System and method for engaging a syringe plunger

Abstract

A plunger for use with a syringe has a plunger body having a proximal end, a distal end, and a circumferential sidewall extending along the longitudinal axis of the plunger between the proximal and distal ends. The plunger also has at least one resiliently deflectable retaining member having a first section attached to the plunger body and a second section projecting toward the distal end of the plunger body and deflectable relative to the first section. The plunger also has at least one actuating member associated with the at least one resiliently deflectable retaining member. The at least one actuating member interacts with the piston to deflect the at least one resiliently deflectable retaining member when the plunger rotates relative to the piston. The plunger is engageable with the piston regardless of the rotational orientation of the piston relative to the plunger.

Description

[0001] This application is a divisional application of the Chinese application with application number 202110333805.8 filed on October 28, 2016, entitled “System and method for engaging a syringe plunger”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Patent Application No. 14 / 925,722, filed on October 28, 2015, entitled “System and Method for SyringePlunger Engagement with an Injector,” the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] The present disclosure generally relates to systems including front-loaded or front-mounted syringes for use with fluid injectors, and also to connection interfaces for securing a syringe plunger to a piston of a fluid injector, and to methods of engaging or disengaging a syringe plunger to or from a piston of a fluid injector. Background Art

[0005] In many medical diagnostic and treatment procedures, medical practitioners, such as physicians, administer one or more medical fluids to patients. In recent years, numerous syringe-actuated syringes and fluid injectors have been developed for pressurized injection of fluids, such as contrast media solutions (often referred to simply as "contrast media"), flushing agents such as saline, and other medical fluids, for use in procedures such as angiography, computed tomography (CT), ultrasound, magnetic resonance imaging (MRI), nuclear medicine, positron emission tomography (PET), and other imaging procedures. Generally, these fluid injectors are designed to deliver a preset amount of fluid at a preset flow rate.

[0006] Various connection interfaces have been developed for the engagement of syringe plunger and the piston of fluid injector. In some aspects, by aligning syringe with the corresponding locking feature provided on fluid injector, the syringe with retention feature is inserted into the syringe port on the fluid injector. Such alignment also aligns the plunger in the syringe with the piston on the fluid injector so that piston can engage plunger, and drives plunger through the syringe barrel, to extract fluid into the syringe barrel, or deliver fluid from the syringe barrel. In other aspects, once engaging with the plunger, the piston can rotate in a clockwise or counterclockwise direction, until the catch (catch) on the piston engagement plunger. In other aspects, the piston has one or more radially extendable pins that engage the lip on the plunger.

[0007] The structure of many existing connection interfaces needs to have the complicated piston head of various sensor elements and active engagement structure.In the art, need improved connection interface, it allows syringe plunger and the piston of fluid injector to engage and separate more simply and more easily.In the art, also need to reduce or eliminate the operator and syringe and fluid injector rotation alignment, to allow the needs of syringe plunger and the piston of described fluid injector to correctly engage.In the art, also need to reduce the rotation angle that operator rotates syringe to release syringe plunger and piston in order to remove syringe.Although various syringe plunger connection interfaces and methods are known in the medical field, still need the improved connection interface between syringe plunger and the piston of fluid injector, and the method for syringe plunger and the piston of fluid injector to engage and separate. Summary of the Invention

[0008] In view of the shortcomings of the existing connection interface between the syringe plunger and the piston of the fluid injector, there is a need in the art for an improved connection interface between the syringe plunger and the piston of the fluid injector to overcome the shortcomings of the prior art. There is also a need for an improved method for engaging and disengaging the syringe plunger with the piston of the fluid injector to allow easy loading and removal of the syringe and the fluid injector.

[0009] According to some aspects, a plunger for use with a syringe can have a plunger body having a proximal end, a distal end, and a circumferential sidewall extending along a longitudinal axis of the plunger between the proximal and distal ends. The plunger can have at least one resiliently deflectable retaining member having a first section attached to the plunger body and a second section projecting toward the distal end of the plunger body and resiliently deflectable relative to the first section, and at least one actuating member associated with the at least one resiliently deflectable retaining member. The at least one actuating member can interact with a piston for engaging the plunger to deflect the at least one resiliently deflectable retaining member when the plunger rotates relative to the piston.

[0010] According to other aspects, at least one alignment member can be associated with the plunger body or the at least one resiliently deflectable retaining member. The at least one alignment member can have an alignment surface to guide the piston into self-orienting alignment with the plunger. The at least one alignment member can have a plurality of alignment members spaced about the longitudinal axis of the plunger. The plurality of alignment members can be spaced at equal radial spacings about the longitudinal axis of the plunger. The second section of the at least one resiliently deflectable retaining member can be radially deflected away from the longitudinal axis of the plunger relative to the first section. The at least one resiliently deflectable retaining member can be linearly or curvilinearly continuous between the first section and the second section. The second section of the at least one resiliently deflectable retaining member can be angled toward the longitudinal axis of the plunger.

[0011] According to other aspects, at least one actuating member can be disposed on a surface of at least one resiliently deflectable retaining member. The at least one actuating member can be at a second section of the at least one resiliently deflectable retaining member. The at least one actuating member can be angled relative to a plane defined by the body of the at least one resiliently deflectable retaining member. The at least one resiliently deflectable retaining member can have a plurality of resiliently deflectable retaining members spaced about the longitudinal axis of the plunger. The plurality of resiliently deflectable retaining members can be spaced at equal radial spacing about the longitudinal axis of the plunger. The end surface of the second section of the at least one resiliently deflectable retaining member can engage a surface of the piston to releasably lock the plunger to the piston. The end surface can be linear. The end surface can be perpendicular or angled relative to the direction of the longitudinal axis of the plunger.

[0012] According to other aspects, the plunger body can define an inner cavity having a conical portion at the distal end of the plunger body and a cylindrical portion at the proximal end of the plunger body. The first section of the at least one elastically deflectable member can be attached to the inner surface of the plunger body. The at least one elastically deflectable retaining member can protrude from the inner surface of the plunger body into the inner cavity. The plunger cover can be disposed over at least a portion of the outer surface of the plunger body. The plunger cover can have an elastic seal disposed around at least a portion of the circumferential sidewall of the plunger cover. The elastic seal can have an inner surface that is at least partially seated in a groove in the circumferential sidewall of the plunger body and an outer surface adapted to slidably engage with the barrel of the syringe. The actuating member can be a cam member.

[0013] According to other aspects, a plunger for use with a syringe may include a plunger body having a proximal end, a distal end, and a circumferential sidewall extending along the longitudinal axis of the plunger between the proximal and distal ends. The plunger may include at least one resiliently deflectable retaining member having a first section attached to the plunger body and a second end projecting toward the distal end of the plunger body and resiliently deflectable relative to the first section, as well as at least one alignment member associated with the plunger body or the at least one resiliently deflectable retaining member. During engagement of the plunger with the piston, the at least one alignment member may guide the piston into self-alignment with the plunger. The plunger may include at least one actuating member associated with the at least one resiliently deflectable retaining member. The at least one actuating member may interact with the piston to deflect the at least one resiliently deflectable retaining member when the plunger rotates relative to the piston during separation from the piston. The distal surface of the second section of the at least one resiliently deflectable retaining member may engage a surface of the piston to releasably lock the plunger to the piston. The at least one actuating member may be located at the second section of the at least one resiliently deflectable retaining member. The second section of the at least one resiliently deflectable retaining member is radially deflectable relative to the first section away from the plunger longitudinal axis.

[0014] According to other aspects, a plunger for use with a syringe can have a plunger body having a proximal end, a distal end, and a circumferential sidewall extending along the longitudinal axis of the plunger between the proximal and distal ends. The plunger can have at least one resiliently deflectable retaining member having a first section attached to the plunger body and a second section deflectable relative to the first section, at least one alignment member associated with the plunger body or the at least one resiliently deflectable retaining member, and at least one actuating member associated with the at least one resiliently deflectable retaining member. During engagement of the plunger with the piston, the at least one alignment member can guide the piston into self-alignment with the plunger. The at least one actuating member can interact with the piston to deflect the at least one resiliently deflectable retaining member when the plunger rotates relative to the piston during separation of the plunger from the piston. The second section of the at least one resiliently deflectable retaining member can protrude toward the distal end of the plunger body, and wherein the second end of the at least one resiliently deflectable retaining member can be radially deflectable relative to the first end away from the longitudinal axis of the plunger. The second end of the at least one resiliently deflectable retaining member may project in a direction circumferentially around the longitudinal axis of the plunger body, and wherein the second end of the at least one resiliently deflectable retaining member is circumferentially deflectable relative to the first end.

[0015] According to other aspects, the barrel can have a barrel having a barrel proximal end, a barrel distal end having a discharge nozzle, and a barrel sidewall extending between the barrel proximal end and the barrel distal end. The syringe can have a plunger slidably disposed within the barrel and reciprocally movable between the barrel proximal end and the barrel distal end. The plunger can have a plunger body having a proximal end, a distal end, and a circumferential sidewall extending along the plunger longitudinal axis between the proximal end and the distal end, at least one resiliently deflectable retaining member having a first section attached to the plunger body and a second section protruding toward the distal end of the plunger body and resiliently deflectable relative to the first section, and at least one actuating member associated with the at least one resiliently deflectable retaining member. The at least one actuating member can interact with a piston for engaging the plunger to radially deflect the at least one resiliently deflectable retaining member when the plunger rotates relative to the piston.

[0016] Aspects of the present disclosure may also be characterized by one or more of the following:

[0017] Clause 1: A plunger for use with a syringe, the plunger comprising:

[0018] a plunger body having a proximal end, a distal end, and a circumferential sidewall extending along a longitudinal axis of the plunger between the proximal end and the distal end;

[0019] at least one resiliently deflectable retaining member having a first section attached to the plunger body and a second section projecting toward a distal end of the plunger body and resiliently deflectable relative to the first section; and

[0020] at least one actuating member associated with said at least one resiliently deflectable retaining member,

[0021] wherein the at least one actuation member interacts with a piston for engaging the plunger to deflect the at least one resiliently deflectable retaining member when the plunger rotates relative to the piston.

[0022] Clause 2: The plunger of clause 1, further comprising at least one alignment member associated with the plunger body or the at least one resiliently deflectable retaining member, the at least one alignment member having an alignment surface to guide the piston into alignment with the plunger self-orientation.

[0023] Clause 3: The plunger of Clause 2, wherein the at least one alignment member comprises a plurality of alignment members spaced about the plunger longitudinal axis.

[0024] Clause 4: The plunger of Clause 1, wherein the plurality of alignment members are spaced at equal radial intervals about the plunger longitudinal axis.

[0025] Clause 5: The plunger of any of clauses 1-4, wherein the second section of the at least one resiliently deflectable retaining member is radially deflectable relative to the first section, away from the plunger longitudinal axis.

[0026] Clause 6: The plunger of any of clauses 1-5, wherein the at least one resiliently deflectable retaining member is linearly or curvilinearly continuous between the first section and the second section.

[0027] Clause 7: The plunger of any of clauses 1-6, wherein the second section of the at least one resiliently deflectable retaining member is angled toward the plunger longitudinal axis.

[0028] Clause 8: The plunger of any of clauses 1-7, wherein the at least one actuation member is disposed on a surface of the at least one resiliently deflectable retaining member.

[0029] Clause 9: The plunger of Clause 8, wherein the at least one actuation member is at the second section of the at least one resiliently deflectable retaining member.

[0030] Clause 10: The plunger of any of clauses 1-9, wherein the at least one actuation member is angled relative to a plane defined by a body of the at least one resiliently deflectable retaining member.

[0031] Clause 11: The plunger of any of clauses 1-10, wherein the at least one resiliently deflectable retaining member comprises a plurality of resiliently deflectable retaining members spaced about the plunger longitudinal axis.

[0032] Clause 12: The plunger of Clause 11, wherein the plurality of resiliently deflectable retaining members are spaced apart at equal radial intervals about the plunger longitudinal axis.

[0033] Clause 13: The plunger of any of clauses 1-12, wherein a distal surface of the second section of the at least one resiliently deflectable retaining member engages a surface of the piston to releasably lock the plunger with the piston.

[0034] Clause 14: The plunger of Clause 13, wherein the end surface is linear.

[0035] Clause 15: The plunger of clause 13 or clause 14, wherein the end surface is perpendicular or angled relative to the direction of the plunger longitudinal axis.

[0036] Clause 16: The plunger of any of clauses 1-15, wherein the plunger body defines an inner cavity having a conical portion at a distal end of the plunger body and a cylindrical portion at a proximal end of the plunger body.

[0037] Clause 17: The plunger of Clause 16, wherein the first section of the at least one resiliently deflectable member is attached to an inner surface of the plunger body.

[0038] Clause 18: The plunger of Clause 17, wherein the at least one resiliently deflectable retaining member protrudes from an inner surface of the plunger body into the inner cavity.

[0039] Clause 19: The plunger of any of clauses 1-18, further comprising a plunger cover disposed over at least a portion of an exterior surface of the plunger body, the plunger cover comprising a resilient seal disposed around at least a portion of a circumferential sidewall of the plunger cover.

[0040] Clause 20: The plunger of Clause 19, wherein the resilient seal comprises an inner surface at least partially seated in a groove in a circumferential sidewall of the plunger body and an outer surface adapted to slidably engage a barrel of a syringe.

[0041] Clause 21: The plunger of any of clauses 1-20, wherein the actuation member is a cam member.

[0042] Clause 22: A plunger for use with a syringe, the plunger comprising:

[0043] a plunger body having a proximal end, a distal end, and a circumferential sidewall extending along a longitudinal axis of the plunger between the proximal end and the distal end;

[0044] at least one resiliently deflectable retaining member having a first section attached to the plunger body and a second end projecting toward a distal end of the plunger body and deflectable relative to the first section; and

[0045] at least one alignment member associated with said plunger body or said at least one resiliently deflectable retaining member,

[0046] wherein the at least one alignment member guides the piston into self-orienting alignment with the plunger during engagement of the plunger with the piston.

[0047] Clause 23: The plunger as described in Clause 22 further includes at least one actuating member associated with the at least one resiliently deflectable retaining member, wherein the at least one actuating member interacts with the piston to deflect the at least one resiliently deflectable retaining member when the plunger rotates relative to the piston during separation of the plunger from the piston.

[0048] Clause 24: The plunger of Clause 23, wherein a distal surface of the second section of the at least one resiliently deflectable retaining member engages a surface of the piston to releasably lock the plunger with the piston.

[0049] Clause 25: The plunger of Clause 23 or Clause 24, wherein the at least one actuation member is at the second section of the at least one resiliently deflectable retaining member.

[0050] Clause 26: The plunger of any of clauses 23-25, wherein the second section of the at least one resiliently deflectable retaining member is radially deflectable relative to the first section, away from the plunger longitudinal axis.

[0051] Clause 27: A plunger for use with a syringe, the plunger comprising:

[0052] a plunger body having a proximal end, a distal end, and a circumferential sidewall extending along a longitudinal axis of the plunger between the proximal end and the distal end;

[0053] at least one resiliently deflectable retaining member having a first section attached to the plunger body and a second section deflectable relative to the first section;

[0054] at least one alignment member associated with the plunger body or the at least one resiliently deflectable retaining member; and

[0055] at least one actuating member associated with said at least one resiliently deflectable retaining member,

[0056] wherein, during engagement of the plunger with the piston, the at least one alignment member guides the piston into self-orienting alignment with the plunger, and

[0057] wherein the at least one actuation member interacts with the piston to deflect the at least one resiliently deflectable retaining member when the plunger rotates relative to the piston during separation of the plunger from the piston.

[0058] Clause 28: The plunger of clause 27, wherein the second section of the at least one resiliently deflectable retaining member projects toward the distal end of the plunger body, and wherein the second end of the at least one resiliently deflectable retaining member is radially deflectable relative to the first end away from the plunger longitudinal axis.

[0059] Clause 29: A plunger as described in clause 27 or clause 28, wherein the second end of the at least one resiliently deflectable retaining member protrudes in a direction circumferentially around the longitudinal axis of the plunger body, and wherein the second end of the at least one resiliently deflectable retaining member is circumferentially deflectable relative to the first end.

[0060] Clause 30: A syringe comprising:

[0061] a barrel having a barrel proximal end, a barrel distal end having a discharge orifice, and a barrel sidewall extending between the barrel proximal end and the barrel distal end; and

[0062] A plunger is slidably disposed in the barrel and reciprocally movable between the proximal end of the barrel and the distal end of the barrel, the plunger comprising:

[0063] a plunger body having a proximal end, a distal end, and a circumferential sidewall extending along a longitudinal axis of the plunger between the proximal end and the distal end;

[0064] at least one resiliently deflectable retaining member having a first section attached to the plunger body and a second section projecting toward a distal end of the plunger body and resiliently deflectable relative to the first section; and

[0065] at least one actuating member associated with said at least one resiliently deflectable retaining member,

[0066] wherein the at least one actuation member interacts with a piston for engaging the plunger to radially deflect the at least one resiliently deflectable retaining member upon rotation of the plunger relative to the piston.

