Syringe

Abstract

The objective is to provide a syringe with a cap that is difficult to remove. [Solution] The syringe of the present invention comprises a barrel having a columnar needle-holding portion extending in the central axis direction and capable of holding an injection needle, and a cylindrical peripheral wall portion surrounding the needle-holding portion in the circumferential direction; a cap having an inner peripheral surface facing the outer peripheral surface of the peripheral wall portion when the peripheral wall portion is inserted inside the cap; a first engaging portion disposed on the inner peripheral surface of the cap; and a second engaging portion disposed on the outer peripheral surface of the peripheral wall portion. The first engaging portion and the second engaging portion engage with each other in the central axis direction to restrict the cap from coming off the peripheral wall portion, and at least one of the first engaging portion and the second engaging portion extends in the circumferential direction.

Description

[Technical Field]

[0001] The present invention relates to a syringe provided with a cap that covers an injection needle. [Background Art]

[0002] Conventionally, a syringe 100 as shown in FIG. 13 has been known (see Patent Document 1).

[0003] Specifically, this syringe 100 includes a syringe body 110 and a cap 120 attached to the syringe body 110.

[0004] The syringe body 110 has a cylindrical barrel 111, an injection needle 112, a holding portion that holds the injection needle 112, and a cylindrical portion formed around the holding portion 113.

[0005] The holding portion 113 protrudes along the central axis from one end of the barrel 111. This holding portion 113 is formed in a cylindrical shape, and the injection needle 112 is inserted inside the holding portion 113.

[0006] The cylindrical portion 114 is formed in a cylindrical shape, and is disposed concentrically with the holding portion 113 so as to cover the holding portion 113.

[0007] The cap 120 has an opening 121 at one end, and is attached to the syringe body 110 in a state where the cylindrical portion 114 is press-fitted into the opening 121. [Prior Art Documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent No. 6273087 [Brief Summary of the Invention] [Problem to be Solved by the Invention]

[0009] In recent years, there has been a demand to make it more difficult for the cap 120 to detach from the syringe body 110.

[0010] Therefore, the object of the present invention is to provide a syringe in which the cap is difficult to remove. [Means for solving the problem]

[0011] The syringe of the present invention is A barrel having a columnar needle-holding portion extending in the central axis direction and capable of holding the injection needle, and a cylindrical peripheral wall portion surrounding the needle-holding portion in the circumferential direction at its tip, A cap having an inner circumferential surface that faces the outer circumferential surface of the circumferential wall when the circumferential wall is inserted inside, The first engaging portion is disposed on the inner circumferential surface of the cap, The peripheral wall portion comprises a second engaging portion disposed on the outer peripheral surface of the peripheral wall portion, The first engaging portion and the second engaging portion engage with each other in the central axis direction in order to restrict the cap from coming off the peripheral wall portion. At least one of the first engaging portion and the second engaging portion extends in the circumferential direction.

[0012] With this configuration, at least one of the first engaging portion and the second engaging portion extends in the circumferential direction, thereby increasing the number of engagement points between the first engaging portion and the second engaging portion, and thereby preventing the cap from unintentionally coming off the circumferential wall. In other words, the cap becomes less likely to come off the circumferential wall.

[0013] In the aforementioned syringe, In at least one of the first engaging portion and the second engaging portion, the circumferential dimension may be larger than the dimension in the central axis direction.

[0014] With this configuration, the force required to engage the first engaging portion and the second engaging portion by inserting the peripheral wall portion of the barrel into the inner surface of the cap can be reduced.

[0015] Furthermore, the syringe is It is equipped with a convex contact portion extending in the direction of the central axis, The convex contact portion is positioned on the inner circumferential surface of the cap and in contact with the outer circumferential surface of the circumferential wall portion, or is positioned on the outer circumferential surface of the circumferential wall portion and in contact with the inner circumferential surface of the cap, At least one of the first engaging portion and the second engaging portion may be a convex ridge extending in the circumferential direction.

[0016] With this configuration, when the cap is placed over the peripheral wall (i.e., when the peripheral wall is inserted inside the inner surface of the cap), the protruding contact portion contacts the outer surface of the peripheral wall or the inner surface of the cap to guide the cap, thereby allowing the cap to be placed over the peripheral wall in the correct position. After the peripheral wall is fully inserted inside the inner surface of the cap and the first and second engaging portions are engaged, the cap is sufficiently prevented from coming off the peripheral wall.

[0017] Furthermore, the syringe is The needle holder is equipped with an injection needle, The cap has an elastic portion into which the injection needle is inserted when the peripheral wall portion is inserted inside the inner circumferential surface. The aforementioned convex contact portion is arranged on the inner circumferential surface of the cap, When the peripheral wall portion is inserted into the inner side of the inner peripheral surface, The aforementioned convex contact portion contacts the outer circumferential surface of the peripheral wall portion before the injection needle penetrates the elastic portion. The first engaging portion and the second engaging portion may engage with each other after the injection needle has penetrated the elastic portion.

[0018] With this configuration, when the peripheral wall is inserted into the inner surface of the cap, the cap is guided by the convex contact portion even before the injection needle penetrates the elastic portion, thereby suppressing bending of the injection needle when it is inserted into the elastic portion. Furthermore, the engagement of the first engaging portion and the second engaging portion restricts the cap from coming off the peripheral wall portion once the injection needle is inserted into the elastic portion.

