Plunger rod and syringe comprising the plunger rod

Abstract

A plunger rod for use with a syringe having a syringe barrel. The plunger includes an elongated body having a proximal end, a distal end opposite the proximal end, a central axis extending between the proximal end and the distal end, a first curved end face, a second curved end face, and a junction joining the first curved end face to the second curved end face. Each of the first curved end face, the second curved end face, and the junction extend between the proximal end and the distal end. The first curved end face and the second curved end face together are included in a circle defined by an outer periphery of the elongated body.

Description

BACKGROUND TECHNICAL FIELD

[0002] The present disclosure relates generally to a plunger rod for use in a syringe barrel that can be associated with an automatic injector. The present disclosure also relates to a syringe, such as a manual syringe, that includes a plunger rod assembly. BACKGROUND

[0004] Syringes, particularly manually operated hypodermic syringes, are well known in the medical arts for dispensing fluids, such as medicaments, or for withdrawing biological fluid samples therein. Conventional syringe assemblies typically include a syringe barrel having a fluid opening at one end and a plunger assembly disposed through the opposite end in slidable arrangement through the syringe barrel. The plunger assembly typically includes a rigid plunger rod having a linear longitudinal axis extending through the barrel, having a plunger head or stop at a distal end of the plunger rod, and having a thumb press disposed at a proximal end of the plunger rod. In use, the plunger rod can be retracted through the syringe barrel to draw a fluid, such as a medicament, or to fill the syringe barrel with a fluid. The plunger rod can also be advanced from one end of the syringe barrel to the other to expel a fluid, such as a medicament, from within the syringe barrel. To deliver a medicament to a patient, the opening of the syringe barrel can be adapted to be in fluid communication with the patient, such as through a hypodermic needle mounted at the distal end of the syringe barrel, or through a standard luer-type fitting extending from the distal end of the syringe barrel for attachment with a fluid line. Operation of the plunger rod assembly within the syringe barrel is well known in the medical arts.

[0005] In a standard medical environment, a large number of syringes are used each year. As a result, it is desirable that the plunger rod of the syringe be manufactured to be as cost effective as possible, that the plunger rod of the syringe be relatively robust (e.g., to withstand loads imparted during use), and that the plunger rod of the syringe be manufactured during molding with a relatively short cycle time. Accordingly, there is a need in the art for an improved plunger rod and syringe including the same. SUMMARY

[0006] In one aspect, a plunger rod for use with a syringe having a syringe barrel is provided. The plunger includes an elongate body having a proximal end, a distal end opposite the proximal end, a central axis extending between the proximal end and the distal end, a first curved end face, a second curved end face, and a junction joining the first curved end face to the second curved end face. Each of the first curved end face, the second curved end face, and the junction extend between the proximal end and the distal end. The first curved end face and the second curved end face together are included in a circle defined at least in part by an outer periphery of the elongate body.

[0007] On the other hand, a plunger rod is provided for use with a syringe having a syringe barrel. The plunger rod includes: an elongated body having a proximal end, a distal end opposite the proximal end, and a central axis extending between the proximal and distal ends; and a connecting portion extending between the proximal and distal ends, the connecting portion at least partially defining an arcuate outer periphery of the elongated body. The connecting portion does not intersect the central axis.

[0008] In another aspect, a syringe assembly includes: a syringe barrel having sidewalls, a distal end, and a proximal end; and a plunger rod including: an elongated body having a proximal end, a distal end opposite the proximal end of the elongated body, and a central axis extending between the proximal and distal ends of the elongated body; a first curved end face; a second curved end face; and a junction that engages the first curved end face to the second curved end face, each of the first curved end face, the second curved end face, and the junction extending between the proximal and distal ends of the elongated body. The first and second curved end faces are together included within a circle defined by the outer periphery of the elongated body.

[0009] In another aspect, a syringe assembly includes: a syringe barrel having sidewalls, a distal end, and a proximal end; and a plunger rod including: an elongated body having a proximal end, a distal end opposite the proximal end of the elongated body, and a central axis extending between the proximal and distal ends of the elongated body; and a junction extending between the proximal and distal ends of the elongated body, the junction at least partially defining an arcuate outer periphery of the elongated body. The junction does not intersect the central axis.