[0067] These and other features and characteristics of syringes, syringe plungers, and systems having syringes and / or syringe plungers, as well as the methods of operation and function of the related elements of the structure, and the combination of parts and manufacturing economy will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this application, in which like reference numerals refer to corresponding parts in the various drawings. However, it will be expressly understood that the drawings are for illustration and description purposes only. As used in the specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 is a top perspective view of a system including a fluid injector and at least one syringe according to aspects of the present disclosure;

[0069] Figure 2 is a side cross-sectional view of a syringe according to one aspect of the present disclosure;

[0070] Figure 3A is a top perspective view of a plunger according to one aspect of the present disclosure;

[0071] Figure 3B yes Figure 3A A bottom perspective view of the plunger shown in FIG;

[0072] Figure 3C yes Figure 3A A bottom view of the plunger shown in FIG;

[0073] Figure 3D yes Figure 3A A side view of the plunger shown in FIG;

[0074] Figure 3E yes Figure 3A A side sectional view shown in FIG;

[0075] Figure 4A is a top perspective view of a piston according to one aspect of the present disclosure;

[0076] Figure 4B yes Figure 4A An exploded perspective view of the piston shown in FIG;

[0077] Figure 4C yes Figure 4A A side view of the piston shown in FIG;

[0078] Figure 5A is a side view of the plunger and piston in the assembled state;

[0079] Figure 5B is a side cross-sectional view of the plunger and piston during initial engagement of the piston with the plunger;

[0080] Figure 5C is a side cross-sectional view of the plunger and piston prior to full engagement of the piston with the plunger;

[0081] Figure 5D is a side cross-sectional view of the plunger and piston during full engagement of the piston with the plunger;

[0082] Figure 6A is a top perspective view of a plunger according to another aspect of the present disclosure;

[0083] Figure 6B yes Figure 6A A bottom perspective view of the plunger shown in FIG;

[0084] Figure 7A yes Figures 6A-6B A perspective cross-sectional view of the plunger and the piston prior to initial engagement of the piston with the plunger;

[0085] Figure 7B yes Figure 7A A side cross-sectional view of the plunger and piston shown in FIG;

[0086] Figure 8A is a perspective cross-sectional view of the plunger and piston during initial engagement of the piston with the plunger;

[0087] Figure 8B yes Figure 8A A side partial cross-sectional view of the plunger and piston shown in FIG;

[0088] Figure 9A is a perspective cross-sectional view of the plunger and piston prior to full engagement of the piston with the plunger;

[0089] Figure 9B yes Figure 9A A side cross-sectional view of the plunger and piston shown in FIG;

[0090] Figure 10A is a perspective cross-sectional view of the plunger and piston during full engagement of the piston with the plunger;

[0091] Figure 10B yes Figure 10A A side cross-sectional view of the plunger and piston shown in FIG;

[0092] Figure 11A is a perspective cross-sectional view of the plunger and piston during initial separation as the plunger rotates relative to the piston;

[0093] Figure 11B yes Figure 11A A side cross-sectional view of the plunger and piston shown in FIG;

[0094] Figure 12Ais a perspective cross-sectional view of the plunger and piston during separation from the locking ring of the piston in the forward position;

[0095] Figure 12B yes Figure 12A A side cross-sectional view of the plunger and piston shown in FIG;

[0096] Figure 13 is a side cross-sectional view of a first adapter configured to connect an incompatible plunger to a piston according to one aspect of the present disclosure;

[0097] Figure 14 is a side cross-sectional view of a second adapter configured to connect a plunger to an incompatible piston according to one aspect of the present disclosure;

[0098] Figure 15A is a front perspective view of a piston according to another aspect;

[0099] Figure 15B yes Figure 15A A side view of the piston head shown in FIG;

[0100] Figure 15C yes Figure 15A A front perspective view of the piston shown in FIG and the plunger removed from the piston;

[0101] Figure 15D When the plunger is assembled on the piston Figure 15C A front perspective view of the piston and plunger shown in FIG;

[0102] Figure 15E yes Figure 15D A side cross-sectional view of the plunger and piston shown in FIG;

[0103] Figure 15F yes Figure 15A An exploded perspective view of the piston shown in FIG;

[0104] Figure 15G is a bottom perspective view of a plunger according to another aspect of the present disclosure;

[0105] Figure 16 yes Figure 15C A cylindrical plane projection view of the piston and plunger shown in FIG;

[0106] Figure 17 is a cylindrical plane projection view of a piston and a plunger according to another aspect of the present disclosure;

[0107] Figure 18 is a cylindrical plane projection view of a piston and a plunger according to another aspect of the present disclosure;

[0108] Figure 19is a cylindrical plane projection view of a piston and a plunger according to another aspect of the present disclosure;

[0109] Figure 20A is a top perspective view of a piston according to another aspect;

[0110] Figure 20B According to one aspect of the present disclosure Figure 20A A top perspective view of the piston and plunger shown in FIG;

[0111] Figure 20C yes Figure 20B A bottom perspective view of the plunger shown in FIG;

[0112] Figure 20D yes Figure 20C A side cross-sectional view of the plunger shown in FIG;

[0113] Figure 21A is a front perspective view of a piston and plunger according to another aspect of the present disclosure;

[0114] Figure 21B The engagement between the piston and the plunger is shown Figure 21A Detailed cross-sectional side view of;

[0115] Figure 21C The engagement between the piston and the plunger is shown Figure 21A A cross-sectional top view of

[0116] Figure 22A is a top perspective view of a plunger according to another aspect of the present disclosure;

[0117] Figure 22B yes Figure 22A A bottom perspective view of the plunger shown in FIG;

[0118] Figure 22C yes Figure 22A a cross-sectional side view of the plunger shown in , illustrating the engagement between the piston and the plunger;

[0119] Figure 22D yes Figure 22A a cross-sectional top view of the plunger shown in , illustrating the engagement between the piston and the plunger;

[0120] Figure 23A is a top perspective view of a plunger according to another aspect of the present disclosure;

[0121] Figure 23B yes Figure 23A a first cross-sectional side view of the plunger shown in , illustrating the engagement between the piston and the plunger;

[0122] Figure 23C yes Figure 23Aa second cross-sectional side view of the plunger shown in , illustrating the engagement between the piston and the plunger;

[0123] Figure 23D yes Figure 23A a cross-sectional top view of the plunger shown in , illustrating the engagement between the piston and the plunger;

[0124] Figure 24A is a top perspective view of a piston and plunger according to another aspect of the present disclosure;

[0125] Figure 24B In assembled state Figure 24A a side cross-sectional view of the piston and plunger; and

[0126] Figure 24C yes Figure 24B A top cross-sectional view of the piston and plunger is shown in FIG. DETAILED DESCRIPTION

[0127] For the purposes of the description below, the terms "upper", "lower", "right", "left", "vertical", "horizontal", "top", "bottom", "lateral", "longitudinal" and their derivatives will be associated with the components as they are oriented in the accompanying drawings. When associated with the use of a syringe and / or plunger, the term "proximal" refers to the portion of the syringe and / or plunger that is closest to the fluid syringe when the syringe and / or plunger is oriented to be connected to a fluid syringe. The term "distal" refers to the portion of the syringe and / or plunger that is farthest from the fluid syringe when the syringe and / or plunger is oriented to be connected to a fluid syringe. The term "radial" refers to the direction in a cross-sectional plane that is normal to the longitudinal axis of the syringe, plunger and / or piston extending between the proximal end and the distal end. The term "circumferential" refers to the direction around the inner or outer surface of the side wall of the syringe, plunger and / or piston. The term "axial" refers to the direction along the longitudinal axis of the syringe, plunger and / or piston extending between the proximal end and the distal end. The term "self-orienting" means that the piston head or plunger orients itself to the correct orientation relative to the plunger or piston head, respectively, without the effect of rotation by the technician or the fluid injector. The term "curvilinearity" refers to the shape of a surface having one or more curves, one or more straight lines, and one or more curves, and / or one or more straight line segments arranged non-linearly. However, it should be understood that the present invention can assume alternative variations and step sequences, unless expressly specified to the contrary. It should also be understood that the specific devices and processes shown in the accompanying drawings and described in the following description are merely exemplary aspects of the present disclosure. Therefore, the specific dimensions and other physical characteristics associated with the aspects disclosed herein are not to be considered limiting.

[0128] With reference to the accompanying drawings, in which like reference numerals refer to like parts throughout the several views, the present disclosure generally relates to a syringe plunger and a connection interface for connecting the syringe plunger to the piston of a fluid injector. Various aspects relate to a syringe plunger that can be connected to and separated from the piston. In various aspects, such a plunger can be activated manually, hydraulically, or electrically. In addition, the present disclosure provides a quick and simple solution for engaging and separating the syringe plunger from the piston without requiring a specific rotational orientation of the plunger about the longitudinal axis of the plunger relative to the longitudinal axis of the piston. For example, as described herein, regardless of the rotational orientation of the piston about the longitudinal axis of the syringe relative to the plunger, the piston can be advanced until it engages with the plunger. In addition, a simple angular rotation of the plunger relative to the piston about the longitudinal axis of the syringe can allow the two elements to separate. In certain aspects, the syringe and plunger can engage with a syringe port and a piston extending from the syringe port, respectively. The accompanying separation of the syringe from the syringe port and the plunger from the piston may require an operator or technician to manually rotate the syringe. According to various aspects, as described herein, rotation of the syringe can first cause the plunger to separate from the piston, and then the syringe to separate from the syringe port, such as described in U.S. Patent Application Serial Nos. 14 / 526,294 and 14 / 526,395, filed October 28, 2014, U.S. Patent No. 6,652,489, issued November 25, 2003, and U.S. Patent No. 7,540,856, issued June 2, 2009, the disclosures of each of which are incorporated herein by reference. In particular aspects, because rotation of the syringe also causes rotation of the plunger, due to the friction fit of the plunger within the syringe, in order to achieve separation of the plunger from the piston before the syringe can separate from the syringe port, the plunger must rotate relative to the piston to separate the plunger from the piston must be less than the rotation distance that the syringe must rotate relative to the syringe port to separate the syringe from the port. Various aspects of the present disclosure provide piston / plunger interface mechanisms having features that provide this sequential separation requirement.

[0129] refer to Figure 1, a fluid injector 10 (hereinafter referred to as "injector 10"), such as an automatic or powered fluid injector, is adapted to interface with and actuate at least one syringe 12, each of which can be independently filled with a medical fluid F, such as a contrast medium, a saline solution, or any desired medical fluid. The syringe 10 can be used during a medical procedure to inject the medical fluid into a patient by driving a plunger 26 of at least one syringe 12 with at least one piston. The syringe 10 can be a multi-syringe syringe, in which several syringes 12 can be oriented in a side-by-side arrangement or other arrangement and contain plungers 26 that are separately actuated by corresponding pistons associated with the syringe 10. In aspects where two syringes are arranged in a side-by-side relationship and filled with two different medical fluids, the syringe 10 can deliver fluid from one or both of the syringes 12.

[0130] The syringe 10 can be enclosed in a housing 14 formed of a suitable structural material (such as plastic or metal). Depending on the desired application, the housing 14 can have various shapes and sizes. For example, the syringe 10 can be a freestanding structure that is configured to be placed on the floor by a stationary or movable platform. Alternatively, the syringe 10 can be configured to be placed on a suitable table or support frame. The syringe 10 includes at least one syringe port 16 for connecting at least one syringe 12 to a corresponding piston element. In some aspects, at least one syringe 12 includes at least one syringe retaining member for retaining the syringe 12 in the syringe port 16 of the syringe 10. As described herein, at least one syringe retaining member can operably engage a locking mechanism disposed on or in the syringe port 16 of the syringe 10 to facilitate loading the syringe 12 into the syringe 10 and / or removing the syringe 12 from the syringe 10. The syringe retaining member and the locking mechanism together define a connection interface for connecting the syringe 12 to the syringe 10.

[0131] At least one fluid path kit 17 can be fluidically connected to at least one syringe 12 for delivering the medical fluid F from the at least one syringe 12 to a catheter, needle, or other fluid delivery device (not shown) inserted into the patient at a vascular access site. The fluid flow from the at least one syringe 12 can be regulated by a fluid control module (not shown). The fluid control module can operate various pistons, valves, and / or flow control structures based on user-selected injection parameters (such as injection flow rate, duration, total injection volume, and / or the ratio of contrast medium to saline) to regulate the delivery of medical fluids (such as saline solution and contrast medium) to the patient. An example of a suitable front-loading fluid injector 10 that can be modified for use with the above-described system comprising at least one syringe 12 and at least one syringe interface for connecting the at least one syringe 12 to the syringe described herein is disclosed in U.S. Patent No. 5,383,858 to Reilly et al., and U.S. Patent Application Serial Nos. 14 / 526,294 and 14 / 526,395 (both filed on October 28, 2014). Figure 1 The described fluid injector 10 is self-orientingly loaded and releasably retained, and the above-mentioned document is incorporated by reference in its entirety. Another example of a related multi-fluid delivery system that can be modified for use with the present system is found in U.S. Patent No. 7,553,294 to Lazzaro et al., U.S. Patent No. 7,666,169 to Cowan et al., International Patent Application Publication No. WO 2012 / 155035, and U.S. Patent Application Publication No. 2014 / 0027009 to Riley et al., the disclosures of which are incorporated herein by reference. Other aspects may include novel fluid injector systems designed to include various aspects of the piston plunger interface described herein.

[0132] Having described the general structure and function of the syringe 10, the at least one barrel 12 will now be discussed in greater detail. Figure 2 The syringe 12 generally has a cylindrical syringe barrel 18 formed of glass, metal, or a suitable medical grade plastic. The barrel 18 has a proximal end 20 and a distal end 24 with a sidewall 19 extending therebetween along a syringe longitudinal axis 15 extending through the center of the barrel 18. The barrel 18 can be made of a transparent or translucent material and can include at least one fluid verification member 11 (in the syringe barrel 18) for verifying the presence of a fluid F within the syringe barrel 18. Figure 118 ). A nozzle 22 extends from a distal end 24 of the barrel 18. The barrel 18 has an outer surface 21 and an inner surface or wall 23 defining an interior volume 25 for receiving a fluid therein. The proximal end 20 of the barrel 18 can be sealed with a plunger 26 that can slide through the barrel 18. The plunger 26 can have a plunger cap 58 that forms a fluid-tight seal against the inner surface 23 of the sidewall 19 of the barrel 18 as the plunger 26 travels through the barrel 18. Details of various aspects of the plunger body and plunger cap are set forth herein.

[0133] A drip flange 35 can extend radially outward from the outer surface 21 of the syringe barrel 18 relative to the longitudinal axis 15. The drip flange 35 can extend around at least a portion of the outer circumference of the barrel 18. The drip flange 35 can prevent fluid that drips from the nozzle 22 from entering the syringe port 16 on the syringe 10. In this manner, the drip flange 35 helps to reduce the amount of fluid that can enter the syringe port 16 and clog or otherwise interfere with the connection interface and / or internal mechanics and electronics of the syringe 10. In some aspects, the drip flange 35 defines a stop surface that delimits the point at which the insertion portion 30 of the syringe 12 can be inserted into the syringe port 16 (at Figure 1 The drip flange 35 may be formed integrally with the barrel 18, or it may be adhered or otherwise secured to the outer surface 21 of the barrel 18, such as using a friction fit and / or adhesive, welding, or molding. In other aspects, the drip flange 35 may be formed on the outer surface 21 of the barrel 18 by etching, laser cutting, or machining.

[0134] Continue to refer Figure 2 The proximal end 20 of the barrel 12 is sized and adapted to be removably inserted into the barrel port 16 of the syringe 10 (at Figure 1In some aspects, the proximal end 20 of the syringe 12 defines an insertion portion 30 that is removably inserted into the syringe port 16 of the injector 10, while the remainder of the syringe 12 remains outside of the syringe port 16. In certain aspects, the proximal end 20 of the syringe 12 includes one or more syringe retaining members (not shown) that are adapted to form a locking engagement with a corresponding locking mechanism in the syringe port 16 of the injector 10 to releasably retain the syringe 12 in the syringe port 16. For example, various retaining members for releasably locking the syringe 10 with the barrel 12 are described in U.S. patent application Ser. No. 14 / 526,294, filed on Oct. 28, 2014, and entitled “Self-Orienting Syringe and Syringe Interface,” and U.S. patent application Ser. No. 14 / 526,395, filed on Oct. 28, 2014, and entitled “Self-Orienting Syringe and Syringe Interface,” the disclosures of which are incorporated herein by reference in their entireties.

[0135] Reilly et al., U.S. Patent No. 5,383,858, describe a device adapted to Figure 1 Exemplary syringes that may be used with the syringe 10 depicted in and adapted for use with the fluid authentication system are disclosed in U.S. Patent Nos. 6,322,535 to Hitchins et al. and 6,652,489 to Trocki et al., both of which are assigned to the assignee of the present application and the disclosures of which are incorporated by reference in their entireties. Additional exemplary syringes are disclosed, for example, in U.S. Patent Nos. 6,322,535 to Hitchins et al. and 6,652,489 to Trocki et al., both of which are assigned to the assignee of the present application and the disclosures of which are incorporated by reference in their entireties.

