plunger rod and syringe including the plunger rod

Abstract

This invention relates to a plunger rod and a syringe including the plunger rod. The plunger rod is 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, 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 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 extends 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 by the outer periphery of the elongated body.

Description

[0001] This application is a divisional application of Chinese invention patent application filed on March 10, 2021, with application number 202180020987.1 and entitled "Plunger Rod and Syringe Including the Plunger Rod". Technical Field

[0002] The present disclosure generally relates to a plunger rod for use in a syringe barrel that can be associated with an autoinjector. The present disclosure also relates to a syringe including a plunger rod assembly, such as a manual syringe. Background Technology

[0003] Syringes, particularly manually operated hypodermic syringes, are well-known in the medical field for dispensing fluids (e.g., medications) or for aspirating biological fluid samples therein. A typical syringe assembly typically includes: a syringe barrel having a fluid opening at one end; and a plunger assembly configured to pass through the opposite end in a slidably arranged arrangement through the syringe barrel. The plunger assembly typically includes a rigid plunger rod having a linear longitudinal axis extending through the barrel, a plunger head or stop located at the distal end of the plunger rod, and a thumb press portion located at the proximal end of the plunger rod. In use, the plunger rod can be retracted through the syringe barrel to aspirate fluid (e.g., medication) or to fill the syringe barrel with fluid. The plunger rod can also be advanced from one end of the syringe barrel to the other to expel fluid (e.g., medication) from the syringe barrel. For drug delivery to a patient, the opening of the syringe barrel can be adapted to be in fluid communication with the patient, for example, via a hypodermic needle mounted at the distal end of the syringe barrel, or via a standard Luer-type fitting extending from the distal end of the syringe barrel for attachment to a fluid line. The operation of the plunger rod assembly within the syringe barrel is well known in the medical field.

[0004] In standard medical settings, a large number of syringes are used annually. Consequently, it is desirable that the syringe plunger be manufactured as cost-effectively as possible, that the plunger be relatively robust (e.g., to withstand loads applied during use), and that the plunger be manufactured during molding with a relatively short cycle time. Accordingly, there is a need in the art for an improved plunger and a syringe incorporating such a plunger. Summary of the Invention

[0005] In one aspect, a plunger rod is provided 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, and a central axis extending between the proximal and distal ends; 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 extends between the proximal and distal ends. The first and second curved end faces are together included in a circle at least partially defined by the outer periphery of the elongated body.

[0006] 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.

[0007] 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.

[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; 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.

[0009] Various other aspects of this disclosure are enumerated in one or more of the following provisions: 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.

[0010] Clause 2: The plunger rod according to Clause 1, wherein 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, and 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.

[0011] Clause 3: The plunger rod as described in Clause 2, wherein the first connecting surface is a first angular face relative to the intermediate surface, and wherein the second connecting surface is a second angular face relative to the intermediate surface.

[0012] Clause 4: The plunger rod according to Clause 3, wherein the first angular facet and the second angular facet each extend from the intermediate facet at a corresponding angle equal to or greater than 90 degrees relative to the intermediate facet.

[0013] Clause 5: The plunger rod according to Clause 1, wherein the first curved end face, the second curved end face, and the joint do not intersect the central axis of the elongated body.

[0014] Clause 6: The plunger rod according to Clause 1, wherein the joint intersects the central axis and extends directly from the first curved end face to the second curved end face.

[0015] Clause 7: The plunger rod as described in Clause 6, wherein the elongated body has a generally S-shaped cross section.

[0016] Clause 8: The plunger rod according to Clause 1, wherein the plunger rod further includes a plurality of support ribs extending from the elongated body between the proximal end and the distal end.

[0017] Clause 9: The plunger rod as described in Clause 1, wherein the arcuate outer perimeter is discontinuous.

[0018] 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; and a joint extending between the proximal end and the distal end, the joint at least partially defining an arcuate outer periphery of the elongated body, wherein the joint does not intersect the central axis.

[0019] Clause 11: The plunger rod according to Clause 10, wherein the arcuate outer periphery is concave towards the central axis.

[0020] Clause 12: The plunger rod according to Clause 10, wherein the plunger rod further includes a plurality of support ribs extending from the elongated body between the proximal end and the distal end.

[0021] Clause 13: The plunger rod according to Clause 10, wherein the arcuate outer perimeter is discontinuous.

[0022] Clause 14: The plunger rod as described in Clause 10 further includes a stop that is overmolded on the elongated body.

[0023] Clause 15: A syringe assembly comprising: a syringe barrel having sidewalls, 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 and the distal end of the elongated body; a first curved end face; a second curved end face; and a joint engaging 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, wherein the first curved end face and the second curved end face are together included in a circle defined by the outer periphery of the elongated body.