[0010] Various other aspects of this disclosure are enumerated in one or more of the following provisions:

[0011] Clause 1: A plunger rod for use with a syringe having a syringe barrel, the plunger rod comprising: an elongated body having a proximal end, a distal end opposite to the proximal end, and a central axis extending between the proximal end and the distal end; a first curved end face; a second curved end face; and a joint that engages the first curved end face to the second curved end face, each of the first curved end face, the second curved end face, and the joint extending between the proximal end and the distal end, wherein the first curved end face and the second curved end face together are included in a circle defined by the outer periphery of the elongated body.

[0012] Clause 2: The plunger rod of Clause 1, wherein the junction comprises: a middle face; a first connecting face extending from the middle face to the first curved end face; and a second connecting face extending from the middle face to the second curved end face, and wherein the middle face, the first curved end face, and the second curved end face are included in a circle bounded by an outer perimeter of the elongated body together with the middle face, the first curved end face, and the second curved end face.

[0013] Clause 3: The plunger rod of Clause 2, wherein the first connecting face is a first angular face relative to the middle face, and wherein the second connecting face is a second angular face relative to the middle face.

[0014] Clause 4: The plunger rod of Clause 3, wherein the first angular face and the second angular face each extend from the middle face at a respective angle equal to or greater than 90 degrees relative to the middle face.

[0015] Clause 5: The plunger rod of Clause 1, wherein the first curved end face, the second curved end face, and the junction do not intersect the central axis of the elongated body.

[0016] Clause 6: The plunger rod of Clause 1, wherein the junction intersects the central axis and extends directly from the first curved end face to the second curved end face.

[0017] Clause 7: The plunger rod of Clause 6, wherein the elongated body has a generally S-shaped cross-section.

[0018] Clause 8: The plunger rod of Clause 1, wherein the plunger rod further comprises a number of support ribs extending from the elongated body between the proximal end and the distal end.

[0019] Clause 9: The plunger rod of Clause 1, wherein the arcuate outer perimeter is discontinuous.

[0020] Clause 10: A plunger rod for use with a syringe having a syringe barrel, the plunger rod comprising: an elongated body having a proximal end, a distal end opposite the proximal end, and a central axis extending between the proximal end and the distal end; a junction extending between the proximal end and the distal end, the junction at least partially defining an arcuate outer perimeter of the elongated body, wherein the junction does not intersect the central axis.

[0021] Clause 11: The plunger rod of Clause 10, wherein the arcuate outer perimeter facing the central axis is concave.

[0022] Clause 12: The plunger rod of clause 10, wherein the plunger rod further comprises a number of support ribs extending from the elongated body between the proximal end and the distal end.

[0023] Clause 13: The plunger rod of clause 10, wherein the arcuate outer periphery is discontinuous.

[0024] Clause 14: The plunger rod of clause 10, further comprising a stopper overmolded on the elongated body.

[0025] Clause 15: A syringe assembly comprising: a syringe barrel having a sidewall, a distal end, and a proximal end; and a plunger rod comprising: an elongated body having a proximal end, a distal end opposite the proximal end of the elongated body, and a central axis extending between the proximal end of the elongated body and the distal end of the elongated body; a first curved end face; a second curved end face; and a junction joining the first curved end face to the second curved end face, each of the first curved end face, the second curved end face, and the junction extending between the proximal end of the elongated body and the distal end of the elongated body, and wherein the first curved end face and the second curved end face together are included in a circle defined by an outer periphery of the elongated body.

[0026] Clause 16: The syringe assembly of clause 15, wherein the junction comprises: an intermediate face; a first connecting face extending from the intermediate face to the first curved end face; and a second connecting face extending from the intermediate face to the second curved end face, and wherein the intermediate face, the first curved end face, and the second curved end face are included in a circle defined by the outer periphery of the elongated body together with the intermediate face, the first curved end face, and the second curved end face.

[0027] Clause 17: The syringe assembly of clause 16, wherein the first connecting face is a first angled face relative to the intermediate face, and wherein the second connecting face is a second angled face relative to the intermediate face.

[0028] Clause 18: The syringe assembly of clause 17, wherein the first angled face and the second angled face each extend from the intermediate face at an angle equal to or greater than 90 degrees relative to the intermediate face.