[0136] refer to Figures 3A-3B , shows a plunger 26 according to one aspect of the present disclosure. For clarity, the barrel 18 of the syringe 12 is shown from Figures 3A-3B Omitted. The plunger 26 includes a plunger body 32 that defines a plunger longitudinal axis 34 (at Figure 3A 36, and has a proximal end 36, a distal end 38, and a circumferential sidewall 39 connecting the proximal end 36 and the distal end 38. The sidewall 39 can have a uniform or non-uniform thickness between the proximal end 36 and the distal end 38. The sidewall 39 can have a continuous outer surface. In some aspects, the sidewall 39 can have a discontinuous outer surface having one or more portions of the sidewall 39 separated by one or more gaps or openings. The plunger body 32 can be formed from glass, metal, plastic, or other suitable materials, including medical-grade versions.

[0137] Continue to refer Figures 3A-3B, the plunger body 32 has an inner cavity 40 defined by a conical portion 42 at the distal end 38 of the plunger body 32 and a cylindrical portion 44 at the proximal end 36 of the plunger body 32. The conical portion 42 can be formed monolithically with the cylindrical portion 44. In some aspects, the conical portion 42 can be adhered or otherwise secured to the cylindrical portion 44 of the plunger body 32, such as using a friction fit and / or adhesive, welding, or by molding. The conical portion 42 can have a truncated end 46 having a central opening 48. In some aspects, the distal end 38 of the plunger body 32 can be partially or completely enclosed such that the plunger 26 does not have a central opening 48. In other aspects, the distal end 38 of the plunger body 32 can have one or more radial openings, such as Figure 20B Opening 49 is shown.

[0138] refer to Figure 3E , the plunger 26 can have a plunger cap 58 with a resilient seal 59 that covers at least a portion of an outer surface 60 of the plunger body 32. The seal 59 can be a resilient and flexible seal that engages the inner surface 23 (e.g., Figure 2 , such that the seal 59 seals the interior volume 25 of the syringe barrel 18 in a fluid-tight manner. The plunger cap 58 can be provided separately from the plunger body 32, or it can be formed integrally with the plunger body 32, such as by co-molding. In some aspects, the outer surface 60 of the plunger body 32 can have a circumferential groove 62. At least a portion of the plunger cap 58 can be retained within the circumferential groove 62. The outer surface 64 of the seal 59 can have one or more lips, protrusions, or other sealing elements 66 that engage the inner surface 23 of the syringe barrel 18. In some aspects, the one or more sealing elements 66 of the seal 59 can be formed by resiliently engaging the syringe barrel 18 (at Figure 2 At least one extension 56 on the plunger body 32 can prevent the seal 59 from being disengaged from the axial engagement with the syringe 12 as the plunger 26 moves through the syringe barrel 18.

[0139] Reference again Figures 3A-3B , the plunger 26 can have at least one resiliently deflectable retaining member 68 (hereinafter referred to as "retaining member 68") protruding from the plunger body 32. In some aspects, the at least one retaining member 68 can protrude in a direction from the proximal end 36 toward the distal end 38 of the plunger body 32. In some aspects, the at least one retaining member 68 can protrude distally and radially inwardly from the inner surface 52 of the plunger body 40 into the lumen 40. In various aspects, the at least one retaining member 68 can be formed as a cantilever spring element, a coil spring element, or a spring portion of the plunger body 32.

[0140] refer to Figure 3E At least one retaining member 68 has a first section or first end 70 connected to the plunger body 32 and a second section or second end 72 projecting distally from the first end 70. The second end 72 can be deflected or twisted relative to the first end 70. As described herein, when the at least one retaining member 68 engages the piston of the fluid injector 10, the second end 72 can be radially deflectable relative to the first end 70. In some aspects, when deflected by a portion of the piston during the engagement process, the retaining member 68 can be deflected radially outward away from the longitudinal axis 34. The resiliently deflectable retaining member 68 can then be moved radially inward under the action of the restoring force of the retaining member 68 to engage a portion of the piston, thereby releasably locking the plunger body 26 to the piston. In some aspects, where the retaining member 68 is circumferential to the plunger body 32 (described herein), the second end 72 can be circumferentially deflectable relative to the first end 70. The first end 70 and the second end 72 can be spaced apart in a direction extending substantially along the direction of the plunger longitudinal axis 34 of the plunger 26. The at least one retaining member 68 can be linearly, stepped, or curvilinearly continuous between the first end 70 and the second end 72. In some aspects, the one or more retaining members 68 can extend generally in a direction parallel to the direction of the plunger longitudinal axis 34. In other aspects, the one or more retaining members 68 can extend in a direction that is angled relative to the direction of the plunger longitudinal axis 34. For example, the one or more retaining members 68 can be angled at an angle A from the inner surface 52 of the plunger body 32 toward or away from the plunger longitudinal axis 34. The inner surface 52 of the plunger body 32 can have one or more recesses 69 recessed into the sidewall 39 in a radially outward direction to allow for increased deflection of the second end 72 relative to the first end 70 of the at least one retaining member 68.

[0141] refer to Figure 3A , the at least one retaining member 68 may include a plurality of retaining members 68 radially spaced relative to the plunger longitudinal axis 34 along the circumference of the inner surface 52 of the lumen 40. The retaining members 68 may be separated from each other by portions of the inner surface 52 of the lumen 40. In aspects where two or more retaining members 68 are provided, the retaining members 68 may be evenly spaced from each other. In one exemplary and non-limiting aspect (three retaining members 68 having equal angular center-to-center spacing therebetween, such as Figure 3C), each retaining member 68 is separated from the adjacent retaining member 68 on either side by 120 degrees. In another exemplary and non-limiting aspect (six retaining members 68 with equal angular separation between them), each retaining member 68 is separated from the adjacent retaining member 68 on either side by 60 degrees. In some aspects, the retaining members 68 can have unequal angular extensions and / or unequal angular spacings around the inner surface 52 of the inner cavity 40 between the retaining members 68. As described herein, the radial spacing of at least one retaining member 68 relative to the longitudinal axis 34 of the plunger is selected to correspond to the outer shape of the piston or to operatively interact with the outer shape of the piston. In another exemplary and non-limiting aspect with two or more retaining members 68, each retaining member 68 has a center-to-center separation of an integer 60 degrees from the adjacent retaining member 68 on either side, and furthermore each retaining member 68 has an angular range of less than 60 degrees, for example, 15 to 45 degrees. This enables the plunger 26 to be released from the piston 88 with a relative rotation of 15 to 45 degrees. Optionally, the relative rotation is less than 30 degrees.

[0142] refer to Figure 3E , the second end 72 of the retaining member 68 has at least one catch 74. The at least one catch 74 can be a distal surface of the second end 72 of the retaining member 68. As described herein, the at least one catch 74 is shaped to be received within at least a portion of a recess, lip, or ledge on the piston to releasably lock the at least one retaining member 68, along with the plunger 26, to the piston relative to movement in at least one direction. In some aspects, the at least one catch 74 can be linear or curvilinear to fit within a recess, lip, or ledge on the piston to releasably lock the at least one retaining member 68 and resist movement of the plunger 26 through the syringe 12 (at Figure 2 1 and 2. The at least one catch 74 can be oriented in a direction substantially perpendicular to the direction of the plunger longitudinal axis 34. In other aspects, the at least one catch 74 can be angled relative to the direction of the plunger longitudinal axis 34. The at least one catch 74 can be continuous or discontinuous. In some aspects, the at least one catch 74 can protrude radially inward or outward relative to the body of the retaining member 68. The at least one catch 74 can be integrally formed with the second end 72 of the at least one retaining member 68, or it can be co-molded, affixed to, or otherwise secured to the second end 72 of the at least one retaining member 68, for example, using a friction fit and / or adhesive, welding, or by molding. In other aspects, the at least one catch 74 can be formed on the second end 72 of the at least one retaining member 68 by etching, laser cutting, or machining.

[0143] At least one retaining member 68 can have at least one actuating member associated therewith. In various aspects, when the plunger 26 is connected to the piston 88, the at least one actuating member on the retaining member 68 of the plunger 26 is configured to interact with a corresponding actuating surface, such as the piston 88 (at Figure 4A ). At least one actuating member can interact with a corresponding actuating surface on the piston 88 to cause the at least one retaining member 68 to be released from the piston 88, for example when it is desired to separate the piston 88 from the plunger 26. Relative rotation between the piston 88 and the plunger 26 about the plunger longitudinal axis 34 causes at least a portion of the actuating member to engage at least a portion of the piston 88, for example, the corresponding actuating surface on the piston 88. For example, the piston can be substantially fixed to prevent rotation in the direction of the plunger 26, while the plunger 26 is rotated about the plunger longitudinal axis 34 by frictional contact with the inner wall of the syringe during rotation of the syringe to cause the actuating member on the plunger 26 to engage with the corresponding actuating surface on the piston 88 by rotational contact. Alternatively, the plunger 26 can be fixed while the piston 88 is rotated about the piston longitudinal axis 115 (in Figure 4A 88) is rotated so that the actuating surface on the plunger 26 engages the corresponding actuating surface on the piston 88 through rotational contact. As a further alternative, the piston 88 and the plunger 26 can rotate in opposite directions relative to each other about their respective longitudinal axes, or the piston 88 and the plunger 26 can rotate in the same direction (e.g., clockwise or counterclockwise) about their respective longitudinal axes at different rotational rates. The engagement between the actuating member on the plunger 26 and the corresponding actuating surface on the piston can be by sliding contact that occurs when the rotational position of the actuating member on the plunger 26 is rotationally aligned with the rotational position of the corresponding actuating surface on the piston 88. In some aspects, during the relative rotational movement between the piston 88 and the plunger 26, the sliding contact between the actuating member on the plunger 26 and the corresponding actuating surface on the piston 88 causes at least one retaining member 68 to move to a disengaged position to release the plunger 26 from the piston 88.

[0144] refer to Figures 3A-3B , the plunger 26 can have at least one actuating member, such as at least one first cam member 78. In some aspects, the first cam member 78 can be disposed directly on the retaining member 68, or it can be disposed on a portion of the plunger body 32 or an extension thereof, such that movement of the cam member 78 causes a corresponding separation of the retaining member 68. In some aspects, the at least one first cam member 78 can be disposed between the first end 70 and the second end 72 of the retaining member 68. As described herein, the at least one first cam member 78 is coupled to the fluid injector 10 (in Figure 168. The at least one retaining member 68 is radially deflected by the at least one first cam member 78 when the plunger 26 rotates relative to the piston. In some aspects, the position of the at least one first cam member 78 can be selected to allow for increased radial deflection of the at least one first cam member 78 when there is relative rotation between the plunger 26 and the piston. In such aspects, the at least one first cam member 78 can be positioned closer to the second end 72 of the retaining member 68.

[0145] In some aspects, the at least one retaining member 68 can have a catch 74 formed thereon, while the actuating member (e.g., cam member 78) can be formed as a separate component that interacts with the at least one retaining member 68. The actuating member (e.g., cam member 78 for separating the at least one retaining member 68) can be a second, separate member attached to the plunger body 32. Alternatively, the actuating member can be formed on a second, separate member attached to the plunger body 26 and interacting with the piston 88 and the at least one retaining member 68 to transfer force, motion, or displacement from the piston 88 to the at least one retaining member 68 to deflect it to separate from the plunger 26.

[0146] In some aspects, the at least one first cam member 78 can project at an angle relative to a plane defined by the body of the retaining member 68. Figure 3CThe at least one first cam member 78 can be angled at an angle B relative to a plane defined by the body of the retaining member 68. In various aspects, the at least one first cam member 78 can be formed as a sidewall, lip, extension, or protrusion associated with the body of the retaining member 68. The at least one first cam member 78 can be planar, curved, or a combination thereof. The at least one first cam member 78 can be formed as a continuous surface or a discontinuous surface formed from two or more separate surfaces that together form the at least one first cam member 78. As described herein, the at least one first cam member 78 can have an angled engagement surface 83 that interacts with the piston to separate the plunger 26 from the piston. As described herein, the position of the at least one first cam member 78 between the first end 70 and the second end 72 of the retaining member 68 minimizes radial protrusion of the at least one first cam member 78 while still allowing full radial deflection of the at least one retaining member 68 when the plunger 26 rotates relative to the piston 88 to allow the plunger 26 to separate from the piston 88. In some aspects, the at least one first cam member 78 can be disposed on at least a portion of the at least one catch 74. A plurality of first cam members 78 can be axially spaced apart along the length of the retaining member 68 between the first end 70 and the second end 72. The at least one first cam member 78 can be integrally formed with the at least one retaining member 68, or it can be affixed or otherwise secured to the at least one retaining member 68, such as using a friction fit and / or adhesive, welding, or molding. In other aspects, the at least one first cam member 78 can be formed on the at least one retaining member 68 by etching, laser cutting, or machining.

[0147] refer to Figure 3A According to certain aspects, the plunger 26 can have at least one first alignment member 71 projecting radially inward from the plunger body 32. In some aspects, the at least one first alignment member 71 can project in a direction from the distal end 38 toward the proximal end 36 of the plunger body 32. In some aspects, the at least one first alignment member 71 can project proximally from the inner surface 52 of the lumen 40 of the plunger body 32.

[0148] refer to Figure 3EAt least one first alignment member 71 has a first end 73 connected to the plunger body 32 and a second end 75 projecting radially inward from the first end 73. The at least one first alignment member 71 is shaped and / or configured to facilitate self-orienting alignment of the piston 88 with the plunger 26. In some aspects, at least a portion of the at least one first alignment member 71 can extend in a direction angled relative to the direction of the plunger longitudinal axis 34. For example, the at least one first alignment member 71 can have a proximal alignment surface 77a angled at an angle C relative to the longitudinal axis 34 to facilitate positioning the retaining member 68 during connection of the plunger 26 to the plunger. The at least one first alignment member 71 can have a distal alignment surface 77b angled in a direction opposite the proximal alignment surface 77a to facilitate positioning the retaining member 68 when the plunger 26 is decoupled from the plunger. As described herein, the proximal alignment surface 77a helps guide the piston 88 into self-orienting alignment with the plunger 26 upon partial rotation of the piston 88 relative to the plunger 26, for example, using a one-way clutch associated with the piston 88.

[0149] refer to Figure 3C , a plurality of first alignment members 71 can be radially spaced apart relative to the plunger longitudinal axis 34 along the circumference of the inner surface 52 of the lumen 40. In some aspects, the number of first alignment members 71 can be equal to or unequal to the number of retaining members 68. When the number is equal, the first alignment members 71 can be disposed between the retaining members 68 such that each first alignment member 71 has a retaining member 68 on either side of the first alignment member 71. The first alignment members 71 can be separated from each other by portions of the inner surface 52 of the lumen 40. In aspects in which two or more first alignment members 71 are provided, the first alignment members 71 can be evenly spaced apart from each other. In one exemplary and non-limiting aspect (three first alignment members 71 having equal angular separation therebetween, such as Figure 3C), each first alignment member 71 is separated from the adjacent first alignment member 71 on either side by 120 degrees. In another exemplary and non-limiting aspect (where six first alignment members 71 have approximately equal angular center-to-center separation therebetween), each first alignment member 71 is separated from the adjacent first alignment member 71 on either side by 60 degrees. In some aspects, the first alignment members 71 may have unequal angular extensions and / or unequal angular spacing between the first alignment members 71 around the inner surface 52 of the lumen 40. As described herein, the radial spacing of the at least one first alignment member 71 relative to the plunger longitudinal axis 34 is selected to correspond to or operatively interact with the outer shape of the piston 88 to allow alignment of the plunger 26 with the piston 88. The at least one first alignment member 71 may be constructed or composed of multiple members, optionally separately attached to the inner surface 52 of the plunger body 32, with alignment surfaces (whether real or virtual) interacting to perform the alignment function. Similarly, the at least one retaining member 68 can be constructed or comprised of multiple components, optionally separately attached to the inner surface 52 of the plunger body 32, with the catches 74 interacting to perform an engaging, connecting, attaching, or retaining function. Similarly, the at least one actuating member can be constructed or comprised of multiple components, optionally separately attached to the inner surface 52 of the plunger body 32, which interact to provide activation of the at least one retaining member 68 to perform a separating, disconnecting, separating, or releasing function. Optionally, the at least one alignment member 71, the at least one retaining member 68, and / or the at least one actuating member can be attached to and interact with each other, either directly transmitting force from one to the other, or alternatively can be separate and interact with each other through surfaces therebetween that transmit force, motion, or deflection from one to the other, either directly or indirectly, or through their action on the plunger body 32.

[0150] Similarly, the force, motion, or deflection used to initiate the release of retaining member 68 may occur via motion or force transferred from second retaining member 68 or an intermediate linkage or mechanism.

[0151] refer to Figure 4A , piston 88 (in Figure 4A Only the distal portion of the piston 88 is shown in FIG. 8 ) is configured to engage with the plunger 26 (in Figure 3A ) interact to releasably lock the plunger 26 so that it can be opened in the barrel of the syringe 12 (shown in Figure 2 The piston 88 is driven from the housing 14 (shown in FIG. 1 ) of the fluid injector 10 via a power unit (not shown) preferably contained within the housing 14. Figure 1The fluid injector 10 may be extendable and retractable (shown in FIG). The power unit may comprise, for example, a motor, a hydraulic system, or a pneumatic system, including suitable gears (not shown). As is known in the art, the fluid injector 10 may also include a controller (not shown) to control the operation of the power unit and, thereby, the operation of the piston 88.

