Interlock for Metering Pump of Medical Injector

Abstract

In the medical injector metering pump interlock, a metering pump for a medical injector includes a housing, a sleeve at least partially contained within the housing, a piston at least partially contained within the sleeve, the piston and sleeve defining a chamber, and an interlock member. 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 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 outlet are isolated from the chamber. The interlock member is configured to limit movement of the sleeve until the sleeve exceeds a predetermined torque value, and the interlock member is integrally formed with a portion of the housing.

Description

[Technical field]

[0001] This application claims priority to U.S. Provisional Application No. 63 / 288,973, entitled "INTERLOCK FOR MEDICAL INJECTOR METERING PUMP," filed December 13, 2021, the entire disclosure of which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to an interlock for a medical injector metering pump. [Background technology]

[0003] Wearable medical devices, such as auto-injectors, have the advantage of providing treatment to patients at locations remote from clinical facilities and / or while worn individually under the patient's clothing. The wearable medical device can be applied to the patient's skin and can be configured to automatically administer a dose of a pharmaceutical composition within a predetermined period of time, such as after a delay of 27 hours, after application of the wearable medical device to the patient's skin. After the device administers the pharmaceutical composition to the patient, the patient can subsequently 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 in the housing, and a piston at least partially received in the sleeve, the piston and sleeve defining 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 is greater than the second volume. The sleeve has 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. The metering pump further includes an interlock member configured to limit movement of the sleeve until the sleeve exceeds a predetermined torque value, the interlock member being integrally formed with a portion of the housing.

[0005] The piston may be configured to rotate and move axially relative to the housing and sleeve, the piston configured to rotate with the sleeve relative to the housing. The piston may be connected to the sleeve via a pin housed 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 aspirate fluid in the chamber and move the sleeve from the first rotational position to a second rotational position, and rotation of the piston in a second rotational direction may be configured to pump fluid in the chamber and move the sleeve from the second rotational position to the first rotational position, with the second rotational direction being opposite the first rotational direction.

[0006] The sleeve may include a detent and the interlocking member may include a protrusion, the detent configured to deflect the protrusion and rotate past the protrusion when the sleeve exceeds a predetermined torque value. The interlocking member may include a first arm extending from the housing and a second arm extending from the housing, the protrusion disposed between the first arm and the second arm. The first and second arms may be configured to permit movement of the protrusion between a deflected position and an undeflected position, the first and second arms biasing the protrusion toward the undeflected position. The first and second arms may each include a recess through which the first and second arms extend from the housing. The first and second arms may each include a curved portion through which the first and second arms extend from the protrusion. The first and second arms may each be L-shaped. The interlocking member may include a living hinge.

[0007] The predetermined torque value may be 5 to 15 millinewton meters.The predetermined torque value may be 5 to 9 millinewton meters. [Brief description of the drawings]

[0008] The above and other features and advantages of the present disclosure, as well as the manner in which they are accomplished, will become more apparent, and the disclosure itself will be better understood, by reference to the following description of embodiments of the disclosure taken in conjunction with the accompanying drawings. [Figure 1] FIG. 1 is a perspective view of a conventional interlock and metering pump assembly. [Diagram 2] FIG. 2 is a perspective view of the interlock and metering pump assembly of FIG. 1 showing a pre-dispense stage of operation. [Diagram 3] 3 is a perspective view of the interlock and metering pump assembly of FIG. 1 showing the pre-aspiration stage of operation. [Figure 4] FIG. 4 is a schematic diagram of a conventional medical injector. [Diagram 5]FIG. 5 is a perspective view of an interlock and metering pump assembly according to one aspect or embodiment of the present application showing the interlock in an unbiased position. [Figure 6] FIG. 6 is a perspective view of an interlock and metering pump assembly according to one aspect or embodiment of the present application showing a deflected position of the interlock.

[0009] Corresponding reference characters indicate corresponding parts throughout the several views. The illustrations presented herein illustrate exemplary embodiments of the present disclosure, and such illustrations are not to be construed as limiting the scope of the present disclosure in any way. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Spatial or directional terms such as "left," "right," "inner," "outer," "above," "below," etc. should not be considered limiting as the present invention may contemplate various alternative orientations.