[0029] Clause 19: The syringe assembly of clause 15, wherein the first curved end face, the second curved end face, and the junction do not intersect the central axis of the elongated body.

[0030] Clause 20: The syringe assembly of Clause 15, wherein the plunger rod further comprises a thumb press disposed at the proximal end of the elongate body, and wherein the thumb press is wider than the syringe barrel.

[0031] Clause 21 : The syringe assembly of Clause 15, wherein the plunger rod further comprises a coupling portion disposed at the distal end; and wherein the syringe assembly further comprises a stopper coupled to the coupling portion and disposed internally relative to the syringe barrel.

[0032] Clause 22: The syringe assembly of Clause 15, wherein the arcuate outer perimeter is discontinuous.

[0033] Clause 23 : A syringe assembly comprising: a syringe barrel having a sidewall, a distal end, and a proximal end; and a plunger rod comprising: an elongate body having a proximal end, a distal end opposite the proximal end of the elongate body, and a central axis extending between the proximal end of the elongate body and the distal end of the elongate body; an engagement portion extending between the proximal end of the elongate body and the distal end of the elongate body, the engagement portion at least partially defining an arcuate outer perimeter of the elongate body, wherein the engagement portion does not intersect the central axis.

[0034] Clause 24: The syringe assembly of Clause 23, wherein the arcuate outer perimeter is concave facing the central axis.

[0035] Clause 25: The syringe assembly of Clause 23, wherein the plunger rod further comprises a thumb press disposed at the proximal end of the elongate body, and wherein the thumb press is wider than the syringe barrel.

[0036] Clause 26: The syringe assembly of Clause 23, wherein the plunger rod further comprises a coupling portion disposed at the distal end of the elongate body; and wherein the syringe assembly further comprises a stopper coupled to the coupling portion and disposed internally relative to the syringe barrel.

[0037] Clause 27: The syringe assembly of Clause 23, wherein the arcuate outer perimeter is discontinuous.

[0038] Further details and advantages of the various examples described in detail herein will become apparent to those of ordinary skill in the art, by reading the following detailed description, taken in conjunction with the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0039] The above mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the disclosure itself will be better understood by reference to the following description of embodiments of the disclosure taken together with the accompanying drawings, wherein:

[0040] Figure 1 isometric view of a syringe according to one non-limiting aspect of the concepts of the present disclosure;

[0041] Figure 2 is a syringe of Figure 1 Figure 1 cross-sectional view of the syringe of

[0042] Figure 3 is a syringe of Figure 1

[0043] Figure 4 is a syringe of Figure 1

[0044] Figure 5 is a syringe of Figure 3

[0045] Figure 6 is a syringe of Figure 5 Figure 5 cross-sectional view of the syringe of

[0046] FIG. 7 is a side view of a prior art plunger rod;

[0047] FIG. 8 is a cross-sectional view of the plunger rod of FIG. 7 taken along line C-C of FIG. 7; and

[0048] Figure 9 is a cross-sectional view of another plunger rod that can be used with the syringe of Figure 1

[0049] Corresponding reference characters indicate corresponding parts throughout the several views. The examples set forth herein illustrate exemplary aspects of the disclosure and do not limit the scope of the disclosure in any way. DETAILED DESCRIPTION

[0050] The following description is provided so as to enable any person skilled in the art to make and use the described implementations of the present concepts. Various modifications, equivalents, variations, and alternatives, however, will remain apparent to those skilled in the art. Any and all such modifications, variations, equivalents, and alternatives are intended to fall within the spirit and scope of the present concepts.

[0051] ​​​​​​For the purposes of the description below, the terms "upper", "lower", "right", "left", "vertical", "horizontal", "top", "bottom", "lateral", "longitudinal", and derivatives thereof shall relate to the present concept as oriented in the drawings. However, it is to be understood that the present concept can assume various alternative orientations, except where expressly specified to the contrary. It is also to be understood that the specific devices illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the present concept. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting, unless otherwise indicated.

[0052] In the following discussion, "distal" refers to the direction generally toward the end of the syringe assembly adapted to interface with a separate device, such as a needle assembly or IV connection assembly, and "proximal" refers to the direction opposite the distal, i.e., away from the end of the syringe assembly adapted to interface with a separate device. The above references are used for the purposes of the present disclosure to describe components of a syringe assembly according to the present disclosure.

