Indwelling needle assembly

Abstract

To create an indwelling needle assembly that can stably accommodate the inner needle. [Solution] The indwelling needle assembly comprises a housing 101, an inner needle unit 103 having an inner needle 131 and an inner needle hub 132 inserted through an outer needle 121, and a safety mechanism 105 for moving the inner needle hub 132 from the use position to the retracted position. The safety mechanism 105 has an inner needle hub engaging portion 155 that releasably holds the inner needle hub 132 in the use position against the biasing force of a spring 151. The housing 101 has a plurality of ribs 114 that protrude radially inward and extend axially, and the inner needle hub 132 has a sliding portion 140 that slides in contact with the ribs 114 from the use position to the retracted position, and the ribs 114 have a portion configured such that the frictional force generated between them and the sliding portion 140 decreases in the direction of movement from the use position to the retracted position.

Description

Technical Field

[0001] The present disclosure relates to an indwelling needle assembly, and particularly to an indwelling needle assembly having a safety mechanism for accommodating a needle.

Background Art

[0002] An indwelling needle assembly is known as a medical device for performing treatments such as infusion, blood collection, hemodialysis, etc. The indwelling needle assembly has an outer needle and an inner needle. After the inner needle inserted into the outer needle punctures the patient's blood vessel, the inner needle is withdrawn from the outer needle, and the outer needle is left in the patient's blood vessel for use in treatment.

[0003] In order to prevent injury caused by the sharp tip of the inner needle, a safety mechanism for accommodating and protecting the withdrawn inner needle is also incorporated in the indwelling needle assembly. As a safety mechanism, there is one that moves the inner needle so as to be withdrawn from the outer needle by the biasing force of a spring and accommodates it in the housing as it is (see, for example, Patent Document 1). Since the entire used inner needle is surrounded by the housing, not only accidental puncture by the sharp needle tip but also contamination by blood or the like adhering to the side surface of the inner needle can be reduced. However, if the used inner needle moves vigorously due to the biasing force of the spring, there is a risk that the blood adhering to the inner needle or remaining in the inner needle will scatter. For this reason, a configuration has been considered in which a ring-shaped friction member is provided on the inner needle hub, and the movement of the inner needle is braked by the frictional force between the friction member and the inner surface of the housing to suppress the pulling speed of the inner needle (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in conventional configurations, the frictional force is constant throughout the entire axial direction of the housing, and no adjustment of the frictional force according to position is made. In a configuration in which the inner needle is pulled into the housing by the biasing force of a spring, the biasing force of the spring gradually weakens towards the proximal end, so if the frictional force is constant throughout the entire axial direction, excessive braking is applied to the biasing force. As a result, the retraction speed of the inner needle decreases excessively, and it takes a long time for the inner needle to be fully retracted into the housing. If it takes a long time for the inner needle to be retracted, for example, if the operator tries to move on to the next action immediately after starting the operation to retract the inner needle, the tip of the inner needle may still be exposed, and there is a risk of accidental puncture. In order to avoid such a situation, it is conceivable to reduce the frictional force throughout the entire axial direction, but in that case, the effect of suppressing blood splatter will be limited.

[0006] Furthermore, as a mechanism for retracting the inner needle into the housing, when a button is pressed with a finger, the inner needle hub engagement part moves downward, releasing the engagement with the inner needle hub, and the inner needle is retracted into the housing by the biasing force of a spring. However, depending on the position of the finger when the button is pressed, the inner needle hub engagement part may tilt at an angle. For example, in a configuration where the inner needle hub engagement part is located on the tip side of the button, if the base end of the button is pressed down, the inner needle hub engagement part located on the tip side will tilt at an angle and will not be able to move smoothly downward. If the button is pressed down forcefully to try to move the tilted inner needle hub engagement part downward, the tip of the inner needle may wobble significantly.

[0007] Furthermore, to prevent blood from leaking from the base end of the outer needle hub when the inner needle is withdrawn from the outer needle, a valve unit containing a hemostatic valve and a plunger for opening the hemostatic valve may be installed inside the outer needle hub. In this case, it is desirable that the plunger does not wobble within its range of motion. If the plunger wobbles as it moves toward the tip, the tip of the plunger may not strike the hemostatic valve in the correct position, and the opening state of the hemostatic valve may vary depending on the operator.

[0008] The objective of this disclosure is to improve the overall operability of the indwelling needle assembly. Specifically, at least one of the following objectives is to realize an indwelling needle assembly that allows for rapid insertion of the inner needle while suppressing blood splatter; to enable smooth disengagement of the inner needle hub from the inner needle hub engagement portion; and to realize a valve unit that allows for stable operation. [Means for solving the problem]

[0009] A first aspect of the indwelling needle assembly of the present disclosure comprises a housing, a catheter unit disposed at the tip of the housing and having an outer needle and an outer needle hub, an inner needle unit having an inner needle and an inner needle hub inserted through the outer needle, and a safety mechanism for moving the inner needle hub from a use position where the inner needle protrudes from the tip of the outer needle and is ready for puncture to a retracted position where the inner needle is housed within the housing, the safety mechanism comprising a spring that biases the inner needle hub toward the proximal end, an inner needle hub engaging portion that releasably holds the inner needle hub in the use position against the biasing force of the spring, and an operating portion that releases the holding of the inner needle hub by the inner needle hub engaging portion in order to move the inner needle hub to the retracted position, the housing having a plurality of ribs protruding radially inward and extending axially, the inner needle hub having a sliding portion that slides in contact with the ribs from the use position to the retracted position, the ribs having portions configured such that the frictional force generated between them and the sliding portion decreases in the direction of movement from the use position to the retracted position.

[0010] In a first embodiment of the indwelling needle assembly, the housing has ribs projecting radially inward, and the inner needle hub has a sliding portion that slides in contact with the ribs from the use position to the retraction position. The ribs have a portion configured such that the frictional force generated between them and the sliding portion decreases in the direction of movement from the use position to the retraction position. With this configuration, the retraction speed of the inner needle is suppressed by the frictional force between the ribs and the sliding portion from the use position to the retraction position, and as the biasing force of the spring decreases towards the retraction position, the frictional force also decreases, thus preventing an excessive decrease in the retraction speed of the inner needle. This makes it possible to achieve both prevention of blood splatter and rapid retraction of the inner needle. Furthermore, the frictional force can be finely adjusted by adjusting the width and number of ribs and the diameter of the inscribed circle in the ribs in the axial direction of the housing.

