Rotary metering pump for insulin patch

Abstract

A rotary pump (4000) for a fluid metering system is provided. The rotary pump reciprocates and is reversed by a signal from a limit switch (4506) biased by an actuator arm (4508) on a rotating sleeve (4500) of the pump system. The rotary pump (4000) includes a plunger (5210) and optional stopper (5206) formed from a two-shot molding process, and includes a seal (5214) overmolded onto a head (5212) of the plunger (5210) and a head (5208) of the optional stopper (5206).

Description

Technical Field

[0001] The invention according to the present disclosure relates to a metering system for use in a general, wearable drug infusion patch.

Background Art

[0002] Diabetes is a group of diseases characterized by elevated blood glucose levels due to defects in insulin production, insulin action, or both. Diabetes can lead to serious health complications and premature death, but there are well-known products available to diabetics to help control the disease and reduce the risk of complications.

[0003] Treatment options for diabetics include special diets, oral medications, and / or insulin therapy. The main goal of diabetes treatment is to control the patient's blood glucose levels to increase the chances of a life free of complications. However, achieving good diabetes management while balancing other life demands and circumstances is not always easy.

[0004] Currently, there are two main modes of daily insulin therapy for the treatment of type 1 diabetes. The first mode includes syringes and insulin pens, and the first mode generally requires punctures at each injection, three to four times per day. These devices are simple to use and relatively inexpensive. Another widely applied and effective method of treating diabetes to manage it is the use of an insulin pump. Insulin pumps can help users keep their individual blood glucose levels within the target range based on their individual needs by providing a continuous infusion of insulin at various rates to more faithfully reproduce the behavior of the pancreas. By using an insulin pump, users can tailor their individual insulin therapy to their individual lifestyle rather than adjusting their individual lifestyle to how insulin injections work for them.

[0005] However, conventional insulin pumps suffer from several drawbacks. For example, the lead screw and piston type metering systems used in common insulin pumps require a large height and a large installation area, and are often difficult for users to handle.

[0006] Also, conventional insulin pumps generally require a large number of components and moving parts, which increases the risk of mechanical failure.

[0007] Moreover, conventional insulin pumps generally have a tolerance loop that is too long for dosing accuracy, depending on too many factors that are sometimes difficult to verify. This can result in a loss of dosing accuracy.

[0008] In addition, conventional insulin pumps generally have a fluid path that is too complex. This can result in complex or inadequate priming and air removal.

[0009] Furthermore, conventional insulin pumps generally require a high-precision actuator, which increases the cost of conventional patch pumps.

[0010] Some insulin pumps also have a risk of creating a direct fluid path between the reservoir and the cannula in the insulin patch. This can result in an overdose for the user.

[0011] Conventional insulin pumps also generally require complex sensing methods. This can result in increased costs, reduced accuracy, and reduced reliability.

[0012] In addition, conventional insulin pumps generally have valves that are prone to leakage at elevated system backpressure. This can result in reduced accuracy and reliability.

[0013] In addition, conventional insulin pumps generally require a large working volume and a large system volume that is potentially exposed to high backpressure. This can result in reduced accuracy and reliability.

[0014] In addition, conventional insulin patches generally have a low-efficiency motor that requires a large battery, thereby increasing the size of the insulin patch.

[0015] Therefore, there is a need for a metering system with reduced height and installation area compared to conventional lead screw and piston-type metering systems to increase comfort for the user.

[0016] In addition, there is a need for a metering system with a reduced number of components and moving parts compared to conventional insulin pumps to increase the mechanical safety of the insulin patch.

[0017] In addition, there is a need for a metering system with a short tolerance loop for the dosing accuracy it depends on compared to conventional metering pumps, thereby increasing the dosing accuracy.

[0018] In addition, there is a need for a metering system with a simpler fluid path compared to conventional metering systems, thereby simplifying priming and air removal.

[0019] In addition, there is a need for a metering system that uses a low-precision actuator compared to conventional metering systems, thereby reducing the cost of the insulin patch.

[0020] In addition, there is a need for a metering system that has no direct fluid path between the reservoir and the cannula compared to conventional metering systems, thereby providing greater safety to the user from over-dosing.

[0021] In addition, compared with conventional metering systems, there is a need for a metering system having a simple detection method, thereby reducing costs and increasing the accuracy and reliability of insulin patches.

[0022] In addition, compared with conventional metering systems, there is a need for a metering system having a valve that is robust with respect to leakage at elevated system backpressure, thereby increasing accuracy and the reliability of insulin patches.

[0023] In addition, compared with conventional metering systems, there is a need for a metering system having a small working volume and a low system volume that is potentially exposed to high backpressure, thereby increasing accuracy and the reliability of insulin patches.

[0024] In addition, compared with conventional metering systems, there is a need for a metering system that requires a highly efficient motor with a small battery, thereby reducing the size of the insulin patch. SUMMARY OF THE INVENTION

[0025] One aspect of an exemplary embodiment of the invention according to the present disclosure is to substantially address the above and other concerns and provide a small and reliable metering system.

[0026] One aspect of an exemplary embodiment of the invention according to the present disclosure is to provide a metering system with reduced height and installation area compared to conventional lead screw and piston type metering systems, thereby increasing comfort for the user.

[0027] Another aspect of an exemplary embodiment of the invention according to the present disclosure is to provide a metering system with a reduced number of components and moving parts compared to conventional insulin pumps in order to increase the mechanical safety of insulin patches.

[0028] Another aspect of an exemplary embodiment of the invention according to the present disclosure is to provide a metering system having a short tolerance loop for dosing accuracy that depends on fewer factors compared to a conventional metering pump, thereby increasing dosing accuracy. For example, in an exemplary embodiment of the invention according to the present disclosure, the tolerance loop for dosing accuracy is short and depends only on two easily measurable dimensions, namely the diameter of the pump and the axial dimension of the helical slot.

[0029] Another aspect of an exemplary embodiment of the invention according to the present disclosure is to provide a metering system having a simple fluid path compared to a conventional metering system, thereby simplifying priming and air removal.

[0030] Another aspect of an exemplary embodiment of the invention according to the present disclosure is to provide a metering system that utilizes a low-precision actuator compared to a conventional metering system, thereby reducing the cost of the insulin patch. For example, in an exemplary embodiment of the invention according to the present disclosure, the mechanism can over-rotate at both ends of the stroke and still maintain dosing accuracy.

[0031] Another aspect of an exemplary embodiment of the invention according to the present disclosure is to provide a metering system that does not have a direct fluid path between the reservoir and the cannula compared to a conventional metering system, thereby protecting the user more safely against over-dosing.

[0032] Another aspect of an exemplary embodiment of the invention according to the present disclosure is to provide a metering system having a simple detection method compared to a conventional metering system, thereby reducing costs and increasing the accuracy and reliability of the insulin patch. For example, in an exemplary embodiment of the invention according to the present disclosure, the detection method is based on a contact switch.

[0033] Another aspect of an exemplary embodiment of the invention according to the present disclosure is to provide a metering system that allows the mechanical stroke of the pump to be a simple activation of the cannula insertion mechanism.