[0019] Furthermore, in the syringe, One of the first engaging portion and the second engaging portion is a protruding ridge extending in the circumferential direction, and the other of the first engaging portion and the second engaging portion may be a protruding ridge extending in the central axial direction.

[0020] According to this configuration, when the cap is fitted onto the peripheral wall portion (that is, when the peripheral wall portion is inserted inside the inner circumferential surface of the cap), the protruding ridge extending in the central axial direction guides the cap, so that the cap is fitted onto the peripheral wall portion in a correct posture. Then, after the peripheral wall portion is sufficiently inserted inside the inner circumferential surface of the cap and the first engaging portion and the second engaging portion are engaged with each other, detachment of the cap from the peripheral wall portion is sufficiently restricted. Effects of the Invention

[0021] As described above, according to the present invention, it is possible to provide a syringe in which the cap is less likely to come off. Brief Description of the Drawings

[0022] [Figure 1] Figure 1 is a side view of the syringe according to the first embodiment. [Figure 2] Figure 2 is a side view showing a state where the cap is removed from the syringe body in the syringe according to the first embodiment. [Figure 3] Figure 3 is a longitudinal sectional view of the cap and the distal end portion of the syringe body at the III-III position in Figure 1. [Figure 4] Figure 4 is a view of the cap according to the first embodiment as seen from the proximal end side. [Figure 5] Figure 5 is a sectional view of the cap at the V-V position in Figure 2. [Figure 6] Figure 6 is a sectional view at the VI-VI position in Figure 4. [Figure 7] Figure 7 is a side view showing a state where the cap is removed from the syringe body in the syringe according to the second embodiment. [Figure 8] Figure 8 is a central longitudinal sectional view of the cap and the distal end portion of the syringe body of the syringe according to the second embodiment. [Figure 9]Figure 9 shows the cap of the second embodiment as viewed from the base end. [Figure 10] Figure 10 is a cross-sectional view of position XX in Figure 7. [Figure 11] Figure 11 is a cross-sectional view of the XI-XI position in Figure 9. [Figure 12] Figure 12 shows the assembly force and extraction force for the syringe of the first embodiment and the syringes of the first to third comparative examples. [Figure 13] Figure 13 is a longitudinal cross-sectional view of the center of the cap and tip of the syringe body of a conventional syringe. [Modes for carrying out the invention]

[0023] The first embodiment of the present invention will be described below with reference to Figures 1 to 6.

[0024] The syringe of this embodiment is used, for example, as a pre-filled syringe in which an injection needle is pre-connected and fixed, and a predetermined injection solution is filled. As shown in Figures 1 to 3, this syringe 1 comprises an injection needle 4, a barrel 3 in which the injection needle 4 is placed, a cap 5 covering the injection needle 4, a first engaging portion (third locking projection in this embodiment) 527 placed on the cap 5, and a second engaging portion (engaging groove in this embodiment) 335 placed on the barrel 3.

[0025] Specifically, the syringe 1 comprises a syringe body 2 and a cap 5 that is attached to (placed over) the syringe body 2. The syringe 1 also includes a first engaging portion 527 and a second engaging portion 335. These first engaging portion 527 and second engaging portion 335 engage with each other in a releasable manner. In the syringe 1 of this embodiment, the first engaging portion 527 is included in the cap 5, and the second engaging portion 335 is included in the syringe body 2 (more specifically, the barrel 3 described later). The engagement of the first engaging portion 527 and the second engaging portion 335 prevents the cap 5 from coming off the syringe body 2.

[0026] The syringe body 2 comprises a cylindrical barrel 3 and an injection needle 4 positioned at the tip of the barrel 3.

[0027] The barrel 3 comprises a columnar needle holder 32 for holding the injection needle 4, and a peripheral wall 33 surrounding the needle holder 32.

[0028] More specifically, the barrel 3 comprises a cylindrical body portion 31 extending in the direction of the central axis C of the injection needle 4 (hereinafter simply referred to as the "central axis direction"), a needle holding portion 32 at the tip of the body portion 31 for holding the injection needle 4, and a peripheral wall portion 33 at the tip of the body portion 31 that surrounds the needle holding portion 32.

[0029] This barrel 3 is formed of glass or a transparent synthetic resin. More specifically, barrel 3 is formed of polyolefin (including cyclic polyolefins such as cycloolefin copolymer (COC) or cycloolefin polymer (COP)).

[0030] The body portion 31 is cylindrical, extending in the direction of the central axis C. One end (tip) of the body portion 31 is closed, leaving an opening that communicates with the injection needle 4, while the other end (base) is open. A plunger can be inserted through this opening.

[0031] The needle holder portion 32 is a columnar part that extends from the tip of the body portion 31 in the direction of the central axis C and holds the injection needle 4. In this embodiment, the needle holder portion 32 is cylindrical in shape and extends in the direction of the central axis C, and is formed integrally with the body portion 31. The injection needle 4 is fixed in this needle holder portion 32 with it inserted along the central axis C (see Figure 3).