[0011] All numbers used in the specification and claims should be understood as modified in all instances by the term "about." By "about" is meant a range of plus or minus ten percent of the stated value. As used in the specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. The terms "first," "second," etc. are not intended to refer to any particular order or chronology, but instead refer to different conditions, characteristics, or elements. "At least" means "greater than or equal to."

[0012] With reference to Figures 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 incorporated herein by reference in its entirety. The metering pump 10 is configured to be connected to a DC motor and gearbox assembly (not shown) to rotate a sleeve 14 within a housing 16. The sleeve 14 is provided with a helical groove 18. A coupling pin 20 connected to a piston 22 translates along the helical groove 18 to guide the retraction and insertion of the piston 22 within the sleeve 14 as the sleeve 14 rotates in one direction and then the opposite direction, respectively. The sleeve 14 has an end plug 24. The piston 22 inside the sleeve 14 and two seals 26 on each end of the end plug 24 define a cavity or chamber 28 when the piston 22 retracts, following the aspiration stroke and thus ready to dispense, as shown in Figure 2. Thus, the volume of chamber 28 varies with the degree of retraction of piston 22. As shown in Figure 3, when piston 22 is fully inserted and seals 26 are substantially in contact with each other following the dosing stroke and thus ready to aspirate, the volume of chamber 28 is negligible, or essentially zero.

[0013] Two ports 30, 32 are provided on the housing 16, including an inlet port 30 through which drug can flow from a reservoir 58 (FIG. 4) of the pump 10 (FIG. 4), and an outlet port 32 through which drug drawn into the chamber 28 (e.g., by retracting the piston 22 during the suction phase) can be dispensed from the chamber 28 into a fluid pathway to the patient's cannula 50 (FIG. 4), for example, by reinserting the piston 22 into the chamber 28.

[0014] 1-3, the sleeve 14 includes openings (not shown) that align with the outlet port 32 or the inlet port 30 (i.e., allowing drug in the chamber 28 to flow through the corresponding port 30, 32 depending on the degree of rotation of the sleeve 14, and therefore the degree of translation of the piston 22). For example, a pump metering device 34, such as a sleeve rotation limit switch (FIG. 4), can be provided having 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 each end thereof. The detents 38 on the end faces of the sleeve 14 are adjacent to bumps 40 on the interlock 36.

[0015] Under certain conditions, such as back pressure, friction between the piston 22 and sleeve 14 may be sufficient to rotate the sleeve 14 before the piston 22 and coupling pin 20 reach either end of the helical groove 18, which may result in an incomplete amount of liquid being pumped with each stroke. To prevent this 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 completely within the sleeve 14 until the coupling pin 20 reaches the end of the helical groove 18. Once the coupling pin 20 hits the end of the helical groove 18, further movement by a DC motor and gearbox assembly, or other type of pump and valve actuator 62 (FIG. 4), increases the torque on the sleeve 14 beyond the threshold, flexing the interlock 36 and allowing the detent 38 to pass the bump 40. When rotation of sleeve 14 is complete, detent 38 moves over bump 40 in interlock 36, as shown in Figure 3, so that its port or opening faces cannula or exit port 32. Another sleeve feature 42 may be provided to engage an electrical switch, such as an end stop switch provided on a printed circuit board and positioned relative to sleeve 14 and / or end plug 24 to cooperate with pump measurement device 34, as shown in Figure 4.

[0016] 4, the medical injector 12 may include the metering pump 10, an electronic subsystem 44 for controlling the operation of components in 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, as described above. The power storage subsystem 52 may include, for example, a battery 54 for powering the components in the electronic subsystem 44 and the fluid subsystem 46. The fluid subsystem 46 may include, for example, an optional fill port 56 for filling a reservoir 58 (e.g., with a drug), although the medical injector may optionally be shipped from the manufacturer with its reservoir already filled. The fluid subsystem 46 also has a metering subsystem 60, including the metering pump 10 and a pump and valve actuator 62.

[0017] As mentioned above, the metering pump 10 may have two ports 30, 32 and associated valve subassemblies that control when fluid enters and leaves 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 drug, flows from a reservoir 58 into the metering pump 10 as a result of a pump intake or pull stroke. The fluid leaves 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 a pump exhaust or push stroke of the metering pump 10. The pump and valve actuator 62 may 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, which may rotate relative to the translational motion of the piston 22. The microcontroller 64 may include an integrated or separate memory device having computer software instructions for, for example, rotating the sleeve 14 in a selected direction, translating or axially moving the piston 22 within the sleeve 14 for an aspiration or dosing stroke, and, optionally, rotating the sleeve 14 and piston 22 together during valve state changes as described in the above referenced WO2015 / 157174. The metering pump 10 and interlock 36 may be the same as the metering pump and interlock shown and described in International Publication No. WO2019 / 156848, which is incorporated herein by reference in its entirety.

[0018] The interlock 36 of the metering pump 10 shown in Figures 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 be inconsistent between suction and expulsion motions and also from device to device, which may result in different force profiles or patterns between devices making occlusions more difficult to detect. Forming the interlock 36 separately also requires the manufacture of separate parts and subsequent assembly steps.

[0019] 5 and 6, an interlock member 70 is shown for the metering pump 10 according to one aspect or embodiment of the present application. In one aspect or embodiment, the interlock member 70 replaces the interlock 36 of the metering pump 10 of FIGS. 1-4 with the metering pump 10 otherwise unmodified and performing as described above.

[0020] In one aspect or embodiment, the metering pump 10 includes a housing 16, a sleeve 14 at least partially housed within the housing 16, and a piston 22 at least partially housed within the sleeve 14, the piston 22 and the sleeve 14 defining a chamber 28. As described above, the piston 22 has a first position in which the chamber 28 has a first volume and a second position in which the chamber 28 has a second volume, the first volume being greater than the second volume. The sleeve 14 has a first rotational position in which the inlet port 30 is in fluid communication with the chamber 28, a second rotational position in which the outlet port 32 is in fluid communication with the chamber 28, and a third rotational position in which the inlet port 30 and the outlet port 32 are isolated from the chamber 28. The metering pump 10 also includes an interlock member 70 configured to limit movement of the sleeve 14 until the sleeve 14 exceeds a predetermined torque value, the interlock member 70 being integrally formed with a portion of the housing 16. In one aspect or embodiment, the interlocking member 70 is co-molded and molded from the same material as the housing 16. In one aspect or embodiment, the housing 16 and the interlocking member 70 are formed from plastic.

[0021] Rotation of the piston 22 in a first rotational direction is configured to aspirate fluid in the chamber 28 and move the sleeve 14 from the first rotational position to the second rotational position. Rotation of the piston 22 in the second rotational direction is configured to pump fluid in 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.

[0022] 5 and 6, the sleeve 14 includes a detent 38 and the interlock member 70 includes a protrusion 72 configured to deflect and rotate past the protrusion 72 when the sleeve 14 exceeds a predetermined torque value. More specifically, the piston 22 rotates within the sleeve 14 and moves axially to aspirate or pump fluid from the chamber 28, while the sleeve 14 rotates to control when the chamber 28 is in fluid communication with the inlet port 30 and the outlet port 32. The interlock member 70 prevents the sleeve 14 from rotating to change the valve state of the pump 10 until the coupling pin 20 reaches the end of the helical groove 18, allowing the pump and valve actuator 62 to apply a torque to the sleeve 14 via the pin 20 that is greater than the predetermined torque value. When the torque exceeds a predetermined torque value, the detent deflects and pushes past the projection 72 of the interlock member 70, thereby allowing the sleeve 14 to rotate and change the valve state of the metering pump 10.

[0023] The interlocking member 70 includes a first arm 74 extending from the housing 16 and a second arm 76 extending from the housing 16, with the projection 72 disposed between the first arm 74 and the second arm 76. The first and second arms 74, 76 are configured to permit movement of the projection 72 between a deflected position (FIG. 6) and an undeflected position (FIG. 5). The first and second arms 74, 76 bias the projection 72 toward the undeflected position. The first and second arms 74, 76 each include a recess 78 through which the first and second arms 74, 76 extend from the housing 16 and a curved portion 80 through which the first and second arms 74, 76 extend from the projection 72. The recess 78 and the curved portion 80 are configured to permit flexion of the interlocking member 70 when the projection 72 engages the detent 38. The first and second arms 74, 76 may each be L-shaped, although other suitable shapes and arrangements may be utilized. In one aspect or embodiment, the first interlocking member 70 includes a living hinge or a living spring.

[0024] In one aspect or embodiment, the predetermined torque value for overcoming the interlock member 70 is between 5 and 15 millinewton meters. In a further aspect or embodiment, the predetermined torque value for overcoming the interlock member 70 is between 5 and 9 millinewton meters.

[0025] The interlock member 70 of Figures 5 and 6 is configured to reduce performance variation of the interlock member 70 from device to device and between the aspiration and dispense strokes, thereby improving reliability of occlusion detection. The interlock member 70 of Figures 5 and 6 reduces the part count and assembly complexity of the metering pump 10. Additionally, the interlock member 70 is configured to reduce operational noise of the interlock member 70 as compared to the interlock 36 of Figures 1-3.

[0026] While the present invention has been described in detail for purposes of illustration based on what are currently considered to be the most practical and preferred embodiments or aspects, it is to be understood that such detail is for this purpose only, and that the present invention is not limited to the disclosed embodiments or aspects, but on the contrary, 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 embodiment may be combined with one or more features of any other embodiment.

Claims

1. A metering pump, which is a pump for a medical injector having a reservoir and a cannula, Housing and a sleeve at least partially contained within the housing; a piston at least partially contained within the sleeve, the piston and the sleeve defining 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, the sleeve having 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 outlet are isolated from the chamber; an interlocking member configured to limit movement of the sleeve until the sleeve exceeds a predetermined torque value, the interlocking member being integrally formed with a portion of the housing; and A medical injector pump, including:

2. The pump of 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 with the sleeve relative to the housing.

3. The pump of claim 2 , wherein the piston is connected to the sleeve via a pin received within a helical groove defined by the sleeve.

4. 4. The pump of claim 3, wherein the inlet is configured to be in fluid communication with the reservoir of the medical injector and the outlet is configured to be in fluid communication with the cannula of the medical injector.

5. 5. The pump of claim 4, wherein rotation of the piston in a first rotational direction is configured to aspirate fluid in the chamber and move the sleeve from the first rotational position to the second rotational position, and rotation of the piston in a second rotational direction is configured to pump fluid in the chamber and move the sleeve from the second rotational position to the first rotational position, the second rotational direction being opposite to the first rotational direction.

6. 2. The pump of claim 1, wherein the sleeve includes a detent and the interlock member includes a protrusion, the detent configured to deflect the protrusion and rotate past the protrusion when the sleeve exceeds the predetermined torque value.

7. 7. The pump of claim 6, wherein the interlock member includes a first arm extending from the housing and a second arm extending from the housing, the protrusion being disposed between the first arm and the second arm.

8. 8. The pump of claim 7, wherein the first and second arms are configured to allow movement of the protrusion between a deflected position and an undeflected position, and the first and second arms bias the protrusion toward the undeflected position.

9. The pump of claim 8 , wherein the first and second arms each include a recess through which the first and second arms extend from the housing.

10. The pump of claim 8 , wherein the first and second arms each include a curved portion where the first and second arms extend from the protrusion.

11. 8. The pump of claim 7, wherein the first and second arms are each L-shaped.

12. The pump of claim 1 , wherein the interlocking member comprises a living hinge.

13. 2. The pump of claim 1, wherein the predetermined torque value is between 5 and 15 millinewton meters.

14. 2. The pump of claim 1, wherein the predetermined torque value is between 5 and 9 millinewton meters.

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