Valve-equipped indwelling needle assembly

Abstract

Provided is a valve-equipped indwelling needle assembly that has a novel structure and makes it possible to stably switch a valve body from a transmission state to a shutoff state by repulsion of a plunger to the base end side caused by the elasticity of the valve body.　A valve-equipped indwelling needle assembly 10 is configured such that an inner needle 16 is inserted through an outer needle 72 and an outer needle hub 74, and an inner cavity 76 of the outer needle hub 74 accommodates a valve body 94 that opens / closes by elastic deformation and a plunger 118 that is further to the base end side than the valve body 94, puts the valve body 94 into a transmission state by pressing toward the tip end side, and, when the valve body 94 is in the transmission state, receives return force directed toward the base end side due to reaction force from the valve body 94. A tapered part 124 that tapers toward the tip is provided to the tip end side of the plunger 118, the total length L0 in the axial direction of the plunger 118 is at least 3 times the length L2 in the axial direction of the tapered part 124, the entirety of the plunger 118 is inside the outer needle hub 76, and the length in the axial direction of the tapered part 124 is greater than the effective radius r of the valve body 94.

Description

Valve-equipped indwelling needle assembly

[0001] The present invention relates to an indwelling needle assembly in which an inner needle having an inner needle hub is inserted into an outer needle and the outer needle hub, and in particular to a valved indwelling needle assembly in which the inner cavity of the outer needle hub can be switched between communication and blockage using a valve body.

[0002] Conventionally, indwelling needles that constitute an inlet for administration to a blood vessel or an outlet for blood for infusion, dialysis, etc. have been known, and indwelling needle assemblies used for inserting an indwelling needle into a blood vessel have also been known. As shown, for example, in Japanese Patent Laid-Open Publication No. 2011-115630 (Patent Document 1), an indwelling needle assembly includes an outer needle and an outer needle hub that constitute an indwelling needle, and an inner needle that has an inner needle hub and is inserted through the outer needle and the outer needle hub. The outer needle is inserted into a blood vessel together with the inserted inner needle, and the inner needle is withdrawn from the outer needle while the outer needle is maintained in the inserted state, thereby leaving the indwelling needle including the outer needle in a state where it is inserted into the blood vessel.

[0003] Furthermore, as shown in Patent Document 1, a valved indwelling needle is also known in which a valve is provided in the inner cavity of the outer needle hub to prevent blood from leaking out through the inner cavities of the outer needle and outer needle hub that are left indwelled in a punctured state in a blood vessel. In a valved indwelling needle, for example, the inner cavity of the outer needle hub is blocked by the valve when the inner needle is removed, and the valve is brought into a communicating state by connecting a male luer to the outer needle hub. Note that a valved indwelling needle assembly is formed by inserting the inner needle through the outer needle and outer needle hub of the valved indwelling needle.

[0004] JP 2011-115630 A

[0005] In Patent Document 1, a cylindrical plunger is housed in the lumen of the outer needle hub, closer to the base end than the valve body. The plunger is pushed toward the tip end and penetrates a slit in the valve body, causing the valve body to transition from a blocked state to a communicating state. The plunger is pushed toward the tip end when, for example, a male luer is inserted into the base end opening of the outer needle hub and the tip of the male luer abuts against the plunger.

[0006] In addition, some valved indwelling needles have a valve that, when the male luer is removed from the outer needle hub and the pushing force on the plunger toward the distal end is released, the elasticity of the valve body pushes the plunger back toward the proximal end, returning the valve body to its shut-off state. In this case, the distal end portion of the plunger is formed into a tapered portion to effectively exert the force of the valve body's elasticity pushing the plunger back toward the proximal end. The valve body, deformed to a communicating state, is pressed against the tapered portion, and when the pushing force on the plunger toward the distal end is released, the plunger moves toward the proximal end due to the elasticity of the valve body, returning the valve body to its shut-off state. Therefore, when the proximal opening of the outer needle hub is open, the inner lumen of the outer needle hub is shut off by the valve body, preventing blood leakage.

[0007] However, the inventors' investigations revealed that the return force based on the elasticity of the valve body acting on the plunger varies depending on slight differences in the overall length, hardness, thickness, etc. of the standard-compliant male luer inserted into the outer needle hub, and that in some cases the plunger is not pushed back sufficiently, and the valve body does not enter an appropriate shut-off state. Specifically, for example, it was confirmed that when the male luer is thick and hard, the amount of pushing of the male luer toward the tip side of the outer needle hub is insufficient, and even when the male luer is removed from the outer needle hub, the plunger is not pushed back sufficiently, and the valve body does not enter an appropriate shut-off state.

[0008] It was also confirmed that the insertion length of the male luer inserted into the outer needle hub from the base end varies due to manufacturing errors, variations in hardness, and differences in the user's pushing force, making it difficult to consistently obtain the return force that pushes the plunger back.

[0009] In some cases, a protector that protects the needle tip of the inner needle when it is pulled out from the outer needle is placed between the leg-like portions provided on the base end side of the plunger, but in such cases, there is a risk that the displacement control structure that controls the displacement of the plunger toward the base end side relative to the outer needle hub will interfere with the protector.

[0010] It was also confirmed that as the outer needle hub is made smaller, the valve body may become pinched between the outer needle hub and the plunger, preventing the plunger from moving toward the tip.

[0011] The present invention aims to solve any of the above problems. It is an object of the present invention to provide a valved indwelling needle assembly with a novel structure that can improve the stability of switching the valve body from a communicating state to a blocking state by pushing the plunger back toward the base end based on the elasticity of the valve body. Another object of the present invention is to provide a valved indwelling needle assembly with a novel structure that can reduce the occurrence of interference between the displacement restriction structure that restricts plunger movement and the protector.

[0012] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely examples and may be appropriately combined with one another. Multiple components described in each embodiment may be recognized and employed independently to the greatest extent possible, and may also be appropriately combined with any of the components described in other embodiments. Accordingly, the present invention is not limited to the embodiments described below, and various other embodiments may be realized.

[0013] In a first aspect, an inner needle having an inner needle hub is inserted into an outer needle and the outer needle hub, and a valve body that opens and closes by elastic deformation and a plunger that is arranged base-end side of the valve body and puts the valve body into a communicating state when pushed toward the tip end and receives a return force toward the base end by a reaction force from the valve body are contained and arranged in the inner cavity of the outer needle hub, and a tapered portion is provided on the tip end side of the plunger, the total axial length of the plunger is three times or more the axial length of the tapered portion, the plunger is located within the outer needle hub, and the axial length of the tapered portion is greater than the effective radius that allows free deformation at the tip surface of the valve body.

[0014] In a valved indwelling needle assembly constructed according to this aspect, the axial length of the tapered portion is made longer than the effective radius of the valve disc, thereby enabling smooth opening and closing of the valve disc and ensuring a stable return force exerted on the tapered portion of the plunger by the elastic reaction force of the valve disc. Furthermore, since the overall axial length of the plunger is set to be three times or more the axial length of the tapered portion, the overall axial length of the plunger is set sufficiently long, making it easier to position the base end of the plunger closer to the base-end opening of the outer needle hub than conventionally possible. This allows for a longer relative movement distance of the plunger with respect to the valve disc when inserting the male luer into the outer needle hub. This makes it easier to ensure a large reaction force (return force) of the valve disc acting on the tapered portion of the plunger, improving the stability of the shutoff function of the valve disc, even when, for example, the axial length of the male luer is short or the male luer is not inserted deeply into the outer needle hub due to insufficient pushing.

[0015] In a second aspect, the valved indwelling needle assembly according to the first aspect is characterized in that the axial length of the tapered portion is 3 mm or more, and in a plunger pushing region of the plunger extending from the opening communication position where the opening of the valve body reaches the diameter of the inner bore of the plunger by pushing the plunger into the valve body to a further 3 mm, the resistance force against pushing the plunger into the valve body is maintained greater than the value at the opening communication position.

[0016] According to the second aspect, by providing a push-in region in which the plunger that has reached the opening communication position can be moved further toward the tip, and by setting the taper length so that the return force due to the elasticity of the valve body can be sufficiently applied to the tapered portion even in the push-in region, it is possible to widen the range of the compatible length of the male luer inserted into the outer needle hub from the proximal end side (the axial length of the male luer that can be pushed into the plunger to a position where an effective return force acts) compared to conventional methods. Therefore, even if the axial insertion length of the male luer varies due to manufacturing errors, variations in hardness, differences in the pushing force applied by the user, etc., it is possible to stably obtain a return force toward the proximal end for the plunger that has been pushed into the valve body.

[0017] A third aspect is the valved indwelling needle assembly described in the first or second aspect, wherein the axial length of the tapered portion is at least twice the outer diameter of the tip of the tapered portion and at least twice the effective radius of the valve body, and the outer diameter of the tip of the tapered portion is equal to or smaller than the effective radius that allows free deformation at the tip surface of the valve body.

[0018] According to the third aspect, the axial length of the tapered portion of the plunger is at least twice the outer diameter of the tip, while the outer diameter of the tapered portion is equal to or less than the effective radius of the valve disc. Because the tip of the plunger is narrowed, it is easy to ensure a large inclination angle of the tapered portion. Furthermore, because the axial length of the tapered portion is long, the range of axial lengths of the male luer that can return the plunger to its initial position by the elasticity of the valve disc can be made wider than before. Therefore, even if there are variations due to manufacturing errors in the dimensions and hardness of the male luer and outer needle hub, or variations in the amount of pushing the male luer into the outer needle hub, it is possible to stably obtain a return force for the plunger pushed into the valve disc based on the elasticity of the valve disc.

[0019] A fourth aspect is a valve-equipped indwelling needle assembly described in any one of the first to third aspects, wherein the plunger has a tubular portion tapered toward the tip end and a leg-like portion with multiple legs extending toward the base end, the tubular portion has a regulating step that restricts movement of the plunger toward the base end relative to the outer needle hub by abutting against the outer needle hub, the leg-like portion is provided with a protector that protects the needle tip when the inner needle is pulled out, and the axial length of the leg-like portion is longer than the axial length of the tubular portion.