[0032] The peripheral wall portion 33 is a cylindrical portion that extends from the tip of the body portion 31 in the direction of the central axis and surrounds the needle holding portion 32 in the circumferential direction, and has an inner peripheral surface 331 and an outer peripheral surface (outer peripheral surface) 332 of the peripheral wall portion (see Figure 3). This peripheral wall portion 33 has an engagement groove (recess) 335 that extends in the circumferential direction on the outer peripheral surface 332 of the peripheral wall portion.

[0033] In this embodiment, the peripheral wall portion 33 is cylindrical and integrally formed with the body portion 31. More specifically, the peripheral wall portion 33 is cylindrical with a diameter that is approximately constant at each position in the direction of the central axis C, and is arranged concentrically with the needle holding portion 32. More precisely, the peripheral wall portion 33 is cylindrical with a diameter that decreases slightly towards the tip. Also, the peripheral wall portion 33 surrounds the needle holding portion 32 with a gap between them. That is, the inner diameter of the peripheral wall portion 33 is larger than the outer diameter of the needle holding portion 32. The length of this peripheral wall portion 33 (dimension in the direction of the central axis C) is shorter than the length of the needle holding portion 32 (dimension in the direction of the central axis C). As a result, when viewed from a direction perpendicular to the direction of the central axis C, the tip of the needle holding portion 32 protrudes from the tip (edge ​​on the tip side) of the peripheral wall portion 33 (see Figure 2).

[0034] The engagement groove 335 extends over the entire circumferential area of ​​the outer peripheral surface 332 of the peripheral wall. In the engagement groove 335 of this embodiment, the depth and width (dimensions in the direction of the central axis C) are constant at each position in the circumferential direction. As described above, in the syringe 1 of this embodiment, this engagement groove 335 constitutes the second engagement portion. That is, in the syringe 1 of this embodiment, the second engagement portion (engagement groove) 335 is included in the syringe body 2 (more specifically, the peripheral wall portion 33 of the barrel 3).

[0035] As shown in Figure 3, the cap 5 has an inner circumferential surface (inner circumferential surface of the cap) 526 that faces the outer circumferential surface 332 of the circumferential wall portion 33 when the circumferential wall portion 33 is inserted inside the cap 5. The cap 5 has an elastic portion 51 into which the injection needle 4 is inserted when the circumferential wall portion 33 is inserted inside the inner circumferential surface 526 of the insertable portion.

[0036] Specifically, as shown in Figures 4 to 6, the cap 5 has an elastic portion 51 that seals the injection needle 4 and the needle holder portion 32, and an outer cylinder portion 52 that covers the elastic portion 51 and holds the elastic portion 51.

[0037] The elastic portion 51 is cylindrical and made of an elastic material such as rubber. This elastic portion 51 has an opening 511 at the other end (base end) in the direction of the central axis C and a closed portion 512 at one end (tip end). In other words, the elastic portion 51 is a bottomed cylindrical shape.

[0038] The cross-sectional shape of the elastic portion 51 at each position along the central axis C on its outer circumferential surface (more specifically, the cross-sectional shape perpendicular to the central axis C) is circular. Furthermore, the outer diameter of the tip end of the elastic portion 51 is smaller than the outer diameter of the base end.

[0039] The occlusion portion 512 is the area into which the injection needle 4 is inserted when the cap 5 is placed over the syringe body 2 (see Figures 3 and 6). This occlusion portion 512 has a groove 513 extending in the circumferential direction on its outer surface.

[0040] The outer cylinder portion 52 is a cylindrical member formed from a material that is harder (has higher hardness) than the elastic portion. In this embodiment, the outer cylinder portion 52 is formed from a transparent or light-transmitting synthetic resin. The dimension of the outer cylinder portion 52 in the direction of the central axis C is greater than the dimension of the elastic portion 51 in the direction of the central axis C. That is, in the direction of the central axis C, the outer cylinder portion 52 is longer than the elastic portion 51.

[0041] Specifically, the outer cylinder portion 52 is cylindrical in shape, having a first opening 520a at the other end (base end) in the direction of the central axis and a second opening 520b at one end (tip end). In this embodiment, the outer cylinder portion 52 has a holding portion 521 that holds the elastic portion 51 and an insertion portion 525 into which the peripheral wall portion 33 of the barrel 3 is inserted, and these holding portion 521 and insertion portion 525 are aligned in the direction of the central axis C (see Figure 6).

[0042] The retaining portion 521 has a first locking projection 523 and a second locking projection 524 on its inner circumferential surface (inner circumferential surface of the retaining portion) 522, which engage the elastic portion 51.

[0043] The first locking projection 523 protrudes radially inward from the inner circumferential surface 522 of the holding portion and extends in the circumferential direction. In this embodiment, the first locking projection 523 extends around the entire circumference of the inner circumferential surface 522 of the holding portion. This first locking projection 523 is positioned in a location corresponding to the groove 513 of the elastic portion 51 in the direction of the central axis C, and by fitting into the groove 513, it prevents the relative movement of the elastic portion 51 with respect to the outer cylinder portion 52 in the direction of the central axis C.

[0044] The second locking projection 524 protrudes radially inward from the inner circumferential surface 522 of the holding portion and extends in the circumferential direction. In this embodiment, the second locking projection 524 extends around the entire circumference of the inner circumferential surface 522 of the holding portion and has a notch 524A at one location in the circumferential direction (see Figures 4 and 5). This second locking projection 524 is positioned in the direction of the central axis C to correspond to the base end of the elastic portion 51 (the end on the opening 511 side), and by abutting against the base end from the base end side, it prevents the relative movement of the elastic portion 51 toward the base end side with respect to the outer cylinder portion 52.