[0034] Another aspect of an exemplary embodiment of the invention according to the present disclosure is to provide a metering system having a valve that is robust with respect to leakage at elevated system backpressure compared to conventional metering systems, thereby increasing the accuracy and reliability of the insulin patch. For example, in an exemplary embodiment of the invention according to the present disclosure, the valve has no volume change when its state transitions.

[0035] Another aspect of an exemplary embodiment of the invention according to the present disclosure is to provide a metering system having a small working volume product and a low system volume exposed to potentially high backpressure compared to conventional metering systems, thereby increasing the accuracy and reliability of the insulin patch.

[0036] Another aspect of an exemplary embodiment of the invention according to the present disclosure is to provide a metering system that uses a high-efficiency motor with a small battery compared to conventional metering systems, thereby reducing the size of the insulin patch.

[0037] The foregoing and / or other aspects of the invention according to the present disclosure are achieved by providing a metering system for use in a wearable insulin injection patch. For example, in an exemplary embodiment of the invention according to the present disclosure, the metering system is part of a larger fluidics subsystem that includes a flexible reservoir for storing insulin and a cannula assembly for delivering insulin to subcutaneous tissue. The metering system withdraws a small amount of fluid from the reservoir and then pushes it down the cannula line and into the patient. The fluid dose is small relative to the reservoir volume, and many pump strokes are required to completely empty the reservoir.

[0038] Additional and / or other aspects and advantages of the invention according to the present disclosure will be described in the following description, or will be apparent from the description, or will be able to be known by the practice of the present invention. The invention according to the present disclosure may comprise a method or apparatus or system having one or more of the above aspects and / or one or more of mechanisms and combinations thereof. The invention according to the present disclosure may comprise one or more of the mechanisms and / or combinations of the above aspects, as described, for example, in the appended claims.

Brief Description of the Drawings

[0039] By reading the following detailed description in combination with the accompanying drawings, various objects, advantages, and novel mechanisms of exemplary embodiments of the present invention will be more easily understood.

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[0040] Throughout the drawings, like reference numerals should be understood to refer to like elements, mechanisms, and structures. **DETAILED DESCRIPTION OF THE INVENTION**

[0041] As will be appreciated by those skilled in the art, there are many ways to implement examples, improvements, and arrangements of the metering system in accordance with embodiments of the invention disclosed herein. While reference is made to the exemplary embodiments shown in the drawings and the following description, the embodiments disclosed herein do not cover all of the various alternative designs and embodiments encompassed by the disclosed invention, and those skilled in the art will readily understand that various changes can be made and various combinations can be made without departing from the present invention.

[0042] Without limitation, various people, including patients or healthcare professionals, can operate or use the exemplary embodiments of the invention according to the present disclosure. For the sake of brevity, hereinafter, the operator or user will be referred to as the "user".

[0043] In exemplary embodiments of the invention according to the present disclosure, various fluids can be used. For the sake of brevity, hereinafter, the liquid in the injection device will be referred to as "fluid".

[0044] Exemplary embodiments according to the invention of the present disclosure are depicted in FIGS. 1 - 30. In an exemplary embodiment according to the invention of the present disclosure, a metering system for use with a wearable insulin infusion patch is provided. For example, in an exemplary embodiment according to the invention of the present disclosure, the metering system is part of a larger fluidics subsystem that includes a flexible reservoir for storing insulin and a cannula assembly for delivering insulin to subcutaneous tissue. The metering system withdraws a small amount of fluid from the reservoir and then pushes it down the cannula line and into the patient. The fluid dose is small relative to the reservoir volume, and it takes many pump strokes to completely empty the reservoir.

[0045] Figure 1 shows the structure of a patch pump 100 according to an exemplary embodiment of the invention according to the present disclosure. The patch pump 100 includes a fluid engineering subsystem 120, an electronic device subsystem 140, and a power storage subsystem 160.

[0046] The fluid engineering subsystem 120 includes a filling port 122 that is in fluid communication with a reservoir 124. The reservoir 124 is adapted to receive fluid from a syringe through the filling port.

[0047] The fluid engineering subsystem 120 further includes a volume sensor 126 mechanically coupled to the reservoir 124. The volume sensor 126 is adapted to detect or determine the fluid volume of the reservoir.

[0048] The fluid engineering subsystem 120 further includes a metering subsystem 130, which includes an integrated pump and valve system 132 mechanically coupled to a pump and valve actuator 134. The integrated pump and valve system 132 is in fluid communication with the reservoir 124 of the fluid engineering subsystem 120 and is actuated by the pump and valve actuator 134.

[0049] The fluid engineering subsystem 120 further includes a cannula mechanism having a deployment actuator 128 mechanically coupled to a cannula 129. The deployment actuator 128 is adapted to insert the cannula 129 into a user. The cannula 129 is in fluid communication with the integrated pump and valve system 132 of the metering subsystem 130.

[0050] The fluid engineering subsystem 120 further includes an occlusion sensor 136 mechanically coupled to the fluid path between the cannula 129 and the integrated pump and valve system 132. The occlusion sensor 136 is adapted to detect or determine an occlusion in the path between the cannula 129 and the integrated pump and valve system 132.

[0051] The electronic device subsystem 140 includes a volume sensing electronic device 142 electrically coupled to the volume sensor 126 of the fluid engineering subsystem 120, a pump and valve controller 144 electrically coupled to the pump and valve actuator 134 of the metering subsystem 130, a blockage sensing electronic device 146 electrically coupled to the blockage sensor 136 of the fluid engineering subsystem 120, and an optional deployment electronic device 148 electrically coupled to the cannula 129 of the fluid engineering subsystem. The electronic device subsystem 140 further includes a microcontroller 149 electrically coupled to the volume sensing electronic device 142, the pump and valve controller 144, the blockage sensing electronic device 146, and the deployment electronic device 148.

[0052] The power storage subsystem 160 includes a battery 162 or any other optional power source known in the art. The battery 162 can be adapted to supply power to any component or electronic part of the patch pump 100.

[0053] FIG. 2 shows the layout of the fluid and metering system components of a patch pump 200 according to an exemplary embodiment of the invention according to the present disclosure. The patch pump 200 includes a metering subsystem 230, control electronics 240, a battery 260, a reservoir 222, a filling port 224, and a cannula mechanism 226. The elements of the patch pump 200 are substantially similar to the elements of the exemplary patch pump 100 referenced by like reference numerals and interact substantially in the same manner.

[0054] FIG. 3 is an exploded perspective view of a metering subsystem 300 of a patch pump according to an exemplary embodiment of the invention according to the present disclosure. The metering subsystem 300 includes a DC gear motor 302 mechanically coupled to a pump piston 304 disposed within a pump casing 306. The pump piston 304 is mechanically coupled to a pump housing 308 by a coupling pin 310. The metering subsystem 300 further includes a pump seal 312 between the pump piston 304 and the pump housing 308. The metering subsystem 300 further includes a port seal 314 on a seal carriage 316 disposed within a valve housing 318.