[0020] According to the fourth aspect, since the plunger is provided with a leg-shaped portion having multiple legs extending from the tubular portion toward the proximal end, it is possible to ensure space for arranging the protector between the multiple legs. For example, by positioning the portion of the protector where the diameter dimension increases circumferentially between the multiple legs, it becomes easier to avoid an increase in the diameter of the outer needle hub compared to when the periphery of the protector is surrounded entirely by a tubular plunger.

[0021] The axial length of the leg portion of the plunger is increased, and a restricting step is formed on the cylindrical portion of the plunger, so that the space for restricting the displacement of the plunger toward the proximal end and the space for arranging the protector can be separated within the outer needle hub, thereby preventing the displacement restricting structure that restricts the displacement of the plunger toward the proximal end from interfering with the protector.

[0022] A fifth aspect is a valved indwelling needle assembly described in any one of the first to fourth aspects, wherein the inner cavity of the outer needle hub is provided with a deformable portion that extends linearly from the tip of the valve body toward the tip side with an approximately constant diameter and has an inner diameter larger than the maximum diameter of the tapered portion, the axial length of the deformable portion is longer than the effective radius of the valve body, and the axial length of the tapered portion is longer than the axial distance from the base end of the outer needle hub to the base end of the plunger that is located tip-side of the base end of the outer needle hub.

[0023] According to the fifth aspect, since the axial distance from the base end of the outer needle hub to the base end of the plunger is relatively short, for example, even when the insertion length of the male luer into the outer needle hub is short, the plunger is sufficiently pushed toward the tip side, and the valve body is stably brought into a communicating state. On the other hand, since the deformation-permitting portion is provided, the valve body is less likely to be pinched between the outer needle hub and the plunger when the plunger is pushed toward the tip side. This makes it possible to reduce the situation where a pinched valve body makes it difficult to push the plunger to a predetermined position.

[0024] In a sixth aspect, an inner needle having an inner needle hub is inserted into an outer needle and the outer needle hub, and a valve body that opens and closes by elastic deformation, and a plunger that is arranged base-end side of the valve body and puts the valve body into a communicating state when pushed toward the tip end side, and receives a return force toward the base end side by a reaction force from the valve body, are contained and disposed in the inner cavity of the outer needle hub, wherein the plunger has a tapered portion on the tip end side, and the axial length of the tapered portion is 3 mm or more, and in the pushing region of the plunger, which extends a further 3 mm from the opening communication position where the opening of the valve body due to the plunger being pushed into the valve body reaches the inner bore diameter of the plunger, the pushing resistance force of the plunger against the valve body is kept greater than the value at the opening communication position.

[0025] According to the valved indwelling needle assembly constructed according to this aspect, a push-in region is provided in which the plunger that has reached the opening communication position can be moved further toward the distal end, and the tapered length is such that the return force due to the elasticity of the valve body can be sufficiently applied to the tapered portion even in the push-in region, thereby making it possible to widen the range of the compatible length of the male luer inserted into the outer needle hub from the proximal end side (the axial length of the male luer that can be pushed into the plunger to a position where an effective return force acts) compared to conventional methods. Therefore, even if the insertion length of the male luer varies due to manufacturing errors, variations in hardness, differences in pushing force by users, etc., it is possible to obtain a stable return force toward the proximal end for the plunger that has been pushed into the valve body.

[0026] In a seventh aspect, an inner needle having an inner needle hub is inserted into an outer needle and the outer needle hub, and a valve body that opens and closes by elastic deformation and a plunger that is arranged base-end side of the valve body and puts the valve body into a communicating state when pushed toward the tip end and receives a return force toward the base end by a reaction force from the valve body are contained and disposed in the inner cavity of the outer needle hub, wherein a tapered portion is provided on the tip end side of the plunger, and the axial length of the tapered portion is at least twice the outer diameter of the tip end of the tapered portion and is at least twice the effective radius of the valve body, and the outer diameter of the tip end of the tapered portion is equal to or less than the effective radius that allows free deformation at the tip surface of the valve body.

[0027] In a valved indwelling needle assembly constructed according to this aspect, the axial length of the tapered portion of the plunger is at least twice the outer diameter of the tip and at least twice the effective radius of the valve disc, while the outer diameter of the tip of the tapered portion is equal to or less than the effective radius of the valve disc. The axial length of the tapered portion of the plunger is set long relative to the effective radius of the valve disc, making it easier to avoid increasing the diameter of the outer needle hub. Furthermore, the narrow tip of the plunger makes it easy to ensure a large inclination angle of the tapered portion, and the long axial length of the tapered portion allows the range of axial lengths of the male luer that can return the plunger to its initial position using the elasticity of the valve disc to be wider than conventional ranges. Therefore, even if there are variations in the dimensions and hardness of the male luer and outer needle hub due to manufacturing errors, or variations in the amount of insertion of the male luer into the outer needle hub, it is possible to stably obtain a return force for the plunger inserted into the valve disc based on the elasticity of the valve disc. The valved indwelling needle assembly of this aspect is particularly suitable for use in infusions.

[0028] In an eighth aspect, an inner needle having an inner needle hub is inserted into an outer needle and the outer needle hub, and a valve body that opens and closes by elastic deformation, and a plunger that is arranged base-side to the valve body and puts the valve body into a communicating state when pushed toward the tip side and receives a return force toward the base end by a reaction force from the valve body, are contained and arranged in the inner cavity of the outer needle hub, and the plunger has a tubular portion that is tapered toward the tip side and a leg-like portion with multiple legs extending toward the base end side, and the tubular portion has a restricting step that restricts movement of the plunger toward the base end side relative to the outer needle hub by abutting against the outer needle hub, and a protector is arranged on the leg-like portion to protect the needle tip when the inner needle is pulled out, and the axial length of the leg-like portion is longer than the axial length of the tubular portion.

[0029] In a valved indwelling needle assembly constructed according to this aspect, the plunger is provided with a leg-like portion having multiple legs extending from the tubular portion toward the base end, and therefore space for disposing the protector can be secured between these multiple legs. For example, by positioning the portion of the protector where the diameter increases circumferentially between the multiple legs, it becomes easier to avoid an increase in the diameter of the outer needle hub compared to when the protector is completely surrounded by a tubular plunger.

[0030] The axial length of the leg portion of the plunger is increased, and a restricting step is formed on the cylindrical portion of the plunger, so that the space for restricting the displacement of the plunger toward the proximal end and the space for arranging the protector can be separated within the outer needle hub, thereby preventing the displacement restricting structure that restricts the displacement of the plunger toward the proximal end from interfering with the protector.

[0031] In a ninth aspect, an inner needle having an inner needle hub is inserted into an outer needle and the outer needle hub, and a valve body that opens and closes by elastic deformation, and a plunger that is arranged base-side of the valve body and puts the valve body into a communicating state when pushed toward the tip side, and that, when the valve body is in a communicating state, receives a returning force toward the base end side by a reaction force from the valve body, and is housed and disposed in the inner cavity of the outer needle hub, wherein a tapered portion is provided on the tip side of the plunger, and a deformable portion is provided in the inner cavity of the outer needle hub that extends linearly from the tip of the valve body toward the tip side with an approximately constant diameter and has an inner diameter larger than the maximum diameter of the tapered portion, the axial length of the deformable portion is longer than the effective radius of the valve body, and the axial length of the tapered portion is longer than the axial distance from the base end of the outer needle hub to the base end of the plunger, which is located tip-side of the base end of the outer needle hub.

[0032] In a valved indwelling needle assembly constructed according to this aspect, the axial distance from the base end of the outer needle hub to the base end of the plunger is relatively short, so that even if, for example, the insertion length of the male luer into the outer needle hub is short, the plunger is sufficiently pushed toward the distal end, and the valve body is stably brought into a communicating state. On the other hand, the provision of a deformation-permitting portion makes it difficult for the valve body to be pinched between the outer needle hub and the plunger when the plunger is pushed toward the distal end. This reduces the possibility of the plunger being difficult to push to the predetermined position due to a pinched valve body.

[0033] In a tenth aspect, an inner needle having an inner needle hub is inserted into an outer needle and the outer needle hub, and a valve body that opens and closes by elastic deformation, and a plunger that is disposed proximal to the valve body and puts the valve body into a communicating state when pushed toward the distal end, and that receives a returning force toward the proximal end by a reaction force from the valve body when the valve body is in a communicating state, are contained and disposed in the inner cavity of the outer needle hub, and a tapered portion is provided on the distal end side of the plunger, and a valve body that opens and closes by elastic deformation, and a plunger that opens and closes the valve body ... opens and closes the valve body by elastic deformation, and a plunger that opens and closes the valve body by elastic deformation, and a plunger that opens and closes the valve body by elastic deformation, and a plunger that opens and closes the valve body has a tapered portion whose diameter decreases toward the tip and to whose inner surface a crimping pin that fixes the outer needle is crimped, and when the plunger is pushed into the valve body, the tapered portion moves to a position where it enters the inner circumference of the crimping pin, and in the region in the inner cavity of the outer needle hub from the tip of the valve body to the crimping pin, there is provided a deformation-permitting portion which has a diameter larger than the maximum diameter of the tapered portion and extends linearly longer than the effective radius of the valve body.

[0034] In a valved indwelling needle assembly constructed according to this aspect, even if a reduced diameter portion is provided in the inner cavity of the outer needle hub to crimp and fix the crimping pin, a straight portion is provided between the valve body and the reduced diameter portion, making it less likely that the valve body, deformed by pushing the plunger, will reach the reduced diameter portion and be inserted into the inner periphery of the crimping pin. This prevents the valve body from being pinched between the plunger and the tapered crimping pin that corresponds to the reduced diameter portion, allowing stable movement of the plunger toward the tip. This configuration is preferably employed in combination with, for example, any one of the first to ninth aspects.