[0045] The inserted portion 525 has an inner circumferential surface (inner surface) 526 that faces the outer circumferential surface 332 of the circumferential wall portion 33 when the circumferential wall portion 33 is inserted. The inserted portion 525 also has at least one third locking projection 527 that protrudes inward from the inner circumferential surface 526 of the inserted portion, and at least one protruding contact portion 528 that protrudes inward from the inner circumferential surface 526 of the inserted portion. The inserted portion 525 in this embodiment has a plurality (three in this example) of third locking projections 527 and a plurality (three in this example) of protruding contact portions 528 (see Figures 4 and 5).

[0046] The third locking projection 527 is positioned to face the engagement groove 335 of the peripheral wall portion 33 in the direction of the central axis C when the cap 5 is placed on the syringe body 2, and engages with the engagement groove 335 of the peripheral wall portion 33 in the direction of the central axis C, thereby restricting the cap 5 from coming off the peripheral wall portion 33 (see Figure 3).

[0047] Specifically, the multiple third locking projections 527 are arranged at circumferential intervals on the inner circumferential surface 526 of the insertion portion, and each third locking projection 527 extends in the circumferential direction. The third locking projections 527 in this embodiment are arranged at equal intervals in the circumferential direction. Furthermore, the circumferential dimension of the third locking projection 527 is greater than the dimension in the direction of the central axis C of the third locking projection 527. The third locking projections 527 in this embodiment are projections with a constant dimension in the direction of the central axis C at each position in the circumferential direction. These third locking projections 527 engage with the engagement groove 335 by fitting into the engagement groove 335 of the circumferential wall portion 33. As described above, in the syringe 1 of this embodiment, these third locking projections 527 constitute the first engagement portion. That is, in the syringe 1 of this embodiment, the first engagement portion (third locking projection) 527 is included in the cap 5 (more specifically, the insertion portion 525A).

[0048] The protruding contact portion 528 guides the cap 5 by contacting the peripheral wall portion 33 of the barrel 3 when the cap 5 is placed over the syringe body 2 (i.e., when the peripheral wall portion 33 is inserted into the insertion portion 525). This protruding contact portion 528 is positioned on the inner peripheral surface 526 of the insertion portion of the cap 5 and contacts the outer peripheral surface 332 of the peripheral wall portion 33 (see Figures 3 and 4).

[0049] These multiple protruding contact portions 528 are arranged at circumferential intervals on the inner circumferential surface 526 of the insertion portion. Specifically, the multiple protruding contact portions 528 are arranged at equal intervals in the circumferential direction so that each protruding contact portion 528 is located between adjacent third locking protrusions 527 in the circumferential direction.

[0050] More specifically, each convex contact portion 528 is positioned at a circumferentially separated position (a circumferentially spaced position) from adjacent third locking protrusions 527 in the circumferential direction. In this embodiment, the convex contact portion 528 is positioned midway between two adjacent third locking protrusions 527 in the circumferential direction. This convex contact portion 528 extends from the second locking protrusion 524 to the base end of the insertion portion 525 (cap 5) in the direction of the central axis C. The tip of the convex contact portion 528 is connected to the second locking protrusion 524, and the base end of the convex contact portion 528 has an inclined surface 528a that approaches the inner circumferential surface 526 of the insertion portion as it moves towards the base end. In the convex contact portion 528 of this embodiment, the dimension (height) α in the direction of protrusion from the inner circumferential surface 526 of the inserted portion is smaller (lower: see Figure 4) than the dimension (height) β of the third locking projection 527 in the direction of protrusion from the inner circumferential surface 526 of the inserted portion.

[0051] In the syringe 1 configured as described above, when the cap 5 is placed over the syringe body 2, the injection needle 4 and the peripheral wall portion 33 of the barrel 3 are inserted into the cap 5 in order so that the injection needle 4 enters the opening 511 of the elastic portion 51.

[0052] Then, when the peripheral wall portion 33 is inserted into the insertion portion 525 of the cap 5, the convex contact portion 528 contacts the outer peripheral surface 332 of the peripheral wall portion 33 before the injection needle 4 penetrates the elastic portion 51 (more specifically, the occluded portion 512). After the peripheral wall portion 33 is further inserted into the insertion portion 525 and the injection needle 4 penetrates the elastic portion 51, the peripheral wall portion 33 is further inserted into the insertion portion 525, causing the third locking projection 527 of the insertion portion 525 to fit into the engagement groove 335 of the peripheral wall portion 33 (that is, the third locking projection 527 and the engagement groove 335 engage with each other in the direction of the central axis C). This completes the attachment of the cap 5 to the syringe body 2.