[0055] In an exemplary embodiment of the invention according to the present disclosure, the output shaft 320 of the DC gear motor can rotate 360 degrees in either direction. The pump piston 304 can rotate 360 degrees in either direction and can translate by about 0.050 inches. The pump housing 308 can rotate 180 degrees in either direction. The pump casing 306, the port seal 314, the seal carriage 316, and the valve housing 318 are preferably stationary.

[0056] The metering subsystem 300 includes a positive displacement pump having an integrated flow control valve and a mechanical actuator and drive system. The pump includes a piston 304 and a rotary actuated selection valve. The metering system draws an accurate volume of insulin from a flexible reservoir into a pump volume 320 formed between the piston 304 and the pump housing 308 (see FIG. 5), and then discharges this amount of insulin through a cannula into the subcutaneous tissue of the patient, administering insulin in small, individual doses. The pump stroke creates positive and negative pressure gradients within the fluid path to induce flow. The stroke and inner diameter of the pump volume determine the dosing accuracy and the nominal size. The fluid control valve actively reciprocates between the reservoir and the fluid ports of the cannula at both ends of the pump stroke, alternately closing and opening the ports to make the fluid flow unidirectional (from the reservoir to the patient) and ensure that there is no possibility of free flow between the reservoir and the patient.

[0057] FIG. 4 is an assembly view of the metering subsystem 300 according to an exemplary embodiment of the invention according to the present disclosure. Also shown are the coupling 322 between the motor and the piston, the coupling 324 between the piston and the pump housing, the reservoir port 326, and the cannula port 328.

[0058] FIG. 5 is a cross-sectional view of a metering subsystem 300 of an exemplary embodiment of the invention according to the present disclosure. As shown, a pump volume 320 is formed between a piston and a pump housing 308. The pump housing includes side ports 330 whose orientation alternates between a reservoir port 326 and a cannula port 328 when a motor 302 reciprocates the pump, as will be described in more detail below.

[0059] During operation, an exemplary cycle of a metering system according to the invention of the present disclosure includes four steps: 180-degree pump suction (counterclockwise) (when viewed from the pump towards the motor), 180-degree valve state change (counterclockwise), 180-degree pump discharge (clockwise), and 180-degree valve state change (clockwise). A complete cycle requires a full rotation (360 degrees) in each direction.

[0060] FIG. 6A is an isometric view and FIG. 6B is a cross-sectional view of the metering subsystem 300 in the starting position. In the starting position, the pump piston 302 is fully extended, the pump housing closes the cannula port flow path at the cannula port 328, the reservoir port 326 is open to the side port 330 of the pump housing 308, and the rotation limit sensor 332 is engaged. The pump housing 308 includes a helical groove 334 for receiving a coupling pin 310. The piston 304 is in sliding engagement with the pump housing 308 such that when the piston 304 rotates within the pump housing 308 (by the rotational force of the motor 302), the coupling pin 310 slides along the helical groove 334 to axially translate the piston 304 relative to the pump housing 308. In this embodiment, the helical groove 334 is formed in the pump housing 308 and provides 180 degrees of rotation for the coupling pin 310.

[0061] FIG. 7A is an isometric view and FIG. 7B is a cross-sectional view of the metering subsystem 300 during the intake stroke. The DC motor 302 rotates a pump piston 304 that is driven (rotated and translated) along the spiral groove 334 of the pump housing 308 via a coupling pin 310. The pump piston 304 translates towards the DC motor 302 and draws fluid into the increasing pump volume 320. During the intake stroke, the friction between the seal and the outer diameter of the pump housing 308 is preferably high enough so that the pump housing 308 does not rotate. The pump housing 308 is stationary while the pump volume 320 is expanding. The cannula port 328 is closed, while the reservoir port 326 is open to the fluid flowing into the expanding pump volume 320. There is a sliding engagement between the motor 302 and the pump piston 304.

[0062] FIG. 8A is an assembly view, FIG. 8B is a detailed view, and FIG. 8C is a cross-sectional view of the patch pump during a valve state change after an inhalation stroke. Torque is transmitted from the drive shaft of the motor 302 to the pump piston 304 and then to the pump housing 308 via the coupling pin 310. When the coupling pin 310 rotates to the end of the spiral groove 334, further rotation of the motor 302 causes the coupling pin 310 to rotate the pump housing 308 and the pump piston 304 integrally without relative axial translation. The side port 330 on the pump housing 308 rotates between the reservoir port 326 and the cannula port 328. The surface tension of the side port 330 of the pump housing 308 holds the fluid within the pump volume 320. The pump housing side port 330 transitions from alignment with the reservoir port 326 to alignment with the cannula port 328 over the next 180-degree rotation of the motor 302. During this time, both the cannula port 328 and the reservoir port 326 are closed. The coupling pin 310 is at the end of the spiral groove 334 and transmits torque to the pump housing 308. The coupling pin 310 locks the pump piston 304 and the pump housing 308 together, suppressing relative axial movement between the two components. Therefore, the pump piston 304 and the pump housing 308 rotate integrally and do not translate relative to each other. The pump housing 308 rotates, the pump volume 320 is fixed, and the pump piston 304 rotates. The seal 314, the seal carriage, and the valve housing 318 are preferably stationary.

[0063] FIG. 9A is an assembly view, and FIG. 9B is a cross-sectional view of the metering subsystem at the intake transition stop position ready for injection. As shown, the side port 330 of the pump housing 308 is aligned with the cannula port 328, the pump volume 320 is expanded, and the reservoir port 326 is closed. The rotational limit sensor 332 is engaged by a mechanism on the rotating pump housing 308. The motor 302, the pump piston 304, and the pump housing 308 are stationary.

[0064] FIG. 10A is an assembly view, and FIG. 10B is a cross-sectional view of the metering subsystem 300 during the discharge stroke. At the end of the intake stroke, the pump housing 308 engages a limit switch 332, which causes the direction of the DC motor 302 to switch. Thus, the motor 302 rotates the piston 304 and drives the coupling pin 310 under the helical groove 334 of the pump housing 308 to axially translate the piston 304. The pump piston 304 axially translates away from the DC motor 302 and extrudes fluid from the pump volume 320 through the cannula port 328 into the cannula. During the discharge stroke, the friction between the seal 314 and the outer diameter of the pump housing 308 is preferably high enough to ensure that the pump housing 308 does not rotate. The cannula port 328 is open to the fluid flowing out of the collapsed pump volume 320. The reservoir port 326 is closed. The pump housing 308 is stationary while the pump volume 320 is collapsing, and the pump piston 304 rotates and translates in a helical motion. The motor is slidably connected to the piston 304 and corresponds to the translational movement of the piston as it rotates within the helical groove 334.

[0065] Figure 11A is an assembly diagram, Figure 11B is a detailed diagram, and Figure 11C is a cross-sectional view of the metering subsystem 300 during valve state change after the discharge stroke. Torque is transmitted from the drive shaft of the motor 302 to the pump piston 304, and then to the pump housing 308 via the coupling pin 310. The pump housing 308 and the pump piston 304 rotate together without relative axial movement. The side port 330 on the pump housing 308 rotates between the reservoir port 326 and the cannula port 328, and both are closed during rotation. The surface tension of the side port 330 of the pump housing 308 holds the fluid within the pump volume 320. The coupling pin 310 locks the pump piston 304 and the pump housing 308 together to suppress relative axial movement between the two components. Therefore, the pump piston 304 and the pump housing 308 rotate together and do not translate relative to each other. While the pump housing 308 rotates, the pump volume 320 is fixed. The seal 314, the seal carriage, and the valve housing 318 are preferably stationary.

