Liquid injection device

Abstract

To provide a liquid injection device that is less prone to liquid leakage. [Solution] The liquid injection device 10 comprises an outer cylinder 20 in which a liquid drug is contained and which has a discharge hole 26 at its longitudinal end for discharging the drug, a piston 30 that is airtightly fitted inside the outer cylinder 20 and is freely movable along the longitudinal direction of the outer cylinder 20, and a plug 40 that closes the discharge hole 26, the plug 40 being screwed into the discharge hole 26 of the outer cylinder 20 by a screw portion.

Description

Technical Field

[0001] The present invention relates to a liquid injection device.

Background Art

[0002] As a device for injecting a liquid drug into the body, for example, a liquid injector described in Patent Document 1 has been proposed. As shown in FIG. 8, this type of liquid injector includes an outer cylinder 101 in which a liquid is stored, and a piston 102 that is movably inserted inside the outer cylinder 101. A discharge hole 103 for ejecting the liquid is formed at the tip of the outer cylinder 101. A cover 104 for preventing the liquid from leaking from the discharge hole 103 is provided at the discharge hole 103.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the liquid injector described in Patent Document 1, the discharge hole 103 is sealed by inserting a protrusion 105 provided on the cover 104 into the discharge hole 103. However, since the protrusion 105 is merely inserted into the discharge hole 103, the cover 104 is likely to come off, and the cover 104 may come off during transportation or storage, and the liquid may leak.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a liquid injection device in which liquid is less likely to leak.

Means for Solving the Problems

[0006] To achieve the above object, the present invention includes the subject matter described in the following paragraphs.

[0007] Item 1: An outer cylinder having a liquid drug contained in its internal space and a discharge hole at its longitudinal end for dispensing the drug, A piston is airtightly fitted inside the outer cylinder and is freely movable along the length of the outer cylinder, It comprises a plug portion that closes the discharge hole, A liquid injection device in which the stopper portion is screwed into the discharge hole of the outer cylinder by a screw portion.

[0008] Item 2: The plug portion comprises a main body portion that is inserted into the discharge hole of the outer cylinder, The liquid injection device according to item 1, wherein the screw portion comprises a first screw portion provided on the inner surface of the discharge hole and a second screw portion provided on the outer circumferential surface of the main body of the plug portion and screwed into the first screw portion.

[0009] Item 3: The liquid injection device according to Item 2, wherein the inner surface of the tip side of the discharge hole is tightly fitted with the outer circumferential surface of the main body of the plug.

[0010] Item 4: The plug portion is located on the outside of the main body portion and is equipped with a flange portion surrounding the main body portion. The liquid injection device according to item 2 or 3, wherein the tip of the outer cylinder is inserted into the space between the main body and the flange.

[0011] Item 5: The tip of the piston is provided with an O-ring to maintain airtightness, Item 1 A liquid injection device as described in any one of paragraphs 4. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a liquid injection device that is less prone to liquid leakage. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view along a plane including the axial direction, showing the overall configuration of a liquid injection device according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view showing a magnified view of the tip of the liquid injection device. [Figure 3] It is a side view seen from one axial side of the plug portion. [Figure 4] It is a side view seen from the other axial side of the plug portion. [Figure 5] It is an enlarged cross-sectional view of part A in FIG. 1. [Figure 6] It is an enlarged cross-sectional view of part B in FIG. 1. [Figure 7] It is a cross-sectional view taken along line C-C of FIG. 1. [Figure 8] It is a cross-sectional view showing the prior art.

Mode for Carrying Out the Invention

[0014] (Overall Configuration) Embodiments of the present invention will be described with reference to the drawings. The liquid injection device 10 according to one embodiment injects a liquid drug into the human body. As the drug, for example, a cleaning liquid for cleaning a female genital organ, a lubricant, a contraceptive liquid for contraception, a liquid drug for treating diseases, etc. are used to administer to the female genital organ. However, the use of the liquid injection device 10 of the present invention is not limited to this. The liquid injection device 10 generally has a drug accommodated therein in advance, and a user or a therapist injects the drug into the body manually.