[0053] The syringe 1 described above comprises an injection needle 4, a barrel 3 having a columnar needle holder 32 extending in the direction of the central axis C of the injection needle 4 and holding the injection needle 4, and a cylindrical peripheral wall portion 33 surrounding the needle holder portion 32 in the circumferential direction, a cap 5 having an inner peripheral surface (inner peripheral surface) 526 of the insertion portion that faces the outer peripheral surface (outer peripheral surface) 332 of the peripheral wall portion 33 when the peripheral wall portion 33 is inserted inside, a third locking projection (first engaging portion) 527 positioned on the inner peripheral surface 526 of the insertion portion of the cap 5, and an engaging groove (second engaging portion) 335 positioned on the outer peripheral surface (outer peripheral surface) 332 of the peripheral wall portion 33. The third locking projection 527 and the engaging groove 335 engage with each other in the direction of the central axis C in order to restrict the cap 5 from coming out of the peripheral wall portion 33, and at least one of the third locking projection 527 and the engaging groove 335 extends in the circumferential direction.

[0054] In this way, by having at least one of the third locking projection 527 and the engagement groove 335 extend in the circumferential direction, the number of engagement points between the third locking projection 527 and the engagement groove 335 (in this embodiment, the length and number of engagement points in the circumferential direction, etc.) can be increased, thereby preventing the cap 5 from unintentionally coming off the circumferential wall portion 33 (syringe body 2). In other words, the cap 5 becomes more difficult to remove from the circumferential wall portion 33.

[0055] Furthermore, in the syringe 1 of the first embodiment, at least one of the third locking projection (first engaging portion) 527 and the engaging groove (second engaging portion) 335 has a circumferential dimension that is larger than the dimension in the direction of the central axis C. This makes it possible to suppress the force required when inserting the circumferential wall portion 33 of the barrel 3 into the inside of the inner circumferential surface 526 of the insertion portion of the cap 5 (the area surrounded by the inner circumferential surface 526 of the insertion portion) and engaging the third locking projection 527 and the engaging groove 335.

[0056] Furthermore, the syringe 1 of the first embodiment is equipped with a convex contact portion 528 extending in the direction of the central axis. The convex contact portion 528 is positioned on the inner circumferential surface (inner surface) 526 of the insertion portion of the cap 5 and contacts the outer circumferential surface (outer surface) 332 of the circumferential wall portion 33, and the third locking projection (first engaging portion) 527 is a convex projection extending in the circumferential direction.

[0057] With this configuration, when the cap 5 is placed over the peripheral wall portion 33 (i.e., when the peripheral wall portion 33 is inserted inside the inner peripheral surface 526 of the insertion portion of the cap 5), the protruding contact portion 528 contacts the outer peripheral surface 332 of the peripheral wall portion and guides the cap 5, so that the cap 5 can be placed over the peripheral wall portion 33 in the correct position. After the peripheral wall portion 33 is fully inserted inside the inner peripheral surface 526 of the insertion portion of the cap 5 and the third locking projection 527 and the engagement groove 335 engage, the cap 5 is sufficiently prevented from coming off the peripheral wall portion 33.

[0058] Furthermore, in the syringe 1 of the first embodiment, the cap 5 has an elastic portion 51 into which the injection needle 4 is inserted when the peripheral wall portion 33 is inserted inside the inner peripheral surface (inner surface) 526 of the insertion portion, and the convex contact portion 528 is positioned on the inner peripheral surface 526 of the insertion portion of the cap 5, and when the peripheral wall portion 33 is inserted inside the inner peripheral surface 526 of the insertion portion, the convex contact portion 528 contacts the outer peripheral surface (outer surface) 332 of the peripheral wall portion 33 of the peripheral wall portion 33 before the injection needle 4 is inserted into the elastic portion 51, and the third locking projection (first engaging portion) 527 and the engaging groove (second engaging portion) 335 engage with each other after the injection needle 4 is inserted into the elastic portion 51.

[0059] With this configuration, when the peripheral wall portion 33 is inserted into the inner peripheral surface 526 of the insertion portion of the cap 5, the cap 5 is guided by the convex contact portion 528 even before the injection needle 4 penetrates the elastic portion 51. This suppresses bending of the injection needle 4 when it is inserted into the elastic portion 51. Furthermore, the engagement of the third locking projection 527 and the engagement groove 335 restricts the cap 5 from coming out of the peripheral wall portion 33 when the injection needle 4 is inserted into the elastic portion 51.

[0060] Next, a second embodiment of the present invention will be described with reference to Figures 7 to 11. Note that the same reference numerals are used for components identical to those in the first embodiment, while different components will be described in detail below.

[0061] As shown in Figures 7 and 8, syringe 1A comprises a syringe body 2A and a cap 5A that is attached to (placed over) the syringe body 2A, and the syringe body 2A comprises a cylindrical barrel 3A and an injection needle 4 positioned at the tip of the barrel 3A.

[0062] The barrel 3A comprises a cylindrical body portion 31, a columnar needle holding portion 32 that holds the injection needle 4 at the tip of the body portion 31, and a peripheral wall portion 33A that surrounds the needle holding portion 32 in the circumferential direction at the tip of the body portion 31.

[0063] The peripheral wall portion 33A is a cylindrical portion that extends from the tip of the body portion 31 in the direction of the central axis C and surrounds the needle holding portion 32 in the circumferential direction, and has an inner peripheral surface 331 and an outer peripheral surface (outer peripheral surface) 332A of the peripheral wall portion. The peripheral wall portion 33A has an engaging projection (projection) 336 that extends in the circumferential direction on the outer peripheral surface 332A of the peripheral wall portion.