[0035] In an eleventh aspect, there is provided a valved indwelling needle assembly in which an inner needle having an inner needle hub is inserted into an outer needle and the outer needle hub, and a valve body that opens and closes by elastic deformation, and a plunger that is arranged proximal to the valve body and puts the valve body into a communicating state when pushed toward the distal end, and that receives a returning force toward the proximal end by a reaction force from the valve body when the valve body is in a communicating state, are housed and disposed in the inner cavity of the outer needle hub, and The plunger is accommodated in the valve body, and a tapered portion is provided at the tip side of the plunger. The valve body has a locking groove that opens to the base end face and into which a tip claw portion of a plunger guide that guides axial movement of the plunger is inserted and locked. The locking groove includes an outer peripheral cutout portion that extends inward beyond the tip claw portion of the plunger guide, and the radial width dimension of the outer peripheral cutout portion of the locking groove is 2 / 3 or less of the outer diameter of the tip portion of the tapered portion of the plunger.

[0036] In a valved indwelling needle assembly constructed according to this aspect, the locking groove opening on the base end surface of the valve body includes a peripheral cutout portion that extends more inward than the distal claw portion of the plunger guide. As a result, the portion of the valve body that is made thinner by forming the peripheral cutout portion is allowed to deform without being restrained by the distal claw portion of the plunger guide. Therefore, the peripheral cutout portion more smoothly allows deformation of the valve body when the plunger is pressed in, stabilizing the switching of the valve body to the communicating state.

[0037] The width of the outer peripheral recessed portion is set to 2 / 3 or less of the outer diameter of the tip of the tapered portion, and the width of the outer peripheral recessed portion is not excessively large. Therefore, even if the valve body is thin-walled at the outer peripheral recessed portion, the deformed valve body can effectively restore its shape to its original shape, and the plunger can stably return to the base end side based on this shape restoration force. This configuration is preferably employed in combination with, for example, any one of the first to tenth aspects.

[0038] According to any one of the first to seventh and ninth to eleventh aspects of the present invention, in a valved indwelling needle assembly, the stability of pushing back the plunger toward the base end based on the elasticity of the valve body can be improved.

[0039] According to the eighth aspect of the present invention, interference between the displacement restriction structure, which restricts displacement of the plunger toward the base end side relative to the outer needle hub, and the protector can be reduced.

[0040] 1 is a cross-sectional view of the valved indwelling needle assembly shown in FIG. 1, corresponding to the II-II cross-section of FIG. 3; III-III cross-sectional view of FIG. 2; a left side view of the plunger shown in FIG. 8; a cross-sectional view of the plunger shown in FIG. 8, corresponding to the cross-section XI-XI of FIG. 10; a perspective view of the protector constituting the valved indwelling needle assembly shown in FIG. 1; a perspective view of the protector of FIG. 12, shown at a different angle; a cross-sectional view of the essential parts showing a state in which a connector is connected to the outer needle unit constituting the valved indwelling needle assembly of FIG. 1; an enlarged view of the XV-XV cross-section of FIG. 14; and a graph showing the measurement results of the pushing resistance force acting on the plunger.

[0041] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0042] 1 to 3 show a valved indwelling needle assembly 10 as a first embodiment of the present invention. The valved indwelling needle assembly 10 is constructed by combining an inner needle unit 12 and an outer needle unit 14. In the following description, as a general rule, the front-to-rear direction refers to the left-to-right direction in Fig. 2, which is the needle axial direction, the up-down direction refers to the up-down direction in Fig. 2, and the left-to-right direction refers to the up-down direction in Fig. 3. Furthermore, in the following description, as a general rule, the left side in Fig. 2, which is the side of the needle tip 20 described below, refers to the distal end, and the right side in Fig. 2 refers to the proximal end.

[0043] The inner needle unit 12 has a structure in which an inner needle hub 18 is attached to the proximal end portion of an inner needle 16. The inner needle 16 is a hollow needle made of a medical metal such as stainless steel, and is provided with a sharp needle tip 20 at its distal end. The needle tip 20 is formed by the distal end portion of the inner needle 16 having a cutting edge 22 that widens and inclines relative to the needle axis. The outer diameter of the inner needle 16 is partially enlarged near its distal end. The proximal end portion of the inner needle 16 is inserted into the distal end portion of the cylindrical inner needle hub 18, and the inner needle 16 and inner needle hub 18 are fixed by means of adhesion or the like.

[0044] The inner needle hub 18 is a substantially cylindrical member made of hard synthetic resin. A cylindrical connecting portion 26 that can be fitted into the proximal end opening of the outer needle hub 74, which will be described later, is provided at the distal end of the inner needle hub 18. A filter cap 28 is fitted into the proximal end opening of the inner needle hub 18.

[0045] A protector 30 is attached to the inner needle 16. The protector 30 is attached in an externally fitted state to the inner needle 16 and moves toward the distal end of the inner needle 16 when the inner needle 16 is withdrawn (described later) to prevent the needle tip 20 from being exposed. The protector 30 is formed of a medical metal such as stainless steel. As shown in Figures 4 and 5, the protector 30 has a structure in which a first side plate portion 34 and a second side plate portion 36 extend from both upper and lower end edges of a bottom portion 32 located on the needle base side (opposite the needle tip 20) of the inner needle 16 toward the needle tip 20. In this embodiment, the components constituting the protector 30, which will be described later, are integrally formed.

[0046] The bottom 32 has a generally rectangular flat plate shape. A first side plate 34 and a second side plate 36 are integrally formed on a pair of upper and lower sides of the bottom 32 and extend out to one end of the bottom 32 in the thickness direction. In this embodiment, the first side plate 34 and the second side plate 36 are arranged facing each other at a distance and do not extend in a crosswise direction.

[0047] A needle insertion hole 38 is formed in the bottom portion 32, penetrating in the plate thickness direction. The needle insertion hole 38 in this embodiment is a circular hole large enough to allow the inner needle 16 to be inserted therethrough and large enough to allow the locking portion 24 of the inner needle 16 to be locked without passing through. A needle guide surface 40 is provided on the peripheral edge of the opening on the distal side of the needle insertion hole 38 in the bottom portion 32. The needle guide surface 40 is a tapered surface that widens toward the distal side. In addition, a reinforcing tube portion 42 is provided on the peripheral edge of the opening on the proximal side of the needle insertion hole 38 in the bottom portion 32. The reinforcing tube portion 42 has a generally cylindrical shape and is provided along the peripheral edge of the opening of the needle insertion hole 38, protruding from the bottom portion 32 toward the proximal side.

[0048] The first side plate 34 has a strip shape extending in the front-to-rear direction. The base end of the first side plate 34, which is connected to the bottom 32, has approximately the same width as the bottom 32, and the tip end, which is connected to a first needle tip protection part 44 (described later), is narrower than the bottom 32.

[0049] A first needle tip protection part 44 is provided on the tip side of the first side plate part 34. The first needle tip protection part 44 includes a first step-shaped part 46 that protrudes from the tip of the first side plate part 34 toward the opposite side from the second side plate part 36, and a first needle tip cover part 48 that protrudes at an angle from the protruding tip of the first step-shaped part 46 toward the second side plate part 36. A first needle tip restraining part 50 that protrudes toward the base end is provided at the tip portion of the first needle tip cover part 48. A pair of first side cover pieces 52, 52 that extend approximately perpendicular to the width direction are provided on both widthwise sides of the first needle tip cover part 48.

[0050] A first side cover piece 54 is provided on one widthwise edge of the first side plate 34. The first side cover piece 54 protrudes vertically inward (downward) from the first side plate 34 toward the second side plate 36. A first protruding piece 56 is provided on the other widthwise edge of the first side plate 34. The first protruding piece 56 protrudes vertically inward (downward) toward the second side plate 36, and is disposed opposite the first side cover piece 54 but spaced apart from each other in the widthwise direction.

[0051] The second side plate 36 has a strip shape extending in the front-to-rear direction. The base end of the second side plate 36, which is connected to the bottom 32, has approximately the same width as the bottom 32, and the tip end, which is connected to a second needle tip protection part 58 (described later), has a narrower width than the bottom 32.

[0052] A second needle tip protection portion 58 is provided on the tip side of the second side plate portion 36. The second needle tip protection portion 58 includes a second stepped portion 60 that protrudes from the tip of the second side plate portion 36 toward the opposite side from the first side plate portion 34, and a second needle tip cover portion 62 that protrudes at an angle from the protruding tip of the second stepped portion 60 toward the first side plate portion 34. A second needle tip restraining portion 64 that protrudes toward the base end is provided at the tip portion of the second needle tip cover portion 62. A pair of second side cover pieces 66, 66 that extend approximately perpendicular to the width direction are provided on both widthwise sides of the second needle tip cover portion 62.

[0053] A second side cover piece 68 is provided on the other widthwise edge of the second side plate 36. The second side cover piece 68 protrudes inward (upward) from the second side plate 36 toward the first side plate 34. In addition, a second protruding piece 70 is provided on one widthwise edge of the second side plate 36. The second protruding piece 70 protrudes inward (upward) from the second side plate 36 toward the first side plate 34, and is disposed opposite the second side cover piece 68 but spaced apart from each other in the widthwise direction.

[0054] The protector 30 constructed as described above is attached to the inner needle 16, as shown in Figures 2 and 3. That is, the inner needle 16 is inserted through the needle insertion hole 38 formed in the bottom 32 of the protector 30, and is also inserted between the first needle tip cover portion 48 and the second needle tip cover portion 62. As a result, the inner needle 16 is disposed so as to pass through the space between the opposing first side plate portion 34 and second side plate portion 36 of the protector 30, and the protector 30 is attached in an externally fitted state to the inner needle 16. The inner needle 16 is located between the opposing first side cover piece 54 and second side cover piece 68 of the protector 30, and is surrounded around a portion of the needle axis direction by the first and second side plate portions 34, 36, the first and second side cover pieces 54, 68, and the first and second projecting pieces 56, 70.

[0055] The outer needle unit 14 has a structure in which an outer needle hub 74 is attached to the proximal end portion of an outer needle 72. The outer needle 72 is a tubular member made of synthetic resin or the like. The outer diameter dimension of the tip portion of the outer needle 72 decreases toward the tip.