[0015] As shown in FIG. 1, the liquid injection device 10 includes an outer cylinder 20 having a discharge hole 26 for discharging a drug at the tip in the length direction, with a liquid drug accommodated therein, a piston 30 that is hermetically fitted inside the outer cylinder 20 and is movable freely along the length direction of the outer cylinder 20, and a plug portion 40 that closes the discharge hole 26. The outer cylinder 20, the piston 30, and the plug portion 40 are manufactured by injection molding using a plastic resin as a material, except for the O-ring 34 described later.

[0016] In the following description, along the direction along the length direction of the liquid injection device 10, the direction in which the drug is injected is referred to as the tip side or the front side, and the side opposite to the tip side is referred to as the rear end side or the rear side. The length direction of the outer cylinder 20 is also simply referred to as the length direction or the axial direction.

[0017] (Outer Cylinder 20) The outer cylinder 20 has a cylindrical shape, and the outer shape of the surface (cross-section) orthogonal to the length direction is circular. In its outer shape, the outer cylinder 20 successively includes a front expansion part 21, an intermediate part 22, and a rear expansion part 23 along the length direction from the tip side. The outer diameter of the outer cylinder 20 continuously changes along the length direction except for the part with a constant outer diameter.

[0018] In the front expansion part 21, the outer diameter of the central part in the length direction is formed larger than that of both end parts, and at the tip of the front expansion part 21, a discharge part (tip part) 24 with an approximately constant outer diameter is formed. The outer diameter L1 (FIG. 2) of the discharge part 24 is 2 / 10 to 6 / 10 of the maximum diameter of the outer cylinder 20 (in this embodiment, the outer diameter L2 (FIG. 1) at the rearmost end of the second constant part 23d of the rear expansion part 23), and the length L3 in the length direction of the discharge part 24 is about 1 / 100 to 2 / 100 of the overall length of the outer cylinder 20. The length in the length direction of the front expansion part 21 is about 1 / 2 of the overall length of the outer cylinder 20. Note that the front expansion part 21 may be formed with a constant outer diameter or may be set to the same outer diameter as the intermediate part 22.

[0019] The intermediate part 22 has a constant outer diameter, and the length in the length direction of the intermediate part 22 is about 1 / 4 of the overall length of the outer cylinder 20. The length in the length direction of the rear expansion part 23 is about 1 / 4 of the overall length of the outer cylinder 20. The rear expansion part 2 has a first tapered part 23a whose outer diameter continuously increases from the front to the rear, a first constant part 23b provided continuously to the first tapered part 23a and having a constant outer diameter, a second tapered part 23c provided continuously to the first constant part 23b and whose outer diameter continuously increases, and a second constant part 23d provided continuously to the second tapered part 23c and having a constant outer diameter. By a user placing a finger on the first tapered part 23a or the second tapered part 23c, the movement of the piston 30 is facilitated.

[0020] In this embodiment, the length in the length direction of the outer cylinder 20 is about 100 mm, the outer diameter L2 at the rearmost end of the second constant part 23d is 17 mm, the outer diameter L1 of the discharge part 24 is 7.2 mm, and the maximum outer diameter of the front expansion part 21 is set to 14 mm, but it is not limited thereto. <s

[0021] The outer cylinder 20 contains the drug in its internal space 25. The internal space 25 is formed along its length and has a circular cross-sectional shape. The central part of the internal space 25 has a constant inner diameter L4. At the rear end of the internal space 25, a portion 25a is formed where the diameter increases towards the rear end, making it easier to insert the piston 30. Furthermore, the front end of the internal space 25 has a smaller inner diameter towards the tip, so as to be continuous with the discharge hole 26 provided in the discharge portion 24 of the outer cylinder 20.

