. The sleeve has a first rotational position in which an inlet is in fluid communication with the chamber, a second rotational position in which an outlet is in fluid communication with the chamber, and a third rotational position in which the inlet and the outlet are isolated from the chamber. The interlock includes an elastomeric member positioned on one of the sleeve and the housing and a protrusion positioned on the other of the sleeve and the housing, the engagement between the elastomeric member and the protrusion being configured to limit movement of the sleeve until the sleeve overcomes a predetermined torque value.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of priority to U.S. Utility Patent Application No. 17 / 860,506, filed on July 8, 2022, entitled "Medical Infusion Syringe Dosage Pump with Interlock", the entire disclosure of which is hereby incorporated by reference in its entirety.

Background Art

[0002] Background of the Invention Field of the Invention This disclosure relates to an interlock for a medical infusion syringe dosage pump.

[0003] Description of the Related Art Wearable medical devices, such as auto - injectors, have the advantage of providing treatment to a patient away from a clinical facility and / or while being worn unobtrusively under the patient's clothing. A wearable medical device can be applied to the patient's skin and configured to automatically deliver a dose of a pharmaceutical composition after a predetermined time delay, for example, after a 27 - hour delay, after the wearable medical device has been applied to the patient's skin. After the device has delivered the pharmaceutical composition to the patient, the patient may then remove and discard the device.

Summary of the Invention

[0004] In one aspect or embodiment, a metering pump for a medical injector including a reservoir and a cannula includes a housing, a sleeve at least partially received within the housing, a piston at least partially received within the sleeve, and an interlock. The piston and the sleeve define a chamber, and the piston has a first position where the chamber has a first volume and a second position where the chamber has a second volume, the first volume being larger than the second volume. The sleeve has a first rotational position where an inlet is in fluid communication with the chamber, a second rotational position where an outlet is in fluid communication with the chamber, and a third rotational position where the inlet and the outlet are isolated from the chamber. The interlock includes an elastomeric member positioned on one of the sleeve and the housing and a protrusion positioned on the other of the sleeve and the housing, and the engagement between the elastomeric member and the protrusion is configured to limit movement of the sleeve until the sleeve overcomes a predetermined torque value.

[0005] The elastomeric member may be positioned on the housing and the protrusion may be positioned on the sleeve. The elastomeric member may be elastically deformed by the protrusion when the sleeve is rotated relative to the housing. The elastomeric member may extend radially inwards from the housing and the protrusion may extend radially outwards from the sleeve, and the elastomeric member may be compressed by the protrusion when the sleeve is rotated relative to the housing. The elastomeric member may be overmolded on the housing.

[0006] The piston may be configured to rotate and axially move relative to the housing and the sleeve, where the piston is configured to rotate with the sleeve relative to the housing. The piston may be connected to the sleeve via a pin received in a helical groove defined by the sleeve. The inlet may be configured to be in fluid communication with a reservoir of the medical injector, and the outlet may be configured to be in fluid communication with a cannula of the medical injector. Rotation of the piston in a first rotational direction may be configured to draw fluid into the chamber and move the sleeve from a first rotational position to a second rotational position, and rotation of the piston in a second rotational direction may be configured to pump fluid out of the chamber and move the sleeve from the second rotational position to the first rotational position, where the second rotational direction is opposite the first rotational direction.

[0007] The predetermined torque value may be between 5 and 15 millinewton meters. The predetermined torque value may be between 5 and 9 millinewton meters. The interlock may be configured to generate a maximum torque that is at least equal to the difference in torque between the maximum operating pressure and the minimum operating pressure of the metering pump while maintaining fluid communication between the chamber and the outlet. The torque profile provided by the interlock may be symmetric when the sleeve is moved between the first rotational position and the second rotational position. The maximum torque provided by the interlock may be less when the sleeve is moved from the first rotational position to the second rotational position than when the sleeve is moved from the second rotational position to the first rotational position.