[0056] The outer needle hub 74 is made of, for example, a hard synthetic resin. The outer needle hub 74 is a member having a generally cylindrical shape overall, and has an inner cavity 76 that penetrates in the axial direction. A connector 130, such as a syringe tip (described below), is fitted into the inner cavity 76 of the outer needle hub 74 from the proximal end opening, making it possible to connect an external circuit, such as a syringe or an infusion line, to the inner cavity 76 of the outer needle hub 74. A threaded portion 78 that protrudes outward is formed at the proximal end of the outer needle hub 74. The threaded portion 78 is threadedly engaged with a locking portion (not shown) provided on the connector 130, thereby preventing the connector 130 from being unintentionally removed from the outer needle hub 74.

[0057] The lumen 76 of the outer needle hub 74 has a luer taper at its base end, into which a connector 130 (described later) is inserted, with the luer taper increasing in diameter toward the base end. The connector 130, which has a luer taper on its outer peripheral surface, is fitted into the lumen 76, resulting in close contact between the outer needle hub 74 and the connector 130, thereby positioning them relative to each other and preventing fluid leakage. The lumen 76 of the outer needle hub 74, located distally of the base end where the luer taper is set, serves as a protector housing 80. The protector housing 80 houses the first and second needle tip protection sections 44, 58 of the protector 30, and has a curved cross-sectional shape with a maximum inner diameter at the midpoint in the axial direction in the longitudinal cross section shown in Figure 2. The lumen 76 of the outer needle hub 74, located distally of the protector housing 80, serves as a valve housing 82 that extends axially with a substantially constant inner diameter. Furthermore, the portion of the inner cavity 76 of the outer needle hub 74 distal to the valve accommodating portion 82 is a straight portion 84 that serves as a deformable portion that extends linearly in the axial direction with a substantially constant inner diameter. The straight portion 84 has a smaller diameter than the valve accommodating portion 82, and an annular step 86 is formed at the connection (boundary) between the valve accommodating portion 82 and the straight portion 84 on the inner circumferential surface of the outer needle hub 74.

[0058] The inner cavity 76 of the outer needle hub 74 has a crimped portion 88 distal to the straight portion 84, which forms a crimped portion 88 with a diameter that decreases toward the distal end. The crimped portion 88 has a reduced diameter portion 90, whose proximal portion rapidly decreases in diameter from the distal portion. The proximal portion of the outer needle 72 is inserted into the crimped portion 88 in the inner cavity 76 of the outer needle hub 74, and the outer needle 72 and the outer needle hub 74 are connected by a crimped pin 92 that is fitted into the crimped portion 88 and the proximal portion of the outer needle 72. The crimped pin 92 has a generally funnel-shaped overall shape and is made of a metal such as stainless steel. The proximal portion of the crimped pin 92 is fitted into the reduced diameter portion 90, and the smaller-diameter distal portion protrudes distally beyond the reduced diameter portion 90 and is fitted into the distal portion of the crimped portion 88. The straight portion 84 is provided in the outer needle unit 14 equipped with a valve body 94 described below in a region extending from the tip side of the valve body 94 to the crimping pin 92 .

[0059] A valve element 94 is housed in the lumen 76 of the outer needle hub 74. The valve element 94 is an elastic body made of rubber, resin elastomer, or the like. As shown in FIGS. 6 and 7 , the valve element 94 integrally comprises a substantially disc-shaped valve body 96 and a cylindrical support tube 98 that protrudes from the outer peripheral end of the valve body 96 toward the base end. A slit 100 is formed in the central portion of the valve body 96, penetrating the valve body 96 in the axial direction. The slit 100 extends radially from the radial center of the valve body 96 toward the outer periphery, and in this embodiment, extends in three mutually different radial directions. The valve element 94 opens and closes the slit 100 by elastic deformation, thereby switching between a communication state and a blockage state between the distal end side and the proximal end side of the valve body 96. The slit 100 may be linear, or may be radially extending in four or more mutually different radial directions.

[0060] The valve main body 96 is formed with a locking groove 102 that opens to the base end face. The locking groove 102 is an annular recessed groove that extends circumferentially along the inner circumference of the support tube portion 98 on the outer periphery of the valve main body 96. The valve main body 96 is thin-walled in the axial direction at the portion where the locking groove 102 is formed. The valve main body 96 has a thick-walled convex portion 103 that is thicker than the portion where the locking groove 102 is formed and protrudes toward the base end, on the inner periphery side of the locking groove 102. Furthermore, the locking groove 102 has an outer peripheral recessed portion 104 that is inner than a tip claw portion 106 of a plunger guide 105 (described later). The outer peripheral recessed portion 104 constitutes part of the locking groove 102 and is provided in an annular shape around the thick-walled convex portion 103. The thick-walled convex portion 103 and the outer peripheral recessed portion 104 may not be provided on the valve main body 96, and the base end surface of the valve main body 96 may be flat.

[0061] The valve body 94 is inserted into the valve housing portion 82 of the outer needle hub 74 from the base end side. The outer peripheral surface of the valve main body 96 is pressed against the inner peripheral surface of the outer needle hub 74 in the valve housing portion 82, and the valve main body 96 is fitted onto the outer needle hub 74 in a state where it is compressed inward. Furthermore, the outer peripheral end of the distal surface of the valve main body 96 is superimposed on a step 86 on the inner peripheral surface of the outer needle hub 74, and the valve body 94 is positioned in the axial direction relative to the outer needle hub 74. The outer diameter of the valve main body 96 is larger than the inner diameter of the outer needle hub 74 where the valve main body 96 is located, and it is assembled to the outer needle hub 74 in a radially compressed state, and is configured to easily generate a return force on the plunger guide 105 when the plunger guide 105 moves towards the distal end side.

[0062] The axial length L4 (see FIG. 2) of the straight portion 84 is preferably longer than the effective radius r (see FIG. 7) of the valve body 94, and more preferably is 1.5 times or more the effective radius r of the valve body 94. The axial length L4 of the straight portion 84 is preferably 2.5 times or less the effective radius r of the valve body 94, and more preferably is 2 times or less the effective radius r of the valve body 94, thereby preventing the outer needle hub 74 from becoming excessively long. The effective radius r of the valve body 94 refers to the radius of a portion of the distal end surface of the valve body 94 that is allowed to freely deform when the plunger 118, described below, is pushed into the slit 100. In this embodiment, the effective radius r of the valve body 94 is the radius of a portion of the valve body 94 that is located more inward than the step 86 of the outer needle hub 74, as shown in FIG. 7. Therefore, in this embodiment, the effective radius r of the valve body 94 is set to the same size as the radius of the straight portion 84 in the inner cavity 76 of the outer needle hub 74 .

[0063] The valve body 94 is positioned on the outer needle hub 74 by a plunger guide 105. The plunger guide 105 positions and holds the valve body 94 relative to the outer needle hub 74, and also guides the axial movement of a plunger 118, which will be described later. As shown in Figures 8 and 9, the plunger guide 105 has a generally cylindrical tip portion, and a tip claw portion 106 that is thinned in the radial direction is provided so as to protrude toward the tip side.

[0064] The base end portion of the plunger guide 105 is provided with a pair of guide pieces 108, 108 that are spaced apart and opposed to each other in the vertical direction. The pair of guide pieces 108, 108 are arranged opposite each other in the vertical direction and have approximately symmetrical shapes. The upper and lower outer surfaces of the guide piece 108 have an arc-shaped cross section that corresponds to the inner circumferential surface of the outer needle hub 74, and the upper and lower inner surfaces serve as rotation-restricting surfaces 110 that have a smaller curvature than the outer surfaces. The guide piece 108 is thicker toward the center in the circumferential direction because the curvature of the upper and lower inner surfaces is smaller than that of the upper and lower outer surfaces.

[0065] Groove-shaped recesses 114, 114 that have an arc-shaped cross section and extend in the axial direction are formed at the tip ends of the pair of guide pieces 108, 108, opening onto the inner circumferential surface. The inner surface of the groove-shaped recess 114 is curved and concave, with the inner circumferential surface extending distally beyond the cylindrical guide piece 108 toward the proximal end. The groove-shaped recess 114 does not reach the proximal end of the guide piece 108, and a retaining protrusion 116 that protrudes inward in the opposing direction of the pair of guide pieces 108, 108 is provided on the proximal end side of the groove-shaped recess 114 of the guide piece 108.

[0066] The plunger guide 105 is fixed to the outer needle hub 74 by fitting the outer peripheral surface of the portion excluding the tip claw portion 106 onto the inner peripheral surface of the outer needle hub 74 .

[0067] Furthermore, the tip claw portion 106 of the plunger guide 105 is inserted into the inner periphery of the support tube portion 98 of the valve body 94, and the support tube portion 98 is radially sandwiched between the outer needle hub 74 and the plunger guide 105. Furthermore, the tip portion of the tip claw portion 106 of the plunger guide 105 is inserted into the locking groove 102 of the valve body 94 and abuts against the valve main body 96 in the axial direction at the bottom surface of the locking groove 102, and is locked in the axial direction with the bottom surface of the locking groove 102. Furthermore, the outer peripheral end of the tip surface of the valve main body 96 overlaps the step 86 of the outer needle hub 74 in the axial direction, and the base end surface of the support tube portion 98 overlaps the plunger guide 105 in the axial direction. As a result, the valve body 94 is positioned with respect to the outer needle hub 74. In this embodiment, the outer diameter of the locking groove 102 (the inner diameter of the support cylinder portion 98) is smaller than the effective diameter (the inner diameter of the step 86) on the front side of the valve body 94. The tip surface of the tip claw portion 106 of the plunger guide 105 abuts against the bottom surface of the locking groove 102 at a radially intermediate portion (a portion away from the outer peripheral end), and therefore the tip surface of the plunger guide 105 abutting against both the front and rear surfaces of the valve body 94 and the step 86 are shifted from each other in the axial direction and do not directly face each other.

[0068] A plunger 118 is housed and disposed in the lumen 76 of the outer needle hub 74, closer to the proximal end than the valve body 94. When pushed toward the distal end, the plunger 118 pushes open the slit 100 in the valve body 94, switching the valve body 94 to a communicating state. As shown in Figures 10 to 13, the plunger 118 has a tubular portion 120 that forms the distal end portion, and a leg portion 122 that forms the proximal end portion.

[0069] The tubular portion 120 is a small-diameter, generally cylindrical portion having a circular inner cavity that penetrates in the axial direction. The inner diameter of the tubular portion 120 is generally constant in the axial direction. The tip of the tubular portion 120 is a tapered portion 124 whose outer diameter decreases toward the tip.