[0152] Continue to refer Figure 4A , the piston 88 includes a connection to the syringe 10 (in Figure 10A 90 and a piston head 92 formed on the distal end of the stem 90. The piston head 92 extends distally from the stem 90 at least partially. The piston 88 is constructed of a rigid material such as metal or plastic that resists deformation. The stem 90 can have a cavity 91 for collecting any fluid that drips from the syringe. The piston head 92 has a generally cylindrical structure with a pointed distal end 94 having a cap 95 that is shaped to receive the inner cavity 40 (at Figure 3A ). In some aspects, a sensing member 79, such as a pin connected to a sensor, can be provided. The sensing member 79 can extend along the longitudinal axis of the piston 88 and can protrude through at least a portion of the piston head 92 (such as through at least a portion of the cap 95). The sensing member 79 can be operable to sense contact with a surface (such as a surface of the plunger 26 and / or plunger cover 58) and control movement of the piston 88 based on the sensed condition. For example, initial contact between the sensing member 79 and the plunger 26 and / or plunger cover 58 can cause the pin to move in the proximal direction so that it contacts the sensor. The sensing member 79 can be provided by a resilient element 81 (in Figure 4B The sensor can be connected to a controller of the syringe so that once the sensor is activated by the pin, the controller controls the movement of the drive mechanism. For example, the drive mechanism can be stopped or slowed from a first speed to a second, slower speed.

[0153] The piston head 92 may be rotatable relative to the stem 90. In some aspects, the piston head 92 may be rotatable relative to the stem 90 in only one direction, such as clockwise or counterclockwise. A one-way rotation mechanism 99, such as a one-way clutch mechanism, may be provided. Figure 4B) to allow the piston head 92 to rotate only in a first direction, such as a clockwise or counterclockwise direction. The one-way rotation mechanism 99 can be rotatable about a central axis 101 having a seal 102, such as an O-ring seal. In some aspects, the one-way rotation mechanism 99 can have a stop that prevents the piston head 92 from rotating in a second direction opposite to the first direction, such as a counterclockwise or clockwise direction, respectively. In other aspects, the one-way rotation mechanism 99 can be disposed on at least a portion of the plunger 26.

[0154] refer to Figure 4C , the piston head 92 has a proximal portion 103 connected to a distal portion 105. The terminal ends of the proximal portion 103 and the distal portion 105 can have rounded or chamfered edges 107. At least a portion of the proximal portion 103 has a smaller outer diameter than the outer diameter of the distal portion 105, so that a radial lip 109 is formed at the transition between the proximal portion 103 and the distal portion 105. The radial lip 109 can be continuous or discontinuous around the circumference of the piston head 92. In some aspects, the radial lip 109 defines a locking boss 111 to engage the catch 74 of at least one retaining member 68 when the plunger 26 is fully seated on the piston head 92 (in Figure 5D Due to the rotational position of the plunger 26 relative to the piston head 92 about the piston longitudinal axis 115, Figure 5D At least a portion of the illustrated retaining member 68 is shown hidden behind the piston head 92 .

[0155] Continue to refer Figure 4C , the piston head 92 can have at least one second alignment member 113 projecting radially outwardly from the outer surface of the piston head 92. The at least one second alignment member 113 can be shaped and / or configured to align with the first alignment member 71 (at Figure 5B 8 and plunger 26 to facilitate alignment of the piston 88 with the plunger 26 so as to allow for releasable locking connection of the plunger 26 with the piston 88. In some aspects, at least a portion of the at least one second alignment member 113 can extend in a direction that is angled relative to the direction of the piston longitudinal axis 115. For example, the at least one second alignment member 113 can have a guide surface 117 that is angled at an angle D relative to the piston longitudinal axis 115. The guide surface 117 is desirably angled such that when the proximal alignment surface 77a of the first alignment member 71 contacts the guide surface 117 of the second alignment member 113, the piston head 92 can rotate about the piston stem 90, for example, about the axis of the one-way rotation mechanism 99.

[0156] In some aspects, a plurality of second alignment members 113 can be radially spaced apart along the outer circumference of the piston head 92 relative to the piston longitudinal axis 115. In some aspects, the number of second alignment members 113 can be equal to the total number of retaining members 68 and first alignment members 71 on the plunger 26. The second alignment members 113 are circumferentially spaced apart so that a retaining member 68 or a first alignment member 71 can be received between adjacent second alignment members 113. The second alignment members 113 can be separated from each other by portions of the outer surface of the proximal portion 103 and / or the distal portion 105 of the piston head 92. In aspects in which two or more second alignment members 113 are provided, the second alignment members 113 can be evenly spaced apart from each other. In one exemplary and non-limiting aspect (six second alignment members 113 having equal angular separation therebetween, such as Figure 4A ), each second alignment member 113 is separated by 60 degrees from an adjacent second alignment member 113 on either side. In some aspects, the second alignment members 113 can have unequal angular extensions and / or unequal angular spacings between the second alignment members 113 around the outer surface of the proximal portion 103 and / or distal portion 105 of the piston head 92. The radial spacing of the second alignment members 113 relative to the piston longitudinal axis 115 is selected to correspond to, or operably interact with, the internal shape of the plunger 26 to allow one or more retaining members 68 to be received in the locking boss 111. The locking boss 111 can be radially perpendicular to the longitudinal axis 115, or in some aspects, the locking boss 111 can be radially angled relative to the longitudinal axis 115. In some aspects, the locking boss 111 can be at an angle to the catch 74 (e.g., Figure 3E The angle of the grab hook 74 shown in FIG is angled to a complementary angle.

[0157] refer to Figure 4CEach of the guide surfaces 117 of the second alignment members 113 defines a travel path to guide the proximal alignment surface 77a of the first alignment member 71 into and out of the recesses 119 defined between adjacent second alignment members 113. The guide surfaces 117 may be radially and axially inclined or angled relative to the piston longitudinal axis 115 to guide the movement of the proximal alignment surfaces 77a. By guiding one or more proximal alignment surfaces 77a on the plunger 26 into corresponding recesses 119 on the piston head 92, the guide surfaces 117 assist in self-orienting the piston head 92 as the plunger 26 is brought into contact with the piston 88. In this manner, the piston 88, whose piston longitudinal axis 115 is rotationally misaligned with the plunger longitudinal axis 34, and the one or more first alignment members 71, which are initially misaligned with respect to the corresponding one or more second alignment members 77a, are rotated in the rotational direction of the one-way rotation mechanism 99 and brought into axial and rotational alignment, such that the one or more first alignment members 71 are received within the recesses 119 between adjacent second alignment members 113. In this manner, the one or more retaining members 68 are brought into rotational alignment with the recess 119 having the locking boss 111 adjacent to the recess 119 .

[0158] One or more second alignment members 113 can have a bottom surface 121 that is angled relative to the direction of the piston longitudinal axis 115. For example, the bottom surface 121 can be angled at an angle E relative to the piston longitudinal axis 115. The angle E can be the same as or different from the angle D of the guide surface 117. In another aspect, the bottom surface 121 can be rounded or angled to merge with the proximal wall of the proximal end 103.

[0159] The piston head 92 also has an actuating surface that interacts with an actuating member (e.g., first cam member 78) on the plunger 26. In some aspects, the actuating surface of the piston head 92 can be a second cam member 98, or cam-following surface. In some aspects, as described herein, the actuating surface or second cam member 98 cooperates with the first cam member 78 on the at least one retaining member 68 of the plunger 26. The actuating surface or second cam member 98 desirably has a shape such that upon relative rotation between the piston 88 and the plunger 26, the actuating surface or second cam member 98 engages the first cam member 78 to deflect the at least one retaining member 68 from the piston head 92, disengaging the catch 74 of the retaining member 68 from the locking boss 111, thereby separating and allowing the plunger 26 to be removed from the piston 88. In some aspects, the actuating surface or second cam member 98 can be formed on a second alignment member 113 on the piston head 92. The actuating surface or second cam member 98 can be a surface aligned with the direction of the piston longitudinal axis 115. In some aspects, the actuation surface or second cam member 98 can have a chamfered portion 98a to facilitate initial movement and / or passage of the first cam member 78 after the retaining member 68 has sufficiently deflected to allow the retaining member to be released. In other aspects, the actuation surface 98 can be radially aligned and parallel to the longitudinal axis 115.

[0160] The piston 88 is configured to interact with the plunger 26 to releasably lock with the plunger 26, such as Figure 3A By locking the piston 88 to the plunger 26, the plunger 26 can be opened in the syringe 12 (in Figure 2 26 is reciprocally driven within the barrel of the syringe 26 (shown in FIG). The actuating surface or second cam member 98 on the piston 88 cooperates with the first cam member 78 on the at least one retaining member 68 of the plunger 26 to releasably lock the plunger 26 to the piston 88. In addition, due to the distal arrangement and, in certain aspects, the radially inwardly angled nature of the at least one retaining member 68, as the piston 88 retracts the plunger 26 in the proximal direction during the syringe filling process, the locking force between the locking boss 111 of the piston 88 and the catch 74 of the retaining member 68 increases due to the compressive force. Figures 5A-5C To describe the locking or engagement of the plunger 26 to the piston 88, and the unlocking or disengagement of the plunger 26 from the piston 88. Figures 5B-5D The rest of the Figure 5A The syringe 12 is initially shown in dotted lines.

[0161] To engage the plunger 26 with the piston 88, first insert the syringe 12 into the syringe port 16 of the fluid injector 10 (at Figure 116 ). Once the syringe 12 is inserted into the syringe port 16 or the syringe 12 is inserted into the syringe port 16, various locking mechanisms (not shown) can be used to keep the syringe 12 in the syringe port 16 to prevent the syringe 12 from separating from the syringe port 16. Initially, the plunger 26 can be positioned at the proximal end 20 of the syringe barrel 18. In some aspects, the plunger 26 is positioned at any axial position between the proximal end 20 and the distal end 24 of the syringe barrel 18. The piston 88 can then be advanced distally toward the plunger 26 so that the piston head 92 engages with the plunger 26. In some aspects, the piston 88 can be advanced distally toward the plunger 26 by a power device operated by a controller. In other aspects, the piston 88 can be advanced distally toward the plunger 26 by manual operation.

[0162] refer to Figure 5B , the piston 88 is advanced in the distal direction indicated by arrow A. If the piston 88 is rotationally misaligned about the longitudinal axis 115 relative to the plunger 26, such that the first alignment member 71 on the plunger 26 is not rotationally aligned to be received within the recess 119 on the plunger head 92 (e.g., Figure 4C 13). As shown in FIG. 14, the piston 88 is rotated in a distal direction relative to the longitudinal axis 34, 115. The proximal alignment surface 77a of the first alignment member 71 on the plunger 26 contacts the guide surface 117 of the second alignment member 113 on the piston head 92. The proximal alignment surface 77a and the guide surface 117 are angled in the same direction relative to the longitudinal axes 34, 115, so that continued movement of the piston 88 in the distal direction causes the proximal alignment surface 77a to engage the guide surface 117. The engagement of the proximal alignment surface 77a with the guide surface 117 causes the piston head 92 to automatically rotate in the free rotation direction of the one-way rotation mechanism 99. Such rotation of the piston head 92 aligns the first alignment member 71 and the retaining member 68 to be received within the recess 119 between adjacent second alignment members 113. In this manner, the piston 88 self-orients itself relative to the plunger 26 so that the plunger 26 can be releasably locked with the piston 88. If the piston 88 is rotationally aligned relative to the plunger 26 so that the first alignment member 71 on the plunger 26 is rotationally aligned with the second alignment member 113 on the piston head 92, the first alignment member 71 and the retaining member 68 on the plunger 26 can be received in the recess 119 between adjacent second alignment members 113 without rotating the piston head 92.

[0163] refer to Figure 5C, after aligning the first alignment member 71 and the retaining members 68 to be received within the recess 119 between the adjacent second alignment members 113, the piston 88 is further advanced in the distal direction. This movement of the piston 88 in the distal direction causes the retaining members 68 to initially engage the outer side wall of the distal portion 105 of the piston head 92. Continued distal movement of the piston 92 causes the retaining members 68 to deflect radially outward from a first, undeflected position to a second, radially deflected position relative to the plunger longitudinal axis 34. The piston 88 is advanced distally until the distal end portion of the second end 72 of each retaining member 68 clears the radial lip 109. The retaining members 68 are then deflected radially inward toward or to their initial undeflected position, for example due to a restoring force established in the retaining members 68 during the radial deflection. As shown in 5D, the catch 74 of at least one retaining member 68 is retained within the locking boss 111 to prevent the plunger 26 from separating from the piston head 92. When the sensing member 79 engages a portion of the plunger 26, such as the plunger cap 58 (e.g., Figure 3E 70 and 72). When the piston 88 is at least partially disengaged from the syringe barrel 18, distal movement of the piston 88 can be stopped. As the piston 88 moves in the distal and proximal directions relative to the syringe barrel 18, the plunger 26 resists separation from the piston 88. In one aspect, the retaining member 68 can be designed so that once the piston head 92 moves in the proximal direction, the compressive force applied to the catch 74 substantially prevents radially outward deflection (or bending) of the retaining member 68. For example, once the retaining member 68 is locked to the piston head 92, axial movement of the piston 88 does not introduce a bending moment sufficient to radially deflect the retaining member 68 to cause the plunger 26 to separate from the piston 88. Proximal movement of the piston 88 causes the at least one retaining member 68 to be compressively loaded between the first end 70 and the second end 72, so that the retaining member 68 can be urged in a radially inward direction, thereby increasing the locking force between the plunger 26 and the piston 88.

[0164] To remove the syringe from port 16 (at Figure 1 ) unlocks the syringe 12 and separates the plunger 26 from the piston 88, the syringe 12 is rotated clockwise or counterclockwise about the syringe longitudinal axis relative to the syringe port 16. Figure 2 88 , the plunger 26 does not substantially rotate within the syringe barrel 18 due to the friction of the inner surface 23 of the syringe 12 (shown in FIG). Therefore, rotation of the syringe 12 also causes the plunger 26 to rotate relative to the piston 88. The direction of free rotation of the one-way rotation mechanism 99 is desirably opposite to the direction of rotation of the syringe 12 during release of the syringe 12 from the syringe port 16. Rotation of the syringe 12, and thus the plunger 26, about the plunger longitudinal axis 34 engages the first cam member 78 on the plunger 26 with the actuating surface or second cam member 98 on the piston head 92. Such movement causes the at least one retaining member 68 to radially deflect away from the piston head 92.

[0165] As the at least one retaining member 68 deflects radially outward relative to the plunger longitudinal axis 34, the catch 74 moves out of engagement with the locking boss 111. In this position, the at least one retaining member 68 is in a deflected state that allows the plunger 26 to move axially relative to the piston 88. Such axial movement of the plunger 26 can be achieved by withdrawing the syringe 12 from the syringe port 16 in the distal direction along the syringe longitudinal axis 15, by withdrawing the piston 88 in the proximal direction away from the plunger 26, or both. The plunger 26, along with the syringe 12, can then be completely separated from the piston 88 and the syringe 10. In some aspects, the piston 88 can be released from the plunger 26 by rotating the piston 88 about its longitudinal axis and retracting the piston 88 in the proximal direction to separate the at least one retaining member 68 in the manner described herein.

[0166] refer to Figures 6A-6B , plunger 26 and piston 88 are shown according to another aspect of the present disclosure. Figures 6A-6B The components of the plunger 26 shown in FIG. 1 are substantially similar to those described herein with reference to FIG. Figures 3A-3C The components of the plunger 26 are described. Figures 3A-3C The previous discussion of the plunger 26 generally shown in FIG. 1 is applicable to the present disclosure in FIG. Figures 6A-6B Therefore, only the aspects shown in Figures 3A-4C The plunger 26 and piston 88 shown generally in FIG. Figures 6A-6B The relative differences between plunger 26 and piston 88 are shown in FIG.

[0167] In one exemplary and non-limiting aspect (six locking bosses 111 with equal angular separation therebetween), in order to Figure 3C In the illustrated plunger assembly, each locking boss 111 is separated 60 degrees center-to-center from the adjacent locking boss 111 on either side. In some aspects, the locking bosses 111 can have unequal angular extensions and / or unequal angular spacing between the locking bosses 111 around the outer surface of the piston 88. In another exemplary and non-limiting aspect having two or more locking bosses 111, each retaining locking boss 111 has an integral 60-degree center-to-center separation from the adjacent locking boss 111 on either side, and furthermore, each locking boss 111 has an angular range of less than 60 degrees, for example, 15 to 45 degrees. This enables the plunger 26 to be released from the piston 88 with a relative rotation of 15 to 45 degrees. Optionally, the relative rotation is less than 30 degrees. As described herein, the radial spacing of at least one locking boss 111 relative to the plunger longitudinal axis 34 is selected to correspond to the radial spacing of at least one plunger retaining member 68 or to operatively interact therewith.

[0168] refer to Figures 6A-6B, according to another aspect of the present disclosure, a plunger 260 is shown. For clarity, the barrel 18 of the syringe 12 is shown from Figures 6A-6B The plunger 260 includes a plunger body 320 defining a plunger longitudinal axis 340 and having a proximal end 360, a distal end 380, and a circumferential sidewall 390 connecting the proximal end 360 and the distal end 380. The sidewall 390 may have a uniform or non-uniform thickness between the proximal end 360 and the distal end 380. The plunger body 320 may be formed from glass, metal, or a suitable medical-grade plastic.