[0066] Figure 12A is an assembly diagram, and Figure 12B is a cross-sectional view of the metering subsystem 300 after the pump cycle is completed. The pump mechanism (piston 304) is fully extended to complete the pump cycle. The rotational limit sensor 332 is engaged to reverse the rotation of the motor 302 and restart the pump cycle. The cannula port 328 is closed, while the reservoir port 326 is open to the flow path from the reservoir.

[0067] In the foregoing exemplary embodiments, the pump piston performs both rotation and translation, the pump housing rotates, and the valve housing is stationary. However, in other embodiments, it should be understood that the system can be configured such that the pump piston rotates, the pump housing performs both rotation and translation, the valve housing translates, or any other combination of movements that increase and decrease the pump volume, and the ports communicating with the pump volume transition from alignment with the reservoir port to alignment with the cannula port.

[0068] In the foregoing exemplary embodiments, the pump stroke and the valve state change are constituted by a 180-degree rotation operation from the motor. However, it should be understood that any suitable angle can be selected for segments of the pump cycle.

[0069] In the foregoing exemplary embodiments, there is an air block between the cannula port and the reservoir port during the valve state change. However, it should be understood that in other embodiments, a seal may be configured or additional seals may be added to eliminate the air block during the state change and to seal the pump and valve system.

[0070] In the foregoing exemplary embodiments, a DC gear motor is used to drive the pump and the valve. However, in other embodiments, any suitable drive mechanism may be provided to drive the pump and the valve. For example, a solenoid, a nitinol wire, a voice coil actuator, a piezo motor, a wax motor, and / or any other type of motor known in the art can be used to drive the pump.

[0071] In the foregoing exemplary embodiments, the pump uses a full discharge stroke. However, it should be understood that in other embodiments, a system with an increasingly increasing discharge stroke may be used to administer finer dosages.

[0072] In the foregoing exemplary embodiments, the pump uses an on / off limit switch to determine the state of the system at the limit of rotational transition. However, it should be understood that in other embodiments, other sensors having the ability to determine intermediate states, such as an encoder wheel or an optical sensor, may be used to improve the resolution of the sensing method.

[0073] It should be understood that the inner diameter of the pump may be adjusted to vary the nominal output per cycle.

[0074] In the foregoing exemplary embodiments, the pump uses an elastomeric O-ring seal. However, it should be understood that other arrangements may also be used. For example, the fluid seal may be directly molded onto the seal carriage, other elastomeric seals such as quad rings may be used, or other seal materials such as Teflon or polyethylene lip seals may be used.

[0075] In an alternative embodiment of the present invention, the motion of the pump can be used to initiate or activate the deployment of the cannula.

[0076] In the foregoing example, the system advantageously uses bidirectional operation. The rotation of the motor is reversed to alternate between the suction stroke and the discharge stroke. This provides a safety mechanism to prevent runaway in the event that the motor malfunctions. For the pump to continue supplying the drug from the reservoir, the motor must reciprocate in sequence. However, it should be understood that in other embodiments, the metering system is designed to use a unidirectional actuator.

[0077] In the foregoing exemplary embodiments, the system uses a pouch reservoir having two flexible walls. However, in other embodiments, the reservoir can be formed in any suitable manner, including having one rigid wall and one flexible wall.

[0078] FIG. 13 is an exploded perspective view of a metering subsystem 1300 for a patch pump according to another exemplary embodiment of the invention according to the present disclosure. The metering subsystem 1300 includes a motor and gearbox assembly 1302 and a pump assembly 1304.

[0079] Figure 14 is an exploded perspective view of pump assembly 1304. Pump assembly 1304 includes piston 1306 mechanically coupled to sleeve 1308 via coupling pin 1310 within pump manifold 1312. Pump assembly 1304 further includes port seal 1314, plug 1316, sleeve rotation limit switch 1318, and output gear rotation limit switch 1320.

[0080] Piston 1306 can rotate a total of 196 degrees in either direction and translate approximately 0.038 inches. Sleeve 1308 and plug 1316 rotate 56 degrees in either direction together (as a pair). Pump manifold 1312 and port seal 1314 are stationary.

[0081] Figure 15 is an exploded perspective view of motor and gearbox assembly 1302. Motor and gearbox assembly 1302 includes gearbox cover 1322, compound gear 1324, output gear 1326, shaft portion 1328, gearbox base 1330, motor pinion gear 1332, and DC motor 1334.

[0082] Figures 16A - 16D illustrate the assembly and operation of piston 1306, sleeve 1308, and coupling pin 1310. Figure 16A illustrates piston 1306 including a press - fit hole 1338 for receiving coupling pin 1310 and a piston seal 1340 that hermetically seals the piston within sleeve 1308. Sleeve 1308 includes a helical groove 1342. Piston 1306 is press - fit axially into sleeve 1308, and then coupling pin 1310 is press - fit through helical groove 1342 into hole 1338. This provides the same operation as the embodiments described above, where rotation of piston 1306 causes axial translation of piston 1306 relative to sleeve 1308 due to the interaction of coupling pin 1310 and helical groove 1342. Figure 16B illustrates the assembled piston 1306, sleeve 1308, and coupling pin 1310, together showing coupling pin 1310 at the lower end of helical groove 1342. Figure 16C illustrates the axial stroke length 1344 of piston 1306 relative to sleeve 1308 as a result of helical groove 1342. Figure 16D illustrates a tapered surface 1346, preferably provided at the end of helical groove 1342, for centering coupling pin 1310 within groove 1342.

[0083] Figure 17A illustrates the assembly of the plug 1316 and the sleeve 1308. As shown, the plug 1316 includes a key 1346 and a seal 1348. The seal 1348 provides an interference fit for the plug within the sleeve 1308. The sleeve 1308 is provided with a recess 1350 adapted to receive the key 1346. The key 1346 locks the plug 1316 in rotational engagement with the sleeve 1308. The plug 1316 is pressed against the end face of the (advanced) piston 1306 during assembly to minimize air within the pump chamber. The friction between the seal 1348 and the inner surface of the sleeve 1308 axially retains the plug 1316. With an appropriate selection of seal diameter, squeeze, and material, the plug 1316 can also function as a closure or overpressure sensor. A pump pressure greater than the threshold causes the plug 1616 to transition axially and disengage from engagement with the sleeve rotation limit switch 1318. Friction holds the plug 1316 in place against pressures lower than the desired threshold. Figures 17B and 17C illustrate the axial movement of the piston 1306 within the sleeve 1308. Figure 17B illustrates the piston 1306 in a first state where the pump volume between the piston 1306 and the plug 1316 is minimum or there is no pump volume. As shown, the coupling pin 1310 abuts against the lowermost end of the helical groove 1342. Figure 17C illustrates the piston 1306 in a second state having a maximum pump volume 1352 between the piston 1306 and the plug 1316. As shown, the coupling pin 1310 abuts against the uppermost end of the helical groove 1342.

[0084] Figures 18A - 18D illustrate the assembly of sleeve 1308 onto manifold 1312. As shown in Figure 18A, manifold 1312 includes port seal 1314 to seal reservoir port 1354 and cannula port 1356 respectively. Small side holes 1358 on the sleeve (see Figure 17B) rotate back and forth between two ports that are 56 degrees apart. As shown in Figure 18B, sleeve 1308 includes tab 1360, and manifold 1312 includes corresponding slot 1362 to permit the sleeve 1308 to be assembled onto the manifold 1312. Figure 18C illustrates manifold window 1364 provided in the manifold. Tab 1360 is received and moves within window 1364 when sleeve 1308 is assembled onto manifold 1312. Tab 1360 and window 1364 interact to permit sleeve 1308 to rotate between two positions while suppressing the axial translation of sleeve 1308 relative to manifold 1312. Sleeve 1308 is rotated between a first position where side hole 1358 is aligned with reservoir port 1354 and a second position where side hole 1358 is aligned with cannula port 1356. Figure 18D illustrates sleeve 1308 assembled onto manifold 1312 with tab 1360 disposed within manifold window 1364.

[0085] Figure 19 is a cross - sectional view of the assembled metering system. As shown, port seal 1314 is a face seal compressed between the OD (outer diameter) of sleeve 1308 and the recessed pocket of manifold 1312. Also, as shown, tab 1360 is positioned within manifold window 1364 and side hole 1358 is shown transitioning between reservoir port 1354 and cannula port 1356. Output gear 1326 includes a cam mechanism 1366 that engages a rotation limit switch 1320 to signal the end of the rotational movement of piston 1306 and sleeve 1308 in either direction.

[0086] Figures 20A - 20E are cross-sectional views illustrating the rotation of the sleeve 1308 within the manifold 1312 to transition the side hole from alignment with the reservoir port 1354 to alignment with the cannula port 1356. Figure 20A illustrates the side hole 1358 aligned with the reservoir port 1354. While in this position, the piston 1306 transitions away from the plug 1316 and fills the volume 1352 with fluid from the reservoir. Figure 20B illustrates the sleeve 1308 when it begins to rotate towards the cannula port 1356. In this position, the side hole 1358 is sealed by the seal 1314 on the reservoir port 1354. For this reason, the diameters of the seal 1314 and the side hole 1358 are preferably selected such that the seal 1314 covers the opening of the side hole 1358. Figure 20C illustrates the side hole 1358 of the sleeve 1308 between the seal 1314 of the reservoir port 1354 and the seal 1314 of the cannula port 1356. In this position, neither seal 1314 closes the side hole 1358, but the surface tension of the liquid holds the liquid within the pump chamber. Figure 20D illustrates the side hole 1358 rotated further to a position where the seal 1314 of the cannula port 1356 covers the opening of the side hole 1358. Finally, Figure 20E illustrates the side hole 1358 rotated to align with the cannula port 1356. While in this position, the piston 1306 translates axially to reduce the volume 1352 and force the fluid out of the cannula port 1356 into the cannula.

[0087] Figures 21A to 21C illustrate the operation of the limit switch. As shown in Figure 21A, the plug 1316 includes a cam mechanism 1368 that interacts with the limit switch 1318. When the sleeve 1308 and the plug 1316 rotate, the cam mechanism 1368 causes the metal flexures of the limit switch 1318 to contact each other until the plug 1316 has rotated completely to the next position. When the plug 1316 is at either end point of the plug rotation, one of the raised portions 1370 of the flexure is placed within the cam mechanism 1368 as shown in Figure 21C. The limit switch 1318, which opens and closes with each rotation cycle, signals that the plug 1316 remains properly aligned with the limit switch 1318. In an overpressure or blocked state, an increase in pressure causes the plug 1316 to slide out of the sleeve 1308 and become misaligned with the limit switch 1318. In this way, the overpressure state is detected. The limit switch 1320 is engaged by the cam mechanism 1366 of the output gear 1326 at each end of the rotation cycle. This sends a signal to reverse the rotation of the motor 1334. As shown, using two metal flexures does not allow the limit switch to determine which rotation cycle has been completed. However, as will be understood, a third flexure permits determining the direction of engagement.

[0088] Figures 22A - 22C illustrate the assembly of the motor and gearbox 1302 and the pump assembly 1304. As shown in Figures 22A and 22B, the motor and gearbox 1302 include an opening 1372 for receiving a rotational limit switch 1320. In this way, the output gear 1326 inside the gearbox housing can access and engage the bent portion of the limit switch 1320. Also, the motor and gearbox 1302 include an axial retaining snap 1374 so that the pump assembly 1304 can be snap - fitted to the motor and gearbox 1302. The motor and gearbox 1302 receive the pump assembly 1304 and include a rotation key 1376 within a pump receiving socket 1378 to inhibit rotation of the pump assembly 1304 relative to the motor and gearbox 1302. The output gear 1326 includes a slot 1380 (Figure 22B) adapted to receive a tab 1382 (Figure 22C) provided on the piston 1306. When assembled, the tab 1382 is received in the slot 1380 so that the output gear 1326 can transmit torque to the piston 1306. As the output gear 1326 rotates, the pump piston tab 1382 rotates within the slot and slides axially. The motor connection and the metal spring bent portion of the limit switch are used to make electrical contact with pads on the circuit board during final assembly.

[0089] During operation, the pump cycle of the above - described embodiment includes five steps. First, about 120 degrees of pump discharge (counter - clockwise as viewed from the pump towards the gearbox), a 56 - degree valve state change (counter - clockwise), 140 degrees of pump suction (clockwise), a 56 - degree valve state change (clockwise), and a light swing of about 20 degrees (counter - clockwise) to clear the limit switch. Over the entire pump cycle, 196 degrees of output gear rotation in each direction is required.

[0090] Figures 23A - 30C illustrate the pump cycle. For clarity, only the output gear 1326 of the gearbox assembly 1302 is shown in the figures.

[0091] Figure 23A illustrates the starting position. As shown, the cam 1366 of the output gear 1326 is not in contact with the rotary limit switch 1320 such that the bent portions are not in contact with each other. The pump piston 1306 is retracted as indicated by the position of the coupling pin 1310 within the spiral groove 1342 of Figure 22C. At this position, the sleeve 1308 closes the reservoir flow path, the cannula port 1356 is open to the side holes 1358 of the sleeve 1308, and both the rotary limit sensor 1320 and the sleeve sensor 1318 (see Figure 23B) are open.

[0092] Figures 24A and 24B illustrate the metering subsystem during the discharge stroke. The output gear 1326 rotates the pump piston 1306 in a first rotational direction (see arrow in Figure 24B), which is driven along the spiral path of the spiral groove 1342 within the sleeve 1308 via the coupling pin 1310 (see Figure 24A). The pump piston 1306 translates away from the gear box while rotating, discharging fluid from outside the pump chamber 1352 and the cannula port 1356. During the discharge stroke, the friction between the port seal 1314 and the outer diameter of the sleeve 1308 should be high enough such that the sleeve 1308 does not rotate during this part of the cycle.