[0022] The discharge hole 26 is provided at the tip of the front expansion portion 21 of the outer cylinder 20 and communicates with the internal space 25. The discharge hole 26 has a circular cross-sectional shape, and the axis of the discharge hole 26 coincides with the axis of the internal space 25. As shown in Figure 2, a spiral projection 27 is formed on the inner surface of the discharge hole 26 along the axial direction. This projection 27 constitutes the first threaded portion and screws into the screw groove 42b which constitutes the second threaded portion of the plug portion 40, which will be described later. The threaded portion is formed by the projection 27 which constitutes the first threaded portion and the screw groove 42b which constitutes the second threaded portion. The projection 27 may be formed around one or more times in a plane perpendicular to the axial direction, but it may also be less than one time. In other words, the projection 27 is preferably a circular arc with a central angle of less than 360 degrees around the axis in a plane perpendicular to the axial direction, and in this embodiment, it is a circular arc with a central angle of 270 degrees.

[0023] The inner diameter L7 of the discharge hole 26 is preferably 5 / 10 to 8 / 10 of the inner diameter L4 of the internal space 25. In this embodiment, the inner diameter L7 of the discharge hole 26 is set to 5 mm and the inner diameter L4 of the internal space 25 is set to 8 mm. The axial length L5 of the discharge hole 26 is set to 4.5 mm, and the protruding height L6 of the ridge portion 27 is set to 1 mm.

[0024] As shown in Figure 5, an annular projection 25b is provided adjacent to the front of the portion 25a at the rear end of the internal space 25 where the diameter is larger. In other words, the inner diameter of the annular projection 25b is smaller than the constant inner diameter L4 of the internal space 25. The annular projection 25b contacts the annular projection 33a of the piston 30, which will be described later, and functions as a retainer for the piston 30 to prevent it from coming out.

[0025] (Piston 30) The piston 30 comprises a tip piston portion 31 located towards the front along its length, an intermediate piston portion 32 in the center, and a rear end piston portion 33 at the rear end.

[0026] As shown in Figure 6, an annular groove 31a is formed on the outer circumference of the tip piston portion 31, and a cylindrical O-ring 34 is fitted into the groove. The O-ring 34 is made of rubber, and annular protrusions 34a are formed on both ends of the outer circumference of the O-ring 34 in the longitudinal direction. The airtightness of the internal space 25 is maintained by the contact of these protrusions 34a with the inner surface of the internal space 25. The outer diameter of the front portion 31b of the tip piston portion 31, with the annular groove 31a in between, is... The outer diameter of the rear portion 31c is set to be smaller than the outer diameter of 31c, and the outer diameter of the rear portion 31c is slightly smaller than the inner diameter L4 of the internal space 25. Alternatively, the outer diameter of the rear portion 31c may be approximately the same length as the inner diameter L4 of the internal space 25, and the outer surface of the rear portion 31c may be in contact with the inner surface of the internal space 25. Liquid is contained between the internal space 25 of the outer cylinder 20 and the tip piston portion 31.

[0027] As shown in Figure 7, the intermediate piston section 32 has a cross shape along a plane perpendicular to the axial direction. In other words, the intermediate piston section 32 comprises a central rod 32a and four vane sections 32b arranged at equal intervals around the central rod 32a. The axis of the central rod 32a coincides with the axis of the internal space 25, and the tips of the vane sections 32b are set to a size that does not contact the inner surface of the internal space 25 of the outer cylinder 20. The number of vane sections 32b can be set arbitrarily.

[0028] A rear piston portion 33 is provided continuously with the intermediate piston portion 32. As shown in Figure 5, an annular projection 33a is formed on the tip side of the rear piston portion 33. This annular projection 33a functions as a retainer for the piston 30 by contacting an annular projection 25b provided in front of the portion 25a at the rear end of the internal space 25 where the diameter increases. As shown in Figure 1, the rear piston portion 33 is hollow, and the rear end side has a tapered portion 33b, with the outer and inner diameters increasing towards the rear end.

[0029] (Plug part 40) The plug portion 40 closes the discharge hole 26 and comprises a main body portion 41 inserted into the discharge hole 26 from the outside of the liquid injection device 10, a flat plate portion 44 that seals the tip of the main body portion 41, a flange portion 45 located on the outside of the main body portion 41 and surrounding the main body portion 41, and a gripping portion 46.