[0011] In a first embodiment of the indwelling needle assembly, the surface of the rib facing the sliding portion can be a curved surface that is concave radially outward, and the sliding portion can have a complementary curved surface. With this configuration, the sliding portion makes stable contact along the curved surface of the rib, so that the contact state between the sliding portion and the rib is kept stable during sliding. This allows the sliding portion to move stably.

[0012] In a first embodiment of the indwelling needle assembly, the operating button has a finger rest formed by a recess, and the inner needle hub engagement portion is located directly below the recess. With this configuration, The system guides the operator to naturally press the recessed portion of the control button, and when the operator presses the button, the pressing force is transmitted to the inner needle hub engagement portion in a direction perpendicular to the axial direction. As a result, the inner needle hub engagement portion moves straight in a direction perpendicular to the axial direction without tilting at an angle, allowing for smooth disengagement from the inner needle hub.

[0013] In a first embodiment of the indwelling needle assembly, the outer needle hub has an internally provided valve unit, the valve unit has a hemostatic valve, a plunger, and a plunger guide, the plunger has a tip that gradually tapers toward the tip and a cylindrical shaft provided at the base end of the tip, the shaft has protrusions projecting to both sides and a first plane and a second plane extending in the axial direction, the normals of the first and second planes are perpendicular to the projection direction of the protrusions, the protrusions are provided on the cylindrical portion of the shaft, the protruding end faces of the protrusions face the inner surface of the outer needle hub or the inner surface of the plunger guide, and the first and second planes face the guide plane provided on the plunger guide. When the normals of the first and second planes are in the vertical direction, this configuration guides the plunger so that it does not wobble in the vertical direction. Furthermore, the portion of the plunger on which the protrusions are provided is formed on the outer surface of the cylindrical portion of the shaft, thereby increasing its structural rigidity. In other words, the structure is less prone to distortion or deflection when external forces are applied, such as during molding or connector connection, and the distance between the protruding parts on both sides remains stable. The protruding end faces of these parts face the inner surface of the outer needle hub or the inner surface of the plunger guide, thus guiding the plunger to prevent lateral movement. This suppresses vertical and lateral movement and rotation of the plunger, improving the stability of the guiding effect.

[0014] A second embodiment of the indwelling needle assembly comprises a housing, a catheter unit positioned at the tip of the housing and having an outer needle and an outer needle hub, an inner needle unit having an inner needle and an inner needle hub inserted through the outer needle, and a safety mechanism that moves the inner needle hub from a use position where the inner needle protrudes from the tip of the outer needle and is ready for puncture to a retracted position where the inner needle is housed within the housing, the safety mechanism comprising a spring that biases the inner needle hub toward the proximal end, an inner needle hub engaging portion that releasably holds the inner needle hub in the use position against the biasing force of the spring, and an operating button connected to the inner needle hub engaging portion and exposed on the outside of the housing, the operating button having a finger rest formed by a recess, the inner needle hub engaging portion being located directly below the recess, and pressing the operating button moves the inner needle hub engaging portion in a direction perpendicular to the axis of the housing to release the engagement with the inner needle hub.

[0015] In the second embodiment, the operating button has a finger rest formed by a recess, and the inner needle hub engaging portion is located directly below the recess. This configuration guides the operator to naturally press the recessed portion of the operating button, and when the operator presses the operating button, the pressing force is transmitted to the inner needle hub engaging portion in a direction perpendicular to the axial direction. As a result, the inner needle hub engaging portion moves straight in a direction perpendicular to the axial direction without tilting at an angle, and disengagement from the inner needle hub can be performed smoothly.

[0016] A third embodiment of the indwelling needle assembly comprises a catheter unit having an outer needle and an outer needle hub, and an inner needle unit having an inner needle and an inner needle hub inserted into the outer needle, wherein the outer needle hub has a valve unit provided inside, the valve unit has a hemostatic valve, a plunger that opens the hemostatic valve, and a plunger guide that guides the movement of the plunger, the plunger has a tip that gradually tapers toward the tip, and a shaft provided at the base end of the tip, the shaft has convex portions protruding in both directions, and a first plane and a second plane extending in the axial direction, the normals of the first plane and the second plane are perpendicular to the protruding direction of the convex portion, the convex portion is provided on the cylindrical portion of the shaft, the protruding end face of the convex portion faces the inner surface of the outer needle hub or the inner surface of the plunger guide, and the first plane and the second plane face the guide plane provided on the plunger guide.

[0017] In a third embodiment, the plunger has a tip portion that gradually tapers toward the tip and a shaft portion provided at the base end of the tip portion. The shaft portion has protrusions projecting to both sides and a first plane and a second plane extending in the axial direction. The normals of the first and second planes are perpendicular to the projection direction of the protrusions. The protrusions are provided on the cylindrical portion of the shaft. The protruding end faces of the protrusions face the inner surface of the outer needle hub or the inner surface of the plunger guide. The first and second planes face the guide plane provided on the plunger guide. When the normals of the first and second planes are in the vertical direction, this configuration guides the plunger so that it does not wobble in the vertical direction. Furthermore, the portion of the plunger with the protrusions is formed on the outer surface of the cylindrical portion of the shaft, which increases its structural rigidity. That is, distortion and deflection are less likely to occur when external forces are applied, such as during molding or connector connection, and the distance between the protrusions projecting to both sides remains stable. The protruding end face of this convex portion faces the inner surface of the outer needle hub or the inner surface of the plunger guide, thereby guiding the plunger to prevent it from wobbling in the lateral direction. This suppresses wobbling and rotation of the plunger in the vertical and lateral directions, improving the stability of the guiding effect. [Effects of the Invention]

[0018] According to one embodiment of the indwelling needle assembly of this disclosure, the inner needle can be quickly inserted while suppressing blood splatter. In another embodiment, the engagement and disengagement of the inner needle hub and the inner needle hub engagement portion can be performed smoothly, and in yet another embodiment, the valve unit can be operated stably. In any of these embodiments, the operability of the indwelling needle assembly can be improved. [Brief explanation of the drawing]