[0070] On the proximal side of the tapered portion 124 of the cylindrical portion 120, the outer circumferential surface extends linearly without being inclined relative to the axial direction, and flat portions 126 that extend approximately perpendicular to the up-down direction are provided on both the upper and lower sides of the outer circumferential surface. The outer shape of the cylindrical portion 120 is approximately circular on the distal side of the flat portions 126, and is non-circular (flattened) in the proximal end portion where the flat portions 126 are formed, with the up-down dimension being smaller than the left-right dimension.

[0071] Since the flat surface 126 is provided from the base end of the cylindrical portion 120 to partway in the axial direction toward the tip, a restriction step 127 is formed on the tip side of the flat surface 126 on the outer circumferential surface of the cylindrical portion 120. A pair of restriction steps 127 are formed on both the top and bottom sides due to the difference in outer diameter between the portion where the flat surface 126 is formed and the tip side of the flat surface 126, and they extend in a direction intersecting the axial direction. In this embodiment, the restriction step 127 is a flat surface that extends in a direction approximately perpendicular to the axis.

[0072] The overall length L0 of the plunger 118 (see FIG. 13 ) is desirably at least three times, preferably at least four times, and more preferably at least five times the axial length L2 of the tapered portion 124 of the cylindrical portion 120 of the plunger 118. The overall length L0 of the plunger 118 is preferably no more than ten times, more preferably no more than seven times the axial length L2 of the tapered portion 124 of the cylindrical portion 120 of the plunger 118. This ensures that the proportion of the axial length of the tapered portion 124 in the plunger 118 is sufficiently large, and the axial length of the tapered portion 124 can be secured while preventing the plunger 118 from becoming excessively long.

[0073] The axial length L2 of the tapered portion 124 of the plunger 118 is preferably equal to or greater than ¼, and more preferably equal to or greater than ⅓, of the axial length L1 of the cylindrical portion 120. Furthermore, the axial length L2 of the tapered portion 124 is preferably equal to or less than ¾ of the axial length L1 of the cylindrical portion 120, so that the proportion of the axial length of the tapered portion 124 in the cylindrical portion 120 is sufficiently large, and the axial length of the tapered portion 124 can be secured while preventing the cylindrical portion 120 from becoming excessively long.

[0074] The axial length L2 of the tapered portion 124 is preferably 2.5 mm or more, and more preferably 3.0 mm or more, and is preferably 5 mm or less, and more preferably 4 mm or less.

[0075] The axial length L2 of the tapered portion 124 is desirably at least twice, and preferably at least 2.5 times, the outer diameter R2 of the tip end of the tapered portion 124 of the plunger 118. The axial length L2 of the tapered portion 124 is desirably at most four times, and preferably at most 3.5 times, the outer diameter R2 of the tip end of the tapered portion 124 of the plunger 118. This prevents the tapered portion 124, and therefore the plunger 118, from becoming excessively long.

[0076] The leg portion 122 includes a plurality of legs 128 extending toward the base end. The leg portion 122 of this embodiment is configured to include a pair of legs 128, 128 facing each other in the left-right direction. The leg portion 128 of this embodiment is substantially rectangular plate-shaped, and its left and right outer surfaces are circumferentially arc-shaped curved surfaces that correspond to the inner peripheral surface of the outer needle hub 74. The pair of legs 128, 128 protrude outward from the tubular portion 120 to the left and right. The axial length L3 of the leg portion 128 is longer than the axial length L1 of the tubular portion 120. In this way, the axial length L1 of the tubular portion 120 is relatively short, thereby preventing the plunger 118 and, ultimately, the outer needle hub 74 that houses the plunger 118 from becoming too long.

[0077] The plunger 118 having such a structure is housed in the lumen 76 of the outer needle hub 74, as shown in Figures 2 and 3. The plunger 118 is disposed closer to the base end than the valve main body 96 of the valve body 94, and the tip portion of the tubular portion 120 is inserted into the plunger guide 105. The pair of guide pieces 108, 108 of the plunger guide 105 extend further to the base end than the tapered portion 124 of the plunger 118, and the removal prevention protrusions 116, 116 provided on the base ends of the guide pieces 108, 108 are positioned on the flat portions 126, 126 of the plunger 118. The removal prevention protrusions 116, 116 of the plunger guide 105 overlap with a pair of upper and lower restriction steps 127, 127 of the plunger 118 when projected in the axial direction. The engagement of the retaining projections 116 with the restricting steps 127 forms a displacement restricting structure that restricts the amount of displacement of the plunger 118 toward the base end. The restricting steps 127 are provided on the cylindrical portion 120 of the plunger 118 and are spaced apart toward the tip end of the leg portion 122 of the plunger 118 that houses the protector 30. This prevents, for example, the retaining projections 116 of the plunger guide 105 that are engaged with the restricting steps 127 from interfering with the protector 30. When the plunger 118 is positioned in the axial direction by the retaining projections 116, the tip is in close proximity to or in contact with the thick-walled convex portion 103 of the valve body 94.

[0078] Furthermore, because the restricting steps 127, 127 are provided on the tubular portion 120 of the plunger 118 and engage with the retaining projections 116, 116 of the plunger guide 105, there is no need to provide the surface on the outer needle hub 74 side that engages with the restricting steps 127, 127 in the axial direction directly on the inner surface of the outer needle hub 74. Therefore, there is no need to provide an undercut shape on the inner surface of the outer needle hub 74 or to construct the outer needle hub 74 from multiple parts, and the good moldability and shape stability of the outer needle hub 74 are achieved with a small number of parts, enabling stable mass production of products.

[0079] The plunger 118 is entirely located and housed within the lumen 76 of the outer needle hub 74, with its base end located more distal than the base end of the outer needle hub 74. The length L2 (see FIG. 13 ) of the tapered portion 124 of the plunger 118 is desirably longer than the axial distance d (see FIG. 3 ) from the base end of the outer needle hub 74 to the base end of the plunger 118 (base ends of the legs 128), and is more preferably 1.4 times or more the axial distance d. Furthermore, the length L2 of the tapered portion 124 is desirably no more than 2.5 times the axial distance d, and more preferably no more than twice the axial distance d, thereby preventing the tapered portion 124 from becoming excessively long. In this embodiment, since the tip surface of the plunger 118 is attached in a state in which it is in contact with the rear surface of the valve body 94, the sum of the axial length L0 of the plunger 118 and the axial distance d from the base end of the plunger 118 to the opening of the outer needle hub 74 is the effective axial depth on the rear surface side of the valve body from the rear surface of the valve body 94 to the opening end in the outer needle hub 74.

[0080] The axial length L2 (see FIG. 13) of the tapered portion 124 is preferably greater than the effective radius r (see FIG. 7) of the valve body 94 attached to the outer needle hub 74, and more preferably is at least twice the effective radius r of the valve body 94. Furthermore, the axial length L2 of the tapered portion 124 is preferably no more than four times the effective radius r of the valve body 94, and more preferably no more than three times the effective radius r of the valve body 94, thereby preventing the tapered portion 124, which abuts against the deformed valve body 94, from becoming excessively long.

[0081] The distal end outer diameter R2 (see FIG. 13) of the tapered portion 124 is preferably smaller than twice the effective radius r (see FIG. 7) of the valve body 94, and more preferably equal to or less than the effective radius r of the valve body 94. Furthermore, the distal end outer diameter R2 of the tapered portion 124 is preferably at least ⅓ times the effective radius r of the valve body 94, and more preferably at least ½ times the effective radius r of the valve body 94. As a result, the distal end of the tapered portion 124, which is pressed into the deformable region of the valve main body 96 of the valve body 94, has a sufficiently large diameter, thereby effectively realizing the opening operation of the valve body 94 and ensuring a sufficient opening area when the valve body 94 is in a communicating state. Furthermore, the inner diameter of the straight portion 84 of the outer needle hub 74 is larger than the proximal end outer diameter, which is the maximum outer diameter of the tapered portion 124.

[0082] The width dimension W of the outer peripheral cutout 104 in the locking groove 102 of the valve body 94 is preferably smaller than the outer diameter R2 of the tip end of the plunger 118, and more preferably is not more than two-thirds of the outer diameter R2 of the tip end of the plunger 118. Furthermore, the width dimension W of the outer peripheral cutout 104 is preferably not less than one-quarter of the outer diameter R2 of the tip end of the plunger 118, and more preferably not less than one-third of the outer diameter R2 of the tip end of the plunger 118, so that the thin-walled portion of the valve body 94 formed by the outer peripheral cutout 104 can be provided with a sufficient width.

[0083] The outer needle unit 14, which includes the outer needle hub 74 housing a valve mechanism consisting of the valve body 94, plunger guide 105, and plunger 118, is combined with the inner needle unit 12 to form the valved indwelling needle assembly 10. That is, the inner needle 16 is inserted into the lumen 76 of the outer needle 72 and the outer needle hub 74 from the proximal end side and the connecting part 26 of the inner needle hub 18 is fitted into the proximal opening of the outer needle hub 74, whereby the inner needle unit 12 and the outer needle unit 14 are combined with each other to form the valved indwelling needle assembly 10.

[0084] In the valved indwelling needle assembly 10, the inner needle 16 passes through a slit 100 in the valve body 94. The inner needle 16 is also inserted into a cylindrical portion 120 of a plunger 118. The distal end portion of the inner needle 16 protrudes further distally than the outer needle 72, and the needle tip 20 is exposed and not covered by the outer needle 72.

[0085] The protector 30 attached to the inner needle 16 is housed in the lumen 76 of the outer needle hub 74 on the proximal side of the plunger 118. The protector 30 is disposed between a pair of legs 128, 128 of the plunger 118, and the first and second side plate portions 34, 36 and the first and second needle tip protection portions 44, 58 are exposed on both the top and bottom sides between the pair of legs 128, 128. The pair of legs 128, 128 of the plunger 118 extend toward the proximal side on both the left and right sides of the protector 30, with the proximal ends reaching near the bottom 32 of the protector 30. In this way, the protector 30 is disposed between the opposing pair of legs 128, 128 of the plunger 118, and the pair of legs 128, 128 are positioned on the left and right outer sides of the protector 30, so that the plunger 118 can be extended to the vicinity of the proximal opening of the outer needle hub 74 while ensuring installation space for the protector 30. In the plunger 118 of this embodiment, the axial length L3 of the leg-like portion 122 consisting of the pair of legs 128, 128 is longer than the axial length L1 of the tubular portion 120. This ensures sufficient installation space for the protector 30.

