[0001] REUSABLE, PATIENT CONTROLLED SYRINGE DRIVE DEVICE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is related to U.S. Provisional Patent Application No. 62/356,892, filed June 30, 2017 and claims the earlier filing date of the provisional application which is incorporated in the entirety herein by reference.

BACKGROUND OF THE INVENTION

[0003] The present invention relates to a reusable, patient controlled injector having a drive system for autoinjection of a medication. More particularly, the present invention relates to a reusable, patient controlled injector having adrive system allowing the user to control the rate of injection dynamically during the injection.

[0004] International Application Publication No. WO 2014/036285 A2 (Hanson et al), hereafter referred to as "Hanson", is directed to variable rate controlled delivery drive mechanisms for drug delivery pumps. More particularly, Hanson discloses a drug pump having a spring-based drive mechanism that acts upon a piston to force a fluid drug out of a drug container. A gear drive controls the motion of the piston, but does not apply the force necessary for drug delivery. Instead, the gear drive merely meters or permits translation of the piston which is being driven to axially translate by the biasing member. A user accessible activation button is coupled to a power and control system that accepts various inputs from the user to dynamically control a drive mechanism to meet a desired drug delivery rate. The inputs may include partial or full activation, depression, and/or release of the activation button, to set, initiate, stop, or otherwise adjust the control of the spring-biased drive mechanism. Hanson does not disclose details regarding the structure and operation of the control system

[0005] U. S. Patent No. 8,920,374 (Bokelman et al), hereafter referred to as Bokelman, is directed to an automatic injector configured to accept a variety of syringes as cartridges for drug delivery. The Bokelman auto injector provides user control of the injection rate via a series of touch sensitive pads requiring the user to select an injection rate prior to initiation of the injection. The Bokelman auto injector does not allow for adjustment of the injection rate during injection.

[0006] The drive control mechanism for the Bokelman automatic injector includes a drive screw, a cartridge carrier, a plunger carrier, and one or more control transfer instruments. Longitudinal movement of the plunger carrier is provided by a gear train that includes a rack and pinion gear arrangement. Rotation of the pinion gear engaged with the rack causes the rack and associated plunger carrier to move between proximal and distal positions within the automatic injector housing. The Bokelman drive control mechanism lacks a worm gear mounted to a motor shaft and a pinion gear meshed with the worm and mounted on a pinion shaft.

[0007] For the foregoing reasons, there is a need in the art for a reusable, patient controlled injector drive system allowing the user to control the rate of injection dynamically during the injection. BRIEF SUMMARY OF THE INVENTION

[0008] Briefly stated, one embodiment of the present invention is directed to a reusable patient-controlled injector having a drive system for controlling a drug injection rate from a drug injector having a drug-injector piston a movement of which forces a fluid drug out of the drug injector. The reusable patient-controlled injector comprises an injector housing having a housing longitudinal axis. A rack and pinion assembly disposed in the injector housing. The rack and pinion assembly has a rack longitudinal axis parallel to the housing longitudinal axis. A reusable drug-injector mount is fixedly dispose in the injector housing adjacent the rack and pinion assembly. The drug-injector mount is configured to releasibly receive the drug injector. A carriage is coupled to the rack and pinion assembly. The carriage has a downwardly- extending carriage member spaced from an upwardly-extending carriage member by a carriage central body. The carriage is driven in translation parallel to the rack longitudinal axis by a reversible electric motor and is configured to engage and move the drug-injector piston when the drug injector is removably retained in the drug-injector mount. An electrical control system is in communication with the electric motor. The electrical control system has a movable, patient-accessible injection-rate control actuator. The drug injection rate varies proportional to the movement, patient-accessible injection-rate control actuator. The rack and pinion assembly comprises a pair of generally U-shaped rail mounts spaced apart along the housing longitudinal axis. Each rail mount has a rail-mount base fixedly attached to the injector housing, a first upwardly-extending rail support and a second upwardly-extending rail support spaced laterally from the first upwardly-extending rail support. The first upwardly-extending rail support is shorter than the second upwardly-extending rail support. An upper rail extends between and is attached to the first upwardly-extending rail support of each rail mount. The upper rail has a downwardly-facing rail surface with upper-rail teeth. An upper-rail pinion gear is mounted on an upper-rail pinion shaft and meshes with the upper-rail teeth. The upper-rail pinion shaft extends laterally inwardly through an upper-rail pinion-shaft journal in the upwardly-extending carriage member and terminates with an upper-rail pinion-shaft worm gear. A lower rail extends between and is attached to the second upwardly-extending rail support of each rail mount. The lower rail has an upwardly-facing rail surface with lower-rail teeth. A lower-rail pinion gear is mounted on a lower-rail pinion shaft and meshes with the lower-rail teeth, the lower-rail pinion shaft extending laterally inwardly through a lower-rail pinion-shaft journal in the downwardly extending carriage member and terminating with a lower-rail pinion-shaft worm gear.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0009] The foregoing summary, as well as the following detailed description of a preferred embodiment of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, the drawings show an embodiment of a prototype patient controlled injector drive system which is presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