[0064] The peripheral wall portion 33A in this embodiment is cylindrical. More specifically, the peripheral wall portion 33A is cylindrical with a substantially constant diameter at each position in the direction of the central axis C, and is arranged concentrically with the needle holding portion 32. Furthermore, the peripheral wall portion 33A surrounds the needle holding portion 32 with a gap between them (see Figure 8).

[0065] The engaging projection 336 extends over the entire circumferential area of ​​the outer peripheral surface 332A of the peripheral wall. In this embodiment, the height (amount of protrusion from the outer peripheral surface 332A of the peripheral wall) and width (dimension in the central axis direction) of the engaging projection 336 are constant at each position in the circumferential direction. In the syringe 1A of this embodiment, this engaging projection 336 constitutes the second engaging portion. That is, in the syringe 1A of this embodiment, the second engaging portion (engaging projection) 336 is included in the syringe body 2A (more specifically, the peripheral wall portion 33A of the barrel 3A).

[0066] As shown in Figures 9 to 11, the cap 5A has an elastic portion 51 that seals the needle holding portion 32 and an outer cylindrical portion 52A that covers the periphery of the elastic portion 51.

[0067] The elastic portion 51 is a bottomed cylindrical shape with an opening 511 at the base end and a closed portion 512 at the tip end.

[0068] The outer cylinder portion 52A is cylindrical, having a first opening 520a at its base end and a second opening 520b at its tip end. This outer cylinder portion 52A has a holding portion 521 that holds the elastic portion 51 and an insertion portion 525A into which the peripheral wall portion 33A of the barrel 3 is inserted. These holding portion 521 and insertion portion 525A are aligned in the direction of the central axis C (see Figure 11).

[0069] The retaining portion 521 has a first locking projection 523 and a second locking projection 524 on its inner circumferential surface 522, which engage the elastic portion 51.

[0070] The inserted portion 525A has an inner circumferential surface (inner surface) 526A that faces the outer circumferential surface 332A of the circumferential wall portion 33 when the circumferential wall portion 33A is inserted. The inserted portion 525A also has at least one fourth locking projection 529 that protrudes inward from the inner circumferential surface 526A of the inserted portion. In this embodiment, the inserted portion 525A has a plurality (five in this example) of fourth locking projections 529.

[0071] The fourth locking projection 529 is positioned such that when the cap 5A is placed over the syringe body 2A, the engaging projection 336 of the peripheral wall 33A abuts against the fourth locking projection 529 from the tip side in the direction of the central axis C. This contact (engagement) between the engaging projection 336 of the peripheral wall 33A and the tip of the fourth locking projection 529 restricts the cap 5 from coming off the peripheral wall 33A (see Figure 8).

[0072] Specifically, the multiple fourth locking projections 529 are arranged at circumferential intervals on the inner circumferential surface 526A of the insertion portion, and each fourth locking projection 529 extends in the direction of the central axis C. More specifically, each fourth locking projection 529 extends from a position at a predetermined distance from the second locking projection 524 (a distance corresponding to the position of the engaging projection 336 in the direction of the central axis C) to the base end of the insertion portion 525A (cap 5) (see Figures 8 and 11).

[0073] The tip of the fourth locking projection 529 has a first inclined surface 529a that approaches the inner circumferential surface 526A of the insertion portion as it moves toward the tip. The base end of the fourth locking projection 529 has a second inclined surface 529b that approaches the inner circumferential surface 526A of the insertion portion as it moves toward the base end (see Figure 11). The inclination of this second inclined surface 529b with respect to the inner circumferential surface 526A of the insertion portion (in the direction of the central axis C) is smaller than the inclination of the first inclined surface 529a with respect to the inner circumferential surface 526A of the insertion portion (in the direction of the central axis C). The fourth locking projection 529 in this embodiment is a projection with a constant circumferential dimension at each position in the direction of the central axis C. In the syringe 1A of this embodiment, this fourth locking projection 529 constitutes the first engagement portion. In other words, in the syringe 1A of this embodiment, the first engaging portion (fourth locking projection) 529 is included in the cap 5A (more specifically, the portion to be inserted 525A).

[0074] In the syringe 1A configured as described above, when the cap 5A is placed over the syringe body 2A, the injection needle 4 and the peripheral wall portion 33A of the barrel 3A are inserted into the cap 5A in order so that the injection needle 4 enters the opening 511 of the elastic portion 51.

[0075] Then, when the peripheral wall portion 33A is inserted into the insertion portion 525A of the cap 5A, the fourth locking projection 529 contacts the outer peripheral surface 332A of the peripheral wall portion 33A before the injection needle 4 penetrates the elastic portion 51 (more specifically, the occluding portion 512). After the peripheral wall portion 33A is further inserted into the insertion portion 525A and the injection needle 4 penetrates the elastic portion 51, the engaging projection 336 of the peripheral wall portion 33A engages between each of the fourth locking projections 529 and the second locking projection 524 in the direction of the central axis C (that is, the engaging projection 336 and the tip of the fourth locking projection 529 engage with each other in the direction of the central axis C). This completes the attachment of the cap 5A to the syringe body 2A.