[0019] [Figure 1] This is a side view showing an indwelling needle assembly of one embodiment. [Figure 2] This is a cross-sectional view showing an indwelling needle assembly of one embodiment. [Figure 3] This is a cross-sectional view showing the inner needle in the retracted position. [Figure 4] This is a perspective view showing the sliding part. [Figure 5] It is a cross-sectional view taken along the V-V line of FIG. 1. [Figure 6] It is a cross-sectional view taken along the VI-VI line of FIG. 1. [Figure 7] It is a cross-sectional view taken along the VII-VII line of FIG. 1. [Figure 8] It is a cross-sectional view showing the first cylindrical portion. [Figure 9] It is a cross-sectional view showing the second cylindrical portion. [Figure 10] It is a perspective view showing the lock portion. [Figure 11] It is a cross-sectional view of the state where the lock portion is in the first position. [Figure 12] It is a cross-sectional view of the state where the lock portion is in the second position. [Figure 13] It is a perspective view showing a modified example of the lock portion. [Figure 14] It is a side view showing the inner needle hub. [[ID=~]] [Figure 15] It is a cross-sectional view showing a part of the valve unit. [Figure 16] It is a perspective view showing the pusher. [Figure 17] It is a perspective view showing the pusher guide.

Mode for Carrying Out the Invention

[0020] As shown in FIGS. 1 and 2, the indwelling needle assembly according to one embodiment includes a housing 101, a catheter unit 102 having an outer needle 121 and an outer needle hub 122, an inner needle unit 103 having an inner needle 131 and an inner needle hub 132, and a safety mechanism 105 for drawing the inner needle unit 103 into the housing 101.

[0021] The orientation when using the indwelling needle assembly is not particularly limited. Hereinafter, the side of the catheter unit 102 will be described as the axial tip side, the side of the housing 101 as the proximal end side, the side where the operation button 156 of the safety mechanism 105 is provided as the upper side in the vertical direction, the opposite side as the lower side, and the direction orthogonal to the axial direction and the vertical direction as the width direction.

[0022] As shown in Figure 3, in this embodiment, by operating the operating button 156 of the safety mechanism 105, the inner needle hub 132 moves from a use position where the inner needle 131 protrudes from the tip of the outer needle 121 and is capable of puncture, to a retracted position where the inner needle 131 is housed within the housing 101. As a result, the entire inner needle 131 is housed within the housing 101, allowing for safe disposal.

[0023] In this embodiment, the housing 101 is a hard resin molded body having a cavity inside, and can be formed from, for example, polycarbonate or polypropylene. Four ribs 114 are formed on the inner surface of the housing 101, projecting radially inward and extending axially. The inner needle hub 132 has a hub body 135 and a sliding part 140 fixed to the base end of the hub body 135. The sliding part 140 is in contact with the ribs 114 at its sliding surface 144. Therefore, when the inner needle hub 132 moves from the use position to the retraction position, a frictional force acts between the sliding part 140 and the ribs 114, acting as a brake, thereby suppressing the retraction speed of the inner needle unit 103 and making it less likely for blood on the surface or inside of the inner needle 131 to splatter. In this case, it is preferable that the sliding part 140 is in contact with the ribs 114 both in the use position and the retraction position, and is in contact with the ribs 114 over the entire distance from the use position to the retraction position. As a result, the brake is constantly applied from the moment the inner needle 131 starts to be retracted until the inner needle 131 is fully retracted, thus more effectively preventing blood splatter. However, it is also possible to configure the sliding part 140 to contact the rib 114 only in a portion of the distance from the usage position to the retraction position.

[0024] In this embodiment, the sliding surface 144 of the sliding part 140 contacts only the rib 114. Therefore, the strength of the brake due to the frictional force generated between the sliding surface 144 of the sliding part 140 and the rib 114 can be precisely controlled. The frictional force between the sliding surface 144 and the rib 114 can be controlled by adjusting elements such as the width and number of ribs 114 and the diameter of the inscribed circle of the rib 114 in the axial direction, which will be described later. On the other hand, in the case where the sliding surface 144 contacts the entire inner surface of the housing 101 without providing the rib 114, the strength of the brake is determined by the inner diameter dimension of the housing 101. Therefore, the structure of the housing 101 is restricted, such as by increasing the diameter of the housing 101, and it is difficult to precisely control the strength of the brake. On the other hand, with the configuration using the rib 114, the strength of the brake can be precisely controlled without depending on the structure of the housing 101, so the retraction speed of the inner needle 131 can be adjusted with precision. As mentioned above, the braking force can be controlled by adjusting various elements of the rib 114, but the method of adjusting the diameter of the inscribed circle of the rib 114 is preferred. Since the diameter of the inscribed circle of the rib 114 can be continuously changed along the axial direction, the braking force can be smoothly changed by adjusting the diameter of the inscribed circle of the rib 114. Furthermore, since the diameter of the inscribed circle of the rib 114 can be measured with a pin gauge, dimensional control can be easily performed. Thus, the method of adjusting the diameter of the inscribed circle of the rib 114 is more useful than methods of adjusting other elements in terms of the accuracy of braking force control and the ease of dimensional control.

[0025] In this embodiment, as shown in Figure 4, the sliding portion 140 is cylindrical, having a cylindrical body portion 141 provided at the tip and a flange-like portion 142 provided at the base end of the cylindrical body portion 141, which has a larger diameter than the cylindrical body portion 141, and has a through hole in the central part. By providing a through hole, an escape route for air during flashback can be secured. The through hole does not necessarily have to be formed in the central part. Furthermore, it may not be provided if an escape route for air can be secured at another location.

[0026] The sliding portion 140 can be formed from rubber such as silicone rubber or an elastomer, with silicone rubber being particularly preferred. However, the material of the sliding portion 140 is not particularly limited as long as it generates frictional force with the rib 114. Also, the cylindrical portion 141 and the flange portion 142 may be made of the same material or of different materials. The cylindrical portion 141 can be fitted and fixed into the sliding portion fixing portion 138 provided at the base end of the hub body 135. The flange portion 142 has a sliding surface 144 with a constant outer diameter and a tapered surface 145 provided on the base end side of the sliding surface 144, the outer diameter of which gradually decreases toward the base end. By providing the tapered surface 145, it is possible to avoid burrs that may be generated near the end of the sliding portion 140 during molding coming into contact with the rib 114 and hindering sliding. The sliding portion 140 contacts the rib 114 provided on the inner surface of the housing 101 at the sliding surface 144. The outer shape of the sliding portion 140 at the sliding surface 144 is not limited to a circular shape; it can be a polygon, a cross, or any other shape that can contact the rib 114. However, a circular shape eliminates the need to control the circumferential position during assembly.