[0053] Referring to Figure 1 and Figure 2 , the syringe assembly 2 includes a syringe barrel 4 having a distal end, a proximal end, and a sidewall defining a syringe interior therein. The syringe assembly 2 further includes a piston or stopper 6 positionable within the syringe interior of the syringe barrel 4, a flange 8 extending radially outward from the proximal end of the syringe barrel 4, and a plunger rod 10 insertable within the syringe interior of the syringe barrel 4. In an exemplary embodiment, the plunger rod 10 includes the stopper 6 which can be overmolded onto an elongated body 12 of the plunger rod 10. The stopper 6 can be a polymeric material such as polyurethane (PU), silicone, and thermoplastic elastomer (TPE). The syringe assembly 2 can be adapted for the dispensing and delivery of a fluid and / or the collection of a fluid. For example, the syringe assembly 2 can be used to inject or infuse a fluid, such as a medication, into a patient. The syringe assembly 2 can also be adapted for the aspiration of a fluid into the syringe barrel 4, such as the withdrawal of a medication into the syringe interior and / or the withdrawal of a fluid sample into the syringe interior. The syringe assembly 2 is contemplated for connection with a patient needle, for example by connecting the syringe assembly 2 to a separate needle assembly (not shown), or alternatively for connection with an intravenous (IV) connection assembly (not shown). It can be appreciated that the present disclosure can be used with any type of syringe, including those placed in a controlled storage environment with limited storage space. These types of syringes include traditional pre-filled syringe assemblies, metered dose syringes, and aspiration syringes for withdrawing fluid from a patient or withdrawing a medication from a container, among others.

[0054] The structure of an exemplary plunger rod 10 will now be discussed in detail.Figure 3 A perspective view of a plunger rod 10 is shown. As shown, the plunger rod 10 includes an elongated body 12 having a central axis 14 extending between a proximal end 16 and a distal end 18. In an exemplary embodiment, the central axis 14 of the plunger rod 10 can coincide with the corresponding central axis of the syringe barrel 4. The elongated body 12 of the plunger rod 10 has a proximal end 16, a distal end 18, a first curved end face 20, a second curved end face 22, and a junction 24 joining the first curved end face 20 to the second curved end face 22. The first curved end face 20 and the second curved end face 22 can also be formed by a straight segment or a plurality of corresponding adjacent segments. In an exemplary embodiment, each of the first curved end face 20, the second curved end face 22, and the junction 24 extends between the proximal end 16 and the distal end 18. In one configuration, at least the first curved end face 20 and the second curved end face 22 together are included in a circle defined by an outer periphery 40 (as shown) of the elongated body 12. As shown, the outer periphery 40 can be discontinuous. As will be discussed below, the geometry of the improved plunger rod 10 allows the plunger rod 10 to be manufactured with less material and molded in a shorter cycle time. Figure 6 As shown, the outer periphery 40 can be discontinuous. As will be discussed below, the geometry of the improved plunger rod 10 allows the plunger rod 10 to be manufactured with less material and molded in a shorter cycle time.

[0055] With continued reference to Figure 3 Optionally, the plunger rod 10 can also include a thumb press 52 at the proximal end 16 of the elongated body 12, and a threaded coupling 62 at the distal end 18 of the elongated body 12. The thumb press 52 can include a portion that is wider than the interior of the syringe barrel 4 and provide a structure for the user to press on when advancing the plunger rod 10 from one end of the syringe barrel 4 to the other. As shown, Figure 3 The arcuate outer periphery 40 described above can be lower than the arcuate outer periphery of the thumb press 52. As shown, Figure 2 The threaded coupling 62 can be threadably coupled to the stopper 6. Alternatively, the stopper 6 can also be clipped onto the plunger rod 10. As a result, this allows the plunger rod 10 to advance the stopper 6 as a combined assembly from one end of the syringe barrel 4 to the other. Further, the stopper 6 is sized relative to the syringe barrel 4 to provide a sealing abutment with the interior surface of the sidewall of the syringe barrel 4. It is noted herein that any suitable stopper 6 can be used with the plunger rod of the present invention.