[0024] Clause 16: The syringe assembly according to Clause 15, wherein the engagement 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, and 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.

[0025] Clause 17: The syringe assembly according to Clause 16, wherein the first connecting surface is a first angular surface relative to the intermediate surface, and wherein the second connecting surface is a second angular surface relative to the intermediate surface.

[0026] Clause 18: The syringe assembly according to Clause 17, wherein the first angular facet and the second angular facet each extend from the intermediate facet at an angle equal to or greater than 90 degrees relative to the intermediate facet.

[0027] Clause 19: The syringe assembly according to Clause 15, wherein the first curved end face, the second curved end face, and the joint do not intersect the central axis of the elongated body.

[0028] Clause 20: The syringe assembly according to Clause 15, wherein the plunger rod further includes a thumb press portion disposed at the proximal end of the elongated body, and wherein the thumb press portion is wider than the syringe barrel.

[0029] Clause 21: The syringe assembly according to Clause 15, wherein the plunger rod further includes a coupling portion disposed at the distal end; and wherein the syringe assembly further includes a stop coupled to the coupling portion and disposed internally relative to the syringe barrel.

[0030] Clause 22: The syringe assembly as described in Clause 15, wherein the arcuate outer periphery is discontinuous.

[0031] Clause 23: A syringe assembly comprising: a syringe barrel having sidewalls, 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 and the distal end of the elongated body; and a junction extending between the proximal end and the distal end of the elongated body, the junction at least partially defining an arcuate outer periphery of the elongated body, wherein the junction does not intersect the central axis.

[0032] Clause 24: The syringe assembly according to Clause 23, wherein the arcuate outer periphery facing the central axis is concave.

[0033] Clause 25: The syringe assembly according to Clause 23, wherein the plunger rod further includes a thumb press portion disposed at the proximal end of the elongated body, and wherein the thumb press portion is wider than the syringe barrel.

[0034] Clause 26: The syringe assembly according to Clause 23, wherein the plunger rod further includes a coupling portion disposed at the distal end of the elongated body; and wherein the syringe assembly further includes a stop member coupled to the coupling portion and disposed internally relative to the syringe barrel.

[0035] Clause 27: The syringe assembly as described in Clause 23, wherein the arcuate outer periphery is discontinuous.

[0036] Further details and advantages of the various examples described herein will become apparent when the accompanying drawings are read in conjunction with the following detailed descriptions of the various examples. Attached Figure Description

[0037] The above and other features and advantages of this disclosure, as well as the ways in which they are implemented, will become more apparent and the disclosure itself will be better understood by referring to the following description of embodiments of this disclosure taken in conjunction with the accompanying drawings: Figure 1 A perspective view of a syringe based on a non-limiting aspect of the concept of this disclosure; Figure 2 for Figure 1 syringe along Figure 1 A cross-sectional view taken by line AA; Figure 3 for Figure 1 A three-dimensional diagram of the plunger rod used in a syringe; Figure 4 In order to be able to Figure 1 A perspective view of another plunger rod used in the same syringe; Figure 5 for Figure 3 Side view of the plunger rod; Figure 6 for Figure 5 The plunger rod along Figure 5 A cross-sectional view taken by the BB line; Figure 7 A side view of a prior art plunger rod; Figure 8 for Figure 7 The plunger rod along Figure 7 A cross-sectional view taken by the CC line; and Figure 9 For another non-limiting aspect of the concept according to this disclosure, which can be combined with Figure 1 A cross-sectional view of another plunger rod used with the syringe.

[0038] The corresponding reference numerals in the accompanying drawings denote the corresponding parts in several views. The examples set forth herein illustrate exemplary aspects of this disclosure, and these examples should not be construed as limiting the scope of this disclosure in any way. Detailed Implementation

[0039] The following description is provided to enable those skilled in the art to manufacture and use the described embodiments intended for implementing the present concept. However, various modifications, equivalents, variations, and substitutions will still be apparent to those skilled in the art. Any and all such modifications, variations, equivalents, and substitutions are intended to fall within the spirit and scope of the present concept.

[0040] For the purposes described below, the terms “up,” “down,” “right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” “lateral,” “longitudinal,” and their derivatives will refer to the present concept as oriented as shown in the figures. However, it should be understood that the present concept may present various alternative variations unless explicitly stated otherwise. It should also be understood that the specific devices shown in the figures and described in the following specification are merely exemplary embodiments of the present concept. Therefore, specific dimensions and other physical characteristics associated with the embodiments disclosed herein should not be considered limiting.