[0086] The first and second needle tip protection parts 44, 58 of the protector 30 are disposed in a protector housing portion 80 in the inner cavity 76 of the outer needle hub 74. The protector housing portion 80 has a concave cross section and a large inner diameter, and therefore can house the first and second needle tip protection parts 44, 58 that protrude vertically and outward beyond the first and second side plate parts 34, 36. The first and second needle tip protection parts 44, 58 of the protector 30 are spaced apart toward the base end in the axial direction from the tubular part 120 of the protector 30.

[0087] A circumferential portion of the connecting portion 26 of the inner needle hub 18 protrudes more toward the tip side and is inserted below the second side plate portion 36 of the protector 30. This limits relative rotation of the protector 30 with respect to the inner needle hub 18, and the protector 30 is held in an appropriate orientation around the needle axis. The inner needle hub 18 and the outer needle hub 74 are positioned relative to each other in the circumferential direction, for example, by using a threaded portion 78. Therefore, relative rotation of the protector 30 with respect to the outer needle hub 74 via the inner needle hub 18 is also limited, and the protector 30 is housed in the lumen 76 of the outer needle hub 74 in an appropriate orientation.

[0088] In such a valved indwelling needle assembly 10, for example, the inner needle 16 and the outer needle 72 are inserted into a patient's blood vessel. When the blood vessel is punctured, blood flows into the lumen of the inner needle hub 18 through the lumen of the inner needle 16. Therefore, by making the inner needle hub 18 transparent or semi-transparent, for example, so that the interior of the inner needle hub 18 can be seen, it is possible to confirm that the inner needle 16 has properly punctured the blood vessel by visually observing the blood flowing into the inner needle hub 18. The blood that has flowed into the lumen of the inner needle hub 18 is prevented from leaking to the outside through the opening on the proximal end by a filter in a filter cap 28 attached to the inner needle hub 18.

[0089] After the inner needle 16 and the outer needle 72 have punctured the blood vessel, the inner needle unit 12 is pulled toward the base end while the outer needle unit 14 is held in the puncture position, whereby the inner needle 16 is withdrawn from the outer needle 72 toward the base end.

[0090] When the inner needle 16 is withdrawn from the outer needle 72 toward the proximal end, the protector 30 housed in the protector housing 80 of the outer needle hub 74 is restricted from moving toward the proximal end as the first and second needle tip protecting parts 44, 58 catch on the inner surface of the protector housing 80. As a result, as the inner needle 16 is withdrawn, the protector 30 moves toward the needle tip 20 while making sliding contact with the outer peripheral surface of the inner needle 16. Then, when the needle tip 20 of the inner needle 16 moves further proximally than the first and second needle tip protecting parts 44, 58, the first and second needle tip protecting parts 44, 58 are permitted to approach each other, and the first and second needle tip protecting parts 44, 58 approach each other due to the elasticity of the first and second side plate parts 34, 36, etc. As a result, the distal end side of the needle tip 20 of the inner needle 16 is covered by the first and second needle tip protecting parts 44, 58, and the needle tip 20 is protected by the first and second needle tip protecting parts 44, 58. In this needle tip protected state, the needle tip 20 is prevented from being re-exposed at the distal end side. Note that in the needle tip protected state, the engagement between the first and second needle tip protecting parts 44, 58 and the protector housing part 80 of the inner needle hub 18 is released, and axial movement of the protector 30 relative to the outer needle hub 74 is permitted.

[0091] By further withdrawing the inner needle 16 from the needle tip protected state, the locking portion 24 of the inner needle 16 locks with the bottom portion 32 of the protector 30. Then, by further withdrawing the inner needle 16 while the locking portion 24 and the bottom portion 32 are locked together, the protector 30 moves toward the base end relative to the outer needle hub 74 together with the inner needle 16, and is withdrawn toward the base end from the outer needle hub 74. As a result, the inner needle unit 12, with the needle tip 20 of the inner needle 16 protected by the protector 30, separates from the outer needle unit 14, and the outer needle unit 14 is left indwelling in a state of being inserted into the blood vessel. In this way, in this embodiment, the outer needle unit 14 is an indwelling needle with a valve.

[0092] When the inner needle 16 of the placed outer needle unit 14 is withdrawn, the slit 100 of the valve body 94 is blocked, and the lumen 76 of the outer needle hub 74 is blocked by the valve body 94. This makes it possible to avoid the problem of blood in the blood vessel leaking to the outside through the lumen 76 of the outer needle hub 74.

[0093] As shown in Fig. 14 , a connector 130 is connected to the placed outer needle unit 14. The connector 130 is, for example, a connector for connecting a syringe tip or an infusion line, and is equipped with a male luer 132 that is fitted into the proximal opening of the outer needle hub 74. The male luer 132 is fitted into the proximal portion of the outer needle hub 74, thereby connecting the connector 130 to the outer needle unit 14. The outer peripheral surfaces of the male luers 132, each having a luer taper, and the inner peripheral surface of the outer needle hub 74 are fitted together in a tight contact state, thereby positioning the male luer 132 in the axial direction relative to the outer needle hub 74. The connector 130 may be provided with a locking portion (not shown) that is threaded onto the threaded portion 78 of the outer needle hub 74 and maintains the connection between the connector 130 and the outer needle hub 74. Note that Figure 14 shows a state in which a thin male luer 132 made of a soft material is used and is pushed in firmly using the torque generated by tightening a locking section (not shown), and the axial length of the portion of the male luer 132 inserted into the outer needle hub 74 is 6.5 mm.

[0094] Typically, the male luer 132 and the outer needle hub 74 are connected using the torque of the locking part. When the torque of the locking part is used to connect the male luer 132 and the outer needle hub 74, the user tends to tighten the locking part too much, which can cause the plunger 118 to be pushed too far toward the tip of the valve body 94. However, when a male luer made of a thick, hard material is used, the plunger moves little even when the torque of the locking part is used, and in conventional plungers that are returned to their initial position by the reaction force of the valve body 94, it has been confirmed that removing the male luer does not provide sufficient reaction force to return the plunger. In the outer needle unit 14 of this embodiment, the axial length of the tapered portion 124 of the plunger 118 is greater than the effective radius r of the valve body 94, and the total axial length of the plunger 118 is at least three times the axial length of the tapered portion 124, making the total axial length of the plunger 118 sufficiently long. As a result, when the male luer 132 described below is inserted into the outer needle hub 74, even if the male luer 132 is inserted shallowly, the plunger 118, which has extended to a position close to the base end opening of the outer needle hub 74, moves sufficiently toward the tip side, making it easier to ensure a large abutment reaction force (elastic force) of the valve body 94 acting on the tapered portion 124 of the plunger 118, and it has been confirmed that the stability of the blocking function of the valve body 94 is improved.

[0095] Incidentally, indwelling needles for infusions are required to be small because they are placed in various locations. Conventional plungers, which are returned to their initial position by the reaction force of the valve body 94, have a large outer diameter at the tip of the tapered portion and a short axial length of the tapered portion relative to the size of the valve body 94. As a result, the range of connector compatibility for the plunger's returnability and the blocking functionality of the valve body 94 is narrow. It has been found that, due to manufacturing errors, variations in hardness, and differences in the amount of depression by users, it is difficult to consistently obtain a return force (reaction force of the valve body 94) that pushes the plunger, which has been pushed by the male luer 132 inserted into the outer needle hub 74, back toward the base end. For example, when the plunger is pushed too far, the valve body 94 may exceed the tapered portion of the plunger and ride up, preventing the plunger from returning to the base end even after the male luer 132 is removed from the outer needle hub 74. On the other hand, in the outer needle unit 14 of this embodiment, the axial length of the tapered portion 124 of the plunger 118 is more than twice the outer diameter of the tip, while the outer diameter of the tip of the tapered portion 124 is equal to or less than the effective radius of the valve body 94, and the tip of the tapered portion 124 is set to be thinner than the valve body 94, so that it is possible to ensure a large inclination angle of the tapered portion 124 while increasing the axial length of the tapered portion 124. Therefore, a wider range of variation in the amount of depression of the plunger 118 by the male luer 132 is tolerated, and the return force acting on the tapered portion 124 of the plunger 118 is stabilized, which is expected to stabilize the shutoff function of the valve body 94. Furthermore, the axial length of the tapered portion 124 of the plunger 118 is set to be at least twice the effective radius of the valve body 94, and the axial length L2 of the tapered portion 124 of the plunger 118 is set to be longer than the effective radius r of the valve body 94, thereby preventing the outer needle hub 74 from becoming larger, making it suitable for use in infusion.

[0096] When the outer needle unit 14 and the connector 130 are connected, the tip of the connector 130 abuts against the pair of legs 128, 128 of the plunger 118 from the base end side, and the plunger 118 is pushed toward the tip side by the connector 130. As shown in Fig. 14 , the plunger 118 moves toward the tip side, and the tapered portion 124 of the plunger 118 pushes open the slit 100 of the valve body 94 and is inserted into the slit 100. This releases the blockage of the lumen 76 of the outer needle hub 74 by the valve body 94, and the blood vessel and the connector 130 are connected to each other via the lumen of the outer needle unit 14. Then, using the outer needle unit 14 to which the connector 130 is connected, it is possible to administer medication or infusion to a blood vessel, or to draw blood from a blood vessel, for example. The outer periphery on the tip side of the valve body 94 abuts against a step 86 in the outer needle hub 74, and the tapered portion 124 of the plunger 118 is located radially inward of the step 86. From the viewpoint of stabilizing the return properties of the plunger 118, when the axial length of the male luer 132 in the outer needle hub 74 (i.e., the insertion length of the male luer 132) is 6.5 mm, it is preferable that the tapered portion 124 be located radially inward of the step 86. Also when the axial length of the male luer 132 in the outer needle hub 74 is 4.5 mm, it is preferable that the tapered portion 124 be located radially inward of the step 86.