[0076] The syringe 1A described above comprises a needle 4, a barrel 3A having a columnar needle holder 32 extending in the direction of the central axis C of the needle 4 and holding the needle 4, and a cylindrical peripheral wall portion 33A surrounding the needle holder portion 32 in the circumferential direction, a cap 5A having an inner peripheral surface (inner peripheral surface) 526A of the insertion portion that faces the outer peripheral surface (outer peripheral surface) 332A of the peripheral wall portion 33A when the peripheral wall portion 33A is inserted inside, a fourth locking projection (first engaging portion) 529 positioned on the inner peripheral surface 526A of the insertion portion of the cap 5A, and an engaging projection (second engaging portion) 336 positioned on the outer peripheral surface 332A of the peripheral wall portion 33A. Furthermore, the fourth locking projection 529 and the engaging projection 336 engage with each other in the direction of the central axis C in order to restrict the cap 5A from coming off the peripheral wall 33A, and at least one of the fourth locking projection 529 and the engaging projection 336 extends in the circumferential direction.

[0077] In this way, by having at least one of the fourth locking projection 529 and the engaging projection 336 extend in the circumferential direction, the number of engagement points (in this embodiment, the number of engagement points, etc.) between the fourth locking projection 529 and the engaging projection 336 can be increased, thereby preventing the cap 5A from coming off unintentionally from the peripheral wall 33A. In other words, the cap 5A becomes more difficult to remove from the peripheral wall 33A. Furthermore, in the syringe 1A of the second embodiment, the engaging projection (second engaging portion) 336 is a projection extending in the circumferential direction, and the fourth locking projection (first engaging portion) 529 is a projection extending in the direction of the central axis C.

[0078] With this configuration, when the cap 5A is placed over the peripheral wall portion 33A (i.e., when the peripheral wall portion 33A is inserted inside the inner peripheral surface 526A of the insertion portion of the cap 5), the fourth locking projection (protrusion) 529 extending in the direction of the central axis C guides the cap 5A, so that the cap 5A is placed over the peripheral wall portion 33A in the correct position. After the peripheral wall portion 33A is fully inserted inside the inner peripheral surface 526A of the insertion portion of the cap 5A and the fourth locking projection 529 and the engaging projection 336 engage, the cap 5A is sufficiently prevented from coming off the peripheral wall portion 33A. [Examples]

[0079] Here, in order to confirm the effect of the syringe 1 of the first embodiment described above, i) the barrel 3 and cap 5 (outer cylinder portion 52) of the first embodiment, ii) a first comparative example having the same configuration as the barrel 3 and cap 5 of the first embodiment except that the protruding contact portion 528 of the insertion portion 525 of the cap 5 is eliminated, and iii) the barrel 3 and cap 5 of the first embodiment except that the third locking projection 527 of the insertion portion 525 of the cap 5 is eliminated and the number of protruding contact portions 528 is increased to 5. A second comparative example with the same configuration as the first embodiment was prepared, and a third comparative example with the same configuration as the barrel 3 and cap 5 of the first embodiment was prepared, except that the third locking projection 527 was removed from the insertion portion 525 of the cap 5, the number of protruding contact portions 528 was increased to 11, and the amount of protrusion (height) of each protruding contact portion 528 from the inner circumferential surface 526 of the insertion portion was slightly increased. The force used when placing the cap on the barrel (assembly force) and the force used when pulling the cap off the barrel (pull-out force) were measured. The results are shown in Figure 12. In this embodiment 1, the assembly force and pull-out force were measured with the elastic portion positioned inside the outer cylinder portion of each cap.

[0080] From these results, it was confirmed that the pull-out force of the first embodiment (i) is almost the same as the pull-out force of the third comparative example, which has a configuration aimed at strengthening the pull-out force, and therefore the syringe 1 of the first embodiment is a syringe 1 in which the cap 5 is difficult to remove.

[0081] On the other hand, in terms of assembly force, the assembly force of the first embodiment (i) is about 1 / 3 of the assembly force of the third comparative example (iv), about 1.5 times that of the first comparative example (ii), and about 2 times that of the second comparative example (iii). This confirms that syringe 1 of the first embodiment is a syringe that secures a sufficient withdrawal force without significantly increasing the assembly force.

[0082] Furthermore, the syringe of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, and a part of the configuration of one embodiment can be replaced with the configuration of another embodiment. In addition, a part of the configuration of one embodiment can be deleted.

[0083] In the syringe 1 of the first embodiment described above, the first engaging portion (third locking projection) 527 is a projection extending in the circumferential direction, and the second engaging portion (engagement groove) 335 is a recess extending in the circumferential direction, but the configuration is not limited to this.

[0084] The first engaging portion (protrusion) 527 may have a shape in which the dimensions in the direction of the central axis C and the dimensions in the circumferential direction are approximately the same. That is, the first engaging portion 527 does not have to extend in the circumferential direction, and it is sufficient that its circumferential dimension is smaller than the circumferential dimension of the second engaging portion (recess) 335. Also, both the first engaging portion 527 and the second engaging portion 335 may be composed of protrusions.

[0085] Alternatively, the cap 5 may have a second engaging portion (third locking projection) 527, and the barrel 3 may have a first engaging portion (engaging groove) 335. In this case, the projection contact portion 528 is positioned on the peripheral wall portion 33 of the barrel 3.

[0086] In other words, the cap 5 should be configured such that the first engaging portion and the second engaging portion can engage with each other in the direction of the central axis C when the cap 5 is placed over the barrel 3.