[0041] In the following discussion, "distal" refers to the direction generally toward one end of the syringe assembly adapted to engage with a separate device (such as a needle assembly or IV connection assembly), and "proximal" refers to the opposite direction, i.e., away from the end of the syringe assembly adapted to engage with a separate device. For the purposes of this disclosure, the foregoing references are used to describe components of a syringe assembly according to this disclosure.

[0042] Reference Figure 1 and Figure 2The 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 also includes: a piston or stop 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 into the syringe interior of the syringe barrel 4. In an exemplary embodiment, the plunger rod 10 includes the stop 6, which may be overmolded onto an elongated body 12 of the plunger rod 10. The stop 6 may be a polymeric material, such as polyurethane (PU), silicone, or thermoplastic elastomer (TPE). The syringe assembly 2 may be adapted for the dispensing and delivery of fluids and / or the collection of fluids. For example, the syringe assembly 2 may be used to inject or infuse fluids (such as drugs) into a patient. Syringe assembly 2 may also be adapted to aspirate fluid into syringe barrel 4, such as drawing medication into the syringe and / or drawing fluid samples into the syringe. Syringe assembly 2 is intended for connection to a patient needle (e.g., by connecting syringe assembly 2 to a separate needle assembly (not shown)) or alternatively for connection to an intravenous (IV) connection assembly (not shown). It is understood that this 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 conventional pre-filled syringe assemblies, metered-dose syringes, and aspiration syringes for drawing fluid from a patient or medication from a container.

[0043] The structure of the exemplary plunger rod 10 will now be discussed in detail. Figure 3 A perspective view of the 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 may 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 joint 24 that engages 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 may 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 joint 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 are included together by the outer periphery 40 of the elongated body 12 (e.g., Figure 6Within the circle defined by the figure (shown). As shown, the outer perimeter 40 may be discontinuous. As will be discussed below, the improved geometry of the plunger rod 10 allows the plunger rod 10 to be manufactured with less material and molded in a shorter cycle time.

[0044] Continue to refer to Figure 3 Optionally, the plunger rod 10 may further include a thumb press portion 52 located at the proximal end 16 of the elongated body 12 and a threaded connection portion 62 located at the distal end 18 of the elongated body 12. The thumb press portion 52 may include a portion wider than the interior of the syringe barrel 4 and provides a pressing structure for the user to advance the plunger rod 10 from one end of the syringe barrel 4 to the other. Figure 3 As shown, the aforementioned arc-shaped outer periphery 40 can be lower than the arc-shaped outer periphery of the thumb pressing portion 52. For example... Figure 2 As shown, the threaded connection 62 can be threadedly connected to the stop 6. Alternatively, the stop 6 can also be clamped onto the plunger rod 10. As a result, this allows the plunger rod 10 to advance the stop 6 as a combined assembly from one end of the syringe barrel 4 to the other. Furthermore, the stop 6 is sized relative to the syringe barrel 4 to provide a sealing engagement with the inner surface of the sidewall of the syringe barrel 4. It should be noted here that any suitable stop 6 can be used with the plunger rod of the present invention.

[0045] The elongated body 12 is at least partially disposed within the syringe barrel 4 to actuate the stop 6 from one end of the syringe barrel 4 to the other. In one embodiment, the syringe barrel 4 may be in the general form of an elongated cylindrical tube, such as the general shape of a hypodermic syringe known in the art. In alternative embodiments, the syringe barrel 4 may be in other forms for containing fluid for delivery. The syringe barrel 4 may be formed of glass, or may be injection molded from thermoplastic materials (such as polypropylene and polyethylene) according to techniques known to those skilled in the art; however, it should be understood that the syringe barrel 4 may be made of other suitable materials and according to other applicable techniques.

[0046] In one exemplary implementation, such as Figure 3 As shown, 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. Support ribs 26 and 28 may extend radially (e.g., orthogonally) relative to the central axis 14, and the plunger rod according to the concept of this disclosure may include up to five ribs. In another example, as... Figure 4As shown, the plunger rod 80 has a single support rib 96 extending from the elongated body 82 between its proximal end 86 and distal end 88. It should be understood that the plunger rod 80 additionally includes all the same structural features and advantages as the plunger rod 10. The support ribs 26, 28, and 96 advantageously serve to strengthen and stabilize the plunger rods 10 and 80, thereby allowing them to move into and out of the syringe barrel 4 without significant and undesirable bending.