[0030] The main body portion 41 is a hollow cylindrical shape and comprises a small diameter portion 42 at the rear end and a large diameter portion 43 at the front end that is formed continuously with the small diameter portion 42. The outer circumferential surface 42c of the small diameter portion 42 is provided with a second threaded portion that engages with a protruding portion 27, which is a first threaded portion, provided on the inner surface of the discharge hole 26. The second threaded portion is a concave threaded groove 42b between spiral protrusions 42a, and the plug portion 40 is screwed into the discharge hole 26 by the protruding portion 27 of the discharge hole 26 fitting into the threaded groove 42b. The outer diameter of the large diameter portion 43 is set to be the same as the inner diameter L7 of the discharge hole 26, and when the plug portion 40 is screwed into the discharge hole 26, the inner surface at the front end of the discharge hole 26 is in close contact with the outer circumferential surface of the large diameter portion 43 of the main body portion 41 of the plug portion 40 to ensure airtightness.

[0031] It is preferable that the protrusions 42a and screw grooves 42b of the second screw portion are formed at least once in a plane perpendicular to the axial direction. In this embodiment, the screw groove 42b is formed in a plane perpendicular to the axial direction from two turns around the axis and an arc with a central angle of less than 180 degrees.

[0032] The main body portion 41 is hollow and has an open rear end. This hollowness allows the main body portion 41 to bend slightly, facilitating screw fastening of the discharge hole 26 and the plug portion 40. A flat plate portion 44 is provided at the front end of the main body portion 41 along a plane perpendicular to the axial direction, and the front end of the main body portion 41 is sealed by the flat plate portion 44. Furthermore, a flange portion 45 extends from the end of the flat plate portion 44 toward the rear end along the axial direction. The axial length of the flange portion 45 is set to be the same as the axial length L3 of the discharge portion 24 of the outer cylinder 20.

[0033] The radial distance L8 between the inner surface of the flange portion 45 and the large-diameter portion 43 of the main body portion 41, that is, the radial distance of the space enclosed by the main body portion 41, the flange portion 45, and the flat plate portion 44, is set to be the same as, or slightly larger than, the radial distance L9 (thickness) between the inner surface of the discharge hole 26 of the discharge portion 24 of the outer cylinder 20 and the outer surface of the discharge portion 24. Multiple recesses 45a are formed in the circumferential direction on the surface of the rear end of the flange portion 45 along a plane perpendicular to the axial direction due to the manufacturing process.

[0034] When the plug portion 40 is screwed into the discharge hole 26, the protrusion 27 of the first threaded portion of the discharge hole 26 is screwed into the thread groove 42b of the second threaded portion of the plug portion 40, and the large diameter portion 43 of the main body portion 41 of the plug portion 40 and the inner surface of the discharge hole 26 are tightly fitted together, maintaining airtightness. The discharge portion 24 of the outer cylinder 20 is inserted into the space surrounded by the main body portion 41, the flange portion 45 and the flat plate portion 44. Due to the reaction force of the force that the discharge portion 24 of the outer cylinder 20 applies to the flange portion 45 during insertion, the discharge portion 24 of the outer cylinder 20 is pressed toward the main body portion 41 of the plug portion 40, which helps to maintain tight fitting between the large diameter portion 43 of the main body portion 41 of the plug portion 40 and the inner surface of the discharge hole 26.

[0035] In this embodiment, the radial distance L8 between the inner surface of the flange portion 45 and the large diameter portion 43 of the main body portion 41 is set to 1.15 mm, the radial distance L9 (thickness of the discharge portion 24) between the inner surface of the discharge hole 26 of the discharge portion 24 of the outer cylinder 20 and the outer surface of the discharge portion 24 is set to 1.07 mm, and the thickness L10 (radial length) of the flange portion 45 is set to 1.5 mm.