[0056] The elongated body 12 is disposed at least partially within the syringe barrel 4 so as to push the stopper 6 from one end of the syringe barrel 4 to the other. In one embodiment, the syringe barrel 4 can be in the general form of an elongated cylindrical barrel, such as in the general shape of a hypodermic syringe known in the art. In alternative embodiments, the syringe barrel 4 can be in other forms for containing fluid for delivery. The syringe barrel 4 can be formed of glass, or can be injection molded from a thermoplastic material such as polypropylene and polyethylene according to techniques known to those of ordinary skill in the art, although it is to be understood that the syringe barrel 4 can be made of other suitable materials and according to other applicable techniques.

[0057] In an exemplary embodiment, as shown in Figure 3 The plunger rod 10 also has a plurality of support ribs (two support ribs 26, 28 are shown) extending from the elongated body 12 between the proximal end 16 and the distal end 18. The support ribs 26 and 28 can extend radially (e.g., orthogonally) relative to the central axis 14, and a plunger rod according to the concepts of the present disclosure can include up to five ribs. In another example, as shown in Figure 4 The plunger rod 80 has a single support rib 96 extending from the elongated body 82 between the proximal end 86 and the distal end 88. It is to be understood that the plunger rod 80 additionally includes all of the same structural features and advantages of the plunger rod 10. The support ribs 26, 28, and 96 advantageously function to strengthen and stabilize the plunger rods 10, 80, allowing them to be moved into and out of the syringe barrel 4 without significant and undesirable bending.

[0058] Figure 5 is a side view of the plunger rod 10, and Figure 6 is a cross-sectional view of the plunger rod 10. As Figure 6As shown, the junction 24 includes a medial face 30, a first connecting face (e.g., but not limited to, a first angled face 32) extending from the medial face 30 to the first curved end face 20, and a second connecting face (e.g., but not limited to, a second angled face 34) extending from the medial face 30 to the second curved end face 22. The angled faces 32 and 34 can be curved or straight. The junction 24 at least partially defines an arcuate outer periphery 40 of the elongated body 12, which can be concave facing the central axis 14. In an exemplary embodiment, the medial face 30 and the curved end faces 20 and 22 are included in a circle defined by the outer periphery of the elongated body together with the medial face and the curved end faces. Further, the medial face 30 can be curved or straight. Accordingly, it should be appreciated that the arcuate outer periphery 40 can be discontinuous. Further, the first and second connecting faces can include first and second angled faces 32 and 34, respectively, relative to the medial face 30. More particularly, in an exemplary embodiment, the first and second angled faces 32 and 34 each extend from the medial face 30 at a respective angle θ1, θ2relative to the medial face 30 equal to or greater than 90 degrees. Preferably, the angles θ1, θ2relative to the medial face 30 are less than 120 degrees. Further, in one configuration, none of the first curved end face 20, the second curved end face 22, and / or any portion of the junction 24 intersects the central axis 14 (depicted as a circle to represent an axis perpendicular to the page) of the elongated body 12. Accordingly, in this configuration, the central axis 14 of the plunger rod 10 is free of material. It should also be noted that, in certain embodiments, the first curved end face 20 and the second curved end face 22 do not intersect each other, i.e., the first curved end face 20 and the second curved end face 22 do not form a continuous outer periphery.

[0059] In operation, the geometry of the plunger rod 10 provides it with a number of advantages over known plunger rods, such as but not limited to the plunger rod 110 shown in FIGS. 7 and 8. For example, by having a discontinuous arcuate outer periphery 40, and having cross sections that do not intersect each other, the elongated body 12 can advantageously be manufactured using less material than the conventional plunger rod 110. As shown in FIG. 8, the conventional plunger rod 110 has a first planar portion 112 and a second planar portion 114 that intersects the first planar portion 112 at a central region 116. In other words, the elongated body of the plunger rod 110 is generally cruciform, having two planar portions 112, 114 that intersect each other at the central region 116. It can be readily appreciated that, due to the intersection of the first and second planar portions 112, 114, the central region 116 has an undesirable amount of material. This is disadvantageous for at least two reasons. First, by having a large amount of material in this region, the cost of material to manufacture the plunger rod 110 is relatively high due to the increased amount of material present in this region. Second, the cycle time associated with molding the plunger rod 110 is relatively long due to the time required for the large central region 116 to cool.