[0097] When the valve body 94 is in a communicating state, the cylindrical portion 120 of the plunger 118 passes through the slit 100 of the valve body 94, and as shown in Figure 15, when viewed in the axial direction from the tip side, the tip opening of the plunger 118 is open without being covered by the valve body 94.

[0098] In the present embodiment, the axial distance d from the base end of the outer needle hub 74 to the base end of the plunger 118 is shorter than the axial length L2 of the tapered portion 124 of the plunger 118, and the base end of the plunger 118 is brought sufficiently close to the base end opening of the outer needle hub 74. Therefore, by inserting the male luer 132 of the connector 130 into the base end opening portion of the outer needle hub 74, the plunger 118 is pushed sufficiently toward the tip side, and the valve body 94 is stably switched to the communicating state by the plunger 118.

[0099] The amount of distal movement D of the plunger 118 due to connection of the connector 130 to the outer needle hub 74 is desirably equal to or less than the axial length L2 of the tapered portion 124 of the plunger 118. Furthermore, the amount of distal movement D of the plunger 118 is preferably equal to or greater than 50%, and more preferably equal to or greater than 80%, of the axial length L2 of the tapered portion 124. By setting the amount of distal movement D of the plunger 118 in this manner, the tapered portion 124 of the plunger 118 is stably inserted into the slit 100 of the valve body 94 upon connection of the connector 130, thereby stabilizing the communication operation of the valve body 94.

[0100] In the present embodiment, the plunger 118 is in an attached state in which its tip surface is in contact with the rear surface of the valve body 94, and therefore, when connecting the connector 130 to the outer needle hub 74, the difference between the insertion length of the connector 130 into the outer needle hub 74 and the axial distance d from the base end of the plunger 118 to the opening of the outer needle hub 74 is the length by which the plunger 118 is pushed forward in the axial direction by the connector 130, and therefore the forward movement amount D of the plunger 118. Therefore, in the present embodiment, by connecting the connector 130 to the outer needle hub 74, the tubular portion 120 on the tip side of the plunger 118 is inserted into the valve body 94 by this movement amount D, and the slit 100 is pushed open.

[0101] The plunger 118 has a leg portion 122 consisting of a pair of legs 128, 128, whose axial length L3 is longer than the axial length L1 of the tubular portion 120. By providing such long leg portions 122, a guiding effect can be advantageously obtained as the left and right outer surfaces of the leg portions 122 are guided by the inner circumferential surface of the outer needle hub 74, thereby stabilizing the axial movement of the plunger 118. Moreover, the total axial length L0 of the plunger 118 is set to be three or more times the axial length L2 of the tapered portion 124, which also stabilizes the movement of the plunger 118 due to the guiding effect.

[0102] The tip of the plunger 118 abuts against the base end surface of the thick-walled convex portion 103 of the valve body 94, pushing the thick-walled convex portion 103 toward the tip side and deforming the valve body 94 as it is inserted into the slit 100. The locking groove 102, which is provided on the valve body 94 outer circumferential side than the thick-walled convex portion 103, extends further inward than the tip claw portion 106 of the plunger guide 105, and the portion inner circumferentially than the tip claw portion 106 forms an outer circumferential cutout portion 104. The portion of the valve body 94 where the outer circumferential cutout portion 104 is formed is not restrained by the plunger guide 105. This makes it easier for the valve body 94 to deform in the thin-walled portion where the outer circumferential cutout portion 104 is formed, allowing the valve body 94 to smoothly switch to the communicating state.

[0103] In this embodiment, the width W of the outer peripheral cutout 104 is set to be ⅔ or less the outer diameter R2 of the tip end of the tapered portion 124 of the plunger 118. As a result, deformation of the valve body 94 caused by the plunger 118 being pressed in is stably tolerated by the thin-walled portion where the outer peripheral cutout 104 is formed, and the thin-walled portion of the valve body 94 is prevented from becoming excessively large, ensuring a shape restoration force based on the elasticity of the valve body 94.

[0104] When the plunger 118 is pressed into the valve body 94, it moves toward the tip side until its tip enters the inner periphery of the crimping pin 92. The tip of the plunger 118 is inserted into the attachment portion of the crimping pin 92 that is attached to the reduced diameter portion 90 of the inner cavity 76 of the outer needle hub 74, and does not reach the tip portion of the crimping pin 92, which has a reduced diameter.

[0105] When the valve body 94 is in this communicating state, the valve body portion 96 of the valve body 94, which has been deformed by widening the slit 100, is pressed against the outer peripheral surface of the tapered portion 124 of the plunger 118. A force based on the elasticity of the valve body 94 is exerted on the outer peripheral surface of the tapered portion 124 on which the deformed valve body 94 is superimposed. Because the tapered portion 124 has a tapered shape, the force acting on the outer peripheral surface of the tapered portion 124 urges the plunger 118 radially inward and toward the base end. However, when the connector 130 is connected to the outer needle hub 74, the positioning force acting between the outer needle hub 74 and the connector 130 is greater than the force pushing the plunger 118 toward the base end, and the plunger 118 is held in a position where it passes through the slit 100 of the valve body 94.

[0106] A straight portion 84 is provided in the inner cavity 76 of the outer needle hub 74 between the valve body 94 and the crimping pin 92, and the axial length L4 of the straight portion 84 is made larger than the effective radius r of the valve body 94. Therefore, the valve body 94, which is deformed toward the tip side by the plunger 118 being pushed in, is unlikely to enter the inner periphery of the crimping pin 92 fitted into the reduced diameter portion 90, and the opening operation of the valve body 94 is smoothly achieved. It is also possible to prevent the movement of the plunger 118 from being obstructed by the valve body 94 sandwiched between the plunger 118 and the crimping pin 92.

[0107] However, if the connector 130 is detached from the outer needle unit 14 and the valve body 94 remains in a communicating state, blood will leak to the outside. Therefore, the outer needle unit 14 is configured so that the valve body 94 switches from a communicating state to a blocked state when the connector 130 is detached.

[0108] That is, when the connector 130 is detached from the outer needle unit 14, the force of the connector 130 pushing the plunger 118 toward the distal end is released. When the valve body 94 is in the communicating state, the deformed valve body 94 is pressed against the outer peripheral surface of the tapered portion 124 of the plunger 118, and the axial component of the elastic force of the valve body 94 acts on the plunger 118 as a returning force toward the proximal end. Therefore, as the valve body 94 restores its shape to the blocked state, the plunger 118 is pushed back toward the proximal end, returning the plunger 118 to the position it was in before being pushed by the connector 130, and the slit 100 in the valve body 94 closes, blocking the lumen 76 of the outer needle hub 74. In this way, in the outer needle unit 14, the plunger 118 is pushed back toward the proximal end by utilizing the elastic force of the valve body 94, without requiring a separate biasing means. This makes it possible to reduce the number of parts in the outer needle unit 14 incorporating a valve mechanism.

[0109] FIG. 16 shows a graph of the measurement results of the push-back resistance (return force) due to the elasticity of the valve body 94 relative to the push-back stroke of the plunger 118 toward the distal end. In this graph, if the plunger 118 is located in a stroke region where the push-back resistance increases or remains constant with increasing push-back stroke, the elasticity of the valve body 94 effectively pushes the plunger 118 back toward the proximal end when the connector 130 is disconnected. The open communication position of the plunger 118 in the graph of FIG. 16 refers to the position where the plunger 118 penetrates the valve body 94 and the entire lumen of the plunger 118 is completely open, visible without being covered by the valve body 94 when viewed axially from the distal end. The reaction force reduction start position of the plunger 118 in the graph of FIG. 16 refers to the position where the reaction force (pushing back resistance) acting on the plunger 118 toward the proximal end due to the elasticity of the valve body 94 begins to decrease without subsequently increasing with increasing push-back stroke.

[0110] 16 shows that, in the outer needle unit 14 of this embodiment, the plunger 118 reaches the opening communication position when the pushing stroke of the plunger 118 reaches 1.8 mm, and reaches the reaction force reduction start position when the pushing stroke of the plunger 118 reaches 5.1 mm. In other words, in at least the pushing region up to when the pushing stroke of the plunger 118 reaches 5.1 mm, the pushing resistance acting on the plunger 118 is maintained greater than the reaction force acting on the plunger 118 at the opening communication position. In other words, in the outer needle unit 14 of this embodiment, in the pushing region of the plunger 118 where the plunger 118 reaches a further 3.3 mm from the opening communication position, the pushing resistance of the plunger 118 against the valve body 94 is maintained greater than the pushing resistance at the opening communication position.

[0111] Therefore, if the pushing stroke of plunger 118 is 1.8 mm or more, it is possible to stably switch valve element 94 to the communicating state by pushing plunger 118. Furthermore, if the pushing stroke of plunger 118 is 5.1 mm or less, the elasticity of valve element 94 stably causes plunger 118 to return toward the base end when connector 130 is disconnected, and valve element 94 is switched to the blocking state.

[0112] The plunger 118 used in the measurements that obtained the results in Figure 16 had a length L2 of the tapered portion 124 of 3.4 mm, a minimum outer diameter (tip outer diameter) R2 of the tapered portion 124 of 1.0 mm, and a maximum outer diameter (base outer diameter) of the tapered portion 124 of 2.45 mm.

[0113] 16 , the outer needle unit 14 has a tapered portion 124 with an axial length of 3 mm or more, and in the relationship between the pushing resistance of the plunger 118 against the valve body 94 and the position of the plunger 118, the pushing resistance of the plunger 118 against the valve body 94 is maintained greater than the value at the opening communicating position in a pushing region of the plunger 118 that extends a further 3 mm from the opening communicating position where the opening of the valve body 94 reaches the inner bore diameter of the plunger 118 due to the plunger 118 being pushed into the valve body 94. By providing a pushing region where the plunger 118 that has reached the opening communicating position can move further toward the tip, and by setting the taper length so that the returning force due to the elasticity of the valve body 94 acts sufficiently on the tapered portion 124 even in the pushing region, the plunger 118 of this embodiment has a wider range of compatibility with the insertion length of the male luer 132 than conventional plungers that cause a returning action. Therefore, even if the insertion length of the male luer 132 varies due to manufacturing errors, variations in hardness, differences in the pushing force by the user, etc., it is possible to obtain a stable return force toward the base end of the plunger 118 that has been pushed into the valve body. Furthermore, even if the shapes and dimensions of the plunger 118 and other components are changed as appropriate from the shapes and dimensions shown in the figures, it is possible to achieve an outer needle unit 14 with stable return operation.