[0036] The gripping portion 46 extends from the main body portion 41 toward the tip and comprises a cylindrical portion 47 that is continuous with the main body portion 41 and provided coaxially, and a knob portion 48 provided at the tip of the cylindrical portion 47. The knob portion 48 is a flat plate with chamfered corners, and its shape along a plane perpendicular to the axial direction is a regular hexagon. The length of the diagonal of the regular hexagon of the knob portion 48 is set to be shorter than the diameter of the flat plate portion 44. As shown in Figure 2, a recess 48a is formed on the front surface of the knob portion 48 along the plane perpendicular to the axial direction, and a mark 49 indicating the direction of rotation for releasing the screw is attached to the surface of the recess 48a. The mark 49 includes letters, arrows, patterns, etc. The length of the diagonal of the knob portion 48 is set to 9.5 mm.

[0037] When a user uses the liquid injection device 10, they rotate the stopper 40 in the direction of the mark 49 to remove the stopper 40, position the outer cylinder 20 in the predetermined position inside the body, and then push the piston 30 forward. This causes the liquid to be discharged from the discharge hole 26.

[0038] With the above configuration, the plug portion 40 and the discharge hole 26 are screwed together, so the plug portion 40 will not come off and liquid will not leak from the discharge hole 26. In addition, the inner surface at the tip of the discharge hole 26 and the large diameter portion 43 of the main body portion 41 of the plug portion 40 are tightly fitted together, making it even less likely for liquid to leak. Furthermore, by providing a grip portion 46 on the plug portion 40, the user can remove the plug portion 40 by grasping the grip portion 46. The knob portion 48 of the plug portion 40 is provided with a mark 49 indicating the direction of rotation, so the user will understand that the plug portion 40 should be removed by rotating it rather than pulling it out. Furthermore, the inner diameter L7 of the discharge hole 26 is set to 5 / 10 to 8 / 10 of the inner diameter L4 of the internal space 25, and since it is a relatively large size, a large amount of liquid can be discharged relative to the travel distance of the piston 30.

[0039] Note that the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Expressions indicating that things such as "in a certain direction", "along a certain direction", "the same", "identical", "equal", and "homogeneous" are in an equal state represent not only a strictly equal state, but also a state in which there are tolerances or differences that allow the same function to be obtained. Expressions representing triangular, quadrangular, or circular shapes represent not only geometrically precise shapes, but also shapes including concave and convex portions, chamfered portions, etc. within a range where the same effect can be obtained. The expressions "comprising", "having", "including", or "possessing" one component are not exclusive expressions that exclude the existence of other components. "Parallel" and "orthogonal" mean substantially "parallel" and "orthogonal", and include not only a strictly "parallel" and "orthogonal" state, but also a state including an error of about several degrees. In addition, an expression such as "... part" may be used, for example, like "end part". For example, the "end part" means a part having a certain range including the "end". The same applies to other expressions with "... part".

Explanation of Reference Numerals

[0040] 10 Liquid injection device 20 Outer cylinder 24 Discharge part (tip part) 25 Internal space 26 Discharge hole 27 Ridge part (first screw part) 30 Piston 34 O-ring 40 Plug part 41 Main body part 42b Thread groove (second screw part) 45 Flange part

Claims

1. An outer cylinder having a liquid drug contained in its internal space and a discharge hole at its longitudinal end for dispensing the drug, A piston is airtightly fitted inside the outer cylinder and is freely movable along the length of the outer cylinder, It comprises a plug portion that closes the discharge hole, A liquid injection device in which the stopper portion is screwed into the discharge hole of the outer cylinder by a screw portion.

2. The plug portion comprises a main body portion that is inserted into the discharge hole of the outer cylinder, The liquid injection device according to claim 1, wherein the screw portion comprises a first screw portion provided on the inner surface of the discharge hole and a second screw portion provided on the outer circumferential surface of the main body of the stopper portion and screwed into the first screw portion.

3. The liquid injection device according to claim 2, wherein the inner surface of the tip side of the discharge hole is tightly fitted with the outer circumferential surface of the main body of the plug.

4. The stopper portion is located on the outside of the main body portion and has a flange portion surrounding the main body portion. The liquid injection device according to claim 2, wherein the tip of the outer cylinder is inserted into the space between the main body and the flange.

5. The liquid injection device according to claim 1, wherein an O-ring for maintaining airtightness is provided at the tip of the piston.

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