[0093] Figures 25A - 25C illustrate the metering subsystem during the valve state change after the discharge stroke. As shown in Figure 25A, after the coupling pin 1310 reaches the distal end of the spiral groove 1342, torque continues to be transmitted from the output gear 1326, through the pump piston 1306, and to the sleeve 1308 via the coupling pin 1310. The sleeve 1308 and the pump piston 1306 rotate together with no relative axial movement. The side holes 1358 on the sleeve 1308 (not shown in Figures 25A - 25C) transition between the reservoir port 1354 and the cannula port 1356. The tab 1360 transitions within the window 1364 of the manifold 1312 in the direction indicated by the arrow. As shown in Figure 25B, the sleeve limit switch 1318 is closed by the cam surface of the plug 1316.

[0094] Figures 26A and 26B show the metering subsystem in the discharge rotation stop position. The side holes 1358 of the sleeve (not shown in Figures 26A or 26B) are aligned with the reservoir port 1354, the pump volume 1352 is collapsed, and the cannula port 1356 is in a closed state. The plug 1316 is in the stop position and the sleeve limit switch 1318 is open. The output gear cam 1366 contacts the rotation limit switch 1320 to indicate the end of rotation so that the output gear 1326 stops reverse rotation.

[0095] Figures 27A and 27B show the metering subsystem during the suction stroke. The output gear 1326 rotates the pump piston 1306 in the direction indicated by the arrow in Figure 27B. The piston 1306 is axially translated relative to the sleeve 1308 by the interaction of the coupling pin 1310 within the helical groove 1364. The pump piston 1306 translates towards the gear box, drawing fluid from the reservoir into the pump chamber 1352. During the suction stroke, the friction between the seal and the outer diameter of the sleeve 1308 is desirably high enough to ensure that the sleeve 1308 does not rotate relative to the manifold 1312.

[0096] Figures 28A - 28C show the metering subsystem during the valve state change after the suction stroke. The coupling pin 1310 reaches the upper end of the helical groove 1342, the motor 1302 continues to supply torque, and rotates the sleeve 1308 and the piston 1306 together. The tab 1360 on the sleeve 1308 transitions in the direction indicated by the arrow in Figure 28A within the window 1364 of the manifold 1312. The cam surface 1368 of the plug 1316 closes the sleeve limit switch 1318 when the plug 1316 rotates with the sleeve 1308. The sleeve 1308 and the pump piston 1306 rotate integrally with no relative axial movement. During this rotation, the side hole 1358 of the sleeve 1308 transitions between the reservoir port 1354 and the cannula port 1356.

[0097] Figures 29A and 29B show the metering subsystem at the intake rotation stop position. At this position, the side holes 1358 of the sleeve 1308 are aligned with the cannula port 1356, the pump volume 1352 is expanded, and the reservoir port 1354 is closed. The cam 1366 of the output gear 1326 engages the rotation limit switch 1320 to signal that the rotation is complete. The motor 1302 stops reverse rotation. The sleeve limit switch 1318 is open.

[0098] Figures 30A - 30C show the metering subsystem after the pump cycle is completed. The output gear cam 1366 is gently shaken away from the rotation switch 1320, ready to start another cycle.

[0099] Figures 31A - 31C illustrate another metering system 3100a according to an exemplary embodiment of the invention according to the present disclosure. Figure 31A shows the motor and gearbox assembly 3101 and the modified pump assembly 3100. The motor and gearbox assembly 3101 is substantially similar to the motor and gearbox assembly illustrated and described above in connection with Figures 13 - 30C.

[0100] Figure 32 is an exploded perspective view of the pump assembly 3100. The pump assembly 3100 includes a pump manifold 3102, a port seal 3104, a seal retainer 3106, a piston 3108 that rotates ±196 degrees and translates axially by ±0.038 inches, a coupling pin 3110, a sleeve 3112 having a conductive pad, and a sleeve rotation limit switch 3114 having a flexure arm 3128. The sleeve 3112 having the conductive pad rotates ±56 degrees as shown.

[0101] The pump assembly 3100 includes three flexure arms 3128 that operate as a rotational transition limit switch 3114. The rotational transition limit switch 3114 will be described in more detail below. The rotational transition limit switch 3114 directly senses the position of the sleeve 3112 rather than the position of the output gear. This enables more accurate angular alignment of the sleeve 3112 with respect to the manifold 3102 and the cannula port.

[0102] Figures 33A - 33B illustrate the assembly of the piston 3108 to the sleeve 3112. In this embodiment, the inner wall 3113 within the sleeve 3112 forms the end face of the pump chamber. The mechanism on the piston sleeve is designed to allow minimizing the gap between the end face of the piston 3108 and the face of the inner wall 3113 of the sleeve.

[0103] Figures 34A - 34E illustrate the assembly of the sleeve 3108 to the manifold 3102. As shown, the port seal 3104, seal retainer 3106, and sleeve 3112 are inserted into the manifold 3102. The small side holes 3115 (see Figure 34E) on the sleeve 3112 rotate reciprocally between the reservoir port and the cannula port, preferably 56 degrees apart. The sleeve 3112 is inserted past the retaining tab 3116 (see Figure 34D) within the manifold 3102 and then rotated to a predetermined position to suppress axial translation. Since this embodiment suppresses or minimizes the axial movement of the plug, occlusion detection due to the axial movement of the plug is generally not provided.

[0104] Figure 35 illustrates a cross - section of the sleeve 3112 and manifold 3102 assembly taken through the port seal 3104 and through the axis of the side port with respect to the manifold 3102. The side port with respect to the manifold 3102 includes a cannula port 3118 and a reservoir port 3120. The port seal 3104 is a face seal and is compressed between the outer diameter of the sleeve 3112 and the recessed pocket of the manifold 3102.

[0105] Figures 36A through 36C are cross-sectional views through the axis of the side ports as the sleeve 3112 rotates from the reservoir port 3120 to the cannula port 3118 to illustrate the valve state change. In the initial position shown in Figure 36A, the sleeve side hole 3115 is open to the reservoir port 3120. At this position, the cannula port 3118 is closed. In the intermediate position shown in Figure 36B, the sleeve side hole 3115 is being closed by the port seal 3104 during transition. In the final position shown in Figure 36C, the sleeve side hole 3115 is open to the cannula port 3118. At this position, the reservoir port 3120 is closed.