[0010] In the drawings:

[0011] Fig. 1 is left side perspective view of a preferred embodiment of the prototype patient controlled injector in accordance with the present invention;

[0012] Fig. 2 is an exploded right side perspective view of the injector of Fig. 1; and

[0013] Fig. 3 is a schematic block diagram of the injector of Fig. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0014] Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0015] As used in the description of the invention and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The words "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The words

"comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0016] The words "right," "left," "lower" and "upper" designate directions in the drawings to which reference is made. The words "inwardly" and "outwardly" refer to directions toward and away from, respectively, the geometric center of the injector, and designated parts thereof. The terminology includes the words noted above, derivatives thereof and words of similar import.

[0017] Although the words first, second, etc., are used herein to describe various elements, these elements should not be limited by these words. These words are only used to distinguish one element from another. For example, a first rail support could be termed a second rail support, and, similarly, a second rail support could be termed a first rail support, without departing from the scope of the present invention.

[0018] As used herein, the words "if may be construed to mean "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [a stated condition or event] is detected" may be construed to mean "upon determining" or "in response to determining" or "upon detecting [the stated condition or event]" or "in response to detecting [the stated condition or event]," depending on the context.

[0019] The following description is directed towards various embodiments of a injector drive system in accordance with the present invention.

[0020] Referring to the drawings in detail, where like numerals indicate like elements throughout, there is shown in Figs. 1-3 a first preferred embodiment of a prototype reusable, patient-controlled injector, generally designated 10, and hereinafter referred to as the "injector" in accordance with the present invention. The injector 10 is shown in Fig. 1 and is preferably designed for controlling a drug injection rate from a drug injector (not shown) having a drug- injector piston, a linear movement of which forces a fluid drug out of the drug injector. While reference is made herein generically to a drug injector having a piston, it is understood that the present invention is not so limited. For example, the injector 10 described in detail below may also be used or reused with nearly any type of drug injector having a linear mechanism for injecting a drug.

[0021] The injector 10 has an injector housing 12 having a housing longitudinal axis A _H . A rack and pinion assembly 14 is disposed on the injector housing 12. The rack and pinion assembly 14 has a rack longitudinal axis A _R parallel to the housing longitudinal axis A _H . A drug-injector mount 16 is fixedly dispose on the injector housing 12 adjacent the rack and pinion assembly 14. The drug-injector mount 16 is configured to releasably receive the drug injector. A carriage 18 is coupled to the rack and pinion assembly 14. The carriage 18 is driven in translation parallel to the rack longitudinal axis A _R by an electric motor and is configured to engage and move the drug-injector piston when the drug injector is in the drug-injector mount 16.

[0022] The rack and pinion assembly 14 comprises a pair of generally U-shaped rail mounts 20 spaced apart along the housing longitudinal axis A _H . Each rail mount 20 has a rail-mount base 22 fixedly attached to the injector drive-system housing 12, a first upwardly-extending rail support 24 and a second upwardly-extending rail support 26 spaced laterally from the first upwardly-extending rail support 24. The first upwardly-extending rail support 24 is shorter than the second upwardly-extending rail support 26.

[0023] An upper rail 28 extends between and is attached to the first upwardly-extending rail support 24 of each rail mount 20. The upper rail 28 has a downwardly-facing upper-rail surface 30 with upper-rail teeth 32. An upper-rail pinion gear 34 is mounted on an upper-rail pinion shaft 36 and meshes with the upper-rail teeth 32. The upper-rail pinion shaft 36 extends laterally inwardly through an upper-rail pinion-shaft journal 38 in an upwardly-extending carriage member 40 and terminates with an upper-rail pinion-shaft worm gear 42.

[0024] A lower rail 44 extends between and is attached to the second upwardly-extending rail support 26 of each rail mount 20. The lower rail 44 has an upwardly-facing lower-rail surface 46 with lower-rail teeth 48. A lower-rail pinion gear 50 is mounted on a lower-rail pinion shaft 52 and meshes with the lower-rail teeth 48. The lower-rail pinion shaft 52 extends laterally inwardly through a lower-rail pinion-shaft journal 54 in a downwardly-extending carriage member 56 and terminates with a lower-rail pinion-shaft worm gear 58.