[0060] The plunger rod 10 of the present application of the present application solves these problems. First, by spacing the material around the central axis 14, but empty at the central axis 14, and without intersecting or overlapping areas that can create a large amount of material, costs can be reduced. Additionally, the plunger rod 10, 80 having the inventive structure described herein can resist breaking during movement within the syringe barrel 4 with better resistance to bending (e.g., displacement away from the central axis 14) compared to the conventional plunger rod 110, and can do so using significantly less material. Because of the increased resistance to breaking, unlike the plunger rod 110, the plunger rod 10, 80 can be made from different materials (e.g., not limited to thermoplastic materials such as polycarbonate material, polypropylene, polystyrene, etc.).

[0061] Because the relatively thick areas that can require long periods of cooling during molding are eliminated, the cycle time associated with manufacturing the plunger rod 10 (e.g., and the plunger rod 80) can advantageously be reduced. Additionally, despite the use of less material by the plunger rod 10, 80, the structural and functional integrity is advantageously not compromised due to the improved geometry. In particular, while less material is used to manufacture the plunger rod 10, 80, as shown, the improved shape provides beneficial stability to assist during entry and exit of the syringe barrel 4. The improved shape maintains the functional attributes necessary to perform the plunging operation, but advantageously allows for a significant reduction in material costs and cycle time. Moreover, in an exemplary embodiment, the curved end faces 20, 22 and the intermediate face 30 are substantially evenly spaced from one another along the arcuate outer periphery 40 of the elongated body 12. Furthermore, by having an angle, when viewed from the perspective of Figure 6 Figure 6 the angle faces 32, 34 advantageously define three substantially equal sized portions of the elongated body 12 when viewed from the perspective of

[0062] The table 1 reproduced below shows 3D modeling data for different plunger rods, including a prior art "X cross-section" plunger rod and several "Omega cross-section" plunger rods (e.g., the plunger rod 10, 80) according to the concepts of the present disclosure, where "Omega" represents the general cross-sectional shape of the plunger rod 10, 80, as shown in Figure 6 ​"thickness" is the maximum thickness of the PR cross-section (measured at the cross center point of the X cross-section PR, and at the circular area of the Omega cross-section PR). In items 3 to 6, "T" is the PR thickness of item 2. The cross-sectional surface is measured anywhere on the PR except where the ribs are located. Compressive and bending displacements are calculated by numerical simulation in response to an axial force of 10 N. Table 1 gives the various configurations studied, where #1 is the current X standard, #2 to #5 correspond to Omega profiles with various combinations of thickness and number of ribs, and #6 is a configuration of S profile. Table 1 reflects technical information such as cross-sectional surface (different from the flange surface) and main use results (applied force by index on the X-shaped base 100).

[0063] Table 1

[0064]

[0065] * Volume includes elongated body, ribs, flanges, and threaded section.

[0066] Table 2 reproduced below presents the same configurations as Table 1 with % change (percent change) relative to the reference X shape. This allows for easy comparison between configurations.

[0067] Configuration 2 has 3 times the resistance to thumb force with only a 14% increase in price. This is very high performance for a limited cost increase. Configurations 3 and 4 have 2 times the resistance to force with a 17% savings. This is high performance for a lower cost. Configuration 5 has 45% higher resistance than the X shape #1 with a 25% reduction in cost. This is improved performance for a very low cost. Configurations 3 and 4 show that the number of ribs has no significant effect on performance for this size. Configuration 6 shows slightly lower performance with a limited cost savings. This solution is specific to a particular application and size, typically a plunger rod with a small cross-section.

[0068] Table 2: Normal and Tangential Displacement of 10 N Force at Main Point

[0069]

[0070] In Figure 9 In another example embodiment of the disclosed concept shown, the junction 224 intersects the central axis 214 and extends directly from the first curved end face 220 to the second curved end face 222. In Figure 9 In an embodiment of the plunger rod 210, the elongated body has a generally S-shaped cross-section. It should be appreciated that the plunger rod 210 functions substantially the same as the plunger rods 10, 80 discussed above in other respects and provides the same improvements over the prior art plunger rod 110 (e.g., reduced material cost, reduced cycle time during molding).