[0169] Continue to refer Figures 6A-6B , the plunger body 320 has an inner cavity 400 having a conical portion 420 at the distal end 380 of the plunger body 320 and a cylindrical portion 440 at the proximal end 360 of the plunger body 320. The conical portion 420 can be formed monolithically with the cylindrical portion 440. In some aspects, the conical portion 420 can be adhered or otherwise secured to the cylindrical portion 440 of the plunger body 320, such as using a friction fit and / or adhesive, welding, or by molding. The conical portion 420 can have a truncated end 460 having a central opening 480. In some aspects, the distal end 380 of the plunger body 320 can be enclosed. In some aspects, the plunger 260 can have a plunger cap (e.g., Figure 2 The plunger cover 58 is shown and is configured to cover at least a portion of the outer surface of the plunger body 320.

[0170] Continue to refer Figures 6A-6B , the plunger 260 can have at least one resiliently deflectable retaining member 680 (hereinafter referred to as "retaining member 680") protruding in a distal direction from the plunger body 320. In some aspects, the at least one retaining member 680 can protrude distally and radially inwardly from the inner surface 520 of the lumen 400 of the plunger body 320. The at least one retaining member 680 has a first section or first end 700 connected to the plunger body 320 and a second section or second end 720 that is radially deflectable relative to the first end 700. As described herein, when the at least one retaining member 680 engages the fluid injector 10 (at Figure 1 , the second end 720 can be radially deflectable relative to the first end 700. The first end 700 and the second end 720 can be spaced apart in a direction extending substantially along the direction of the plunger longitudinal axis 340 of the plunger 260. The at least one retaining member 680 can be linearly or curvilinearly continuous between the first end 700 and the second end 720.

[0171] In some aspects, a plurality of retaining members 680 are radially spaced from the plunger longitudinal axis 340 along the circumference of the inner surface 520 of the lumen 400. In such aspects, the retaining members 680 are separated from each other by portions of the inner surface 520 of the lumen 400. In aspects where more than one retaining member 680 is provided, the retaining members 680 can be evenly spaced from each other. In one exemplary and non-limiting aspect (three retaining members 680 with equal angular separation therebetween), the center of each retaining member 680 is separated from the center of the adjacent retaining member 680 on either side by 120 degrees. In another exemplary and non-limiting aspect (six retaining members 680 with equal angular separation therebetween), the center of each retaining member 680 is separated from the center of the adjacent retaining member 680 on either side by 60 degrees. In some aspects, the retaining members 680 can have unequal angular extensions and / or unequal angular spacing between the retaining members 680 around the inner surface 520 of the lumen 400. As described herein, the radial spacing of the at least one retaining member 680 relative to the plunger longitudinal axis 340 is selected to correspond to features on the outer circumference of the piston.

[0172] In some aspects, one or more retaining members 680 can be parallel to the longitudinal axis 340. In other aspects, one or more retaining members 680 can be angled relative to the longitudinal axis 340. For example, one or more retaining members 680 can be angled inwardly toward the longitudinal axis 340 in a direction from the first end 700 toward the second end 720.

[0173] Continue to refer Figures 6A-6B The second end 720 of the retaining member 680 has at least one catch 740. The at least one catch 740 can be a distal surface of the second end 720 of the retaining member 680. In some aspects, the at least one catch 740 can protrude radially from the retaining member 680. For example, the at least one catch 740 can protrude radially inward toward the plunger longitudinal axis 340 of the plunger body 320, or radially outward away from the plunger longitudinal axis 340. As described herein, the at least one catch 740 is shaped to engage at least a portion of a recess on the piston to releasably lock the at least one retaining member 680 relative to the piston. The at least one catch 740 can be integrally formed with the second end 720 of the at least one retaining member 680, or it can be adhered or otherwise secured to the second end 720 of the at least one retaining member 680, for example, using a friction fit and / or adhesive, welding, or molding. In other aspects, the at least one catch 740 can be formed on the second end 720 of the at least one retaining member 680 by etching, laser cutting, or machining.

[0174] Continue to refer Figures 6A-6B, the plunger 260 can have at least one first cam member 780 disposed between the first end 700 and the second end 720 of the retaining member 680. As described herein, the at least one first cam member 780 is configured to engage with the fluid injector 10 (in Figure 1 20) interacts with the piston 880 to radially deflect the at least one retaining member 680 when the plunger 260 rotates relative to the piston. Compared to providing the at least one first cam member 780 at the second end 720, the location of the at least one first cam member 780 between the first end 700 and the second end 720 of the retaining member 680 allows the at least one first cam member 780 to be positioned between the plunger 260 and the piston 880 (at the Figures 7A-7B The at least one first cam member 780 can be parallel to the surface of the retaining member 680. In some aspects, the at least one first cam member 780 can be angled relative to the surface of the retaining member 680.

[0175] In some aspects, the at least one first cam member 780 projects radially inwardly toward the plunger longitudinal axis 340 of the plunger body 320. In other aspects, the at least one first cam member 780 projects radially outwardly relative to the plunger longitudinal axis 340 of the plunger body 320. As described herein, the location of the at least one first cam member 780 between the first end 700 and the first end 720 of the retaining member 680 can minimize radial protrusion of the at least one first cam member 720 while still allowing full radial deflection of the at least one retaining member 680 once the plunger 260 rotates relative to the piston 880. In some aspects, the at least one first cam member 780 can be disposed on at least a portion of the at least one catch 740. A plurality of first cam members 780 can be spaced axially along the length of the retaining member 680 between the first end 700 and the second end 720. The at least one first cam member 780 can be integrally formed with the at least one retaining member 680, or it can be affixed or otherwise secured to the at least one retaining member 680, such as using a friction fit and / or adhesive, welding, or molding. In other aspects, the at least one first cam member 780 can be formed on the at least one retaining member 680 by etching, laser cutting, or machining.

[0176] refer to Figure 6A, at least one first cam member 780 can have at least one tooth 800 configured to engage a corresponding groove on the piston. The at least one tooth 800 on the at least one first cam member 780 is desirably shaped to generally correspond to the corresponding groove on the piston. Each tooth 800 can have, for example, a peak 820 leading to a groove 840 along a gear surface 860. The at least one tooth 800 on the at least one first cam member 780 can be in the shape of a gear tooth having a spur gear profile or a helical gear profile. Although Figures 6A-6B One non-limiting aspect of the at least one first cam member 780 is illustrated, but various other shapes are also contemplated. For example, the at least one first cam member 780 of the at least one retaining member 680 can have a generally circular, triangular, square, rectangular, or any suitable polygonal shape or cross-section. In each aspect, the at least one first cam member 780 is configured to engage at least a portion of the piston to cause the at least one retaining member 680 to deflect from the piston when the plunger 260 rotates relative to the piston. Generally, the at least one first cam member 780 can have at least one corrugated, wavy, or multi-stepped surface, in a singular or regularly or irregularly repeating pattern, configured to engage a corresponding cam member on the piston of the fluid injector.

[0177] Continue to refer Figures 6A-6B , the plunger 260 can have at least one first alignment member 825 disposed between the first end 700 and the second end 720 of the retaining member 680. The first alignment member 825 has a proximal edge or tip 826, a distal edge 827, and a proximal alignment surface 828. The first alignment member 825 is aligned with the second alignment member 1010 on the piston head 920 (at Figure 7A 80) cooperates to rotationally guide, self-align, move, or drive the plunger 260 and piston 880 into proper rotational alignment for attachment or engagement and subsequent removal. The proximal alignment surface 828 can be a continuous surface or can be a plurality of discrete surfaces that, when cooperating with the second alignment member 925 of the piston head 920 during engagement of the plunger with the piston, serve to provide continuous alignment activation. The first alignment member 825 can optionally be located on the retaining member 680, can be part of the first cam member 780, and / or can be rigidly associated with another aspect of the plunger 260.

[0178] refer to Figure 7A The piston 880 is ejected from the housing 14 (at Figure 1The fluid injector 10 may further comprise a controller for controlling the operation of the power unit and, thereby, the operation of the piston 880, as is known in the art.

[0179] Continue to refer Figure 7A , the piston 880 includes a stem 900 and a piston head 920 formed on the distal end of the stem 900. The piston 880 is constructed of a relatively rigid material, such as metal or plastic, that resists deformation due to repeated engagement with and disengagement from the plunger 260. The piston head 920 has a substantially cylindrical structure with a pointed or conical distal end 940 that is configured to be received within at least a portion of the inner cavity 400 of the plunger 260. In some aspects, a sensing member 1500, such as a spring-loaded pin connected to a sensor, may be provided. The sensing member 1500 may extend along the longitudinal axis of the piston 880 and may protrude through at least a portion of the piston head 920. The sensing member 1500 may be operable to sense a surface (e.g., a surface of the plunger 260 and / or the plunger cap 58, in Figure 3E ) and controls the movement of the piston 880 based on the sensed condition. For example, initial contact between the sensing member 1500 and the plunger 260 and / or the plunger cap 58 can cause the pin to retract in the proximal direction, causing it to contact the sensor. The sensor can be connected to the drive mechanism of the piston 880 so that once the sensor is activated by the pin, the sensor controls the movement of the drive mechanism. For example, the drive mechanism can be stopped or slowed from a first rate to a second, slower rate.

[0180] The proximal end 960 of the piston head 920 has an actuating member that interacts with an actuating member on the plunger 260, such as the first cam member 780. In some aspects, the actuating member on the piston head 920 can be a second cam member 980. In some aspects, the second cam member 980 is a tooth of a gear 990 that extends around at least a portion of the outer circumference of the piston head 920. As described herein, the second cam member 980 is configured to cooperate with the first cam member 780 on the at least one retaining member 680 of the plunger 260. The second cam member 980 is desirably shaped such that, once self-aligned, relative rotation between the piston 880 and the plunger 260 engages the first cam member 780, causing the at least one retaining member 680 to deflect from the piston head 920, allowing the plunger 260 to be removed from the piston 880.

[0181] In some aspects, the second cam member 980 can be parallel to the longitudinal axis 340. In other aspects, the second cam member 980 can be angled relative to the longitudinal axis 340. For example, the second cam member 980 can be angled toward the longitudinal axis 340 at an angle corresponding to the angle of inclination of the at least one retaining member 680. In various aspects, regardless of the angular orientation of the at least one retaining member 680, the first cam member 780 is desirably parallel to the second cam member 980.

[0182] Continue to refer Figures 7A-7B , the piston head 920 may have a second alignment member 1010 to align with the first alignment member 825 on the plunger 260 (in Figure 6B ) interact. Alignment member 1010 has a first edge 927 and a second edge 926, and a surface 928 between the first edge 927 and the second edge 926. The longitudinal, radial, and circumferential positions of the first edge 927 and the second edge 926 and the profile and extent of the surface 928 of the second alignment member 1010 are selected to interact with the edge and surface of the first alignment member 825 to provide rotational force and motion as the piston 880 and plunger 260 move axially together. The piston head 920 and optional collar 1100 can be rotated via a one-way rotation mechanism (e.g., reference Figure 4B The one-way rotation mechanism 99 discussed herein is connected to the piston stem 900 so that the piston 880 and the plunger 260 can be rotated into alignment in response to the interaction of the first and second alignment surfaces. Alternatively, if the amount of rotation is small enough, the plunger cap (in Figure 3E The elasticity or sliding of the plunger 260 relative to the syringe barrel (shown in ) can be sufficient to allow the plunger 260 to rotate into alignment with the piston head 920.

[0183] Continue to refer Figures 7A-7BThe piston 880 can include a collar 950 surrounding at least a portion of the stem 900 and / or piston head 920. The collar 950 can project radially outward relative to the outer radial surfaces of the stem 900 and piston head 920, such that an annular space 970 is defined between the piston 880 and the collar 950. The collar 950 can have an open top end and a closed bottom end defined by a bottom sidewall 1000 that connects the collar 950 to the stem 900 and / or piston head 920. The bottom sidewall 1000 defines a seat 1020 for a first end 1040 of a resilient, elastic member (e.g., a spring 1060) surrounding the stem 900. In other aspects, the seat 1020 can be configured as a radial flange protruding from the outer surface of the stem 900. The second end 1080 of the spring 1060 engages the proximal end of the movable capture ring 1100. Capture ring 1100 has a substantially annular shape and surrounds at least a portion of the outer circumference of stem 900. In some aspects, at least a portion of the outer diameter of capture ring 1100 can have an outer diameter equal to or greater than the outer diameter of piston head 920. Spring 1060 biases capture ring 1100 toward first radial lip 1120 of piston head 920. Capture ring 1100 is axially movable between a first position, in which it engages first radial lip 1120 of piston head 920, and a second position, in which spring 1060 is compressed and deflected toward bottom sidewall 1000 of collar 950 by at least a portion of at least one retaining member 680. In some aspects, capture ring 1100 can be movable between the first position and the second position when urged into contact with, for example, first end 700 of at least one retaining member 680. A stop member (not shown) can be provided to limit movement of capture ring 1100 toward the second position. During separation of the plunger 260 from the piston 880, the capture ring 1100 urges the at least one retaining member 680 in the distal direction due to the restoring force of the spring 1060. In some aspects, the capture ring 1100 can have a grooved radial edge 1530 configured to engage the first cam member 780 of the at least one retaining member 680.

[0184] Continue to refer Figures 7A-7B The piston head 920 further defines a second radial lip 1510 at a distal end of the at least one second cam member 980. When the plunger 260 is engaged with the piston 880, the second radial lip 1510 acts as a retaining surface for the at least one catch 740 of the at least one retaining surface 680. The piston head 920 may also have a guide groove 1520 disposed distally from the second radial lip 1510. In some aspects, the guide groove 1520 may have a shape corresponding to the shape of the first cam member 780. In this manner, as the plunger 260 and the piston head 920 move toward each other, the teeth 800 of the first cam member 780 may be guided into the guide groove 1520.

[0185] Having described the structure of the plunger 260 and the piston 880 according to one non-limiting aspect of the present disclosure, reference will now be made to Figures 7A-12B The engagement of the plunger 260 with the piston 880 and the separation of the plunger 260 from the piston 880 are described. Figure 7B-12B The rest of the Figure 7A The syringe 12 is initially shown in dotted lines.

[0186] As described herein, in order to engage the plunger 260 with the piston 880, the syringe 12 is first inserted into the syringe port 16 of the fluid injector 10. Once the syringe 12 is inserted into the syringe port 16, various locking mechanisms (not shown) can be used to releasably retain the syringe 12 within the syringe port 16 to prevent the syringe 12 from separating from the syringe port 16. Initially, the plunger 260 can be positioned at the proximal end 20 of the syringe barrel 18. In some aspects, the plunger 260 is positioned at any axial position between the proximal end 20 and the distal end 24 of the syringe barrel 18. The piston 880 can then be advanced distally toward the plunger 260 to engage the piston head 920 with the plunger 260. In some aspects, the piston 880 can be advanced distally toward the plunger 260 by a power device operated by a controller. In other aspects, the piston 880 can be advanced distally toward the plunger 260 by manual operation.

[0187] refer to Figures 8A-8B , the piston 880 is advanced axially in the distal direction such that at least a portion of the pointed or conical distal end 940 of the piston head 920 contacts the at least one retaining member 680 of the plunger 260. Initially, at least a portion of the piston head 920, such as the guide groove 1520, contacts, for example, the first alignment member 825 (at the Figure 6B ). The piston head 92 can be rotated by a one-way rotation mechanism (e.g., Figure 4B The one-way rotation mechanism 99 discussed herein is connected to the piston stem 900 so that the piston 880 and plunger 260 can rotate into self-alignment in response to the interaction of the first and second alignment surfaces. Alternatively, if the amount of rotation is small enough, the plunger cap (in Figure 3E The spring force or sliding motion relative to the syringe barrel (shown in ) can be sufficient to allow the plunger 260 to rotate into alignment with the piston head 920.

[0188] Due to the angled orientation of the at least one retaining member 680 relative to the longitudinal axis, continued axial movement of the piston head 920 relative to the plunger 260 causes the at least one retaining member 680 to deflect radially outward due to contact between the at least one retaining member 680 and the outer surface of the piston head 920. In aspects having multiple retaining members 680, each of the retaining members 680 can deflect radially outward relative to the piston head 920.

[0189] refer to Figures 9A-9B During continued axial movement of the piston 880 in the distal direction, at least a portion of the retaining member 680 engages the distal end of the capture ring 1100. For example, the first end 720 of the retaining member 680 and / or the first cam member 780 can engage the distal end of the capture ring 1100. The contact between at least a portion of the retaining member 680 and the distal end of the capture ring 1100 urges the capture ring 1100 against the restoring force of the spring 1060 and away from the first radial lip 1120 of the piston head 920.

[0190] refer to Figures 10A-10B , at least a portion of the retaining member 680 (such as the first end 720 of the retaining member 680 and / or the first cam member 780) urges the capture ring 1100 against the restoring force of the spring 1060. When the at least one retaining member 680 is deflected from its natural, undeflected state to the radially deflected state, the body of the at least one retaining member 680 has an inherent restoring force built into the material of the at least one retaining member 680. Due to this inherent restoring force developed within the body of the at least one retaining member 680 during radial deflection of the at least one retaining member 680, the second end 720 and / or the catch 740 snap radially into the second radial lip 1510. Such radial movement of the first end 720 and / or the catch 740 also or further engages the first cam member 780 on the plunger 260 with the second cam member 980 on the piston head 920. Specifically, peak 820 of first cam member 780 is received in groove 103 of second cam member 980, and groove 840 of first cam member 780 receives peak 101 of second cam member 980 (at Figure 6A and Figure 7A1510 ). In this manner, the gear surface 860 of the first cam member 780 engages the gear surface 105 of the second cam member 980. The capture ring 1100 maintains at least partial contact with the retaining member 680 to urge the second end 720 and / or the catch 740 into contact with the second radial lip 1510. After the plunger 260 is retained on the piston head 920 by engaging the second end 720 and / or the catch 740 in the second radial lip 1510 of the piston head 920, the plunger 260 resists separation from the piston 88 once the piston 880 moves in the distal and proximal directions relative to the syringe barrel 18. In one aspect, the second end 720 and / or the catch 740 can be designed such that once the piston 920 moves in the proximal direction, the compressive force applied to the second end 720 and / or the catch 740 substantially prevents the catch 740 from deflecting (or bending) radially outward. For example, once the catch 740 is engaged, axial movement of the piston 880 does not introduce a bending moment that could radially deflect the catch 740 to disengage the plunger 260 from the piston 880 .

[0191] To remove the syringe from port 16 (at Figure 1 880, the syringe 12 is unlocked and the plunger 260 is separated from the piston 880, and the syringe 12 is rotated clockwise or counterclockwise about the syringe longitudinal axis relative to the syringe port 16. Due to the friction between the plunger seal 59 and the inner surface 23 of the syringe sidewall 19, the plunger 260 does not substantially rotate within the syringe barrel 18, so that rotation of the syringe 12 also causes the plunger 260 to rotate relative to the piston 880. Figures 11A-11B , rotation of the plunger 260 about its longitudinal axis 340 engages the first cam member 780 on the plunger 260 with the second cam member 980 on the piston head 920. Specifically, the rotational movement of the plunger 260 causes the gear surface 860 of the first cam member 780 to move along the gear surface 105 of the second cam member 980, causing the peak 820 of the first cam member 780 to move out of the groove 101 of the second cam member 980 and toward the peak 101 of the second cam member 980. Such movement results in radial deflection of the at least one retaining member 680 away from the piston head 920. When the peak 820 of the first cam member 780 on the plunger 260 is positioned above or aligned with the peak 101 of the second cam member 980 on the piston head 920, the at least one retaining member 680 is at its maximum radial deflection.

[0192] As the at least one retaining member 680 deflects radially outward relative to the plunger longitudinal axis 340, the second end 720 and / or the catch 740 moves from the second radial lip 1510 of the piston head 920. As the catch 740 moves out of its engaged position, the capture ring 1100 is urged in the distal direction by the restoring force of the spring 1060. Figures 12A-12B As shown, distal movement of the capture ring 1100 causes the capture ring 1100 to maintain the position of the at least one retaining member 680 in a radially outwardly deflected position, for example by moving beneath at least a section of the at least one first cam member 780 or another portion of the at least one retaining member 680. In this position, the at least one retaining member 680 remains in a deflected state, which allows the plunger 260 to move axially relative to the piston 880. Such axial movement of the plunger 260 can be achieved by withdrawing the syringe 12 from the syringe port 16 in a distal direction along the syringe longitudinal axis 15 or by withdrawing the piston 880 in a proximal direction away from the plunger 260. The plunger 260, along with the syringe 12, can then be completely separated from the piston 880 and the syringe 10. In some aspects, the piston 880 can be released from the plunger 260 by rotating the piston 880 about its longitudinal axis and retracting the piston 880 in a proximal direction to separate the at least one retaining member 680 in the manner described herein.

[0193] refer to Figure 13 The first adapter 114 can be connected to an incompatible plunger P that does not have at least one retaining member 68 as described herein to removably engage the plunger 88 of a syringe having a piston head 92 with a second cam member 98 according to one aspect described herein. In various aspects, the first adapter 114 can be connected to the plunger P for subsequent engagement with the plunger 88. For example, the first adapter 114 can be releasably or permanently connected to the incompatible plunger P. Such a first adapter 114 can have a connection interface having at least one retaining member 68 with a first cam member 78 according to various aspects described herein. According to another aspect, the first adapter 114 can be releasably connected to a syringe having a plunger 88 as described herein. The first adapter 114 and plunger P can be connected before being connected to the plunger 88, or the first adapter 114 can be connected to the plunger 88 before the plunger P is connected to the first adapter 114. After use, the first adapter 114 and plunger P can be removed from the plunger 88 and the first adapter 114 can be discarded along with the plunger P, or removed from a used plunger P and stored for subsequent use with a different plunger P. Alternatively, the first adapter 114 may be reversibly or irreversibly connected to the piston 88 for use with multiple syringes.

[0194] In one aspect, the first portion 116 of the first adapter 114 can permanently or releasably receive a plunger P that is not compatible for use with the piston 88 described herein. The first adapter 114 allows the connection mechanism 118 of the incompatible plunger P to engage a corresponding attachment mechanism 215 on the first adapter 114 so that the plunger P can be retained on the first adapter 114. In some aspects, the first adapter 114 can have separate mechanisms for engaging and disengaging the plunger P while the first adapter 114 remains connected to the piston 88. According to any aspect described herein, the second portion 120 of the first adapter 114 can have at least one retaining member 68. In some aspects, the first adapter 114 can have at least one retaining member 68, which can have an actuating member, such as described herein with reference to Figures 3A-3B The first cam member 78 is described herein with reference to Figures 6A-12B depicted first cam member 780; Figure 15A - first cam member 78 shown in G; Figure 20A - A first cam member 78 shown in D; Figure 21A - a first cam member 78 shown in C; Figure 22A - A first cam member 78 shown in D; Figure 23A - first cam member 78 shown in D; and / or Figure 24A -C. According to any aspect described herein, the second portion 120 of the first adapter 114 can be releasably connected to a syringe having a piston 88 with a piston head 92. In this manner, a variety of incompatible plungers P can be used. The first adapter 114 can be non-permanently, permanently, or semi-permanently connected to a syringe having a piston 88 with a piston head 92 as described herein, allowing plungers P with alternative connection mechanisms to be used with the syringe.

[0195] refer to Figure 14The second adapter 122 can connect the plunger 26 to a syringe that does not have a piston 88 with a piston head 92 according to any aspect described herein. In various aspects, the second adapter 122 can be connected to a plunger 26 having at least one retaining member 68 according to any aspect described herein for subsequent engagement with an incompatible piston P'. For example, the second adapter 122 can be releasably or permanently connected to the plunger 26. Such a second adapter 122 can have a connection interface that has features of a piston head 92 according to various aspects described herein. The second adapter 122 and plunger 26 can be connected before being connected to the piston P', or the second adapter 122 can be connected to the piston P' before the plunger 26 is connected to the second adapter 122. After use, the second adapter 122 and plunger 26 can be removed from the piston P' and the second adapter 122 discarded along with the plunger 26, or removed from the used plunger 26 and stored for subsequent use with a different plunger 26.

[0196] In one aspect, the first portion 124 of the second adapter 122 can be configured to permanently or releasably engage a plunger 26 that is not compatible for use with the piston P'. The second adapter 122 allows the connection mechanism 126 of the incompatible piston P' to engage a corresponding connection mechanism 125 on the second adapter 122. The second portion 128 of the second adapter 122 can have features of the piston head 92 according to aspects described herein. In some aspects, the second portion 128 can have features as described herein with reference to FIG. Figure 4A 、 15A , 20A and / or 24A described second cam member 98, and / or reference herein Figure 7A The second cam member 980 is shown. The second portion 128 of the second adapter 122 can be releasably connected to the plunger 26 described herein. In this manner, the plunger 26 can be connected to a variety of incompatible syringes using the second adapter 122.

[0197] refer to Figures 15A-15G , according to another aspect of the present disclosure, a piston 88 and a plunger 26 are shown. The piston 88 is configured to be in contact with the plunger 26 (in Figure 15C ) interact to releasably lock the plunger 26 so that it can be opened in the barrel of the syringe 12 (shown in Figure 2 The plunger 26 is driven reciprocatingly in the inner portion (shown in FIG).

[0198] Continue to refer Figure 15A, the piston 88 includes a stem 90 and a piston head 92 formed on the distal end of the stem 90. The piston head 92 is constructed of a rigid material such as metal or plastic that resists deformation. The stem 90 can have a cavity 91 for collecting any fluid that may drip from the syringe and an annular collar 93 surrounding the cavity 91. One or more buttresses 97 connect the annular collar 93 to the stem 90. The piston head 92 has a generally cylindrical structure with a pointed or conical distal end 94 having a cap 95 that is shaped to be received within the inner cavity 40 (at Figure 3A In some aspects, a sensing member 79, such as a pin connected to a sensor, can be provided. The sensing member 79 can extend along the longitudinal axis of the piston 88 and can protrude through at least a portion of the piston head 92 (such as through at least a portion of the cap 95). The sensing member 79 can be operable to sense a surface (e.g., a surface of the plunger 26 and / or the plunger cap 58, in the embodiment of the present invention) and / or the like. Figure 3E ) and controls the movement of the piston 88 based on the sensed condition. For example, initial contact between the sensing member 79 and the plunger 26 and / or the plunger cap 58 may cause the pin to retract in the proximal direction so that it contacts the sensor. The sensing member 79 may be provided by a resilient element 81 (in FIG. Figure 15E The sensor can be coupled to a control mechanism that controls the drive mechanism of piston 88, such that once the sensor is activated by the pin, the controller controls the movement of the drive mechanism. For example, the drive mechanism can be stopped or slowed from a first speed to a second, slower speed.

[0199] refer to Figure 15B , the piston head 92 has a proximal portion 103 connected to a distal portion 105. The distal ends of the proximal portion 103 and the distal portion 105 can have rounded edges 107. At least a portion of the proximal portion 103 has a smaller outer diameter than the outer diameter of the distal portion 105, so that a radial lip 109 is formed at the transition between the proximal portion 103 and the distal portion 105. The radial lip 109 can be continuous or discontinuous around the circumference of the piston head 92. In some aspects, the radial lip 109 defines a locking boss 111 to engage the catch 74 of the at least one retaining member 68 when the plunger 26 is fully seated on the piston head 92.

[0200] Continue to refer Figure 15BThe piston head 92 may have at least one second alignment member 113 projecting radially outward from an outer surface of the piston head 92. At least the second alignment member 113 is shaped and / or configured to interact with the first alignment member 71 of the plunger 26 to facilitate alignment of the piston 88 with the plunger 26 to allow for releasable, locked connection of the plunger 26 with the piston 88. In some aspects, at least a portion of at least the second alignment member 113 may extend in a direction that is angled relative to the direction of the piston longitudinal axis 115. For example, at least the second alignment member 113 may have a guide surface 117 that is angled at an angle D relative to the piston longitudinal axis 115. The guide surface 117 is desirably angled such that when the proximal alignment surface 77a of the first alignment member 71 contacts the guide surface 117 of the second alignment member 113, the piston head 92 may be rotated about the piston stem 90, for example, about the axis of the one-way rotation mechanism 99.

[0201] In some aspects, a plurality of second alignment members 113 can be radially spaced apart along the outer circumference of the piston head 92 relative to the piston longitudinal axis 115. In some aspects, the number of second alignment members 113 can be equal to the total number of retaining members 68 and first alignment members 71 on the plunger 26. The second alignment members 113 are circumferentially spaced apart such that a retaining member 68 or a first alignment member 71 can be received between adjacent second alignment members 113. The second alignment members 113 can be separated from one another by portions of the outer surface of the proximal portion 103 and / or the distal portion 105 of the piston head 92.

[0202] Continue to refer Figure 15B Each guide surface 117 of the second alignment member 113 defines a travel path for guiding the proximal alignment surface 77a of the first alignment member 71 to move into and out of the recess 119 defined between adjacent second alignment members 113 (see FIG. Figure 15G ). The guide surface 117 can be radially and axially inclined or angled relative to the piston longitudinal axis 115 to guide the movement of the proximal alignment surface 77a. By guiding one or more proximal alignment surfaces 77a on the plunger 26 into corresponding recesses 119 on the piston head 92, as the plunger 26 (see Figure 15G ) is brought into contact with the piston 88, with the guide surface 117 assisting in self-orienting the piston head 92. In this manner, the piston 88, which has its piston longitudinal axis 115 rotationally misaligned with the plunger longitudinal axis 34, and the one or more first alignment members 71, which are initially misaligned in the rotational direction relative to the corresponding one or more second alignment members 113, are brought into axial and rotational alignment such that the one or more first alignment members 71 are received within the recesses 119 between adjacent second alignment members 113. The one or more second alignment members 113 may have a bottom surface 121 that is angled relative to the direction of the piston longitudinal axis 115.

[0203] The piston head 92 also has an actuating surface that interacts with an actuating member (e.g., first cam member 78) on the plunger 26. In some aspects, the actuating surface on the piston head 92 can be a second cam member 98. In some aspects, as described herein, the second cam member 98 cooperates with the first cam member 78 on at least one retaining member 68 of the plunger 26. The second cam member 98 desirably has a shape that, upon relative rotation between the piston 88 and the plunger 26, engages the first cam member 78 to cause the at least one retaining member 68 to deflect from the piston head 92 so that the plunger 26 can be removed from the piston 88. In some aspects, the second cam member 98 can be formed on or intersect with the second alignment member 113 on the piston head 92. In certain aspects, the second cam member 98 can have a cam surface 98a that extends radially outward and parallel to the longitudinal axis 115. The cam surface 98a can be aligned in the direction of the piston longitudinal axis 115. The second cam member 98 may have a chamfered portion (not shown) to facilitate passage of the first cam member 78 after the retaining member 68 has been sufficiently deflected to allow release of the retaining member.

[0204] refer to Figure 15C , the piston 88 is configured to interact with the plunger 26 to releasably lock with the plunger 26, e.g. Figure 15D By locking the piston 88 to the plunger 26, the plunger 26 can be opened in the syringe 12 (in Figure 2 The second cam member 98 on the piston 88 cooperates with the first cam member 78 on at least one retaining member 68 of the plunger 26 to releasably lock the plunger 26 to the piston 88.

[0205] refer to Figure 15F , the piston head 92 can be rotatable relative to the stem 90. In some aspects, the piston head 92 can be rotatable relative to the stem 90 in only one direction, such as clockwise or counterclockwise. Figure 15E The one-way rotation mechanism 99 of the one-way clutch mechanism shown in FIG. 1 allows the piston head 92 to rotate only in a first direction, such as a clockwise or counterclockwise direction. The one-way rotation mechanism 99 can be rotatable about a central axis 101 having a seal 102, such as an O-ring seal. In some aspects, the one-way rotation mechanism 99 can have a stop that prevents the piston head 92 from rotating in a second direction opposite to the first direction, such as a counterclockwise or clockwise direction, respectively. In other aspects, the one-way rotation mechanism 99 can be provided on at least a portion of the plunger 26.

[0206] refer to Figure 15G, the at least one first alignment member 71 can be disposed directly on one or more of the retaining members 68. In such an aspect, the at least one retaining member 68 can have a proximal alignment surface 77a disposed directly on the body of the at least one retaining member 68. As described herein, the first cam member 78 can also be disposed directly on the retaining member 68 such that engagement of the cam member 78 causes corresponding movement of the retaining member 68. The cam member 78 can be disposed on a side surface of the retaining member 68, or can be disposed on an edge of the at least one first alignment member 71, or can be disposed directly on one or more of the retaining members 68.

[0207] refer to Figure 16 , shows a cylindrical planar projection view of one aspect of the piston 88 and the plunger 26. If the piston 88 is rotationally misaligned relative to the plunger 26, such that the first alignment member 71 on the retaining member 68 directly on the plunger 26 is not rotationally aligned to be received within the recess 119 on the plunger head 92, the proximal alignment surface 77a (shown as a dotted line) of the first alignment member 71 on the plunger 26 contacts the guide surface 117 of the second alignment member 113 on the piston head 92. The engagement of the proximal alignment surface 77a with the guide surface 117 causes the piston head 92 to automatically rotate in the free rotation direction of the one-way rotation mechanism 99. Such rotation of the piston head 92 aligns the first alignment member 71 and the retaining member 68 to be received within the recess 119 between adjacent second alignment members 113. In this way, the piston 88 self-orients itself relative to the plunger 26 so that the plunger 26 can be releasably locked with the piston 88. If the piston 88 is rotationally aligned relative to the plunger 26, such as Figure 16 As shown in FIG, the first alignment member 71 and the retaining member 68 on the plunger 26 can be received in the recess 119 between adjacent second alignment members 113 without rotating the piston head 92.