[0087] Furthermore, in the insertion portion 525 of the cap 5 in the first embodiment described above, the third locking projection 527 and the projection contact portion 528 are spaced apart in the circumferential direction, but the third locking projection 527 and the projection contact portion 528 may be connected.

[0088] Furthermore, in the syringe 1A of the second embodiment described above, the first engaging portion (fourth locking projection) 529 is a projection extending in the direction of the central axis C, and the second engaging portion (engaging projection) 336 is a projection extending in the circumferential direction, but the configuration is not limited to this.

[0089] The first engaging portion 529 does not necessarily have to extend in the direction of the central axis C. In this case, it is preferable that the cap 5A or barrel 3A has a configuration corresponding to the convex contact portion 528 of the first embodiment. This allows the configuration corresponding to the convex contact portion 528 to contact the outer peripheral surface 332A of the peripheral wall portion 33A or the inner peripheral surface 526A of the part to be inserted into the cap 5A when the cap 5A is placed over the peripheral wall portion 33A (i.e., when the peripheral wall portion 33A is inserted inside the inner peripheral surface 526A of the part to be inserted into the cap 5A), guiding the cap 5A so that the cap 5A can be placed over the barrel 3A (peripheral wall portion 33A) in the correct position.

[0090] Alternatively, the cap 5A may have a second engaging portion (fourth locking projection) 529, and the barrel 3A may have a first engaging portion (engaging projection) 336.

[0091] Furthermore, in the syringes 1 and 1A of the first and second embodiments described above, the syringe body 2 and 2A are equipped with an injection needle 4, but the configuration is not limited to this. The syringes 1 and 1A may have an injection needle 4 that is added later. In this case, the syringe body 2 and 2A consists only of barrels 3 and 3A having a needle holding portion 32 and peripheral wall portions 33 and 33A. That is, the syringes 1 and 1A may consist of barrels 3 and 3A and caps 5 and 5A. [Explanation of symbols]

[0092] 1, 1A... Syringe, 2, 2A... Syringe body, 3, 3A... Barrel, 31... Body, 32... Needle holder, 33, 33A... Peripheral wall, 331... Inner surface of peripheral wall, 332, 332A... Outer surface of peripheral wall (outer surface), 335... Engagement groove (second engagement part), 336... Engagement projection (second engagement part), 4... Injection needle, 5, 5A... Cap, 51... Elastic part, 511... Opening, 512... Closure part, 513... Groove, 52, 52A... Outer cylinder, 520a... First opening, 520b... Second opening, 521... Holder, 522... Inner surface of holder, 523... First locking 524... Second locking projection, 524A... Notch, 525, 525A... Inserted portion, 526, 526A... Inner surface of inserted portion (inner surface), 527... Third locking projection (first engaging portion), 528... Protruding contact portion, 528a... Inclined surface, 529... Fourth locking projection (first engaging portion), 529a... First inclined surface, 529b... Second inclined surface, 100... Syringe, 110... Syringe body, 111... Body, 112... Injection needle, 113... Holding portion, 114... Cylinder portion, 120... Cap, 121... Opening, α... Height of protruding contact portion, β... Height of third locking projection

Claims

1. A barrel having a columnar needle-holding portion extending in the central axis direction and capable of holding an injection needle, and a cylindrical peripheral wall portion surrounding the needle-holding portion in the circumferential direction, A cap having an inner circumferential surface that faces the outer circumferential surface of the circumferential wall when the circumferential wall is inserted inside, The first engaging portion is disposed on the inner circumferential surface of the cap, The peripheral wall portion comprises a second engaging portion disposed on the outer peripheral surface of the peripheral wall portion, The first engaging portion and the second engaging portion engage with each other in the central axis direction in order to restrict the cap from coming off the peripheral wall portion. At least one of the first engaging portion and the second engaging portion is a syringe extending in the circumferential direction.

2. The syringe according to claim 1, wherein in at least one of the first engaging portion and the second engaging portion, the circumferential dimension is greater than the dimension in the central axis direction.

3. It is equipped with a convex contact portion extending in the direction of the central axis, The convex contact portion is positioned on the inner circumferential surface of the cap and in contact with the outer circumferential surface of the circumferential wall portion, or is positioned on the outer circumferential surface of the circumferential wall portion and in contact with the inner circumferential surface of the cap, The syringe according to claim 1, wherein at least one of the first engaging portion and the second engaging portion is a convex ridge extending in the circumferential direction.

4. The needle holder is equipped with an injection needle, The cap has an elastic portion into which the injection needle is inserted when the peripheral wall portion is inserted inside the inner circumferential surface. The aforementioned convex contact portion is arranged on the inner circumferential surface of the cap, When the peripheral wall portion is inserted into the inner side of the inner peripheral surface, The aforementioned convex contact portion contacts the outer circumferential surface of the peripheral wall portion before the injection needle penetrates the elastic portion. The syringe according to claim 3, wherein the first engaging portion and the second engaging portion engage with each other after the injection needle has pierced the elastic portion.

5. One of the first engaging portion and the second engaging portion is a convex ridge extending in the circumferential direction, The syringe according to claim 1, wherein the other of the first engaging portion and the second engaging portion is a convex ridge extending in the direction of the central axis.

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