[0047] Figure 5 This is a side view of the plunger rod 10, and... Figure 6 This is a cross-sectional view of the plunger rod 10. (Example) Figure 6 As shown, the joint 24 includes: a mid-face 30; a first connecting surface (e.g., but not limited to, a first angled surface 32) extending from the mid-face 30 to a first curved end face 20; and a second connecting surface (e.g., but not limited to, a second angled surface 34) extending from the mid-face 30 to a second curved end face 22. Angles 32 and 34 may be curved or straight. The joint 24 at least partially defines an arcuate outer periphery 40 of the elongated body 12, which may be concave towards the central axis 14. In an exemplary embodiment, the mid-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 mid-face and these curved end faces. Furthermore, the mid-face 30 may be curved or straight. Accordingly, it should be understood that the arcuate outer periphery 40 may be discontinuous. Furthermore, the first connecting surface and the second connecting surface may respectively include a first angled surface 32 and a second angled surface 34 relative to the mid-face 30. More specifically, in one exemplary embodiment, the first angled face 32 and the second angled face 34 each extend from the intermediate face 30 at corresponding angles θ1, θ2 equal to or greater than 90 degrees. Preferably, the angles θ1, θ2 relative to the intermediate face 30 are less than 120 degrees. Furthermore, in one configuration, no portion of the first curved end face 20, the second curved end face 22, and / or the joint 24 intersects the central axis 14 of the elongated body 12 (depicted as a circle to represent the axis perpendicular to the page). Accordingly, in this configuration, the central axis 14 of the plunger rod 10 is without material. It should also be noted that in some 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 perimeter.

[0048] In operation, the geometry of the plunger rod 10 provides it with many advantages over known plunger rods (e.g., but not limited to...). Figure 7 and Figure 8 The advantages of the plunger rod 110 shown are illustrated. For example, by having a discontinuous arcuate outer perimeter 40 and cross-sections that do not intersect each other, the elongated body 12 can advantageously be manufactured using less material than a conventional plunger rod 110. Figure 8As shown, a conventional plunger rod 110 has a first planar portion 112 and a second planar portion 114, which intersects with the first planar portion 112 at a central region 116. In other words, the elongated body of the plunger rod 110 is typically cross-shaped, having two planar portions 112, 114 that intersect each other at the central region 116. It is readily understood that, due to the intersection of the first planar portion 112 and the second planar portion 114, the central region 116 contains an undesirable large amount of material. This is disadvantageous for at least the following reasons: First, the material cost of manufacturing the plunger rod 110 is relatively high due to the increased amount of material present in this region, resulting from the large amount of material in this region. Second, the cycle time associated with molding the plunger rod 110 is relatively long due to the time required for cooling the large central region 116.

[0049] The plunger rod 10 of this invention solves these problems. First, by spacing the material around the central axis 14 but leaving it empty at the central axis 14, and without creating a large area of ​​intersecting or overlapping material, costs can be reduced. Furthermore, compared to a conventional plunger rod 110, the plunger rods 10, 80 having the structure of the invention described herein are able to resist fracture with better bending resistance (e.g., displacement away from the central axis 14) during movement within the syringe barrel 4, and this can be achieved using significantly less material. Due to the increased fracture resistance, unlike the plunger rod 110, the plunger rods 10, 80 can be made of different materials (e.g., not limited to thermoplastic materials such as polycarbonate, polypropylene, polystyrene, etc.).

[0050] By eliminating relatively thick areas that might require prolonged cooling during molding, it is advantageous to reduce the cycle time associated with manufacturing plunger rod 10 (e.g., and plunger rod 80). Furthermore, although plunger rods 10 and 80 use less material, structural and functional integrity is advantageously not compromised due to the improved geometry. Specifically, while less material is used to manufacture plunger rods 10 and 80, as... Figure 6 As shown, the improved shape provides beneficial stability to assist during insertion and exit from the syringe barrel 4. The improved shape maintains the functional properties necessary for performing the plucking operation, but advantageously allows for a significant reduction in material costs and cycle time. Furthermore, in an exemplary embodiment, the curved end faces 20, 22 and the intermediate face 30 are substantially uniformly spaced from each other along the arcuate outer periphery 40 of the elongated body 12. Additionally, by having an angle, when... Figure 6 When viewed from a certain angle, angle surfaces 32 and 34 advantageously define three parts of the elongated body 12 that are of essentially equal size.

[0051] Table 1, reproduced below, shows 3D modeling data for different plunger rods, including prior art "X-section" plunger rods and several "Ω-section" plunger rods (e.g., plunger rods 10, 80) according to the concept of this disclosure, where "Ω" represents the general cross-sectional shape of plunger rods 10, 80, as... Figure 6 As shown. "Thickness" refers to the maximum thickness of the PR section (measured at the cross center point of the X-section PR and at the circular region of the Ω-section PR). In entries 3 through 6, "T" refers to the PR thickness of entry 2. The cross-sectional surface is measured at any location on the PR except where there are ribs. Compressive and bending displacements were calculated by numerical simulation in response to an axial force of 10 N. Table 1 presents the various configurations studied, where #1 is the current X standard, #2 through #5 correspond to various combinations of Ω profiles with different thicknesses and numbers of ribs, and #6 is the configuration of the S profile. Table 1 reflects technical information such as the cross-sectional surfaces (different from the flange surfaces) and key usage results (applicable forces with respect to the pass index of X-shaped base 100).

[0052] Table 1

[0053] The volume includes the elongated body, ribs, flanges, and threaded sections.

[0054] Table 2, reproduced below, presents the same configuration as Table 1, with a % change (percentage change) relative to the reference X shape. This allows for easy comparison between configurations.

[0055] Configuration 2 offers 3x improved resistance to thumb force with only a 14% price increase. This is very high performance for a limited cost increase. Configurations 3 and 4 offer 2x improved resistance to force with a 17% saving. This is high performance for a lower cost. Configuration 5 offers 45% higher resistance than X-shape #1 with a 25% lower cost. This is improved performance for a very low cost. Configurations 3 and 4 show that for this size, the number of ribs has no significant impact on performance. Configuration 6 shows slightly lower performance with limited cost savings. This solution is designed for specific applications and sizes, typically plunger rods with small cross-sections.

[0056] Table 2: Normal and tangential displacements at the principal point under a 10N force

[0057] exist Figure 9 In another exemplary embodiment of the concept of this disclosure, the joint 224 intersects the central axis 214 and extends directly from the first curved end face 220 to the second curved end face 222. Figure 9In the embodiment, the elongated body of the plunger rod 210 has a generally S-shaped cross-section. It should be understood that the plunger rod 210 functions substantially the same as the plunger rods 10 and 80 discussed above in other respects, and provides the same improvements over the prior art plunger rod 110 (e.g., reduced material costs, reduced cycle time during molding).

[0058] An element of a public aspect can be combined with one or more other elements of a public aspect to form different combinations, all of which are considered to be within the scope of this concept.

[0059] While this disclosure has been described as having an exemplary design, it can be further modified within the spirit and scope of this disclosure. Therefore, this application is intended to cover any variations, uses, or adaptations of the disclosure made using the general principles of this application. Furthermore, this application is intended to cover any deviations from this disclosure that are obtained within the known or customary practice of the art to which this disclosure pertains and fall within the scope of the appended claims.

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 of the elongated body, wherein the first curved end face and the second curved end face are together included in a circle at least partially defined by the discontinuous arcuate outer periphery of the elongated body, and wherein the joint intersects the central axis and extends directly from the first curved end face to the second curved end face.

2. The plunger rod according to claim 1, wherein, The elongated body has an approximately S-shaped cross-section.

3. The plunger rod according to claim 1, wherein, The joint extends continuously from the proximal end of the elongated body to the distal end of the elongated body.

4. The plunger rod according to claim 1, wherein, The first curved end face and the second curved end face together are included in a circle defined at least partially by the discontinuous arcuate outer periphery of the elongated body, which is defined by the diameter of the distal end of the elongated body.

5. The plunger rod according to claim 1, wherein, The joint intersects the central axis and extends directly from the first curved end face to the second curved end face in a straight line.

6. 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.

7. The plunger rod according to claim 1, wherein the plunger rod further comprises a stop member, the stop member being overmolded on the elongated body.

8. 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 portion that joins the first curved end face to the second curved end face, wherein each of the first curved end face, the second curved end face, and the joint portion extends continuously from the proximal end of the elongated body to the distal end of the elongated body. The central axis of the elongated body coincides with the corresponding central axis of the syringe barrel. The joint intersects the central axis and extends directly from the first curved end face to the second curved end face. The first curved end face and the second curved end face together at least partially form a circle defined by the arcuate outer periphery of the elongated body.

9. The syringe assembly of claim 8, wherein, The elongated body has an approximately S-shaped cross-section.

10. The syringe assembly of claim 8, wherein, The joint intersects the central axis and extends directly from the first curved end face to the second curved end face in a straight line.

11. The syringe assembly of claim 8, wherein, The plunger rod also includes a thumb pressing portion located at the proximal end of the elongated body, wherein the thumb pressing portion is wider than the syringe barrel.

12. The syringe assembly of claim 8, wherein, The plunger rod further includes a connecting portion disposed at the distal end of the elongated body; 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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