[0208] In some aspects, for example Figure 17As shown, the plunger 26 can have one or more first alignment members 71 positioned adjacent to one or more retaining members 68. In some aspects, the width of the second alignment members 113 on the piston head 92 can be reduced in the circumferential direction so that the first alignment member 71 and the retaining member 68 can be received in the same space defined between adjacent second alignment members 113 on the piston head 92. The one or more first alignment members 71 can have a first end 71a connected to the body 32 of the plunger and a second end 71b protruding in a proximal direction opposite to the protruding direction of the second end 72 of the one or more retaining members 68. The second end 72b of the first alignment retaining member 71 can be deflectable in a radial direction relative to the first end 71a. The first alignment member 71 can also have an angled guide surface (e.g., defined by an outer surface of the second end 71b) that cooperates with the second alignment member 113 of the piston head 92 to align the plunger 26 relative to the piston 88. During the engagement / disengagement process, the second end 71b of the first alignment member 71 can deflect radially outward as it passes over the area defined by the groove 119 and the second alignment member 113, and deflect back in a radially inward direction once the second end 71b exits the groove 119. One or more of the first alignment members 71 can have a latching member (not shown) to lock with at least a portion of the piston head 92 (e.g., the radial lip 109).

[0209] In another aspect, such as Figure 18 As shown in FIG, the one or more first alignment members 71 may be spaced apart from the one or more retaining members 68 such that each first alignment member 71 and retaining member 68 is received in a separate space defined between adjacent second alignment members 113 on the piston head 92. Figure 19 , at least one first alignment member 71 can be bifurcated and formed of two separate parts. Each part can be separately attached to the plunger body 32. In some aspects, the two parts can be joined together at the second end 71b, for example Figure 19 In various aspects, the interaction of the at least one first alignment member 71 on the plunger 26 with the one or more second alignment members 113 on the piston 88 results in self-orientation of the piston 88 such that the at least one retaining member 68 is received in the recess 119 on the piston head 92 .

[0210] refer to Figure 20AAccording to certain aspects, at least portions of the second alignment members 113 (such as the lower or proximal ends of the second alignment members 113) can be connected by a continuous lip 123 that extends continuously around the outer circumference of the piston head 92 at a radial position, which can be flush, radially recessed, or radially protruding relative to the outer surface of the second alignment members 113. In aspects where two or more second alignment members 113 are provided, the second alignment members 113 can be evenly spaced apart from each other. In one exemplary and non-limiting aspect (six first alignment members 113 with equal angular separation therebetween), each second alignment member 113 is separated from the adjacent second alignment member 113 on either side by 60 degrees. In some aspects, the second alignment members 113 can have unequal angular extensions and / or unequal angular spacing between the second alignment members 113 around the outer surface of the proximal portion 103 and / or distal portion 105 of the piston head 92. The radial spacing of the at least one second alignment member 113 relative to the piston longitudinal axis 115 is selected to correspond to the internal shape of the plunger 26 (at Figures 20B-20D ), to allow the retaining member 68 and the first alignment member 71 to be received between adjacent second alignment members 113.

[0211] refer to Figures 20C-20D , at least one first alignment member 71 can be disposed directly on one or more of the retaining members 68. In such aspects, at least one retaining member 68 can have a proximal alignment surface 77a and a distal alignment surface 77b disposed directly on the body of the at least one retaining member 68. The proximal alignment surface 77a can be angled relative to the plunger longitudinal axis 34. In some aspects, the proximal alignment surface 77a can align with the piston 88 (at Figure 20A The guide surface 117 on the piston head 92 is aligned so that the proximal alignment surface 77a is guided to the piston head 92 (shown in FIG. Figure 20A As described herein, the first cam member 78 may also be disposed directly on the retaining member 68 such that engagement of the cam member 78 causes corresponding movement of the retaining member 68, such as during rotation of the plunger 26 relative to the piston head 92. The retaining member 68 may have at least one catch 74 formed on the second end 72 of the retaining member 68. The at least one catch 74 may be shaped to be received on the piston 88 (at Figure 20A) to lock the plunger 26 axially relative to the piston 88. In some aspects, the at least one catch 74 can be linear or curvilinear. In some aspects, the at least one catch 74 can be oriented in a direction substantially perpendicular to the direction of the plunger longitudinal axis 34. In other aspects, the at least one catch 74 can be angled relative to the direction of the plunger longitudinal axis 34. The at least one catch 74 can be continuous or discontinuous. In some aspects, the at least one catch 74 can project radially inward toward the plunger longitudinal axis 34. Figure 20B , the distal end 38 of the plunger body 32 can have one or more openings 49 extending through the plunger body 32. The one or more openings 49 can be radially spaced relative to the plunger longitudinal axis 34. The openings 49 can have equal or unequal angular extensions and / or equal or unequal angular spacings between each other. In some aspects, the one or more openings 49 can be formed to facilitate molding of the plunger body 32. For example, the one or more openings 49 define a path that a molding tool follows during the molding process of the plunger 26.

[0212] refer to Figures 21A-21C , plunger 26 and piston 88 are shown according to another aspect of the present disclosure. Figures 21A-21C The components of the plunger 26 shown in FIG. 1 are substantially similar to those described herein with reference to FIG. Figures 3A-3C The components of the plunger 26 are described. Similarly, Figures 21A-21C The components of the piston 88 shown in FIG. 8 are substantially similar to those described herein with reference to FIG. Figures 4A-4C Components of piston 88 are described. Figures 21A-21C The reference numerals in the figure are used to illustrate Figures 3A-4C The same parts in FIG. have corresponding reference numerals. Figures 3A-4C The previous discussion of the plunger 26 and piston 88 generally shown in FIG. 1 is applicable to the present disclosure in FIG. Figures 21A-21C Therefore, only the aspects shown in Figures 3A-4C The plunger 26 and piston 88 shown generally in FIG. Figures 21A-21C The relative differences between plunger 26 and piston 88 are generally shown in FIG.

[0213] refer to Figure 21A, the plunger 26 can have at least one resiliently deflectable retaining member 68 (hereinafter referred to as "retaining member 68") protruding from the plunger body 32. In some aspects, the at least one retaining member 68 can protrude in a circumferential direction extending around the inner circumference of the inner surface 52 of the lumen 40. In some aspects, the at least one retaining member 68 can extend substantially perpendicular to the longitudinal axis 34 of the plunger body 32. In other aspects, the at least one retaining member 68 can be angled in a distal or proximal direction relative to a plane extending perpendicular to the longitudinal axis 34 of the plunger body 32. For clarity, features such as the at least one alignment member 71 are omitted.

[0214] Continue to refer Figure 21A At least one retaining member 68 has a first section or first end 70 connected to the plunger body 32, and a second section or second end 72 extending circumferentially relative to the first end 70 around at least a portion of the inner circumference of the plunger body 32. The second end 72 can be deflected and / or twisted relative to the first end 70. As described herein, the second end 72 can be deflected circumferentially and / or radially relative to the first end 70 toward or away from the inner surface of the plunger body 32. The first end 70 and the second end 72 can be spaced apart in a direction extending substantially circumferentially around the inner surface of the plunger body 32. The at least one retaining member 68 can be continuous linearly, stepped, or curvilinearly between the first end 70 and the second end 72. In some aspects, a plurality of retaining members 68 can be radially spaced relative to the plunger longitudinal axis 34 along the circumference of the inner surface 52 of the lumen 40. The retaining members 68 can be separated from each other by portions of the inner surface 52 of the lumen 40, such as by equal or unequal spacing. As described herein, the radial spacing of the at least one retaining member 68 relative to the plunger longitudinal axis 34 is selected to correspond to or operatively interact with the outer shape of the piston.

[0215] refer to Figure 21B , the second end 72 of the retaining member 68 has at least one catch 74 that is shaped to engage at least a portion of a recess, lip, or boss on the piston to lock the at least one retaining member 68, along with the plunger 26, relative to the piston. In some aspects, the at least one catch 74 can project radially inward or outward relative to the body of the retaining member 68. The at least one catch 74 can be integrally formed with the second end 72 of the at least one retaining member 68, or it can be affixed or otherwise secured to the second end 72 of the at least one retaining member 68, such as using a friction fit and / or adhesive, welding, or by molding.

[0216] refer to Figure 21C , the plunger 26 may have a piston ( Figure 17. The at least one retaining member 68 can be provided with at least one actuating member (e.g., a first cam member 78) that interacts with the at least one retaining member 68 (shown in FIG. 1 ) to radially deflect the at least one retaining member 68 upon rotation of the plunger 26 relative to the piston. The at least one first cam member 78 can be disposed at the second end 72 of the retaining member 68. The at least one first cam member 78 can be angled relative to the body of the retaining member 68. In some aspects, the at least one cam member 78 can be on at least one surface of a recess 170 formed on the second end 72 of the at least one retaining member 68.

[0217] The plunger 26 may have at least one alignment member such as Figure 3A 8. The first alignment member 71 is shown protruding from the plunger body 32. As described herein, the at least one first alignment member 71 is shaped and / or configured to facilitate self-orienting alignment of the plunger 26 with the piston 88.

[0218] To engage the plunger 26 with the piston 88, as described herein, the syringe 12 is first inserted into the fluid injector 10 (at Figure 1 1 and 12. The piston 88 is rotated out of alignment relative to the plunger 26 so that the one or more alignment members on the plunger 26 are not rotationally aligned to be received within the recess 119 on the plunger head 92, the one or more alignment members 71 on the plunger 26 contact the guide surface 117 of the second alignment member 113 on the piston head 92 to rotate the piston head 92 into alignment for connection to the plunger 26. In this manner, the piston 88 orients itself relative to the plunger 26 so that the plunger 26 can be releasably locked with the piston 88. The distal movement of the piston 92 causes the retaining members 68 to deflect circumferentially from a first, undeflected position to a second, deflected position relative to the plunger longitudinal axis 34. The piston 88 is advanced distally until the distal end portions of the second end 72 clear the retaining members 68, thereby allowing them to deflect radially inward toward or into their initial, undeflected position. The catch 74 of the at least one retaining member 68 is retained within the locking boss 111 of the recess 119 or beneath the locking boss 111a on the proximal end of the at least one second alignment member 113 formed on the piston head 92 to prevent the plunger 26 from separating from the piston head 92, for example by frictionally fitting against the second portion of the inner wall of the plunger 26. In some aspects, such as Figure 21B As shown, at least a portion of the piston 88 (such as the at least one second alignment member 113) may have a locking boss 111a that engages the catch 74 when the plunger 26 is connected to the piston 88 to prevent the plunger 26 from being locked when the plunger 26 is within the syringe barrel 18 ( Figure 2 ) when moved in the proximal direction, the plunger 26 disengages from the piston 88.

[0219] To remove the syringe from port 16 (at Figure 18 (shown in FIG), unlocks the syringe 12 and separates the plunger 26 from the piston 88, the syringe 12 is rotated clockwise or counterclockwise about the syringe longitudinal axis relative to the syringe port 16. Rotation of the syringe 12, and thereby the plunger 26, about the plunger longitudinal axis 34 engages the first cam member 78 on the plunger 26 with the second cam member 98 on the piston head 92. Such movement causes the at least one retaining member 68 to deflect away from the piston head 92 to unlock the plunger 26 from the piston head 92 and allow removal of the syringe 12.

[0220] refer to Figures 22A-22D , plunger 26 and piston 88 are shown according to another aspect of the present disclosure. Figures 22A-22D The components of the plunger 26 shown in FIG. 1 are substantially similar to those described herein with reference to FIG. Figures 3A-3C The components of the plunger 26 are described. Similarly, Figures 22A-22D The components of the piston 88 shown in FIG. 8 are substantially similar to those described herein with reference to FIG. Figures 4A-4C Components of piston 88 are described. Figures 22A-22D The reference numerals in the figure are used to illustrate Figures 3A-4C The same parts in FIG. have corresponding reference numerals. Figures 3A-4C The previous discussion of the plunger 26 and piston 88 generally shown in FIG. 1 is applicable to the present disclosure in FIG. Figures 22A-22D Therefore, only the aspects shown in Figures 3A-4C The plunger 26 and piston 88 shown generally in FIG. Figures 22A-22D The relative differences between plunger 26 and piston 88 are generally shown in FIG.

[0221] refer to Figure 22AThe plunger 26 can have at least one resiliently deflectable retaining member 68 (hereinafter referred to as "retaining member 68") protruding from the plunger body 32. In some aspects, the at least one retaining member 68 can be U-shaped, with a first portion 130 having a first end 132 connected to the plunger body 32 and a second end 134 extending in a direction toward the proximal end of the plunger body 32. The at least one retaining member 68 can also have a transition portion 136 connected to the second end 134 of the first portion 130. A first end 138 of a second portion 140 can be connected to the transition portion 136 at an end opposite from the connection to the second end 134 of the first portion 130. The transition portion 136 extends in a radial direction with respect to the longitudinal axis 34 of the plunger body 32 and connects the first portion 130 to the second portion 140. A second end 142 of the second portion 140 extends toward the distal end of the plunger body 32. The first portion 130, the second portion 140, or both can deflect or twist relative to the plunger body 32. For example, the second end 134 of the first portion 130 can be deflectable in a radial or circumferential direction relative to the first end 132 and the plunger body 32. Alternatively or additionally, the second end 142 of the second portion 140 can be deflectable in a radial or circumferential direction relative to the first end 138 and, therefore, the first portion 130 and the plunger body 32. In some aspects, a plurality of retaining members 68 can be radially spaced relative to the plunger longitudinal axis 34 along the circumference of the inner surface 52 of the lumen 40. The retaining members 68 can be separated from each other by portions of the inner surface 52 of the lumen 40, such as at equal or unequal intervals. As described herein, the radial spacing of at least one retaining member 68 relative to the plunger longitudinal axis 34 is selected to correspond to or operatively interact with the outer shape of the piston.

[0222] refer to Figure 22A , the second end 142 of the second portion 140 of the retaining member 68 has at least one catch 74 that is shaped to engage at least a portion of a recess, lip, or boss on the piston to lock the at least one retaining member 68, along with the plunger 26, relative to the piston. In some aspects, the at least one catch 74 can project radially inward or outward relative to the body of the retaining member 68. The at least one catch 74 can be integrally formed with the second end 142 of the second portion 140 of the at least one retaining member 68, or it can be adhered or otherwise secured to the second end 72 of the at least one retaining member 68 using, for example, a friction fit and / or adhesive, welding, or by molding.

[0223] refer to Figure 22C , the plunger 26 may have a piston (in Figure 12 and 3. The at least one first cam member 78 may be provided on a second portion 140 of the at least one retaining member 68. The at least one first cam member 78 may be angled relative to the body of the retaining member 68 at an angle B.

[0224] refer to Figure 22A , the plunger 26 can have at least one first alignment member 71 defined on at least a portion of the at least one retaining member 68, such as the transition portion 136. The at least one first alignment member 71 is shaped and / or configured to facilitate self-orienting alignment of the plunger 26 with the piston 88. In some aspects, at least a portion of the at least one first alignment member 71 can extend in a direction that is angled relative to the direction of the plunger longitudinal axis 34. For example, the at least one first alignment member 71 can have a proximal alignment surface 77a that is angled at an angle C relative to the longitudinal axis 34 to facilitate positioning the retaining member 68 during connection of the plunger 26 to the piston. As described herein, the proximal alignment surface 77a helps guide the plunger 26 into self-orienting alignment with the piston.

[0225] To engage the plunger 26 with the piston 88, as described herein, the syringe 12 is first inserted into the fluid injector 10 (at Figure 1 1 and 12. The piston 88 is rotated out of alignment relative to the plunger 26 so that the one or more alignment members on the plunger 26 are not rotationally aligned to be received within the recess 119 on the plunger head 92, the one or more alignment members on the plunger 26 contact the guide surface 117 of the second alignment member 113 on the piston head 92 to rotate the piston head 92 into alignment for connection to the plunger 26. In this manner, the piston 88 orients itself relative to the plunger 26 so that the plunger 26 can be releasably locked with the piston 88. Distal movement of the piston 92 causes the retaining members 68 to deflect outwardly from a first, undeflected position to a second, radially deflected position relative to the plunger longitudinal axis 34. The piston 88 is advanced distally until the distal ends of the second end 72 clear the retaining members 68, thereby allowing them to deflect radially inwardly toward or into their initial, undeflected position. The catch 74 of the at least one retaining member 68 is retained within the locking boss 111 to prevent the plunger 26 from separating from the piston head 92 .

[0226] To remove the syringe from port 16 (at Figure 18 (shown in FIG), unlocks the syringe 12 and separates the plunger 26 from the piston 88, the syringe 12 is rotated clockwise or counterclockwise about the syringe longitudinal axis relative to the syringe port 16. Rotation of the syringe 12, and thereby the plunger 26, about the plunger longitudinal axis 34 engages the first cam member 78 on the plunger 26 with the second cam member 98 on the piston head 92. Such movement causes the at least one retaining member 68 to deflect away from the piston head 92 to unlock the plunger 26 from the piston head 92 and allow removal of the syringe 12.

[0227] refer to Figures 23A-23D , plunger 26 and piston 88 are shown according to another aspect of the present disclosure. Figures 23A-23D The components of the plunger 26 shown in FIG. 1 are substantially similar to those described herein with reference to FIG. Figures 3A-3C Components of the plunger 26 described herein and other aspects described herein. Similarly, Figures 23A-23D Some components of the piston 88 shown in FIG. 8 are substantially similar to those described herein with reference to FIG. Figures 4A-4C Some components of piston 88 are described. Figures 23A-23D The reference numerals in the figure are used to illustrate Figures 3A-4C The same parts in FIG. have corresponding reference numerals. Figures 3A-4C The previous discussion of the plunger 26 and piston 88 generally shown in FIG. 1 is applicable to the present disclosure in FIG. Figures 23A-23D Therefore, only the aspects shown in Figures 3A-4C The plunger 26 and piston 88 shown generally in FIG. Figures 23A-23D The relative differences between plunger 26 and piston 88 are generally shown in FIG.