[0106] Figures 37A - 37D illustrate the operation for the sleeve rotation limit switch 3114. With a three - point contact switch design, the patch system can distinguish two rotation limits via the switch input signal rather than tracking the angular orientation of the sleeve via software. The manifold 3102 preferably includes a manifold mounting post 3122. The switch contacts 3114 are joined to the post 3122 using an adhesive, ultrasonic welding, heat staking, or any other suitable joining method. The sleeve 3112 includes conductive pads 3124 at the ends of the sleeve 3112. These may be printed or overmolded metal inserts, or provided by any other suitable means. The sleeve rotation limit switch 3114 includes a plastic overmold 3126 for the bend spacing and the mounting mechanism. Also, the sleeve rotation limit switch 3114 includes three metal bends 3128. The manifold 3102 is provided with alignment slots 3130 to receive the bends 3128. In the first position shown in FIG. 37B, the side holes 3115 on the sleeve 3112 are aligned with the cannula port 3118. In this position, the conductive pads 3124 on the sleeve 3112 bridge the center and right contacts 3128a, 3128b. At the intermediate position shown in FIG. 37C, the side holes 3115 on the sleeve 3112 are midway between the ports 3118 and 3120. In this position, both sides of the switch 3114 are open. In the final position shown in FIG. 37D, the side holes 3115 on the sleeve 3112 are aligned with the reservoir port 3120. In this position, the conductive pads 3124 on the sleeve 3112 bridge the center and left contacts 3128b, 3128c.

[0107] The pump described above has a modified operating sequence. The operating sequence is substantially the same as that described above, except that a slight backward sway of 20 degrees is no longer necessary. The slight backward sway is not required in the above-described three-point contact switch design, and a complete pump cycle consists of the following four segments. First, there is a pump discharge of approximately 140 degrees, which is counterclockwise when looking from the pump towards the gearbox. Next, there is a valve state change of 56 degrees, which is also counterclockwise. Third, there is a pump suction of 140 degrees, which is clockwise. Fourth, there is a valve state change of 56 degrees clockwise. The total of this pump cycle requires an output gear rotation of 196 degrees in each direction.

[0108] Figures 38A and 38B illustrate an exploded view of another version of the pump assembly in which the elastomer port and piston seal are overmolded onto the manifold and pump piston, respectively. This version of the pump functions in substantially the same manner as that described above, but has fewer individual components and is easier to assemble. By directly overmolding the seals onto the manifold and piston, it is possible to reduce the dimensions contributing to seal compression, suppress variations in sealing performance, and control it more precisely.

[0109] FIG. 39A illustrates an exploded view of a pump assembly 3900 having an alternative rotational limit switch design. This version of the pump assembly includes a two-point contact design for the sleeve rotational limit switch. In this design, the pump will gently rock backwards appropriately at the end of the pump cycle so that the contact switch 3902 is placed in an open state. As shown in FIG. 39B, in the first position, the side hole 3115 on the sleeve is aligned with the cannula port. In this position, the first rib 3904 on the sleeve forcibly closes the engagement. In the intermediate position shown in FIG. 39C, the side hole 3115 on the sleeve is midway between the ports and is open as neither rib 3904, 3906 touches the contact switch 3902. In the third position shown in FIG. 39D, the side hole 3115 on the sleeve is aligned with the reservoir port. In this position, the second rib 3906 on the sleeve forces the contact switch 3902 to close again.

[0110] FIG. 40 is an exploded perspective view of another exemplary embodiment of the metering assembly 4000. Since this embodiment is substantially similar to the above-described embodiment, the following description focuses on the differences. The metering assembly 4000 includes a sleeve 4002 having a helical groove 4004, a plug 4006, a seal 4008, a plunger 4010, a coupling pin 4012, a manifold 4014, a port seal 4016, and a flexible interlock 4018. FIG. 41 illustrates the metering assembly in the loaded position. The seal 4008 is preferably formed of an elastomeric material and is integral in construction. One seal 4008 is attached to the plug 4006 and the other seal 4008 is attached to the plunger 4010. The plug 4006 is preferably fixed to the sleeve 4002 by adhesion, heat sealing, or any other suitable means. The end face of the plug forms one side of the pump volume. The plunger 4010 is inserted into the sleeve 4002 and the coupling pin 4012 is press-fitted into the plunger 4010 and projects into the helical groove 4004 to provide axial translation of the plunger 4010 when rotated by a motor (not shown). The end face of the plunger 4010 forms the opposing side of the pump volume. The port seal 4016 is preferably a single molded piece of elastomeric material. In this embodiment, the number of parts is reduced and manufacturability is improved. FIG. 42 is a cross-sectional view of the assembled metering assembly.

[0111] Figures 43A - 43C illustrate the interaction between the interlock 4018 and the sleeve 4002. As shown in FIG. 41, the interlock 4018 is attached to the manifold 4014 at either end of the interlock 4018. As shown in FIG. 43A, the end face of the sleeve 4002 includes a detent 4020 that abuts the raised portion 4022 of the interlock 4018 when the metering assembly is in the first position (the side hole aligned with the reservoir pump). Under certain conditions such as backpressure, the friction between the piston 4010 and the sleeve 4008 may be sufficient to rotate the sleeve before the plunger 4010 and the coupling pin 4012 reach either end of the helical groove 4004. As a result, the volume of liquid delivered per stroke may be incomplete. To suppress this situation, the interlock 4018 inhibits the sleeve 4002 from rotating until the torque exceeds a predetermined threshold. This ensures that the piston 4010 rotates completely within the sleeve 4008 until the coupling pin 4012 reaches the end of the helical groove 4004. When the coupling pin hits the end of the helical groove 4004, further operation by the motor increases the torque on the sleeve beyond the threshold, deflecting the interlock and allowing the detent 4020 to pass by the raised portion 4022. This is illustrated in FIG. 43B. At the completion of the rotation of the sleeve 4008 such that the side hole is directed with the cannula port, the detent 4020 transitions over the raised portion 4022 in the interlock 4018. This is illustrated in FIG. 43C.

[0112] FIG. 44 illustrates a cross - section of another exemplary embodiment of the metering system 4400. The metering system 4400 includes a modified sleeve 4402 having a face 4404 that forms one side of the pump volume. This embodiment eliminates the need for a plug as in the previous embodiment and simplifies manufacturing.

[0113] FIG. 45 illustrates another exemplary embodiment having a modified sleeve 4500 and a switching mechanism 4502. FIG. 46 is a perspective view of the modified sleeve 4500 including a detent 4504 similar to the sleeve described above for interacting with an interlock (not shown). The switch mechanism 4502 includes a limit switch arm 4506 adapted to rotate in either direction away from its neutral position. The sleeve 4500 includes a switching lever (actuator arm) 4508 adapted to interact with the limit switch 4506 as the sleeve 4500 rotates. FIG. 47 illustrates the limit switch 4506 rotating about an axis. The switch mechanism 4502 provides an electrical signal indicative of the position of the limit switch 4506. FIG. 48 is a top view illustrating the sleeve 4500 rotated to an orientation where the limit switch 4506 has rotated from its neutral position to its maximum angle (α). Further rotation of the sleeve causes the limit switch 4506 to become free of the actuator arm 4508 and return to its neutral position. This change in the orientation of the switch arm indicates the end of rotation of the sleeve 4500 in one direction and reverses the rotation of the metering pump. FIG. 49 is a side view facing the sleeve surface and illustrates the same interaction between the limit switch 4506 and the actuator arm 4508. FIG. 50 is a side view showing the sleeve 4500 and the switching mechanism 4502 incorporated into a metering pump together with an interlock collar 4510.