[0025] The downwardly-extending carriage member 56 is spaced from the upwardly- extending carriage member 40 by a carriage central body 60. An electric motor 62 having a motor shaft 64 to which a motor-shaft worm 66 is affixed for rotation therewith is mounted on the carriage central body 60 such that the motor-shaft worm 66 meshes with the upper-rail pinion-shaft worm gear 42 and the lower-rail pinion-shaft worm gear 58.

[0026] In a preferred embodiment of the injector 10, the motor 62 is a 12-volt gear motor having a 1030 RPM free-run, 44 oz-in torque and a 5.6 amp stall capability. Preferably, the motor shaft 64 is 44-mm and has a "D" cross sectional shape. [0027] The downwardly-extending carriage member 56 has an outwardly-extending downwardly-extending carriage-member lip 68 slideably engaging a downwardly-facing lower- rail surface 70. The upwardly-extending carriage member 40 has an outwardly-extending upwardly-extending carriage-member lip 72 slideably engaging an upwardly-facing upper-rail surface 74.

[0028] The upper rail 28 and the lower rail 44 of the rack and pinion assembly 14 are preferably made of brass; the upper-rail teeth 32 and the lower rail teeth 48 preferably have a 48-degree pitch, a 20-degree pressure angle and a face width of about 1/8 inch. The upper-rail pinion gear 34 and the lower-rail pinion gear 50 preferably are brass external tooth spur gears with a 20-degree pressure angle and a 0.208 inch pitch diameter. The worm gear preferably has a 48-inch pitch diameter with a 14.5-degree pressure angle. The pinion gears 34, 50 and the worm gears 42, 58 are mounted on opposite ends of a 3/16-inch diameter steel pinion shaft 36, 52. The motor-shaft worm 66 is preferably made of steel and is a 48 pitch gear with a 14.5- degree pressure angle and a 0.333-inch pith diameter. When messed with the worm gears 42, 58, a single rotation of the worm 66 produces a l/20 ^th turn of the worm gears 42, 58.

[0029] Referring to Fig. 3, an electrical control system 76 is in communication with the electric motor 62. The electrical control system 76 has a movable, patient-accessible injection- rate control actuator 78. The electrical control system 76 includes a linear motion potentiometer 80 in electrical communication with the electric motor 62. The drug injection rate depends on an electrical state of the potentiometer 80 which, in turn, depends on the extent of the movement of the injection-rate control actuator 78.

[0030] The electrical control system 76 has a user interface 82 configured to provide a user perceptible communication representing a state of the injector 10. In some embodiments, the user perceptible signal may be a visual signal. In such embodiments, the user interface 82 preferable may include a light-emitting diode assembly and the visual signal emitted by the light-emitting diode assembly may be a red emittance when the injector is not ready for use, a green emittance when the injector is ready for use and a blue emittance when the injector is in use. In other embodiments, the user perceptible communication may be an audible or tactile signal. In still other embbodiments, the user perceptible communication may be any

combination of the foregoing form of communication.

[0031] The rack and pinion assembly 14 has a pair of spaced-apart limit switches 86 in electrical communication with the electrical control system 76. The limit switches 86 are positioned on the one of the upper rail 28 or lower rail 44 of the rack and pinion assembly 14 to prevent the carriage 18 from hitting either end of the rack and are activated by contact with the carriage 18. In some embodiments, the limit switches 86, upon contact with the carriage 14 may reverse the direction of the motor 62.

[0032] Fig. 3 is a schematic diagram of the control system 76 for the prototype injector drive system 10. The control system 76 includes the injection-rate control button 78 coupled to a linear motion potentiometer 80. The button 78 changes the resistance of the potentiometer 80 based on the depth to which the button 78 is depressed.

For optimization of a control system and user interface for a production injector drive system, the prototype control system 76 also includes an H-bridge, such as a Texas instruments DVR8833 H-Bridge motor drive chip allowing communication between the motor 62 and a realtime embedded evaluation board for reconfigurable input/output, such as a National Instruments myRIO Student Embedded Device.

[0033] The foregoing detailed description of the invention has been disclosed with reference to a specific embodiment. However, the disclosure is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Those skilled in the art will appreciate that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. For example, the foregoing embodiments of the injector 10 need not be limited to rack and pinion assemblies having only two rails. Although assemblies with two rails are preferable, in some injector embodiments having a rack and pinion assembly with more than two rails, such as three or four rail assembly may be desirable to allow a modified gear assembly to have three or four point contact with the drive motor worm. Therefore, the disclosure is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims