Plunger drive system for a medication delivery device

Abstract

Plunger drive systems used with injectors to expel a fluid drug for injection into a patient include a housing and a plunger rod that extends from the housing. The plunger rod includes a first leg and a second leg individually coupled with separate rollers over one portion of the first leg and second leg and engaged together over another portion of the first leg and second leg to form a column. The legs may include a reinforcement member. The first leg and second leg meet at a location between the rollers and are engaged with one another through complementary registration surfaces. When the rollers are rotated, typically through action of an electric motor, the rollers rotate in opposite directions to increase a length of the column. The column may be operatively coupled to a plunger of a syringe to dispense a fluid drug as the column increases in length.

Description

PLUNGER DRIVE SYSTEM FOR A MEDICATION DELIVERY DEVICEFIELD OF THE DISCLOSURE

[0001] The present disclosure relates to medication delivery devices and related methods of use. Specifically, the present disclosure relates to plunger drive systems for use with medication delivery devices for dispensing a medication.BACKGROUND OF THE DISCLOSURE

[0002] Patients suffering from various diseases must frequently have medication injected. In some settings, injection of medication can be performed via motorized device that operates to expel medication from a container. Medical professionals and / or patients can control the motorized device to have the medication injected either on-demand, periodically according to a schedule, or as a result of an event driven system. A drive member is movable in response to a motor to advance a plunger to dispense the contained medication from an outlet from an outlet of the container, and then, typically, through a needle in fluid communication with the container. Control of the movement of the plunger controls the timing and amount of medication delivered by the medication delivery device.SUMMARY

[0003] Exemplary embodiments of the present disclosure include plunger drive systems useful with medication delivery devices in which a position of a plunger rod can be changed to expel a fluid drug from the medication delivery device. In other words, the present disclosure relates to a plunger drive system having a plunger rod that can be moved relative to a housing to expel a fluid drug from an injector.

[0004] In a first embodiment, a plunger drive system for expelling a fluid drug is provided. The drive system includes one or more of the following. A plunger rod includes a first leg and a second leg. Each of the first leg and the second leg includes a flexible body with a first side having gear drivable features and a second side, opposite the first side, having teeth or traction features. The teeth of the first leg configured to confront and interlock with the teeth of the second leg to form a column. At least one of the first leg and the second leg has a composite construction including a first material comprising the flexible body and a reinforcement member coupled to the first material. A drive system has a motor, a first rollerassociated with the first leg, and a second roller associated with the second leg. At least one of the first roller and the second roller is configured to be driven by the motor. The column is configured to increase in length when the first roller and the second roller are driven by the motor, wherein an increase in length of the column causes expulsion of the fluid drug.

[0005] In another embodiment, a plunger drive system for expelling a fluid drug is provided, having one or more of the following. A first leg of a plunger rod has a flexible body with a first side having a first registration surface and a second side, opposite the first side, having a second registration surface. The flexible body of the first leg includes a composite construction having a first flexible material and a first reinforcement member coupled to the first flexible material. The first flexible material has a compliance higher than a compliance of the first reinforcement member. A second leg of the plunger rod has a flexible body with a first side having a first registration surface and a second side, opposite the first side, having a second registration surface. The second registration surface of the second leg configured to confront and interlock with the second registration side of the first leg to form a column. A drive system has a motor, a first roller associated with the first leg, and a second roller associated with the second leg. At least one of the first roller and the second roller is configured to be driven by the motor having a first registration surface configured to interengage with the first registration surface from the at least one of the first roller and the second roller. During a first mode of operation, driven rotation of the at least one of the first roller and the second roller by the motor increase a length of the column to cause expulsion of the fluid drug.

[0006] In another embodiment, a plunger drive system includes one or more of the following. A housing has an opening at a first end. A plunger rod has a first leg and a second leg. At least a portion of the plunger rod is disposed within the housing. The first leg has a first portion is interlocked with a first portion of the second leg to form a column. The first leg has a second portion that is not interlocked with a second portion of the second leg. A drive system has a first roller at least partially disposed in the housing and a second roller at least partially disposed in the housing. The second portion of the first leg positioned within the housing and circumferentially engaged with at least a portion of the first roller at a radial distance. The second portion of the second leg is positioned within the housing and circumferentially engaged with at least a portion of the second roller at a radial distance. The first leg includes a composite construction having a first flexible material and a first reinforcement member. The first reinforcement member is configured to provide a bucklingload of the column higher than a buckling load of the column if the first leg did not include the first reinforcement member. The first reinforcement member has a compliance that permits the first reinforcement member to be circumferentially oriented when the at least portion of the first roller is circumferentially engaged at the radial distance.

[0007] Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing aspects and many additional features of the present invention and accompanying methods will become more readily appreciated and become better understood by reference to the following detailed description when taken in conjunction with the accompanying figures. The detailed description of the drawings particularly refers to the accompanying figures in which:

[0009] FIG. 1 illustrates a medication delivery device of the present disclosure having a plunger drive system and an injector;

[0010] FIG. 2 illustrates a perspective view of one embodiment of the plunger drive system of FIG. 1;

[0011] FIG. 3 illustrates a perspective view of another embodiment of the plunger drive system of FIG. 1;

[0012] FIG. 4 illustrates a perspective view of an embodiment of the plunger drive system of FIG. 1;

[0013] FIG. 5 illustrates an exploded view of the plunger drive system of FIG. 2;

[0014] FIG. 6 illustrates a view of one portion of the plunger drive system of FIG. 3;

[0015] FIG. 7 illustrates a perspective view of the plunger drive system of FIG. 6;

[0016] FIG. 8 illustrates a magnified view of a cutout portion from FIG. 7;

[0017] FIG. 9 illustrates a perspective view of another embodiment of the plunger drive system of FIG. 1;

[0018] FIG. 10 illustrates a view of one portion of an embodiment of the plunger drive system of FIG. 1;

[0019] FIG. 11 illustrates a view of one portion of an embodiment of the plunger drive system of FIG. 1;

[0020] FIG. 12 illustrates a view of one portion of an embodiment of the plunger drive system of FIG. 1;

[0021] FIG. 13 illustrates a view of one portion of an embodiment of the plunger drive system of FIG. 1;

[0022] FIG. 14 illustrates a view of a column of a plunger rod having a foot;

[0023] FIG. 15 illustrates an embodiment of a foot of a plunger drive system;

[0024] FIG. 16 illustrates an embodiment of a foot of a plunger drive system;

[0025] FIG. 17 illustrates an embodiment of a foot of a plunger drive system;

[0026] FIG. 18 illustrates an embodiment of a foot of a plunger drive system;

[0027] FIG. 19 illustrates an embodiment of a foot of a plunger drive system;

[0028] FIG. 20 illustrates an embodiment of electric motor operatively coupled with a first roller and second roller of a plunger drive system via one embodiment of a transmission;

[0029] FIG. 21 illustrates an embodiment of electric motor operatively coupled with a first roller and second roller of a plunger drive system via the embodiment of the transmission depicted in FIG. 20;

[0030] FIG. 22 illustrates an embodiment of electric motor operatively coupled with a first roller and second roller of a plunger drive system via one embodiment of a transmission;

[0031] FIG. 23 illustrates an embodiment of electric motor operatively coupled with a first roller and second roller of a plunger drive system via the embodiment of the transmission depicted in FIG. 22;

[0032] FIG. 24 illustrates an embodiment of electric motor operatively coupled with a first roller and second roller of a plunger drive system via one embodiment of a transmission;

[0033] FIG. 25 illustrates an embodiment of electric motor operatively coupled with a first roller and second roller of a plunger drive system via the embodiment of the transmission depicted in FIG. 24.

[0034] Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of various features andcomponents according to the present disclosure, the drawings are not necessarily to scale, and certain figures may be exaggerated in order to better illustrate and explain the present disclosure.DETAILED DESCRIPTION OF THE DRAWINGS

[0035] For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, which are described herein. The embodiments disclosed herein are not intended to be exhaustive or to limit the invention to the precise form disclosed. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings.Therefore, no limitation of the scope of the claimed invention is thereby intended. The present invention includes any alterations and further modifications of the illustrated devices and described methods and further applications of principles in the invention which would normally occur to one skilled in the art to which the invention relates.

[0036] The terms “couples”, “coupled”, “coupler” and variations thereof are used to include both arrangements wherein the two or more components are in direct physical contact and arrangements wherein the two or more components are not in direct contact with each other (e.g., the components are “coupled” via at least a third component), but yet still cooperate or interact with each other.

[0037] In some instances throughout this disclosure and in the claims, numeric terminology, such as first, second, third, fourth, etc., is used in reference to various components of features. Such use is not intended to denote an ordering of the components or features. Rather, numeric terminology is used to assist the reader in identifying the components or features being referenced and should not be narrowly interpreted as providing a specific order of components or features.

[0038] Referring initially to FIGS. 1-2, an exemplary medication delivery device 100 is illustrated which includes a plunger drive system 102 configured to expel a fluid drug upon activation of plunger drive system 102. Plunger drive system 102 is coupled to an injector 104 which includes the fluid drug and from which the fluid drug is expelled as a result of activation of plunger drive system 102. Plunger drive system 102 can be used to actuate injector 104 for a variety of drug delivery purposes. For example, plunger drive system 102 may be used to activate injector 104 to meter periodic dosages of a fluid drug over a period oftime, may be configured to activate injector 104 to deliver the entirety of contents of the fluid drug at a single administration, or may be configured to activate injector 104 on demand of a healthcare profession and / or a patient.

[0039] The fluid drug expelled from the exemplary medication delivery device 100 can be any suitable medication such as one or more therapeutic agents including, but not limited to, epinephrine, anaesthetics, analgesics, steroids, insulins, insulin analogs such as insulin lispro or insulin glargine, insulin derivatives, GLP-1 receptor agonists such as dulaglutide, glucagon, glucagon analogs, glucagon derivatives, gastric inhibitory polypeptide (GIP), GIP analogs, GIP derivatives, combined GIP / GLP-1 agonists such as tirzepatide or retatrutide, basal insulins, such insulin efistora alfa, oxyntomodulin analogs, oxyntomodulin derivatives, and other treatments for diabetes and / or obesity, such as with lepodisiran (LPA siRNA), volenrelaxin, amylin agonist long acting, PNPLA3 siRNA, APOC3 siRNA, DACRA qw II, GIPR agonist long acting, glucose sensing insulin receptor agonist, nisotirostide, bimagrunab, NRG4 agonist, SCAP siRNA, mazdutide, and therapeutic antibodies including but not limited to IL-23 antibody analogs or derivatives, such as mirikizumab that can be used for treatment of diseases, such as, e.g., Crohn’s disease or ulcerative colitis, IL-17 antibody analogs or derivatives, such as ixekizumab that can be used for treatment of diseases, such as, e.g., plaque psoriasis, IL-13 antibody analogs or derivatives, such as lebrikizumab that can be used for treatment of diseases, such as, e.g., atopic dermatitis, therapeutic agents for pain-related and / or migraine treatments, such as galcanezumab or lasmiditan, for treatment of atopic dermatitis, such as with ucenprubart, for treatment of Alzheimer’s and / or dementia, such as with donanemab, remternetug, or GRN gene therapy, for treatment of Parkinson’s disease and / or Gaucher’s disease, such as with GBA1 gene therapy, for treatment of Hidradenitis Suppurativa, such as with eltrekibart, for treatment of rheumatoid arthritis, such as with peresolimab, for treatment of cancer, and any therapeutic agent, such as CD 19, that is capable of delivery by the devices described herein

[0040] Injector 104 is depicted as a bolus injector in the illustrated embodiment and includes a plunger 106 disposed inside of a container 108. When plunger 106 is displaced in a direction toward an injector outlet 110, a fluid drug 112 contained in container 108 is forced through injector outlet 110 and into tubing 111. Plunger 106 may be displaced via action of plunger drive system 102. Injector 104 used in conjunction with plunger drive system 102 can take the form of a bolus injector, to set forth one non-limiting example. Alternatively, a needle (not shown) can be substituted for the tubing and coupled to the outlet 110 so that thefluid drug can flow through the needle to a patient, such as, for example, subcutaneously or intramuscular.

[0041] Plunger drive system 102 includes a power supply 114 used to provide power to an electric motor 116. Power supply 114 is in the form of an energy storage device such as a battery in the illustrated embodiment. Such an energy storage device can be used to provide power to operate electric motor 116 in the absence of any external power sources. In embodiments, power supply 114 may be an electrical converter that converts from alternating current to direct current, and / or can be a transformer. Electric motor 116 is any suitable motor useful to receive electric power and convert to mechanical power. In embodiments, electric motor 116 can be any type of direct current motor, or any type of alternating current motor. In embodiments, plunger drive system 102 may not include the power supply 114 and / or may not include the electric motor 116.

[0042] Depicted in FIG. 1, plunger drive system 102 includes a housing 118 used to enclose power supply 114 and / or electric motor 116. Housing 118 may be used to hermetically seal one or more components of plunger drive system 102, such as power supply 114 and / or housing 118, but in some forms housing 118 may include one or more openings such that an interior of housing 118 is not hermetically sealed.

[0043] Plunger drive system 102 also includes a plunger drive 120 having a plunger rod 122. Plunger drive 120 is mechanically driven by electric motor 116 so as to move plunger rod 122 and thereby cause associated movement of plunger 106 to expel fluid drug 112 from injector 104. Plunger rod 122 is configured to extend from the plunger drive system 102 in at least a direction toward injector 104 so as to cause movement of plunger 106 and resultant expulsion of fluid drug 112 from container 108. In embodiments, plunger drive system 102 may also cause plunger rod 122 to retract in a direction away from injector 104 such that plunger 106 is moved away from injector outlet 110. Such a movement can be used to draw fluid drag 112 into container 108, such as during a fill operation of injector 104 or to retract the plunger drive system back into the housing 118 for reuse after detachment from plunger 106. Thus, and depending on the configuration, plunger drive system 102 is configured to at least extend plunger rod 122 in a direction to expel fluid drag 112 from container 108 and may also be configured to retract plunger rod 122 in a direction to (a) draw fluid drag 112 into container 108 and / or (b) to retract the plunger drive system for reuse.

[0044] Turning now to FIGS. 2-5, and with continuing reference to FIG. 1, plunger drive 120 is illustrated as including plunger rod 122 at least partially disposed in housing 118. Plunger rod 122 includes a first leg 124 and a second leg 126 that are each operatively coupled, respectively, to a first roller 128 and a second roller 130. Electric motor 116 (see FIGS. 1, 20-25) is operatively coupled to at least one of first roller 128 and second roller 130 such that activation of electric motor 116 may, through consequent movement of first roller 128 and / or second roller 130, drive plunger rod 122 and thereby expel fluid drug 112 from injector 104.

[0045] First leg 124 is illustrated as including a first portion 132 that is engaged with a first portion 134 of second leg 126, and a second portion 136 that is engaged with first roller 128. First leg 124 includes features on a first side 133 and a second side 135 that enable engagement with each of second leg 126 and first roller 128, respectively. For example, first leg 124 includes a first registration surface 140 on first side 133 configured to be engaged with a first registration surface 142 of first roller 128. Each of first registration surface 140 and first registration surface 142 are complementary such that one is configured to engage with the other. In the illustrated embodiment, first registration surface 140 is a gear drivable feature and first registration surface 142 is a gear driven feature to facilitate traction between the leg and roller. As illustrated, first registration surface 140 and first registration surface 142 include a configuration that resembles a gear in which a peak of first registration surface 140 is configured to fit within a valley of first registration surface 142. First registration surface 140 also includes a valley to fit a peak of first registration surface 142. The peak and valley surface is repeated along a length of first leg 124 to match corresponding repetition along first roller 128. In embodiments, the peak and valley pattern might not be repeated. The respective sides of the peak of first registration surface 140 and valley of first registration surface 142 may contact each other to transmit driving force from the electric motor 116, through first roller 128, and to first leg 124. In embodiments, each of peak of first registration surface 140, valley of first registration surface 142, and respective sides of each of peak and valley, may be in contact during a driven operation. In other embodiments, only a portion of each of peak of first registration surface 140, valley of first registration surface 142, and respective sides of each of peak and valley, may be in contact during a driven operation. One of the advantages of the first registration surface 142 having a traction for the legs can be to inhibit liftoff of the legs from the traction surface, for example, during deployment and retraction of the plunger drive system. The spacing between the surfaces ofthe rollers 128, 130 through which the legs are coupled to one another can be reduced as small as possible to strengthen the column formed by the coupled legs.

[0046] Second leg 126 includes features on a first side 143 and a second side 145 that enable engagement with each of first leg 124 and second roller 130, respectively. For example, second leg 126 includes a first registration surface 144 on first side 143 configured to be engaged with a first registration surface 146 of second roller 130. Each of first registration surface 144 and first registration surface 146 are complementary such that one is configured to engage with the other. In the illustrated embodiment, first registration surface 144 is a gear drivable feature and first registration surface 146 is a gear driven feature to facilitate traction between the leg and roller. As illustrated, first registration surface 144 and first registration surface 146 include a configuration that resembles a gear in which a peak of first registration surface 144 is configured to fit within a valley of first registration surface 144. First registration surface 144 also includes a valley to fit a peak of first registration surface 146. The peak and valley surface is repeated along a length of second leg 126 to match corresponding repetition along second roller 130. In embodiments, the peak and valley pattern might not be repeated. The respective sides of the peak of first registration surface 144 and valley of first registration surface 146 may contact each other to transmit driving force from the electric motor 116, through second roller 130, and to second leg 126. In embodiments, each of peak of first registration surface 144, valley of first registration surface 146, and respective sides of each of peak and valley, may be in contact during a driven operation. In other embodiments, only a portion of each of peak of first registration surface 144, valley of first registration surface 146, and respective sides of each of peak and valley, may be in contact during a driven operation.

[0047] As stated above, first leg 124 is illustrated as including a first portion 132 that is engaged with a first portion 134 of second leg 126. The engagement of first portion 132 with first portion 134 forms a column 159 that is of sufficient rigidity to transmit force from electric motor 116 to plunger 106. Column 159 includes a buckling load value higher than a force transmitted from electric motor 116. As first roller 128 and second roller 130 rotate as a result of action of electric motor 116, a length of column 159 increases. Despite the increase in length, the engagement of first portion 134 with second leg 126 via first registration surface 144 and first registration surface 146, a buckling load of column 159 is higher than a force transmitted to column 159 via action of the first roller 128 and second roller 130. It will be appreciated, however, for a given coupled flexible reinforced membercolumn, that a buckling load of column 159 may be higher at smaller lengths of column 159 (e.g., at an early stage of fluid drug 112 expulsion) than at longer lengths of column 159. Thus, the buckling load may vary as a function of length of column 159, with higher buckling load present at smaller lengths of column 159, and or the construction and properties of the reinforcement member.

[0048] Although first leg 124 and second leg 126 include a material that has a compliance suitable for being at least partially wrapped around first roller 128 and second roller 130, respectively, first leg 124 and second leg 126 are made of a composite construction. In particular, first leg 124 includes a first flexible material 164 and a reinforcement member 166, where reinforcement member 166 is configured to provide stiffness to first flexible material 164 and improve the buckling load of column 159. First flexible material 164 may be formed through injection molding. For example, first flexible material 164 may be formed about reinforcement member 166 through an injection molding process. In embodiments, such an injection molding process can be used to mold a straight length of first leg 124 in which second portion 136 of first leg 124 is then wrapped around first roller 128. In other embodiments, such an injection molding process can be used to mold first leg 124 into roughly the shape depicted in the illustrated embodiments, with first portion 132 molded as a straight segment and second portion 136 molded as a curvilinear shape to match a curvature of first roller 128. In embodiments, first flexible material 164 may be fastened and / or bonded to reinforcement member 166. Without reinforcement member 166, the buckling load of column 159 is lower and may not result in sufficient stiffness to transmit force from electric motor 116 to plunger 106 without buckling.Reinforcement member 166 may include a material type having a higher Young’s modulus than a Young’s modulus of the first flexible material 164. Furthermore, the cross-sectional shape of reinforcement member 166 can also provide additional stiffness to column 159. For example, reinforcement member 166 can be relatively flat in cross-sectional shape, with a thickness 168 measured in a radial direction smaller than a width 170 measured in an axial direction. The cross-sectional shape may be rectilinear, but other shapes are contemplated. For example, the cross-sectional shape may take the form of a cross, I-beam, circle, etc. In embodiments, reinforcement member 166 is stamped to thickness. Reinforcement member 166 extends the entirety of a length between a first end 172 and second end 174. In embodiments, reinforcement member 166 extends only partially between first end 172 and second end 174. In still further embodiments, reinforcement member 166 is segmented. Inyet still further embodiments, reinforcement member 166 can be made from a continuous material (e.g., a stamped metal component) or can be a wire mesh construction. Furthermore, in embodiments, reinforcement member 166 may be encapsulated by first flexible material 164 such that reinforcement member 166 resides wholly within first flexible material 164.

[0049] Similar to first leg 124, second leg 126 includes a first flexible material 176 and a reinforcement member 178, where reinforcement member 178 is configured to provide stiffness to first flexible material 176 and improve the buckling load of column 159. First flexible material 176 may be formed through injection molding. For example, first flexible material 176 may be formed about reinforcement member 178 through an injection molding process. In embodiments, such an injection molding process can be used to mold a straight length of second leg 126 in which second portion 138 of second leg 126 is then wrapped around second roller 130. In other embodiments, such an injection molding process can be used to mold second leg 126 into roughly the shape depicted in the illustrated embodiments, with first portion 134 molded as a straight segment and second portion 138 molded as a curvilinear shape to match a curvature of second roller 130. In embodiments, first flexible material 176 may be fastened and / or bonded to reinforcement member 178. Without reinforcement member 178, the buckling load of column 159 is lower and may not result in sufficient stiffness to transmit force from electric motor 116 to plunger 106 without buckling. Reinforcement member 178 may include a material type having a higher Young’s modulus than a Young’s modulus of the first flexible material 164. Furthermore, the cross-sectional shape of reinforcement member 178 can also provide additional stiffness to column 159. For example, reinforcement member 178 can be relatively flat in cross-sectional shape, such as, for example, perforated or meshed-metallic flat, with a thickness measured in a radial direction smaller than a width measured in an axial direction. The cross-sectional shape may be rectilinear, but other shapes are contemplated. In embodiments, reinforcement member 178 is stamped to thickness. Reinforcement member 178 extends the entirety of a length between a first end 180 and second end 182. In embodiments, reinforcement member 178 extends only partially between first end 180 and second end 182. In still further embodiments, reinforcement member 178 is segmented. In yet still further embodiments, reinforcement member 178 can be made from a continuous material (e.g., a stamped metal component) or can be a wire mesh construction, which can generally be 304 stainless steel wire from 80 mesh / wire diameter 0.0055 inch up to 10 mesh / wire diameter 0.089 inch which may provide the benefit in terms of composite strength when encapsulate with elastomericmaterial of flexible rigid material such as Hostaform or Riteflex. The former belongs to the polyoxymethylene (POM) family while the latter is thermoplastic polyester elastomer (TCP-ET) have a size of about 0.0075 m of wire filament. Furthermore, in embodiments, reinforcement member 178 may be encapsulated by first flexible material 176 such that reinforcement member 178 resides wholly within first flexible material 176.

[0050] In embodiments, either or both of first flexible material 164 and first flexible material 176 may be made from a variety of materials and include a variety of material characteristics. For example, either or both of first flexible material 164 and first flexible material 176 can be made of an elastomeric or plastic material. In embodiments, the elastomeric material can include a hardness of 60-70 shore A or greater. Elastomeric material may include but not limited to thermoplastic polyurethane, thermoplastic elastomer, liquid silicone rubber, or other elastomeric compositions. In other embodiments, either or both of first flexible material 164 and flexible material 176 can be made from impact resistant plastic such as polyoxymethylene or its variants. Either or both of first flexible material 164 and first flexible material 176 can be made of a liquid silicone robber material. In embodiments, the liquid silicone robber material can have a hardness of 70-80 shore A or greater. Either or both of first flexible material 164 and first flexible material 176 can be made with elastomeric material and liquid silicone rubber composition. In embodiments, the elastomeric and liquid silicone rubber composition can have a hardness of 70-80 shore A or greater. Either or both of first flexible material 164 and first flexible material 176 can be made with flexible rigid plastic, such as, for example. an impact resistant polyoxymethylene (POM) family with a hardness range '76-85 Shore D or with thermoplastic polyester elastomer (TCP-ET). The later provides flexibility to vary the hardness range from 35-77 Shore D. The use of flexible rigid plastics of hardness higher than elastomeric materials for encapsulation of the wire mesh can increase the composite strength of the drive system.

[0051] Referring specifically to FIG. 3, first flexible material 164 of first leg 124 includes a first portion 184 on a first side of reinforcement member 166 and a second portion 186 on an opposing side of the first side of reinforcement member 166. In embodiments, first leg 124 may only include one of first portion 184 or second portion 186. In such embodiments, registration surfaces may be formed in reinforcement member 166 to account for whichever of first portion 184 or second portion 186 is not present. Similar to first flexible material 164, first flexible material 176 of second leg 126 includes a first portion 188 on a first side of reinforcement member 178 and a second portion 190 on an opposing side ofthe first side of reinforcement member 178. In embodiments, second leg 126 may only include one of first portion 188 or second portion 190. In such embodiments, registration surfaces may be formed in reinforcement member 178 to account for whichever of first portion 188 or second portion 190 is not present.

[0052] In embodiments, one or the other of first leg 124 and second leg 126 may not include reinforcement member 166 or reinforcement member 178, respectively.

[0053] First portion 132 of first leg 124 includes a second registration surface 148 on second side 135 which is configured to engage a second registration surface 150 on second side 145 of first portion 134 of second leg 126. Each of second registration surface 148 and second registration surface 150 are complementary such that one is configured to engage with the other. In the illustrated embodiment, second registration surface 148 includes a plurality of teeth and second registration surface 150 includes a plurality of teeth complementary to the plurality of teeth of second registration surface 148. The teeth are repeated along a length of the first leg 124 to match corresponding repetition along the second leg 126. In embodiments, the pattern of teeth in one or both of first leg 124 and second leg 126 might not be repeated. The sides of teeth of second registration surface 148 may contact the sides of the teeth of second registration surface 150 to coordinate movement and force transmitted along plunger rod 122 and to plunger 106. In embodiments, ends of the teeth of second registration surface 148 and ends of teeth of second registration surface 150 may be in contact during a driven operation. In other embodiments, only a portion of each of teeth of second registration surface 148, teeth of second registration surface 150, and respective ends of the teeth, may be in contact during a driven operation.

[0054] Registration surface 140 extends over a portion of the entirety of length of first side 133 of first leg 124 as can be seen in the embodiment of FIGS. 3 and 5. Likewise, first registration surface 144 extends over a portion of the entirety of length of first side 143 of second leg 126. In embodiments, either or both of first registration surface 140 and first registration surface 144 may extend over the entirety of length of the first side (e.g., FIG. 2).

[0055] Registration surface 148 extends over a portion of the entirety of length of second side 135 of first leg 124 as can be seen in the illustrated embodiment. Likewise, second registration surface 150 extends over a portion of the entirety of length of second side 145 of second leg 126. In embodiments, either or both of first registration surface 148 andfirst registration surface 150 may extend over the entirety of length of respective first leg 124 and second leg 126.

[0056] Engagement of first portion 132 of first leg 124 with first portion 134 of second leg 126 may result in an interlocked engagement of first leg 124 with second leg 126. An advantage, among others, of such interlocked engagement is that it may discourage uncoupling of the first leg 124 and second leg 126 so as to provide a reliable force exerted to expel fluid drug 112 from container 108. The plunger drive systems described here can be beneficial in applications where a constant force is required for dose accuracy, that is, consistency in receiving a full dose which is exemplified by delivering several doses and all doses staying within a tight range (measured by mean / standard deviation etc.). The composite structure for the plunger drive system can be less prone to stress relaxation and creep, allowing it to provide consistent performance.

[0057] Further description below is provided of the interlocked nature of first portion 132 with first portion 134. Plunger rod 122 therefore includes a first portion comprised of interlocked engagement of first portion 132 with first portion 134. Since first leg 124 and second leg 126 are also circumferentially engaged with at least a portion first roller 128 and second roller 130, respectively, plunger rod 122 also includes second portion 136 of first leg 124 that is not interlocked with a second portion 138 of second leg 126.

[0058] Turning now more specifically to FIGS. 4 and 5, housing 118 includes first housing portion 118a and second housing portion 118b which, when mated together, enclose at least a portion of plunger rod 122. As appreciated from the discussion above, second portion of plunger rod 122, which includes the engaged first leg 124 and second leg 126, protrudes from an opening in housing 118 so as to engage injector 104. First housing portion 118a and second housing portion 118b can be coupled together using any suitable technique, including reversible coupling (e.g., threaded fasteners, clips, etc.) and irreversible coupling (e.g., rivets, chemical bonding, ultrasonic welding, etc.).

[0059] First housing portion 118a is configured to support bearing 152a and bearing 152b which are used to provide an interface between rotatable first roller 128 and second roller 130 and static first housing portion 118a. In embodiments, bearing 152a and bearing 152b may take the form of any suitable bearing, including a plain bearing, ball bearing, conical bearing, etc. Bearing 152a and bearing 152b include an outer surface 154a and outer surface 154b, respectively, configured to be operatively coupled to first housing portion 118a.Bearing 152a and bearing 152b also include an inner surface 156a and inner surface 156b, respectively, configured to be operatively coupled to first roller 128 and second roller 130. In embodiments, bearing 152a and 152b may be a washer having a material type that provides suitable friction properties to permit relative motion between first roller 128 and first housing portion 118a and second roller 130 and first housing portion 118a, respectively.

[0060] Second housing portion 118b is configured to support bearing 158a and bearing 158b which are used to provide an interface between rotatable first roller 128 and second roller 130 and static second housing portion 118b. In embodiments, bearing 158a and bearing 158b may take the form of any suitable bearing, including a plain bearing, ball bearing, conical bearing, etc. Bearing 158a and bearing 158b include an outer surface 160a and outer surface 160b, respectively, configured to be operatively coupled to second housing portion 118b. Bearing 158a and bearing 158b also include an inner surface 162a and inner surface 162b, respectively, configured to be operatively coupled to first roller 128 and second roller 130.

[0061] An advantage of the embodiment depicted in FIG. 5, among others, is the ease of assembly of plunger drive system 102. For example, the individual component parts (e.g., first leg 124, second leg 126, first roller 128, second roller 130, inner surface 156a, inner surface 156b, etc.) can be easily stacked up and assembled as an integrated unit.

[0062] As illustrated in FIGS. 2, 3, and 5, plunger drive system 102 also includes a foot 192 useful to couple the free ends, that is, second end 174 of first leg 124 to second end 182 of second leg 126, and to discourage uncoupling of second registration surface 148 of first leg 124 from second registration surface 150 of second leg 126. Foot 192 is also useful to engage plunger 106 of injector 104. Further details of foot 192 are discussed below in FIGS. 14-19.

[0063] FIGS. 3, 6, 7, and 9 illustrate an anchor 194 at first end 172 of first leg 124 that is used to secure first leg 124 to first roller 128. Anchor 194 is integrally formed with the first flexible material 164. In embodiments, anchor 194 can be attached to first leg 124 through any suitable technique, including reversible coupling (e.g., threaded fasteners, clips, etc.) and irreversible coupling (e.g., rivets, chemical bonding, ultrasonic welding, etc.). First roller 128 includes a slot 196 sized to receive anchor 194. The slot 196 may be defined within the circumferential surface of the first roller 128 and / or the lateral surface of the first roller. The anchor 194 may access slot 196 via the lateral surface of the first roller. Theanchor and slot connection between first leg 124 and first roller 128 is used to further ensure that first leg 124 does not slip on first roller 128 when electric motor 116 applies a force to extend column 159. Anchor 194 may have a foot having a size greater than the slot portion along the circumferential surface to inhibit removal of the anchor in the radial direction. A similar anchor and slot coupling is used with second leg 126 and second roller 130. In embodiments, the anchor and slot connection may be replaced and / or augmented through use of any suitable technique, including reversible coupling (e.g., threaded fasteners, clips, etc.) and irreversible coupling (e.g., rivets, chemical bonding, ultrasonic welding, etc.). In further embodiments, the anchor and slot connection may be replaced by bonding the first leg 124 to first roller 128. In some embodiments, as described later, the first ends of the legs are not anchored to the roller but are free ends that may be positioned around a portion of the roller or dangling within the housing.

[0064] FIGS. 7, 8, and 10-12 illustrate in greater detail the engagement between first leg 124 and first roller 128, as well as greater detail of the engagement between first leg 124 and second leg 126. Registration surface 148 of first leg 124 can be seen in both first portion 132 (FIGS. 7-10 and 12) and second portion 136 (FIGS. 7-11). Registration surface 150 of second leg 126 can be seen in both first portion 134 (FIGS. 7-10 and 12) and second portion 138 (FIGS. 7-11). As discussed above, second registration surface 148 and second registration surface 150 are configured to engage each other to form column 159, and in the illustrated embodiment each include a plurality of teeth. Further details of the teeth configuration can be seen in FIGS. 7-12. The teeth configuration may inhibit the interlocked portion of legs from moving laterally away from one another from the pressure of buckling and / or form local resultant forces generated from the push and reaction forces. For example, second registration surface 148 includes a plurality of teeth 198 configured to engage a plurality of teeth 200 of second registration surface 150. Teeth 198 are shaped to include a head 202 and neck 204; teeth 200 are likewise shaped to include a head 206 and neck 208. When first leg 124 is engaged with second leg 126, head 202 of second registration surface 148 is configured to be located between neighboring teeth 200 of second registration surface 150, and specifically, between necks 208 of neighboring teeth 200. Likewise, when second leg 126 is engaged with first leg 124, head 206 of second registration surface 150 is configured to be located between neighboring teeth 198 of second registration surface 148, and specifically, between necks 204 of neighboring teeth 198. A circumferential distance occupied by neck 204 and neck 208 is larger than a circumferential distance betweenneighboring heads 202 and between neighboring heads 206, respectively. Thus, the compliant nature of each of first flexible material 164 and first flexible material 176 permits compression of head 202 and head 206 and / or flexure of teeth 198 and teeth 200 (e.g., flexure about neck 204 and neck 208) to provide insertion of the respective head 202 and head 206 into its appropriate space when first leg 124 is engaged with second leg 126. In embodiments, second registration surface 148 may be engaged with second registration surface 150 by interlacing respective heads 202 and heads 206 through a progressive flexure action akin to a zipper. An exterior surface that runs along teeth 198 of second registration surface 148 to include neck 204 and head 202 may be in contact with an exterior surface that runs along teeth 200 of second registration surface 150 to include neck 208 and head 206. As can be seen in FIG. 12, less than the entirety of the exterior surface that runs along teeth 198 of second registration surface 148 to include neck 204 and head 202 may be in contact with an exterior surface that runs along teeth 200 of second registration surface 150 to include neck 208 and head 206. In embodiments, the entirety of the exterior surface that runs along teeth 198 of second registration surface 148 to include neck 204 and head 202 may be in contact with an exterior surface that runs along teeth 200 of second registration surface 150 to include neck 208 and head 206.

[0065] FIG. 13 illustrates another view of column 159 as second leg 126 is engaged with second leg 126 via second registration surface 148 and second registration surface 150. As illustrated in the embodiment of FIG. 13, second registration surface 148 is substantially engaged with second registration surface 150 over a substantial entirety of contact surface including teeth 198 and teeth 200.

[0066] FIGS. 14-19 illustrate various embodiments of foot 192 as well as coupling of foot 192 to column 159. In any of the embodiments depicted in FIGS. 14-19, foot 192 may be injection molded having a snap-on feature useful to be coupled to column 159. Foot 192 can be used to hold together first portion 132 of first leg 124 with first portion 134 of second leg 126, or at least increase the ability of second registration surface 148 of first leg 124 to remain engaged with second registration surface 150 of second leg 126. In embodiments, foot 192 can be ultrasonically softened to fill one or more cavities in the engagement of first portion 132 of first leg 124 with first portion 134 of second leg 126.

[0067] FIG. 14 illustrates a cutaway section in which foot 192 includes a lip 210 configured to be inserted into a slot 212 of column 159. Slot 212 is formed in both of first leg 124 and second leg 126 which constitute column 159. In embodiments, slot 212 may beformed in only one of first leg 124 and second leg 126. As illustrated, slot 212 is formed on a surface of column 159 where second registration surface 148 engages second registration surface 150. In embodiments, slot 212 may be formed on another surface of column 159 which does not intrude upon the engagement of second registration surface 148 with second registration surface 150. For example, slot 212 can be formed in one or both of a surface of first leg 124 and second leg 126 which does not interfere with engagement of second registration surface 148 with second registration surface 150. For example, FIGS. 15 and 16 illustrate lip 210a of foot 192a fit within slot 212 of first leg 124 and slot 212 of second leg 126 on a surface of first leg 124 and second leg 126, respectively, that does not intrude upon engagement of second registration surface 148 and second registration surface 150.

[0068] FIGS. 17 and 18 illustrate an end 214 of foot 192b that resembles a pitched roof with a chamfered end, as opposed to a blunt end of foot 192 illustrated in FIGS. 14-16 and 19. The ends of the legs 124, 126 are shown modified with a chamfered surface that is sized and shaped to fit within the foot 192b. FIG. 19 illustrates a cross sectional view of the embodiment of the foot 192 of FIG. 14 illustrating slot 212 on opposing sides of column 159a that receives the lip 210. End of column 159a illustrates the ends of the legs 124, 126 are integrated as a single structure end 127 and the legs 124, 126 extend outward from the integrated end 127 and interlocked together as shown in FIG. 9.

[0069] FIGS. 20-25 illustrate various embodiments of plunger drive system 102 having electric motor 116 operatively coupled with each of first roller 128 and second roller 130 through transmission 216. FIGS. 20-21 include transmission 216 in the form of a worm gear 218 driving a spur gear 220a and spur gear 220b which are operatively coupled with each of first roller 128 and second roller 130, respectively. Spur gear 220a and spur gear 220b are affixed to each of first roller 128 and second roller 130 through any suitable technique, including reversible coupling (e.g., threaded fasteners, clips, etc.) and irreversible coupling (e.g., rivets, chemical bonding, ultrasonic welding, etc.). As will be appreciated, worm gear 218 interfaces with spur gear 220a and spur gear 220b through a screw-follower action such that rotation of worm gear 218 via activation of electric motor 116 will cause corresponding rotation of spur gear 220a and spur gear 220b through the screw-follower action. In the embodiment of FIGS. 20-21, rotation of electric motor 116 is directly translated to rotation of worm gear 218. In embodiments, additional gearing can be used to provide a speed changer, provide a change in output direction of electric motor 116, and / or change rotation of electric motor 116 to a translation motion.

[0070] FIGS. 22-23 include transmission 216 in the form of ratchet wheel 222 driving spur gear 220a and spur gear 220b. Ratchet wheel 222 is in the form of a spring-loaded lever arm 224 and is coupled with a ratchet 226a and ratchet 226b useful to ensure one-way motion of column 159 upon activation of electric motor 116. Spur gear 220a and spur gear 220b are affixed to each of first roller 128 and second roller 130 through any suitable technique, including reversible coupling (e.g., threaded fasteners, clips, etc.) and irreversible coupling (e.g., rivets, chemical bonding, ultrasonic welding, etc.). As will be appreciated, ratchet wheel 222 interfaces with spur gear 220a and spur gear 220b through a lever action of spring-loaded lever arm 224. Spring-loaded lever arm 224 in conjunction with spur gear 220a and spur gear 220b can be sized to provide a variety of doses. For example, spur gear 220a and spur gear 220b having a high number of relatively small teeth may provide for relatively small doses compared to spur gear 220a and spur gear 220b having a low number of relatively large teeth. Plunger drive system 102 can provide, for example, 5-6 doses in embodiments in which spur gear 220a and spur gear 220b have relatively large teeth, and can provide, for example, 15-20 doses in embodiments in which spur gear 220a and spur gear 220b have relatively small teeth. In the embodiment of FIGS. 22-23, rotation of electric motor 116 is translated to rotation of spring-loaded lever arm 224. In embodiments, additional gearing can be used to provide a speed changer, provide a change in output direction of electric motor 116, and / or change rotation of electric motor 116 to a translation motion.

[0071] FIGS. 24-25 include transmission 216 in the form of a screw and guide rod 228 driving spur gear 220a and spur gear 220b. Screw and guide rod 228 includes a rack 230 having a registration surface which engages a corresponding registration surface of each of spur gear 220a and spur gear 220b. Spur gear 220a and spur gear 220b are affixed to each of first roller 128 and second roller 130 through any suitable technique, including reversible coupling (e.g., threaded fasteners, clips, etc.) and irreversible coupling (e.g., rivets, chemical bonding, ultrasonic welding, etc.). Rack 230, upon activation of electric motor 116, is configured to translate causing an interengagement of spur gear 220a and spur gear 220b via respective registration surfaces to rotate first roller 128 and second roller 130, respectively. In the embodiment of FIGS. 24-25, rotation of electric motor 116 is translated to translation of rack 230. In embodiments, additional gearing can be used to provide a speed changer, provide a change in output direction of electric motor 116, and / or operatively couple a gear mounted to an output shaft of electric motor 116 directly to the rack 230.

[0072] With reference to FIG. 12, tooth geometry can be at least one of improve ease of interlocking of the teeth during formation of the column and improve resistance to separation of the legs after the column is formed. With the angle having a reference extending radially, an engagement angle (shown as angle a in FIG. 12) of the tooth from about 30 degrees and 40 degrees has been found to be beneficial. In one example, the engagement angle is 36 degrees. In other tooth configurations, the head of the teeth can be enlarged relative to the neck to define a T-configuration. In another embodiment, the head of the teeth can have hook like features.

[0073] Plunger drive systems described herein can provide the legs of the drive that are held in by the respective rollers. The roller diameter can control the drive leg’s length. The pliability or flexing of the drive legs may prevent the use of a reinforcement member such as a coarser mesh, to provide a higher composite strength to the column structure. There is a balance between the column strength of the plunger column and the flexibility for a smaller size roller diameter. That is, to miniaturize the plunger drive system smaller rollers will be needed, and in order to obtain a sufficiently high column strength to push the plunger, a more robust reinforcement member, such as a coarser wire mesh, may be difficult to wind the leg drive elements around the roller. To this end, the idea is to reduce the diameter of the roller, the leg element may not have an anchor coupled to the roller. Without such anchoring, this may provide the ability to use a coarser wire mesh to facilitate a more forceful push of the plunger. The pinching of the leg drive elements with the traction features along the roller and the interlocking teeth between the leg elements should be sufficient to drive the plunger. The extra length of the leg drive elements will be free-floating on top, that is not anchored to the roller. The free end of the leg drive elements may be curled around a portion of the roller or could be made to walk / meander around the top comers of the of the compartment somehow (or even drop-down sideways).

[0074] It should be understood that the various systems, components, features, and methods described relative to these embodiments may be used either individually and / or in any desired combination as the disclosure is not limited to only the specific embodiments described herein. For example, while plunger drive system 102 is described as useful with injector 104 in the form of a bolus injector, plunger drive system 102 may be used with any type of injector which is used to set and deliver a predetermined dose of a medication, such as pen injectors, autoinjectors, infusion, and syringes. The medication may be any one of a type that may be delivered by such a device. The device may be a reusable device capable ofreceiving a replaceable and disposable cartridge of medication or may be an entirely disposable device with a prefilled reservoir of medication.

[0075] While this invention has been described as having exemplary designs, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come with known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

[0076] Various aspects are described in this disclosure, which include, but are not limited to, the following aspects:

[0077] In some embodiments, the reinforcement member is elongate and extends between a first end of the at least one of the legs and a second end of the at least one of the legs.

[0078] In some embodiments, the reinforcement member one of a wire mesh construction, monolithic metal, or a polymer material.

[0079] In some embodiments, the gear drivable features include a plurality of gear teeth, and wherein the first roller includes a plurality of roller gear teeth sized to cooperate with the plurality of gear teeth of the at least one of the first leg and the second leg.

[0080] In some embodiments, the plunger rod and drive system coupled with a housing, and wherein the drive system includes at least one of a worm gear, a ratchet wheel, and a guide rod.

[0081] In some embodiments, the drive system is configured to force the teeth of the first leg into interlocking engagement with the teeth of the second leg.

[0082] In some embodiments, a foot integrated with the column of the plunger rod and located at an end of the column, a coupling interface between the foot and the plunger rod having a lip received in a slot to form a lip-slot connection, the lip-slot connection discouraging removal of the foot from the plunger rod.

[0083] In some embodiments, the first leg includes an anchor end secured to the first roller.

[0084] In some embodiments, a foot is coupled around ends of the first leg and the second leg.

[0085] In some embodiments, a first portion of the first flexible material is positioned on a first side of the first reinforcement member, and wherein a second portion of the first flexible material is positioned on a second side of the first reinforcement member.

[0086] In some embodiments, the first portion of the first flexible material includes the first registration surface of the first leg, and wherein the second portion of the first flexible material includes the second registration surface.

[0087] In some embodiments, the first portion of the flexible material includes a coupling interface configured to be coupled to the first roller.

[0088] In some embodiments, the first leg and the second leg are at least partially wrapped around the first roller and the second roller, respectively, such that a portion of the first leg and a portion of the second leg are not interlocked and do not form the column.

[0089] In some embodiments, the first flexible material is positioned on a side of the first reinforcement member.

[0090] In some embodiments, the first flexible material includes a first registration surface configured to engage with a first registration surface of the first roller.

[0091] In some embodiments, the first registration surface of the first flexible material extends only partially between a first end of the first leg and a second end of the first leg.

Claims

WHAT IS CLAIMED IS:

1. A plunger drive system for expelling a fluid drug, comprising:a plunger rod comprising a first leg and a second leg, each of the first leg and the second leg comprising a flexible body with a first side having gear drivable features and a second side, opposite the first side, having teeth, the teeth of the first leg configured to confront and interlock with the teeth of the second leg to form a column;at least one of the first leg and the second leg having a composite construction including a first material comprising the flexible body and a reinforcement member coupled to the first material; anda drive system having a motor, a first roller associated with the first leg, and a second roller associated with the second leg, at least one of the first roller and the second roller configured to be driven by the motor;wherein the column is configured to increase in length when the first roller and the second roller are driven by the motor, wherein an increase in length of the column causes expulsion of the fluid drug.

2. The plunger drive system of claim 1, wherein the reinforcement member is elongate and extends between a first end of the at least one of the legs and a second end of the at least one of the legs.

3. The plunger drive system of claim 2, wherein the reinforcement member one of a wire mesh construction, monolithic metal, or a polymer material.

4. The plunger drive system of any one of claims 1-3, wherein the gear drivable features include a plurality of gear teeth, and wherein the first roller includes a plurality of roller gear teeth sized to cooperate with the plurality of gear teeth of the at least one of the first leg and the second leg.

5. The plunger drive system of any one of claims 1-4, further comprising a housing, wherein the plunger rod and drive system coupled with the housing, and wherein the drive system includes at least one of a worm gear, a ratchet wheel, and a guide rod.

6. The plunger drive system of any one of claims 1-5, wherein the drive system is configured to force the teeth of the first leg into interlocking engagement with the teeth of the second leg.

7. The plunger drive system of any one of claims 1-6, further comprising a foot integrated with the column of the plunger rod and located at an end of the column, a couplinginterface between the foot and the plunger rod having a lip received in a slot to form a lip-slot connection, the lip-slot connection discouraging removal of the foot from the plunger rod.

8. The plunger drive system of any one of claims 1-7, wherein the first leg includes an anchor end secured to the first roller.

9. The plunger drive system of any one of claims 1-6, 8, further comprising a foot coupled around ends of the first leg and the second leg.

10. A plunger drive system for expelling a fluid drug, comprising:a first leg of a plunger rod having a flexible body with a first side having a first registration surface and a second side, opposite the first side, having a second registration surface, the flexible body of the first leg including a composite construction having a first flexible material and a first reinforcement member coupled to the first flexible material, the first flexible material having a compliance higher than a compliance of the first reinforcement member;a second leg of the plunger rod having a flexible body with a first side having a first registration surface and a second side, opposite the first side, having a second registration surface, the second registration surface of the second leg configured to confront and interlock with the second registration side of the first leg to form a column; anda drive system having a motor, a first roller associated with the first leg, and a second roller associated with the second leg, at least one of the first roller and the second roller configured to be driven by the motor having a first registration surface configured to interengage with the first registration surface from the at least one of the first roller and the second roller;wherein during a first mode of operation, driven rotation of the at least one of the first roller and the second roller by the motor increase a length of the column to cause expulsion of the fluid drug.

11. The plunger drive system of claim 10, wherein a first portion of the first flexible material is positioned on a first side of the first reinforcement member, and wherein a second portion of the first flexible material is positioned on a second side of the first reinforcement member.

12. The plunger drive system of claim 11, wherein the first portion of the first flexible material includes the first registration surface of the first leg, and wherein the second portion of the first flexible material includes the second registration surface.

13. The plunger drive system of claim 12, wherein the first portion of the flexible material includes a coupling interface configured to be coupled to the first roller.

14. The plunger drive system of any one of claims 10-13, wherein the first leg and the second leg are at least partially wrapped around the first roller and the second roller, respectively, such that a portion of the first leg and a portion of the second leg are not interlocked and do not form the column.

15. The plunger drive system of any one of claims 10-14, wherein the second leg includes a second flexible material a second reinforcement member coupled to the second flexible material, wherein a first portion of the second flexible material is positioned on a first side of the second reinforcement member, and wherein a second portion of the second flexible material is positioned on a second side of the second reinforcement member, and wherein the first portion of the second flexible material includes the first registration surface of the second leg, and wherein the second portion of the second flexible material includes the second registration surface.

16. The plunger drive system of any one of claims 10-15, wherein the second registration surface of the first leg includes a cross sectional shape including a head with a head axial length and a neck with a neck axial length, the neck axial length shorter than the head axial length, wherein the head of the second registration surface of the first leg is fit between neighboring necks of the second registration surface of the second leg.

17. A plunger drive system, comprising:a housing having an opening at a first end;a plunger rod having a first leg and a second leg, at least a portion of the plunger rod disposed within the housing, the first leg having a first portion interlocked with a first portion of the second leg to form a column, the first leg having a second portion that is not interlocked with a second portion of the second leg; anda drive system having a first roller at least partially disposed in the housing and a second roller at least partially disposed in the housing, the second portion of the first leg positioned within the housing and circumferentially engaged with at least a portion of the first roller at a radial distance, the second portion of the second leg positioned within the housing and circumferentially engaged with at least a portion of the second roller at a radial distance;wherein the first leg includes a composite construction having a first flexible material and a first reinforcement member, the first reinforcement member configured to provide abuckling load of the column higher than a buckling load of the column if the first leg did not include the first reinforcement member, the first reinforcement member having a compliance that permits the first reinforcement member to be circumferentially oriented when the at least portion of the first roller is circumferentially engaged at the radial distance.

18. The plunger drive system of claim 17, wherein the first flexible material is positioned on a side of the first reinforcement member.

19. The plunger drive system of claim 18, wherein the first flexible material includes a first registration surface configured to engage with a first registration surface of the first roller.

20. The plunger drive system of any one of claims 17-19, wherein the first registration surface of the first flexible material extends only partially between a first end of the first leg and a second end of the first leg.

Images