[0228] refer to Figure 23A , the plunger 26 can have at least one resiliently deflectable retaining member 68 (hereinafter referred to as "retaining member 68") protruding from the plunger body 32. In some aspects, the at least one retaining member 68 can protrude in a proximal direction toward the proximal end of the plunger body 32. In some aspects, the at least one retaining member 68 can extend substantially parallel to the longitudinal axis 34 of the plunger body 32. In other aspects, the at least one retaining member 68 can be angled relative to the longitudinal axis 34 of the plunger body 32.

[0229] Continue to refer Figure 23AAt least one retaining member 68 has a first section or end 70 connected to the plunger body 32 and a second section or end 72 extending in a proximal direction relative to the first end 70. The second end 72 can be deflected or twisted relative to the first end 70. As described herein, the second end 72 can be radially deflectable relative to the first end 70 toward or away from the inner surface of the plunger body 32. The at least one retaining member 68 can be linearly, stepped, or curvilinearly continuous between the first end 70 and the second end 72. In some aspects, a plurality of retaining members 68 can be radially spaced relative to the plunger longitudinal axis 34 along the circumference of the inner surface 52 of the lumen 40. The retaining members 68 can be separated from each other by portions of the inner surface 52 of the lumen 40, such as at equal or unequal intervals. As described herein, the radial spacing of the at least one retaining member 68 relative to the plunger longitudinal axis 34 is selected to correspond to or operatively interact with the outer shape of the piston.

[0230] refer to Figure 23B , the second end 72 of the retaining member 68 has at least one catch 74 that is shaped to engage at least a portion of a recess, lip, or boss on the piston to lock the at least one retaining member 68, along with the plunger 26, relative to the piston. In some aspects, the at least one catch 74 can project radially inward or outward relative to the body of the retaining member 68. The at least one catch 74 can be integrally formed with the second end 72 of the at least one retaining member 68, or it can be affixed or otherwise secured to the second end 72 of the at least one retaining member 68, such as using a friction fit and / or adhesive, welding, or by molding.

[0231] refer to Figure 23C , the plunger 26 may have a piston (in Figure 1 2 and 3. The at least one first cam member 78 may be provided at the second end 72 of the retaining member 68. The at least one first cam member 78 may be angled relative to the body of the retaining member 68 at an angle B.

[0232] The plunger 26 can have at least one alignment member, such as at least one first alignment member 71 that protrudes from the plunger body 32. As described herein, the at least one first alignment member 71 is shaped and / or configured to facilitate self-orientation alignment of the plunger 26 with the piston 88. The at least one first alignment member 71 can be disposed adjacent to the at least one retaining member 68.

[0233] To engage the plunger 26 with the piston 88, as described herein, the syringe 12 is first inserted into the fluid injector 10 (at Figure 11 and 12. The piston 88 is rotated out of alignment relative to the plunger 26 so that the one or more alignment features 71 on the plunger 26 are not rotationally aligned to be received within the recess 119 on the plunger head 92, the one or more alignment features 71 on the plunger 26 contact the guide surface 117 of the second alignment feature 113 to rotate the piston head 92 into alignment for connection to the plunger 26. In this manner, the piston 88 orients itself relative to the plunger 26 so that the plunger 26 can be releasably locked with the piston 88. The distal movement of the piston 88 causes the retaining members 68 to deflect outwardly from a first, undeflected position to a second, radially deflected position relative to the plunger longitudinal axis 34. The piston 88 is advanced distally until the distal ends of the second end 72 clear the retaining members 68, thereby allowing them to deflect radially inwardly toward or into their initial, undeflected position. The catch 74 of at least one retaining member 68 is retained within the locking boss 111 of the recess 119 or within the locking boss 111 formed on the piston head 92 (at Figure 23B ) below the locking boss 111a on the proximal end of at least one second alignment member 113 to prevent the plunger 26 from separating from the piston head 92.

[0234] To remove the syringe from port 16 (at Figure 1 88, the syringe 12 is rotated clockwise or counterclockwise about the syringe longitudinal axis relative to the syringe port 16. Rotation of the syringe 12, and thereby the plunger 26, about the plunger longitudinal axis 34 engages the first cam member 78 on the plunger 26 with the second cam member 98 on the piston head 92. Such movement causes the at least one retaining member 68 to deflect away from the piston head 92 to unlock the plunger 26 from the piston head 92 and allow the syringe 10 (shown in FIG. 1 ) to be removed from the syringe 10. Figure 1 ) Remove syringe 12.

[0235] refer to Figures 24A-24C , plunger 26 and piston 88 are shown according to another aspect of the present disclosure. Figures 24A-24C Some components of the plunger 26 shown in FIG are substantially similar to those described herein with reference to FIG. Figures 3A-4C Components of the plunger 26 are described. Figures 24A-24C The components of the plunger 26 shown in FIG. 1 are otherwise substantially similar to those described herein with reference to FIG. Figures 21A-21C The components of the plunger 26 are described. Similarly, Figures 24A-24C The components of the piston 88 shown in FIG. 8 are substantially similar to those described herein with reference to FIG. Figures 21A-21C Components of piston 88 are described. Figures 24A-24C The reference numerals in the figure are used to illustrate Figures 4A-4C or Figures 21A-21C The same parts with corresponding reference numerals in FIG. Figures 3A-4C The previous discussion of the plunger 26 and piston 88 generally shown in FIG. 1 is applicable to the present disclosure in FIG. Figures 24A-24C Therefore, only the aspects shown in Figures 3A-4C The plunger 26 and piston 88 shown generally in FIG. Figures 24A-24C The relative differences between plunger 26 and piston 88 are generally shown in FIG.

[0236] refer to Figure 24A , the plunger 26 can have at least one resiliently deflectable retaining member 68 (hereinafter referred to as "retaining member 68") associated with the plunger body 32. In some aspects, the at least one retaining member 68 can protrude in a radial direction from the inner surface 52 of the lumen 40. Figure 24A , the at least one retaining member 68 has a first section or first end 70 that extends through, toward, or out of the plunger body 32. For example, the first end 70 of the at least one retaining member 68 can extend through an opening 73 that extends through the sidewall 39 of the plunger body 32. The at least one retaining member 68 can have a second section or second end 72 that extends radially inwardly to the lumen 40 relative to the first end 70. Features such as the at least one alignment member 71 are omitted for clarity.

[0237] The first end 70 of the at least one retaining member 68 may directly or indirectly contact or abut a resilient member, such as a plunger cap (e.g., Figure 3E Alternatively or additionally, the first end 70 of the at least one retaining member 68 may directly or indirectly contact or abut a resilient element such as a metal or plastic spring or other resilient material that urges the at least one retaining member 68 radially inward. Figure 24B, the first end 70 of the at least one retaining member 68 can have at least one stop member 171 that limits the radially inward and / or outward travel of the at least one retaining member 68 so that it does not fall out of the plunger body 32. The stop member 171 can be a resilient element associated with the at least one retaining member 68. The at least one retaining member 68 can be manufactured as a separate piece and inserted into the plunger body 32 before the plunger cap 58 is installed, co-molded with the plunger body 32 using a co-molding process, or can be molded as part of the plunger body 32 with a thin portion (not shown) that deflects or breaks when the at least one retaining member 68 is assembled or deflected in a radially inward or outward direction to allow the desired movement of the at least one retaining member 68. Alternatively, the at least one resilient member 68 can have a stop member 171 or attach the at least one retaining member 68 to a thin portion (not shown) of the plunger body 32. In some aspects, a plurality of retaining members 68 can be radially spaced relative to the plunger longitudinal axis 34 along the circumference of the inner surface 52 of the lumen 40. The retaining members 68 can be separated from one another by portions of the inner surface 52 of the lumen 40, such as by equal or unequal spacing. As described herein, the radial spacing of the at least one retaining member 68 relative to the plunger longitudinal axis 34 is selected to correspond to or operatively interact with the outer shape of the piston.

[0238] refer to Figure 24B , the second end 72 of the retaining member 68 has at least one catch 74 that is shaped to engage at least a portion of a recess, lip, or boss on the piston to lock the at least one retaining member 68, along with the plunger 26, relative to the piston. In some aspects, the at least one catch 74 can project radially inward or outward relative to the body of the retaining member 68. The at least one catch 74 can be integrally formed with the second end 72 of the at least one retaining member 68, or it can be affixed or otherwise secured to the second end 72 of the at least one retaining member 68, such as using a friction fit and / or adhesive, welding, or by molding.

[0239] refer to Figure 24C , the plunger 26 may have a piston (in Figure 1 68) to radially deflect the at least one retaining member 68 upon rotation of the plunger 26 relative to the piston as described herein. The at least one first cam member 78 can be disposed at the second end 72 of the retaining member 68. The at least one first cam member 78 can be angled relative to the body of the retaining member 68.

[0240] The plunger 26 may have at least one alignment member such as Figure 3A23, protruding from the plunger body 32. The at least one first alignment member 71 is shaped and / or configured to facilitate self-orienting alignment of the plunger 26 with the piston 88, as described herein.

[0241] To engage the plunger 26 with the piston 88, as described herein, the syringe 12 is first inserted into the fluid injector 10 (at Figure 1 92 . If the piston 88 is rotationally misaligned relative to the plunger 26 such that the one or more alignment members on the plunger 26 are not rotationally aligned to be received within the recess 119 on the plunger head 92, the one or more alignment members on the plunger 26 contact the guide surface 117 of the second alignment member 113 on the piston head 92 to rotate the piston head 92 into alignment for connection to the plunger 26. In this manner, the piston 88 orients itself relative to the plunger 26 such that the plunger 26 can be releasably locked with the piston 88. Distal movement of the piston 92 causes the retaining members 68 to deflect outwardly from a first, undeflected position to a deflected position relative to the plunger longitudinal axis 34. The piston 88 is advanced distally until the distal ends of the second end 72 clear the retaining members 68, thereby allowing them to deflect radially inwardly toward or into their initial, undeflected position. The catch 74 of the at least one retaining member 68 is retained within the locking boss 111 of the recess 119 or within the locking boss 111 a on the proximal surface of the second alignment member 113 to prevent the plunger 26 from separating from the piston head 92 .

[0242] To unlock the syringe 12 from the syringe port 16 and disengage the plunger 26 from the piston 88, the syringe 12 is rotated clockwise or counterclockwise about the syringe longitudinal axis relative to the syringe port 16. Rotation of the syringe 12, and thereby the plunger 26, about the plunger longitudinal axis 34 engages the first cam member 78 on the plunger 26 with the second cam member 98 on the piston head 92. Such movement causes the at least one retaining member 68 to deflect radially away from the piston head 92 to unlock the plunger 26 from the piston head 92 and allow removal of the syringe 10 (at Figure 1 In an alternative aspect, the grab 74a (in Figure 24A ) may be provided on the distal surface of at least one retaining member 68 to engage Figure 24A The first cam member 78a can be formed into a locking boss 111 as shown to prevent the plunger 26 from separating from the piston head 92. Figure 24A The positioning shown enables the catch 74a to be released upon relative rotation of the plunger 26 and piston 88.

[0243] According to various alternative aspects of the present disclosure, the structural details of the connection interface between the plunger 26 and the piston 88 described herein may be reversed. That is, the connection interface of any plunger 26 may include, for example, the locking mechanism and corresponding features described herein with reference to any piston 88, while the connection interface on the piston 88 may include, for example, the elements described herein as part of the plunger 26.

[0244] Although the present disclosure has been described in detail based on what are presently considered to be the most practical and preferred aspects for purposes of illustration, it should be understood that such detail is for that purpose only, and that the present disclosure is not limited to the disclosed aspects, but rather is intended to cover modifications and equivalent arrangements. For example, it should be understood that, to the extent possible, the present disclosure contemplates that one or more features of any aspect can be combined with one or more features of any other aspect.

Claims

1. A piston for a power fluid injector, the piston comprising: a stem connected to a proximal portion of the piston; and A piston head extending distally from the stem, wherein the piston head comprises: a proximal portion having a first outer diameter; a distal portion having a second outer diameter, wherein the first outer diameter is smaller than the second outer diameter; a radial lip formed at a transition between the proximal portion and the distal portion, wherein the radial lip defines a locking boss; at least one alignment member projecting radially outwardly from an outer surface of the piston head, wherein the at least one alignment member is configured to interact with a first alignment member of a plunger of a syringe; and An actuation surface is configured to interact with an actuation member of the plunger to deflect at least one retaining member of the plunger from the piston head so as to disengage the at least one retaining member from the locking boss of the piston when the plunger is rotated relative to the piston.

2. The piston according to claim 1, wherein The plunger is separated from the piston head by disengaging the at least one retaining member from the locking boss of the piston.

3. The piston according to claim 1, wherein The at least one alignment feature is shaped to facilitate alignment of the piston head with the plunger so as to allow a releasable locking connection between the plunger and the piston.

4. The piston according to claim 3, wherein The at least one alignment member includes a guide surface that is angled relative to a longitudinal axis of the piston.

5. The piston according to claim 4, wherein The angle of the guide surface is configured to rotate the piston head about the piston stem.

6. The piston according to claim 5, wherein The guide surface causes the piston head to rotate about the piston stem via a one-way rotation mechanism.

7. The piston according to claim 6, wherein The one-way rotation mechanism includes a one-way clutch mechanism configured to allow rotation only in a first direction.

8. The piston according to claim 4, wherein The guide surfaces rotate the piston head into self-orienting alignment with the plunger by guiding one or more alignment surfaces on a first alignment member of the plunger into corresponding recesses between adjacent alignment members on the piston head.

9. The piston according to claim 1, wherein The at least one alignment member includes a bottom surface that is angled relative to the direction of the longitudinal axis of the piston.

10. The piston according to claim 1, wherein The actuation surface includes a cam member configured to interact with a first cam member on at least one retaining member of the plunger and cause the at least one retaining member to radially deflect a catch on the at least one retaining member of the plunger away from the piston head and disengage the locking boss.

11. The piston according to claim 10, wherein As the piston retracts the plunger in a proximal direction during a syringe filling procedure, the locking force between the locking boss of the piston and the catch on at least one retaining member of the plunger increases due to compressive forces.

12. The piston of claim 1 further comprising a pointed distal end having a cap shaped to be received within at least a portion of the interior cavity of the plunger.

13. The piston according to claim 12, wherein Also included is a sensing member extending through at least a portion of the cap along a longitudinal axis of the piston.

14. The piston according to claim 1, wherein At least one of the distal end of the proximal portion and the distal end of the piston head has a rounded or chamfered edge.

15. A piston-plunger assembly for a power fluid injector, the piston-plunger assembly comprising: Plunger, including: a plunger body having a proximal end, a distal end, and a circumferential sidewall extending along a plunger longitudinal axis between the proximal and distal ends; at least one resiliently deflectable retaining member having a first section attached to the plunger body and a second section projecting from the first section toward a distal end of the plunger body and deflectable relative to the first section; and at least one actuating member associated with the at least one resiliently deflectable retaining member; and Piston, including: a stem connected to a proximal portion of the piston; and A piston head extending distally from the stem, wherein the piston head comprises: a proximal portion having a first outer diameter; a distal portion having a second outer diameter, wherein the first outer diameter is smaller than the second outer diameter; a radial lip formed at a transition between the proximal portion and the distal portion, wherein the radial lip defines a locking boss; at least one alignment member projecting radially outwardly from an outer surface of the piston head, wherein the at least one alignment member is configured to interact with a first alignment member of a plunger of a syringe; and an actuation surface configured to interact with at least one actuation member of the plunger, wherein at least one retaining member of the plunger is deflected from the piston head so that rotation of the plunger relative to the piston causes the at least one retaining member to disengage from the locking boss of the piston.

16. A piston head for a fluid injector, the piston head comprising: a proximal portion having a first outer diameter; a distal portion having a second outer diameter, wherein the first outer diameter is smaller than the second outer diameter; a radial lip formed at a transition between the proximal portion and the distal portion, wherein the radial lip defines a locking boss; at least one alignment member projecting radially outwardly from an outer surface of the piston head, wherein the at least one alignment member is configured to interact with a first alignment member of a plunger of a syringe; and An actuation surface is configured to interact with an actuation member of the plunger to deflect at least one retaining member of the plunger from the piston head so as to disengage the at least one retaining member from the locking boss of the piston head when the plunger is rotated relative to the piston head.

17. The piston head according to claim 16, wherein: The at least one alignment member includes a guide surface that is angled relative to a longitudinal axis of the piston.

18. The piston head according to claim 17, wherein: The guide surfaces rotate the piston head into self-orienting alignment with the plunger by guiding one or more alignment surfaces on a first alignment member of the plunger into corresponding recesses between adjacent alignment members on the piston head.

19. The piston head according to claim 16, wherein: The actuation surface includes a cam member configured to interact with a first cam member on at least one retaining member of the plunger and cause the at least one retaining member to radially deflect a catch on the at least one retaining member of the plunger away from the piston head and disengage the locking boss.

20. The piston head according to claim 19, wherein: As the piston retracts the plunger in a proximal direction during a syringe filling procedure, the locking force between the locking boss of the piston and the catch on at least one retaining member of the plunger increases due to compressive forces.

Images