[0027] As an alternative to a circular shape, for example, a recess may be provided in the sliding surface 144, and the sliding portion 140 may be formed so that the recess contacts the rib 114. This allows the recess to be guided and slide along the rib 114, thus increasing the design freedom of the sliding surface 144 other than the recess.

[0028] In this embodiment, the sliding portion 140 is composed of a cylindrical portion 141 and a flange-shaped portion 142, but it may also be composed of only the flange-shaped portion 142. In this case, the sliding portion 140 can be fitted onto the hub body 135 or fixed to the base end of the hub body 135 with an adhesive or the like.

[0029] The housing 101 has a first cylindrical portion 111 at the tip and a second cylindrical portion 112 at the base. The tip of the first cylindrical portion 111 is provided with a configuration for assembling a safety mechanism 105. The base end of the second cylindrical portion 112 is closed to prevent the housed inner needle unit 103 from coming out towards the base. However, the base end of the second cylindrical portion 112 does not need to be sealed, and an air vent hole or the like can be provided. The base end of the second cylindrical portion 112 can also be made smaller in diameter or provided with a protruding part that extends inward to prevent the inner needle unit 103 from coming out towards the base.

[0030] By constructing the housing 101 from two parts, it becomes easy to assemble the inner needle unit 103 and the safety mechanism 105 into the housing 101. The shape of the housing 101 is not limited to a cylindrical shape; various shapes that can accommodate the inner needle unit 103 and the safety mechanism 105 can be adopted. Furthermore, even if the length of the inner needle 131 changes, this can be accommodated by changing the length of the second cylindrical part 112 without changing the configuration of the safety mechanism 105. Alternatively, the first cylindrical part 111 can be extended to the necessary position to accommodate the entire inner needle unit 103, and a cap or the like can be attached to its base end. Conversely, the second cylindrical part 112 can be made long enough to accommodate the entire inner needle unit 103, and the first cylindrical part 111 with the inner needle unit 103 and safety mechanism 105 assembled can be attached to the second cylindrical part 112.

[0031] In the housing 101, the inner surface of the first cylindrical portion 111 has a taper that gradually increases in diameter from the tip to the base, and the inner surface of the second cylindrical portion 112 has a taper that gradually decreases in diameter from the tip to the base. In addition, a plurality of ribs 114 are formed on the inner surfaces of the first cylindrical portion 111 and the second cylindrical portion 112, projecting radially inward and extending axially. Preferably, the rib portion 114 has a constant straight shape in which the diameter of the inscribed circle of the rib 114 does not change in the axial direction, or a shape in which the diameter of the inscribed circle of the rib 114 increases in the axial direction in the direction in which the inner diameter of the first cylindrical portion 111 or the second cylindrical portion 112 increases. This makes it easier to remove the first cylindrical portion 111 and the second cylindrical portion 112 from the mold during molding. Although it is not always necessary to provide a taper on the inner surface of the housing 101, it is preferable to provide a taper because it can improve the shape stability of the inner surface of the housing 101.

[0032] As shown in Figures 5-7, in this embodiment, of the four ribs 114, two ribs 114A facing each other in the vertical direction are provided only on the inner surface of the first cylindrical portion 111, while the two ribs 114B facing each other in the width direction are provided from the tip of the first cylindrical portion 111 to the base end of the second cylindrical portion 112. This allows the brake to be weakened at the base end where the biasing force is smaller. Note that the positional relationship between ribs 114A and ribs 114B can be swapped.

[0033] Depending on the magnitude of the biasing force, all ribs 114 can be made to extend to the base end of the second cylindrical portion 112. Alternatively, the number of ribs 114 can be reduced from partway along the first cylindrical portion 111 or partway along the second cylindrical portion 112. Rib 114A can be extended to the base end of the second cylindrical portion 112, while rib 114B can be limited to a certain point. Furthermore, the braking force can be weakened at the base end by varying the circumferential width of the ribs 114 to reduce the contact area between the sliding surface 144 and the ribs 114. The circumferential width of the ribs 114 may also vary along the axial direction, and the braking force can be weakened at the base end by making the circumferential width at the tip end larger than the circumferential width at the base end. The circumferential width may vary continuously or in steps. Additionally, the braking force can be weakened at the base end by making the diameter of the inscribed circle of the rib 114 slightly larger at the base end than at the tip end. Furthermore, by adjusting the surface roughness of the rib 114 at the tip and base ends to be different, the braking force can be reduced at the base end compared to the tip end.

[0034] When the diameter of the inscribed circle of the rib 114 is made larger at the base end than at the tip end to reduce braking at the base end, the diameter of the inscribed circle of the rib 114 can be made larger in the second cylindrical section 112 than in the first cylindrical section 111. For example, when the inner diameters of the first cylindrical section 111 and the second cylindrical section 112 are the same, the diameter of the inscribed circle of the rib 114 can be made larger at the base end than at the tip end by reducing the radial projection height of the rib 114 in the second cylindrical section 112 than in the first cylindrical section 111. Switching the diameter of the inscribed circle of the rib 114 between the first cylindrical section 111 and the second cylindrical section 112 simplifies design and manufacturing. When the diameter of the inscribed circle of the rib 114 is changed between the first cylindrical section 111 and the second cylindrical section 112, a step is created in the rib 114 at the boundary between the first cylindrical section 111 and the second cylindrical section 112. However, the step is larger at the base end and does not hinder the movement of the sliding part 140. Furthermore, to make the step less pronounced, a transition section can be provided at the boundary between the first cylindrical part 111 and the second cylindrical part 112 where the diameter of the inscribed circle of the rib 114 changes gradually. The diameter of the inscribed circle of the rib 114 can be made larger in the second cylindrical part 112 than in the first cylindrical part 111, not only when the number of ribs 114 is the same in the first cylindrical part 111 and the second cylindrical part 112, but also when they are different.

[0035] The rib 114 in the first cylindrical portion 111 can be configured such that the frictional force generated between it and the sliding portion 140 gradually decreases from the tip to the base. For example, by setting the diameter of the inscribed circle of the rib 114 in the first cylindrical portion 111 to increase continuously from the tip to the base, it is possible to configure it so that the frictional force gradually decreases towards the base. In Figure 8, the diameter of the inscribed circle of the rib 114 at the base is larger than the diameter of the inscribed circle φ1 at the tip of the rib 114 (the base of the inner flange 171). As an example, the diameter of the inscribed circle of the rib 114 in the first cylindrical portion 111 can be linearly increased from the tip to the base, such that the diameter of the inscribed circle φ1 at the tip of the rib 114 is 5.4 mm and the diameter of the inscribed circle φ2 at the base is 5.5 mm. With this configuration, even if the biasing force of the spring 151 gradually decreases towards the base end, the frictional force generated between the rib 114 and the sliding part 140 also decreases accordingly. This prevents the frictional force from becoming relatively excessive towards the base end, which would cause the retraction speed of the inner needle 131 to decrease excessively. This makes it possible to achieve both the prevention of blood splatter and the rapid retraction of the inner needle. However, it is also possible to make the diameter of the inscribed circle of the rib 114 increase exponentially from the tip to the base end.

[0036] The rib 114 in the second cylindrical portion 112 can be configured such that the frictional force generated between it and the sliding portion 140 is smaller than the frictional force at the rib 114 at the base end of the first cylindrical portion 111. With this configuration, even if the biasing force of the spring 151 gradually decreases as it moves from the first cylindrical portion 111 towards the second cylindrical portion 112 (i.e., towards the base end of the housing), it is possible to prevent the retraction speed of the inner needle 131 from decreasing excessively. In Figure 9, the diameter φ3 of the inscribed circle of the rib 114 at the tip of the second cylindrical portion 112 is larger than the diameter φ2 of the inscribed circle of the rib 114 at the base end of the first cylindrical portion 111. Also, the diameter φ4 of the inscribed circle of the rib 114 at the base end of the second cylindrical portion 112 is the same as φ3. For example, φ2 can be 5.5 mm, and φ3 and φ4 can be 5.9 mm. In this case, the diameter of the inscribed circle of the rib 114 can be made larger than the diameter φ2 of the inscribed circle at the base end of the rib 114 of the first cylindrical portion 111, along the entire axial direction of the second cylindrical portion 112. However, it is also possible to make φ3 the same as φ2, or to make φ4 larger than φ3. Note that in Figure 9, since the second cylindrical portion 112 is not provided with rib 114A, φ3 and φ4 are the diameters of the inscribed circle of rib 114B.

[0037] As shown in Figure 9, the diameter of the inscribed circle of the rib 114 in the second cylindrical portion 112 can be constant throughout the entire axial direction, but it may also be made to increase continuously from the tip to the base. If it is made to increase continuously from the tip to the base, the diameter of the inscribed circle of the rib 114 in the second cylindrical portion 112 may increase linearly from the tip to the base, or it may increase exponentially. Furthermore, if the diameter is increased linearly from the tip to the base in both the first cylindrical portion 111 and the second cylindrical portion 112, the degree of increase (rate of change) from the tip to the base in each cylindrical portion may be the same. When the diameter of the inscribed circle of the rib 114 in the first cylindrical portion 111 and the second cylindrical portion 112 is set to increase continuously from the tip to the base, it is preferable that the diameter of the inscribed circle of the rib 114 increases linearly and that the rate of change of the diameter of the inscribed circle of the rib 114 in the first cylindrical portion 111 and the second cylindrical portion 112 is the same. In other words, it is preferable that the diameter of the inscribed circle of the rib 114 increases linearly from the tip to the base throughout the entire housing 101. With such a configuration, the frictional force can be gradually reduced at a constant rate throughout the entire housing, making it easier to predict the decrease in the retraction speed of the inner needle 131, and making it easier to achieve both blood splash prevention and rapid retraction of the inner needle 131. Furthermore, since the dimension of the diameter of the inscribed circle of the rib 114 can be measured with a pin gauge, dimensional control of the entire housing 101 can be easily performed.

[0038] In this embodiment, as described above, in the first cylindrical portion 111, the diameter of the inscribed circle of the rib 114 is linearly increased from the tip to the base, and the number of ribs 114 is set to four. In the second cylindrical portion 112, the diameter of the inscribed circle φ3 at the tip of the rib 114 and the diameter of the inscribed circle φ4 at the base are the same diameter and larger than the diameter φ2 of the inscribed circle of the rib 114 at the base of the first cylindrical portion 111, and the number of ribs 114 is set to two. With this configuration, in the first cylindrical portion 111 where the retraction of the inner needle 131 begins, a frictional force corresponding to the biasing force of the spring 151 is applied to the extent that blood splatter is prevented, while the frictional force generated between the rib 114 and the sliding portion 140 is reduced as the retraction progresses. Furthermore, in the second cylindrical portion 112, where the retraction of the inner needle 131 is nearing completion, the diameters of the inscribed circles of the ribs 114, φ3 and φ4, are made larger than the diameter φ2 of the inscribed circle of the ribs 114 at the base end of the first cylindrical portion 111. By further reducing the number of ribs 114 compared to the first cylindrical portion 111, the frictional force can be reduced more effectively than at the base end of the first cylindrical portion 111. However, this embodiment is merely an example, and the present invention is not limited thereto.

[0039] In this embodiment, the braking force is adjusted by configuring the diameter of the inscribed circle of the rib 114 and the number of ribs 114 to be different in the first cylindrical section 111 and the second cylindrical section 112. However, it is also possible to configure the first cylindrical section 111 and the second cylindrical section 112 to be different in only one of the two: the diameter of the inscribed circle of the rib 114 and the number of ribs 114. For example, the diameters of the inscribed circles of the ribs 114 from φ1 to φ4 can be the same (i.e., the diameter of the inscribed circle of the rib 114 is constant from the tip to the base of the housing), and the number of ribs 114 in the second cylindrical section 112 can be reduced compared to the number of ribs 114 in the first cylindrical section 111. Furthermore, the number of ribs 114 can be changed at some point in the first cylindrical section 111 or in the second cylindrical section 112.

[0040] Conversely, the number of ribs 114 can be the same in the first cylindrical section 111 and the second cylindrical section 112 (i.e., the number of ribs 114 is constant from the tip to the base of the housing), and the diameter of the inscribed circle φ4 of the rib 114 at the base of the second cylindrical section 112 can be made larger than the diameter φ1 of the inscribed circle of the rib 114 at the tip of the first cylindrical section 111. Note that the diameter of the inscribed circle can be made to increase continuously along the entire axial direction of the rib 114 so that φ4 is larger than φ1, but it is also possible to have a configuration in which there is a part in which the diameter of the inscribed circle is constant. For example, a configuration in which φ1 and φ2 are the same, or a configuration in which φ2 and φ4 are the same can be used. It is also possible to have a configuration in which there is a part in the first cylindrical section 111 and the second cylindrical section 112 in which the diameter of the inscribed circle of the rib 114 does not change and remains constant. Furthermore, the change in the diameter of the inscribed circle of the rib 114 is not limited to a linear change, but can be configured to change exponentially, for example. Furthermore, the diameter of the inscribed circle of the rib 114 can be configured to change discontinuously. The discontinuous change in the diameter of the inscribed circle of the rib 114 can occur at the connection point between the first cylindrical portion 111 and the second cylindrical portion 112, or it can occur somewhere between the first cylindrical portion 111 and the second cylindrical portion 112.

[0041] In either configuration, the sliding part 140 is strongly braked at the front end of the housing 101 and weakly braked at the base end of the housing 101. This suppresses the initial speed of the inner needle 131's retraction while preventing excessive speed reduction in the later stages of retraction, allowing the inner needle 131 to be quickly retracted into the housing 101 while preventing blood splatter. It is also possible to suppress the initial speed of the inner needle 131's retraction while preventing excessive speed reduction in the later stages of retraction by adjusting factors other than the diameter of the inscribed circle of the rib 114 and the number of ribs 114 (such as the width of the rib 114 and the application of lubricant to the rib 114 and the sliding part 140).

[0042] The diameter of the inscribed circle of the rib 114 in the first cylindrical portion 111 and the second cylindrical portion 112, on which the sliding portion 140 moves, can be kept constant along the entire axial direction of the cylindrical portion, or it can be configured to vary along the axial direction. In either case, the diameter of the inscribed circle of the rib 114 in the first cylindrical portion 111 can be set in the range of 88% to 93% of the outer diameter of the sliding portion 140, and the diameter of the inscribed circle of the rib 114 in the second cylindrical portion 112 can be set in the range of 94% to 99% of the outer diameter of the sliding portion 140. Furthermore, the difference between the diameter of the inscribed circle of the rib 114 at the tip of the second cylindrical portion 112 and the outer diameter of the sliding portion 140 can be set to approximately 5% to 30% of the difference between the diameter of the inscribed circle of the rib 114 at the base end of the first cylindrical portion 111 and the outer diameter of the sliding portion 140.

[0043] In this embodiment, the maximum number of ribs 114 is set to four, but it can also be two, three, or four or more. Since the shaft of the inner needle hub 132 is prone to wobbling during the initial stages of movement when the biasing force is large, it is preferable to provide three or more ribs 114, at least in the tip portion.

[0044] In this embodiment, the first cylindrical portion 111 and the second cylindrical portion 112 are assembled integrally by fitting the overlay portion 118, which is provided at the tip of the second cylindrical portion 112, onto the insertion portion 117, which is provided at the base end of the first cylindrical portion 111. In this configuration, the relative circumferential positions of the first cylindrical portion 111 and the second cylindrical portion 112 can be freely set. For this reason, the circumferential positions of the rib 114B of the first cylindrical portion 111 and the rib 114B of the second cylindrical portion 112 can be made to coincide, or the circumferential positions of the rib 114A of the first cylindrical portion 111 and the rib 114B of the second cylindrical portion 112 can be made to coincide. Furthermore, the rib 114B of the second cylindrical portion 112 can be connected so that it is located between the ribs 114A and 114B of the first cylindrical portion 111. However, a positioning mechanism can also be provided that allows connection only when the first cylindrical portion 111 and the second cylindrical portion 112 are in a specific positional relationship in the circumferential direction (for example, when the circumferential positions of the rib 114B of the first cylindrical portion 111 and the rib 114B of the second cylindrical portion 112 coincide).

[0045] In this embodiment, the annular projection provided on the insertion portion 117 and the annular recess provided on the inner surface of the cover portion 118 are fitted together, allowing the first cylindrical portion 111 and the second cylindrical portion 112 to be securely fixed. Furthermore, a stepped portion is provided at the tip of the insertion portion 117, and the tip of the cover portion 118 abuts against this stepped portion, making it easy to connect the first cylindrical portion 111 and the second cylindrical portion 112.

[0046] In this embodiment, the radially inner end face 115 of the rib 114 facing the sliding portion 140 is a curved surface that is concave radially outward. In this case, it is preferable that the sliding surface 144 has a curved surface that is complementary to the curved surface of the end face 115. For example, the outer shape of the sliding portion 140 in the portion of the sliding surface 144 can be circular. This allows the sliding surface 144 to stably contact the end face 115, thereby reducing the axial wobble of the sliding portion 140 during movement and enabling stable movement. However, the outer shape of the sliding portion 140 in the portion of the sliding surface 144 can be polygonal, or a flat surface can be partially provided on the sliding surface 144, so that the sliding surface 144 and the end face 115 are in contact with each other on a flat surface. In addition, the cross-sectional shape of each rib 114 can be a straight shape such as a square or rectangle, or it can be a T-shape, U-shape or V-shape, etc. Furthermore, the sliding surface 144 may be configured not to have a complementary surface to the end face 115. Alternatively, the sliding surface 144 and the rib 114 may be configured to make line contact.

[0047] The circumferential length of the end face 115 depends on the outer diameter of the sliding surface 144, but is preferably 0.5 mm or more and 2.0 mm or less, and more preferably about 1.0 mm. It is preferable to have the circumferential length of the end face 115 to be within this range not only when the entire end face 115 is in contact with the sliding surface 144, but also when only a part of the end face 115 is in contact with the sliding surface 144. The circumferential length of the end face 115 may be constant from the tip to the base, or it may vary between the tip and the base.

[0048] A lubricant can be applied between the sliding surface 144 and the rib 114 as needed. Applying a lubricant can adjust the sliding resistance between the sliding surface 144 and the rib 114. The lubricant may be applied to only one of the sliding surface 144 and the rib 114, or to both. It may also be applied to the entire sliding surface 144 and the rib 114, or to only a part of them. For example, considering that the sliding resistance increases towards the base end, applying lubricant only to the rib 114 on the base end side makes it possible to move the inner needle hub 132 smoothly at the base end. In this case, the sliding surface 144 may or may not have lubricant applied to it.

[0049] The lubricant is not particularly limited and can be selected considering the material of the sliding part 140, etc. As an example, a silicone-based lubricant can be used. The viscosity of the lubricant is not particularly limited, but is preferably 100 cs or more and 50,000 cs or less. Lubricants with a viscosity of around 10,000 cs are readily available and are very suitable from the viewpoint of their properties. The timing of lubricant application is not particularly limited.

[0050] The method of applying the lubricant is not particularly limited. The lubricant may be applied directly to the sliding surface 144 or the rib 114. For example, the lubricant may be applied to the sliding surface 144 first, and then the rib 114 may be brought into contact with the sliding surface 144 during assembly to apply the lubricant to the rib 114. Alternatively, the lubricant may be applied to the rib 114 first, and then the sliding surface 144 may be brought into contact with the rib 114 to apply the lubricant to the sliding surface 144.

[0051] The safety mechanism 105 assembled to the tip of the housing 101 has a locking part 152 which includes a spring 151, a ring part (internal needle hub engaging part) 155, and an operating button (operating part) 156.

[0052] The spring 151 biases the inner needle hub 132 toward the base end. The spring 151 is also positioned between the inner flange 171, which is provided at the tip of the housing 101, and the spring seat 139, which is provided at the base end of the inner needle hub 132. The inner diameter of the inner flange 171 is slightly larger than the outer diameter of the portion of the inner needle hub 132 that is closer to the tip than the spring seat 139. The maximum outer diameter of the spring seat 139 is slightly smaller than the outer diameter of the sliding surface 144 of the sliding portion 140, and does not come into contact with the rib 114.

[0053] As shown in Figure 10, the locking portion 152 has a ring portion 155, an operating button 156 protruding towards the base end at the upper end of the ring portion 155, and a nose portion 157 protruding towards the tip end. The ring portion 155 holds the inner needle hub 132 in the tip end position against the biasing force of the spring 151. A ring portion insertion slot 173 for inserting the ring portion 155 is formed at the tip end of the first cylindrical portion 111 of the housing 101. A nose portion engagement groove 178 is provided at the upper end of the first cylindrical portion 111, extending from the ring portion insertion slot 173 toward the tip end. The nose portion engagement groove 178 reaches the tip surface of the first cylindrical portion 111, and the tip surface of the first cylindrical portion 111 is approximately C-shaped when viewed from the tip end. When the ring portion 155 is inserted into the ring portion insertion slot 173, the nose portion 157 engages with the nose portion engagement groove 178 and protrudes toward the tip side of the tip surface of the first cylindrical portion 111. An operating button receiving portion 174 is provided on the base side of the ring portion insertion slot 173 at the upper end of the first cylindrical portion 111 to receive the operating button 156 and guide its downward movement. The locking portion 152 can move between an upper first position and a lower second position when the ring portion 155 is inserted into the ring portion insertion slot 173.

[0054] As shown in Figures 11 and 12, the ring portion 155 has an outer shape that is approximately oval in length, with the vertical direction being longer than the width direction, and the lumen 155a surrounded by the peripheral wall has a similar shape. The vertical diameter of the lumen 155a is larger than the maximum outer diameter of the portion of the inner needle hub 132 closer to the tip of the spring seat 139. Therefore, the ring portion 155 can move relative to the inner needle hub 132 in the vertical direction when the inner needle hub 132 is inserted into the lumen 155a. The widthwise diameter of the lumen 155a is approximately equal to the maximum outer diameter of the portion of the inner needle hub 132 closer to the tip of the spring seat 139. Therefore, the relative movement of the ring portion 155 with respect to the inner needle hub 132 in the width direction is limited.

[0055] A protrusion 158 is provided on the upper surface of the operation button 156. By providing the protrusion 158, the operator can be guided to press down on the position of the protrusion 158. The protrusion 158 is located towards the tip of the operation button 156, and the axial position of the tip of the protrusion 158 and the base end of the ring portion 155 are almost aligned. Therefore, by pressing down on the position of the protrusion 158, the ring portion 155 can be moved smoothly downward.

[0056] Figure 13 shows a modified locking mechanism 152A. The operating button 156A covers the top of the nose portion 157. The nose portion 157 is provided to protrude vertically from the ring portion 155 toward the tip, and the operating button 156A extends to match the length of the protruding nose portion 157. The upper surface of the operating button 156A has a finger rest with a concave recess. This naturally guides the operator to press the recessed portion of the operating button 156A. In addition, the ring portion 155 is provided directly below the recessed portion of the operating button 156A. Therefore, when the recessed portion of the operating button 156A is pressed downwards, the ring portion 155 is pushed straight down, making it less likely for the ring portion 155 to become slanted and get caught.

[0057] In this modified example, the recess on the upper surface of the operation button 156A and the ring portion 155 located directly below it are positioned approximately in the axial center of the operation button 156A. Therefore, the operator will press the center of the operation button 156A and push the ring portion 155 straight down, making it less likely for the ring portion 155 to become slanted and get caught. Consequently, the safety mechanism 105 can be operated smoothly. However, the position of the recess on the upper surface of the operation button 156A and the position of the ring portion 155 do not necessarily have to coincide at the axial center of the operation button 156A; they may coincide at other positions in the axial direction.

[0058] The indentation on the top surface of the operation button 156A is not particularly limited, but it can be made gentle enough to fit the shape of a fingertip (for example, the pad of an adult's thumb). In this modified example, the shape is curved only in the axial direction with a depression in the axial center, but it can also be made into a shape with a depression in the center in both the axial and width directions.

[0059] As shown in Figure 14, a part of the outer surface of the hub body 135 of the inner needle hub 132 is carved out to form an engaging recess 147. When the ring portion 155 is in a first position above the inner needle hub 132, the lower part 161 of the peripheral wall of the ring portion 155 engages with the engaging recess 147 and is sandwiched between the front and rear portions of the engaging recess 147, thus restricting the axial movement of the inner needle hub 132. When the ring portion 155 moves relative to the inner needle hub 132 to a second position below, the engagement between the lower part 161 of the peripheral wall and the engaging recess 147 is released. As a result, the inner needle hub 132 becomes movable in the axial direction. Since the inner needle hub 132 is biased toward the base end by the spring 151, the inner needle hub 132 moves quickly toward the base end.