[0114] Figure 51A illustrates the relative angular positions of the limit switch 4506 and the actuator arm 4508. α is the angle of the limit switch 4506. β is the angle of the rotating sleeve and the actuating arm. Figure 51B illustrates the relative change d(α) / d(β) versus β. Reverse rotation is preferably initiated at β = 33 degrees. As shown, as the actuating arm 4608 rotates, it pushes the limit switch 4506 away from the neutral position (α = 0 degrees). When the actuating arm angle β reaches approximately 30β, the actuating arm 4508 clears the limit switch 4506, and the limit switch 4506 returns to neutral (α = 0 degrees), thereby initiating reverse rotation of the rotary pump. When the sleeve 4508 rotates in the other direction, the same procedure occurs in reverse. Thus, the sleeve reciprocates back and forth.

[0115] Improved plunger and pump plug components are next described in connection with FIGS. 52 - 67. As will be explained, the improved plunger 5210 and pump bottom 5206 improve the pump by making the manufacture and assembly of these components easier and eliminating potential causes of fluid leakage from previous designs. The plunger 5210 is illustrated in a plurality of views in FIGS. 52 - 58. The plunger 5210 is substantially similar to the plunger 4010 shown in FIG. 40, except that an O-ring 4008 is not required as a seal is overmolded onto the head 5212 of the plunger 5210 as described below.

[0116] Seal 5214 is illustrated in multiple figures, FIGS. 59 - 62. The seal 5214 is preferably overmolded onto the head 5212 of the plunger 5210. Thus, the sealed plunger is preferably manufactured by a two-shot molding process. The plunger 5210 is molded from a rigid plastic material, and then the seal 5214 is molded onto the plunger 5210 as a second shot from a viscoelastic elastomer. The combination of the plunger 5210 and the seal 5214 makes assembly into the overall pump easier and can reduce the leakage opportunities provided by an O-ring design.

[0117] The pump stopper or plug 5206 is illustrated in FIGS. 63 - 67. The stopper 5206 substantially corresponds to the plug 4006 of FIG. 40, except that a seal 5214 (the same or a substantially similar seal component may be used for both the plunger 5210 and the stopper 5206) is overmolded onto the head 5208 of the stopper 5206 instead of an O-ring. Similar to the plunger 5210 described above, the stopper 5206 and the seal 5214 are preferably manufactured by a two-shot molding process. The stopper 5206 is molded from a rigid plastic material, and the seal 5214 is molded onto the stopper 5206 as the second shot from a viscoelastic elastomer.

[0118] FIG. 68 illustrates an exploded view of the metering assembly 4000, having an improved plunger 5210, stopper 5206, and seal 5214. Just as the plug 4006 was optional in the prior design and replaceable with a wall 4404 as shown in FIG. 44, it will be understood by those skilled in the art that the stopper 5206 is also optional and replaceable with a similar wall.

[0119] Next, a method 6900 of manufacturing and assembling a pump according to an exemplary embodiment of the present invention using the overmolded component described above will be described in relation to FIG. 69. First, in step 6902, a plunger is molded from a rigid plastic. Next, in step 6904, a seal is overmolded onto the head of the plunger. The seal is molded from a viscoelastic elastomer and sized to fit and seal within the pump chamber. Optionally, in step 6906, a pump stopper is molded from a rigid plastic, and in step 6908, a seal is overmolded onto the head of the pump stopper. The plunger and the pump stopper are inserted into the pump chamber of the pump in step 6910. A pin is inserted into the hole of the plunger so that the plunger can be translated axially when the pump motor rotates the pump chamber (step 6912).

[0120] Although only some exemplary embodiments of the invention according to the present disclosure have been described in detail above, those skilled in the art will readily understand that many changes are possible in the exemplary embodiments without substantially departing from the novel teachings and advantages of this invention, and various combinations of the exemplary embodiments are possible. Accordingly, all such changes are intended to be included within the scope of this invention.

Claims

1. A manifold having a reservoir port in fluid communication with a fluid reservoir and a cannula port in fluid communication with a cannula; A sleeve having side holes, adapted to rotate axially between a first orientation in which the side holes are aligned with the reservoir port and a second orientation in which the side holes are aligned with the cannula port within the manifold, and further having a helical groove having a first end and a second end; A plunger having an overmolded seal formed over a plunger head, adapted for rotation and axial translation within the sleeve, wherein axial translation of the plunger within the sleeve changes a pump volume which is in fluid communication with the side holes of the sleeve, and the plunger is adapted to transition between the first end and the second end of the helical groove within the helical groove, and further having a coupling member for axially translating the plunger within the sleeve when the plunger is rotated; A motor adapted to rotate the plunger in the first orientation and increase the pump volume when the sleeve is in the first orientation, and to rotate the sleeve and the plunger together when the coupling member reaches the first end of the helical groove such that the sleeve transitions to the second orientation; A rotational limit switch for reversely rotating the motor after the sleeve has rotated to direct the side holes towards the cannula port; The sleeve has an actuator arm fixed to the sleeve, the actuator arm moves the limit switch from a central position to a maximum angle (α) when the sleeve rotates in either direction, and the limit switch is deflected to return to the central position when the actuator arm passes beyond the limit switch; The maximum angle (α) is the angle of the limit switch; A rotary metering pump, characterized by the above.

2. The rotary metering pump according to claim 1, wherein the sleeve further has tabs, the manifold has windows, and the tabs transition within the windows to prevent axial translation of the sleeve relative to the manifold when the sleeve rotates within the manifold.

3. A plug having an overmolded seal on the head of the plug, the plug being inserted into the sleeve and further comprising a plug that forms a surface of the pump volume facing the plunger, the rotary metering pump according to claim 1.

4. The rotary metering pump according to claim 1, wherein the sleeve has a stop surface that forms a surface of the pump volume facing the plunger.

5. The rotary metering pump according to claim 3, further comprising seals on the plunger and the plug to form a liquid-tight seal between the plunger and the plug and between the plug and the sleeve.

6. The sleeve further has tabs, and the motor has an output gear having slots for receiving the tabs of the plunger, the slots permitting axial movement of the plunger relative to the motor while the motor rotates the plunger, the rotary metering pump according to claim 1.

7. The rotary metering pump according to claim 1, further comprising an interlock that inhibits rotation of the sleeve when the torque applied to the sleeve is below a predetermined threshold, and permits rotation of the sleeve when the torque exceeds the predetermined threshold.

8. The rotary metering pump according to claim 7, wherein the sleeve has a detent that engages a ridge on the interlock to inhibit rotation of the sleeve, and the interlock permits the detent to flex and transition past the ridge on the interlock when the torque applied to the sleeve exceeds a predetermined limit.

9. The rotary metering pump according to claim 1, further comprising at least one port seal that forms a liquid-tight seal between the sleeve and the reservoir port.

10. The rotary metering pump according to claim 1, further comprising at least one port seal that forms a liquid-tight seal between the sleeve and the cannula port.

11. The rotary metering pump according to claim 10, wherein the port seal is an integral elastomeric component.

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