[0114] Conventionally known male luers vary somewhat in size and hardness. A thin male luer has a longer insertion length into the outer needle hub 74 than a thick male luer. Furthermore, a male luer made of a soft material deforms while being inserted into the outer needle hub 74, and therefore has a longer insertion length into the outer needle hub 74 than a male luer made of a hard material. Therefore, when a thick, hard male luer and a thin, soft male luer were prepared and inserted into the outer needle unit 14 of this embodiment, in the case of the thick, hard male luer, the insertion length of the male luer into the outer needle hub 74 was 4.5 mm, the pushing stroke of the plunger 118 was 2.5 mm, and the pushing resistance force of the plunger 118 against the slit 100 of the valve body 94 was 3 N or more. Furthermore, in the case of a thin and soft male luer, the insertion length of the male luer into the outer needle hub 74 was 6.5 mm, the pushing stroke of the plunger 118 was 4.5 mm, and the pushing resistance force of the plunger 118 into the slit 100 of the valve body 94 was 3 N or more. In either case, it was confirmed that when the male luer was removed, the plunger 118 stably returned to the base end, and the valve body 94 switched to the shut-off state.

[0115] Therefore, it was found that the pushing resistance force of the plunger 118 against the slit 100 of the valve body 94 is preferably 3 N or greater when the insertion length of the male luer into the outer needle hub 74 is 4.5 mm and when the insertion length of the male luer into the outer needle hub 74 is 6.5 mm. Note that, because stable returning operation of the plunger 118 toward the base end side was confirmed even when the pushing resistance force of the plunger 118 against the slit 100 of the valve body 94 was 2.5 N, it is preferable that the pushing resistance force be 2.5 N or greater when the insertion length of the male luer into the outer needle hub 74 is 4.5 mm and when the insertion length of the male luer into the outer needle hub 74 is 6.5 mm.

[0116] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the specific descriptions. For example, it is desirable that the protector 30 has a structure in which the needle tip protection portions 44, 58 are provided on the tip sides of a pair of side plate portions 34, 36 arranged opposite each other from the viewpoint of efficient use of installation space, but the specific structure is not limited thereto.

[0117] In the valved indwelling needle assembly according to the fourth and eighth aspects, the plunger is not necessarily limited to a structure having a leg-like portion, and may be, for example, entirely cylindrical.

[0118] REFERENCE SIGNS LIST 10 Valve-equipped indwelling needle assembly (first embodiment) 12 Inner needle unit 14 Outer needle unit 16 Inner needle 18 Inner needle hub 20 Needle tip 22 Blade surface 24 Locking portion 26 Connecting portion 28 Filter cap 30 Protector 32 Bottom portion 34 First side plate portion 36 Second side plate portion 38 Needle insertion hole 40 Needle guide surface 42 Reinforcing tube portion 44 First needle tip protection portion 46 First stepped portion 48 First needle tip cover portion 50 First needle tip restraining portion 52 First side covering piece 54 First side covering piece 56 First protruding piece 58 Second needle tip protection portion 60 Second stepped portion 62 Second needle tip cover portion 64 Second needle tip restraining portion 66 Second side covering piece 68 Second side covering piece 70 Second protruding piece 72 Outer needle 74 Outer needle hub 76 Inner cavity 78 Threaded portion 80 Protector accommodating portion 82 Valve accommodating portion 84 Straight portion (deformation-allowing portion) 86 Step 88 Crimping portion 90 Reduced diameter portion 92 Crimping pin 94 Valve body 96 Valve main body portion 98 Supporting cylindrical portion 100 Slit 102 Locking groove 103 Thick-walled convex portion 104 Outer peripheral lightening portion 105 Pusher guide 106 Tip claw portion 108 Guide piece 110 Rotation restricting surface 114 Groove-shaped recess 116 Removal prevention protrusion 118 Plunger 120 Cylindrical portion 122 Leg-shaped portion 124 Tapered portion 126 Flat portion 127 Restricting step 128 Leg portion 130 Connector 132 Male luer L0 Overall axial length of plunger L1 Axial length of cylindrical part L2 Axial length of tapered part L3 Axial length of leg-like part L4 Axial length of straight part R1 Outer diameter of tip claw part of plunger guide R2 Outer diameter of tip part of tapered part r Effective radius of valve body W Radial width dimension of outer peripheral lightening part d Axial distance from base end of outer needle hub to base end of plunger D Pushing stroke towards tip side of plunger

Claims

1. A valved indwelling needle assembly in which an inner needle having an inner needle hub is inserted into an outer needle and the outer needle hub, a valve body that opens and closes by elastic deformation, and a plunger that is arranged base end side of the valve body and brings the valve body into communication when pushed toward the tip side, and when the valve body is in communication state, receives a returning force toward the base end side due to a reaction force from the valve body, wherein a tapered portion is provided on the tip side of the plunger, the total axial length of the plunger is three times or more the axial length of the tapered portion, the entire plunger is located within the outer needle hub, and the axial length of the tapered portion is greater than the effective radius allowing free deformation at the tip surface of the valve body.

2. The valved indwelling needle assembly according to claim 1, wherein the axial length of the tapered portion is 3 mm or more, and in a plunger pushing region of the plunger extending from an opening communication position where the opening of the valve body due to the plunger being pushed into the valve body reaches the diameter of the plunger's inner bore to a further 3 mm, the resistance force against the plunger pushing into the valve body is maintained greater than the value at the opening communication position.

3. A valved indwelling needle assembly as claimed in claim 1 or 2, wherein the axial length of the tapered portion is at least twice the outer diameter of the tip of the tapered portion, and the outer diameter of the tip of the tapered portion is equal to or smaller than the effective radius allowing free deformation at the tip surface of the valve body.

4. A valved indwelling needle assembly as claimed in any one of claims 1 to 3, wherein the plunger comprises a tubular portion tapered towards the tip and a leg portion having a number of legs extending towards the base end, the tubular portion having a regulating step which regulates movement of the plunger towards the base end relative to the outer needle hub by abutting against the outer needle hub, the leg portion is provided with a protector which protects the needle tip when the inner needle is withdrawn, and the axial length of the leg portion is longer than the axial length of the tubular portion.

5. A valved indwelling needle assembly as claimed in any one of claims 1 to 4, wherein the inner cavity of the outer needle hub is provided with a deformable portion which extends linearly from the tip of the valve body towards the tip side with a substantially constant diameter and has an inner diameter larger than the maximum diameter of the tapered portion, the axial length of the deformable portion is made larger than the effective radius of the valve body, and the axial length of the tapered portion is made longer than the axial distance from the base end of the outer needle hub to the base end of the plunger which is located distal to the base end of the outer needle hub.

6. A valved indwelling needle assembly in which an inner needle having an inner needle hub is inserted into an outer needle and the outer needle hub, a valve body that opens and closes by elastic deformation, and a plunger that is arranged base end side of the valve body and puts the valve body into a communicating state when pushed toward the tip end and receives a returning force toward the base end side by a reaction force from the valve body when the valve body is in a communicating state, wherein a tapered portion is provided on the tip side of the plunger and the axial length of the tapered portion is 3 mm or more, and in a pushing region of the plunger from the opening communication position where the opening of the valve body reaches the inner bore diameter of the plunger when the plunger is pushed into the valve body to a further 3 mm, the pushing resistance force of the plunger against the valve body is maintained greater than the value at the opening communication position.

7. A valved indwelling needle assembly in which an inner needle having an inner needle hub is inserted into an outer needle and the outer needle hub, a valve body that opens and closes by elastic deformation, and a plunger that is arranged base end side of the valve body and brings the valve body into communication when pushed toward the tip side, and when the valve body is in communication state, receives a returning force toward the base end side due to a reaction force from the valve body, wherein a tapered portion is provided on the tip side of the plunger, the axial length of the tapered portion is at least twice the outer diameter of the tip of the tapered portion and is at least twice the effective radius of the valve body, and the outer diameter of the tapered portion is equal to or less than the effective radius at which free deformation is permitted at the tip surface of the valve body.

8. A valved indwelling needle assembly in which an inner needle having an inner needle hub is inserted into an outer needle and an outer needle hub, a valve body that opens and closes by elastic deformation, and a plunger that is arranged base end side of the valve body and brings the valve body into communication when pushed toward the tip side and receives a returning force toward the base end side by a reaction force from the valve body when the valve body is in communication, wherein the plunger has a tubular portion tapered toward the tip side and a leg-like portion having a plurality of legs extending toward the base end side, the tubular portion has a regulating step that regulates movement of the plunger toward the base end side relative to the outer needle hub by abutting against the outer needle hub, and a protector is arranged on the leg-like portion to protect the needle tip when the inner needle is pulled out, and the axial length of the leg-like portion is longer than the axial length of the tubular portion.

9. A valved indwelling needle assembly in which an inner needle having an inner needle hub is inserted into an outer needle and an outer needle hub, a valve body which opens and closes by elastic deformation, and a plunger which is arranged base end side of the valve body and puts the valve body into a communicating state when pushed toward the tip end and receives a returning force toward the base end side by a reaction force from the valve body when the valve body is in a communicating state, are contained and disposed in the inner cavity of the outer needle hub, wherein a tapered portion is provided on the tip end side of the plunger, and a deformation-permitting portion is provided in the inner cavity of the outer needle hub which extends linearly from the tip of the valve body toward the tip side with an approximately constant diameter and has an inner diameter larger than the maximum diameter of the tapered portion, the axial length of the deformation-permitting portion is longer than the effective radius of the valve body, and the axial length of the tapered portion is longer than the axial distance from the base end of the outer needle hub to the base end of the plunger which is located distal to the base end of the outer needle hub.

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