Brief Description of the Drawings

[0008] The above and other features and advantages of the present disclosure, and the manner in which they are achieved, will become more apparent and the present disclosure itself will be better understood by reference to the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings.

[0009]

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DETAILED DESCRIPTION OF THE INVENTION

[0010] Corresponding reference characters indicate corresponding parts throughout the several views. The examples set forth herein are illustrative of exemplary embodiments of the present disclosure and are not to be construed in any way as limiting the scope of the present disclosure.

[0011] DETAILED DESCRIPTION OF THE INVENTION Spatial or directional terms such as "left", "right", "inner", "outer", "upper", "lower", etc. are not considered limiting as the present invention can envision various alternative directions.

[0012] All numbers used in this specification and the claims are to be understood as being modified in all instances by the term "about". "About" means within a range of plus or minus 10% of the recited value. As used in this specification and the claims, the singular forms of "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Terms such as "first", "second", etc. do not denote a particular order or time sequence, but rather different conditions, characteristics, or elements. "At least" means "greater than or equal to".

[0013] Referring to FIGS. 1-4, a conventional metering pump 10 for a medical injector or drug delivery device 12 is shown. The metering pump 10 is a rotary metering pump as described in International Publication No. WO2015 / 157174, which is hereby incorporated by reference in its entirety. The metering pump 10 is configured to be connected to a DC motor and a gearbox assembly (not shown) to rotate a sleeve 14 within a housing 16. A helical groove 18 is provided in the sleeve 14. A coupling pin 20 connected to a piston 22 translates along the helical groove 18 as the sleeve 14 rotates in one direction and then reverses, guiding the retraction and insertion of the piston 22 within the sleeve 14, respectively. The sleeve 14 has an end plug 24. Two seals 26 at the respective ends of the piston 22 within the sleeve 14 and the end plug 24 define a cavity or chamber 28 when the piston 22 is retracted following a suction stroke and thus is in a state where it can be discharged, as depicted in FIG. 2. The volume of the chamber 28 varies according to the degree of retraction of the piston 22. The volume of the chamber 28 is negligible or substantially zero when the piston 22 is fully inserted and the seals 26 are in substantial contact with each other after a discharge stroke, indicating that suction is ready, as depicted in FIG. 3.

[0014] Two ports 30, 32 are provided with respect to the housing 16, an inlet port 30 through which a medicament flows from a reservoir 58 (FIG. 4) of the pump 10 (FIG. 4), and a medicament sucked into the chamber 28 (for example, by retracting the piston 22 during a suction operation phase) is distributed from the chamber 28, for example, to a fluid path to a patient's cannula 50 (FIG. 4) by reinserting the piston 22 into the chamber 28, and an outlet port 32 for this purpose.

[0015] Referring to FIGS. 1 to 3, the sleeve 14 includes an opening (not shown) that aligns with the outlet port 32 or the inlet port 30 (i.e., depending on the degree of rotation of the sleeve 14 and thus the degree of translation of the piston 22, it enables the medicament in the chamber 28 to flow through the corresponding one of the ports 30, 32). A pump measuring device 34 (FIG. 4) such as a sleeve rotation limit switch may be provided, which has, for example, an interlock 36 and one or more detents 38 on the sleeve 14 or its end plug 24 that cooperate with the interlock 36. The interlock 36 can be attached to the housing 16 at both ends thereof. The detent 38 on the end face of the sleeve 14 is adjacent to the bump 40 of the interlock 36.

[0016] Under certain conditions such as back pressure, the friction between the piston 22 and the sleeve 14 may be sufficient to cause the sleeve 14 to rotate before the piston 22 and the coupling pin 20 reach either end of the helical groove 18, which may result in an incomplete amount of liquid being pumped per stroke. To prevent such a situation, the interlock 36 prevents the sleeve 14 from rotating until the torque exceeds a predetermined threshold, as shown in FIG. 2. This ensures that the piston 22 rotates sufficiently within the sleeve 14 until the coupling pin 20 reaches the end of the helical groove 18. When the coupling pin 20 reaches the end of the helical groove 18, further movement by the DC motor and the gearbox assembly or other type of pump and valve actuator 62 (FIG. 4) causes the torque of the sleeve 14 to increase beyond the threshold, causing the interlock 36 to flex and allowing the detent 38 to pass by the bump 40. When the rotation of the sleeve 14 is complete and its port or opening is aligned with the cannula or outlet port 32, the detent 38 moves beyond the bump 40 of the interlock 36, as shown in FIG. 3. Another sleeve feature 42 may be provided to engage an electrical switch (e.g., an end stop switch provided on a printed circuit board and arranged relative to the sleeve 14 and / or the end plug 24 to cooperate with the pump measuring device 34 as shown in FIG. 4).

[0017] Referring to FIG. 4, the medical injector 12 may include the metering pump 10 described above, an electronic device subsystem 44 for controlling the operation of components within a fluid subsystem 46 such as the pump 10, and an insertion mechanism 48 for deploying a cannula 50 for insertion into an injection site on a patient's skin. The power storage subsystem 52 can include a battery 54, for example, for supplying power to components within the electronic device and fluid subsystems 44, 46. The fluid subsystem 46 can include, for example, an optional fill port 56 for filling a reservoir 58 (e.g., a drug), although the medical injector can be optionally shipped from the manufacturer with its reservoir already filled. The fluid subsystem 46 also has a metering subsystem 60 that includes the metering pump 10 and a pump and valve actuator 62.

[0018] As described above, the metering pump 10 can have two ports 30, 32 and an associated valve subassembly that controls the timing of fluid entering and exiting the chamber 28 through the respective ports 30, 32. One of the ports is the inlet port 30, through which fluid such as a liquid medicament flows from the reservoir 58 into the metering pump 10 as a result of the pump suction stroke or draw stroke. The fluid exits the chamber 28 of the metering pump 10 through the outlet port 32 and flows towards the cannula 50 for administration as a result of the pump discharge or push stroke of the metering pump 10. The pump and valve actuator 62 can be a DC motor and gearbox assembly or other pump drive mechanism for controlling the plunger 22 or piston, and other associated pump components such as the sleeve 14 that may rotate relative to the translational movement of the piston 22. The microcontroller 64 can comprise an integrated or separate memory device having, for example, computer software instructions for actuating rotation of the sleeve 14 in a selected direction, translational or axial movement of the piston 22 within the sleeve 14 for the suction or discharge stroke, and optionally, co-rotation of the sleeve 14 and piston 22 during valve state changes as described in the above WO2015 / 157174. The metering pump 10 and the interlock 36 may be the same as the metering pump and interlock shown and described in International Publication No. WO2019 / 156848, which is hereby incorporated by reference in its entirety.

[0019] The interlock 36 of the metering pump 10 shown in FIGS. 1-3 is formed separately from the housing 16. In particular, the interlock 36 is formed from sheet metal and attached to the housing 16. Due to manufacturing tolerances and other variability, the performance of the interlock 36 may not be consistent between the suction and discharge operations and may also not be consistent between devices, resulting in different force profiles or patterns between devices that make it more difficult to detect occlusion. Also, forming the interlock 36 separately requires the manufacture of separate parts and subsequent assembly steps.

[0020] Referring to FIGS. 5 - 8, an interlock member 70 for a metering pump 10 according to one aspect or embodiment of the present invention is shown. In one aspect or embodiment, the interlock member 70 replaces the interlock 36 of the metering pump 10 of FIGS. 1 - 4, and the metering pump 10 otherwise functions as described above.

[0021] In one aspect or embodiment, the metering pump 10 includes a housing 16, a sleeve 14 at least partially received within the housing 16, and a piston 22 at least partially received within the sleeve 14, with the piston 22 and the sleeve 14 defining a chamber 28. As described above, the piston 22 has a first position where the chamber 28 has a first volume and a second position where the chamber 28 has a second volume, and the first volume is larger than the second volume. The sleeve 14 has a first rotational position where the inlet port 30 is in fluid communication with the chamber 28, a second rotational position where the outlet port 32 is in fluid communication with the chamber 28, and a third rotational position where the inlet port 30 and the outlet port 32 are isolated from the chamber 28. The metering pump 10 also includes an interlock 70 having an elastomeric member 72 positioned on one of the sleeve 14 and the housing 16 and a protrusion 74 positioned on the other of the sleeve 14 and the housing 16. The engagement between the elastomeric member 72 and the protrusion 74 is configured to limit movement of the sleeve 14 until the sleeve 14 overcomes a predetermined torque value. Thus, the interlock 70 is configured such that when the piston 22 rotates between the first rotational position and the second rotational position, its linear motion is completed sufficiently. In other words, the predetermined torque value is high enough so as not to prevent the metering pump 10 from functioning or low enough so that the metering pump 10 does not rotate prematurely between the first rotational position and the second rotational position before the piston 22 completes its linear motion.

[0022] Referring to FIGS. 7 and 8, in one aspect or embodiment, the elastomeric member 72 is positioned on the housing 16 and the protrusion 74 is positioned on the sleeve 14. The elastomeric member 72 is elastically deformed by the protrusion 74 when the sleeve 14 is rotated relative to the housing 16. In one aspect or embodiment, the protrusion 74 and the elastomeric member 72 form a cam interference feature. The elastomeric member 72 extends radially inwardly from the housing 16 and the protrusion 74 extends radially outwardly from the sleeve 14, and when the sleeve 14 is rotated relative to the housing 16, the elastomeric member 72 is compressed by the protrusion 74. When the protrusion 74 rotates past the elastomeric member 72, the elastomeric member 72 is disengaged from the protrusion 74. In one aspect or embodiment, the elastomeric member 72 is overmolded on the housing 16, but the elastomeric member 72 may be formed by other suitable methods and arrangements. The elastomeric member 72 may be formed of the same material as a housing seal (not shown) formed between the sleeve 14 and the housing 16. The elastomeric member 72 may be spaced from the housing seal to allow deformation of the elastomeric member 72 without compromising the seal between the housing 16 and the sleeve 14.

[0023] In one aspect or embodiment, the predetermined torque value is 5 to 15 millinewton meters. In one aspect or embodiment, the predetermined torque value is 5 to 9 millinewton meters.

[0024] In one aspect or embodiment, the interlock 70 is configured to generate a maximum torque at least equal to the torque difference between the maximum operating pressure and the minimum operating pressure of the metering pump 10 while maintaining fluid communication between the chamber 28 and the outlet 32. The maximum torque may be determined by the shape of the elastomeric member 72, the shape of the protrusions 74, and / or the elastic and hyperelastic material properties of the elastomeric member 72. In some aspects or embodiments, the torque profile provided by the interlock 70 may be symmetric when the sleeve 14 moves between the first rotational position and the second rotational position. In some aspects or embodiments, the maximum torque provided by the interlock 70 is less when the sleeve 14 moves from the second rotational position to the first rotational position than when the sleeve 14 moves from the first rotational position to the first rotational position.

[0025] Referring again to FIGS. 5 - 8, as described above, the piston 22 is configured to rotate and move axially relative to the housing 16 and the sleeve 14, and the piston 22 is configured to rotate with the sleeve 14 relative to the housing 16. The piston 22 is connected to the sleeve 14 via a pin 20 received within the helical groove 18 defined by the sleeve 14. The inlet 30 is configured to be in fluid communication with the reservoir 58 of the medical injector 12, and the outlet 32 is configured to be in fluid communication with the cannula 50 of the medical injector 12. As described above, rotation of the piston 22 in the first rotational direction is configured to draw fluid out of the chamber 28 and move the sleeve 14 from the first rotational position to the second rotational position, and rotation of the piston 22 in the second rotational direction is configured to pump fluid out of the chamber 28 and move the sleeve 14 from the second rotational position to the first rotational position. The second rotational direction is opposite to the first rotational direction.

[0026] The interlocks 70 of FIGS. 5-8 are configured to have a lower cost for manufacturing, fewer required parts, fewer assembly steps, improved tolerance control, and improved reliability of the interlocks 70 compared to the interlock 35. Also, the interlocks 70 are quieter during operation of the metering pump 10 due to the elastomeric member 72 compared to the interlock 35.

[0027] The present invention has been described in detail for purposes of illustration based on what is presently considered to be the most practical and preferred embodiments, but such details are for that purpose only and the present invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover modifications and equivalent arrangements within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any one embodiment can be combined with one or more features of any other embodiment.

Claims

1. A metering pump for a medical infusion device comprising a reservoir and a cannula, wherein the metering pump is housing, A sleeve, at least partially received within the housing, A piston at least partially received within the sleeve, wherein the piston and the sleeve define a chamber, the piston having a first position in which the chamber has a first volume and a second position in which the chamber has a second volume, the first volume being greater than the second volume, and the sleeve having a first rotational position in which the inlet is in fluid communication with the chamber, a second rotational position in which the outlet is in fluid communication with the chamber, and a third rotational position in which the inlet and the outlet are isolated from the chamber, and An interlock comprising an elastomer member positioned on one of the sleeve and the housing, and a projection positioned on the other of the sleeve and the housing, wherein the engagement between the elastomer member and the projection is configured to restrict the movement of the sleeve until the sleeve overcomes a predetermined torque value, A metering pump equipped with a metering pump.

2. The metering pump according to claim 1, wherein the elastomer member is positioned on the housing and the projection is positioned on the sleeve.

3. The metering pump according to claim 2, wherein the elastomer member is elastically deformed by the projection when the sleeve is rotated relative to the housing.

4. The metering pump according to claim 3, wherein the elastomer member extends radially inward from the housing, the projection extends radially outward from the sleeve, and the elastomer member is compressed by the projection when the sleeve is rotated relative to the housing.

5. The metering pump according to claim 2, wherein the elastomer member is overmolded onto the housing.

6. The metering pump according to claim 1, wherein the piston is configured to rotate and move axially relative to the housing and the sleeve, and the piston is configured to rotate together with the sleeve relative to the housing.

7. The metering pump according to claim 6, wherein the piston is connected to the sleeve via a pin received in a helical groove defined by the sleeve.

8. The metering pump according to claim 7, wherein the inlet is configured to communicate fluidly with the reservoir of the medical injector, and the outlet is configured to communicate fluidly with the cannula of the medical injector.

9. The metering pump according to claim 8, wherein the rotation of the piston in a first rotational direction is configured to draw fluid from the chamber and move the sleeve from the first rotational position to the second rotational position, and the rotation of the piston in a second rotational direction is configured to pump fluid from the chamber and move the sleeve from the second rotational position to the first rotational position, and the second rotational direction is opposite to the first rotational direction.

10. The metering pump according to claim 1, wherein the predetermined torque value is 5 to 15 millinewton meters.

11. The metering pump according to claim 1, wherein the predetermined torque value is 5 to 9 millinewton meters.

12. The metering pump according to claim 1, wherein the interlock is configured to generate a maximum torque at least equal to the torque difference between the maximum and minimum operating pressures of the metering pump, while maintaining fluid communication between the chamber and the outlet.

13. The metering pump according to claim 1, wherein the torque profile provided by the interlock is symmetrical as the sleeve moves between the first and second rotational positions.

14. The metering pump according to claim 1, wherein the maximum torque provided by the interlock is smaller when the sleeve moves from the first rotation position to the second rotation position than when the sleeve moves from the second rotation position to the first rotation position.

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