[0071] Elements of one disclosed aspect can be combined with elements of one or more other disclosed aspects to form different combinations, all of which are contemplated within the scope of the present concept.

[0072] While the present disclosure has been described with reference to exemplary designs, the present disclosure can be further modified within the spirit and scope of the disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which the disclosure pertains.

Claims

1. A plunger rod for use with a syringe having a syringe barrel, the plunger rod comprising: An elongated body having a proximal end, a distal end opposite to the proximal end, and a central axis extending between the proximal end and the distal end. First curved end face, The second curved end face, and A joint that joins the first curved end face to the second curved end face, each of the first curved end face, the second curved end face, and the joint extending between the proximal end and the distal end. The first curved end face and the second curved end face are together included in a circle defined at least partially by the discontinuous arcuate outer periphery of the elongated body, and the first curved end face, the second curved end face and the joint do not intersect the central axis of the elongated body. Wherein, the outer periphery of the arc shape is concave towards the central axis. The joint includes: a middle surface; a first connecting surface extending from the middle surface to the first curved end face; and a second connecting surface extending from the middle surface to the second curved end face, wherein the middle surface, the first curved end face, and the second curved end face are included in a circle defined by the outer periphery of the elongated body together with the middle surface, the first curved end face, and the second curved end face. The first connecting surface, the intermediate surface, and the second connecting surface form three discontinuous portions in the circle between the first curved end face and the second curved end face.

2. The plunger rod according to claim 1, wherein, The first connecting surface is a first angular surface relative to the intermediate surface, and the second connecting surface is a second angular surface relative to the intermediate surface.

3. The plunger rod according to claim 2, wherein, The first angular surface and the second angular surface each extend from the intermediate surface at a corresponding angle equal to or greater than 90 degrees relative to the intermediate surface.

4. The plunger rod according to claim 1, wherein, The plunger rod also includes a plurality of support ribs that extend from the elongated body between the proximal end and the distal end.

5. The plunger rod according to claim 1, wherein the plunger rod further comprises a stop member, the stop member being overlaid and formed on the elongated body.

6. A syringe assembly, the syringe assembly comprising: A syringe barrel having a sidewall, a distal end, and a proximal end; as well as A plunger rod, the plunger rod comprising: An elongated body having a proximal end, a distal end opposite to the proximal end of the elongated body, and a central axis extending between the proximal end and the distal end of the elongated body. First curved end face, The second curved end face, and A joint that joins the first curved end face to the second curved end face, each of the first curved end face, the second curved end face, and the joint extending between the proximal end and the distal end of the elongated body. The first curved end face and the second curved end face are together included in a circle defined by the discontinuous arcuate outer periphery of the elongated body, and the first curved end face, the second curved end face and the joint do not intersect the central axis of the elongated body. Wherein, the outer periphery of the arc shape is concave towards the central axis, and The joint includes: a middle surface; a first connecting surface extending from the middle surface to the first curved end face; and a second connecting surface extending from the middle surface to the second curved end face, wherein the middle surface, the first curved end face, and the second curved end face are included in a circle defined by the outer periphery of the elongated body together with the middle surface, the first curved end face, and the second curved end face. The first connecting surface, the intermediate surface, and the second connecting surface form three discontinuous portions in the circle between the first curved end face and the second curved end face.

7. The syringe assembly of claim 6, wherein, The first connecting surface is a first angular surface relative to the intermediate surface, and the second connecting surface is a second angular surface relative to the intermediate surface.

8. The syringe assembly of claim 7, wherein, The first angular surface and the second angular surface each extend from the intermediate surface at an angle equal to or greater than 90 degrees relative to the intermediate surface.

9. The syringe assembly of claim 6, wherein, The plunger rod also includes a thumb pressing portion disposed at the proximal end of the elongated body, wherein the thumb pressing portion is wider than the syringe barrel.

10. The syringe assembly of claim 6, wherein, The plunger rod further includes a connecting portion disposed at the distal end; and wherein the syringe assembly further includes a stop connected to the connecting portion and disposed internally relative to the syringe barrel.

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