[0060] By configuring the lower part 161 of the peripheral wall 155 to be sandwiched by the engaging recess 147 of the hub body 135, the biasing force of the spring 151 can be received over a wider area compared to the case where a protrusion projecting upward from the lower part 161 of the peripheral wall engages with a recess formed in the hub body 135, thus stably holding the inner needle hub 132 in the working position.

[0061] An engagement groove 161a is formed in the lower part 161 of the peripheral wall of the ring portion 155, and an engagement projection 147a is formed in the engagement recess 147 of the hub body 135. When the lower part 161 of the peripheral wall is engaged with the engagement recess 147, the engagement projection 147a is engaged with the engagement groove 161a. This prevents the inner needle hub 132 from rotating in the operating position. This allows the cutting surface 133 at the tip of the inner needle 131 to be in a specific direction during use. For example, the cutting surface 133 can be positioned upwards. However, the mechanism for preventing the rotation of the inner needle hub 132 can have various configurations and can be provided as needed.

[0062] In this embodiment, the engaging recess 147 is formed by providing a small-diameter portion 148 in the hub body 135, but the engaging recess 147 is not limited to this shape and can employ various configurations that can engage with the lower part of the peripheral wall 161.

[0063] In this embodiment, the hub body 135 is provided with notched sections on both the front and rear of the engaging recess 147. By providing such notches 149, the wall thickness can be made as uniform as possible, and the moldability can be stabilized. The notches 149 can be provided as needed, or they can be omitted.

[0064] When the inner needle hub 132 is in the use position, the tip of the inner needle hub 132 protrudes beyond the tip of the housing 101. The outer needle hub 122 can be engaged with the portion of the inner needle hub 132 that protrudes from the housing 101 to assemble the housing 101, catheter unit 102, and inner needle unit 103 as a single unit. The base end of the outer needle hub 122, which is engaged with the tip of the inner needle hub 132, abuts against the tip surface of the first cylindrical portion 111. The first cylindrical portion 111 has an anti-rotation projection 119 that protrudes beyond the tip surface. The base end of the outer needle hub 122 has a rim 128 with a notch, and the anti-rotation projection 119 engages with this notch. Therefore, the rotation of the catheter unit 102 can be restricted.

[0065] The rim 128 of the outer needle hub 122 also has a function to prevent accidental operation, which prevents the operation button 156 from being pressed when the catheter unit 102 and the inner needle unit 103 are connected. For example, the rim 128 has another notch opposite to the notch into which the anti-rotation projection 119 engages, and when the catheter unit 102 and the inner needle unit 103 are connected, the operation button 156 can be prevented from being pressed by bringing the nose portion 157 into contact with this notch. However, the nose portion 157 does not necessarily have to contact the notch; the operation button 156 can also be prevented from being pressed by having the nose portion 157 contact the outer circumferential surface of the rim 128 without providing a notch. The outer diameter and shape of the rim 128 can be appropriately selected so that the nose portion 157 and the rim 128 make proper contact. Note that the role of preventing accidental operation may also be fulfilled by components other than the rim 128. For example, erroneous operation can be prevented by providing a protrusion or the like that at the base end of the outer needle hub 122, which contacts the nose portion 157 when the catheter unit 102 and the inner needle unit 103 are connected.

[0066] When the outer needle hub 122 is engaged with the inner needle hub 132, which protrudes from the tip of the housing 101, the portion of the nose portion 157 that protrudes towards the tip beyond the tip surface of the first cylindrical portion 111 comes into contact with the upper end of the outer needle hub 122. As a result, downward movement of the nose portion 157 is restricted. When the outer needle hub 122 is detached from the tip of the inner needle hub 132, downward movement of the nose portion 157 becomes possible. In this state, when the operation button 156 is pressed, the ring portion 155 moves from the first position to the second position, and the engagement between the ring portion 155 and the inner needle hub 132 is released. As a result, the inner needle hub 132 moves from the tip end usage position to the base end retraction position due to the biasing force of the spring 151, and the inner needle 131 is housed in the housing 101.

[0067] In this embodiment, projections 162 are formed on both sides of the peripheral wall of the ring portion 155, projecting outward in the width direction. A projection 176 is formed on the inner wall surface of the ring portion insertion slot 173, projecting inward in the width direction. When the ring portion 155 is in the first position, the projections 162 are located above the projections 176, and when the ring portion 155 moves to the second position, the projections 162 move over the projections 176 and below them. With this configuration, the ring portion 155 will not move from the first position to the second position unless a certain amount of force is applied to the operation button 156, thereby preventing unintended movement of the ring portion 155. The mechanism for restricting unintended movement of the ring portion 155 is not limited to this configuration, and various configurations can be adopted. It is also possible to omit the mechanism altogether.

[0068] In this embodiment, an operating button 156 is provided on the ring portion 155 as the actuation part for activating the safety mechanism, but various configurations can be adopted. For example, a configuration in which a lever is provided on the ring portion 155 as the actuation part can be adopted. In this case, when the ring portion 155 is in the first position, the projection 162 is positioned below the projection 176, and by pulling the lever upward, the projection 162 moves over the projection 176 and upward, and the ring portion 155 moves to the second position. As a result, the engagement between the ring portion 155 and the inner needle hub 132 is released, and the safety mechanism is activated.

[0069] The catheter unit 102 includes an outer needle 121 and an outer needle hub 122 that holds the outer needle 121. The outer needle 121 can be made of a material with appropriate flexibility, such as ethylene-tetrafluoroethylene copolymer (ETFE), polyurethane, polyether nylon resin, or other soft resins. The outer circumferential surface of the tip of the outer needle 121 is tapered to reduce puncture resistance to the body. Furthermore, the tip of the outer needle 121 is designed to minimize the gap between it and the inserted inner needle 131. A side hole can also be provided at the tip of the outer needle 121.

[0070] The proximal end of the outer needle 121 is fixed to the tip of the outer needle hub 122. The outer needle hub 122 has a stepped, substantially cylindrical shape that extends axially. The proximal end of the outer needle 121 is inserted into and fixed to the tip portion, which has a smaller diameter than the proximal end portion. The outer needle 121 can be fixed by crimping, adhesive fixing, etc. The proximal end portion of the outer needle hub, which has a larger diameter, houses the valve unit 124. The proximal end portion is also a female connector with a Luer taper. A rim 128 is formed at the proximal end of the proximal end portion, having a groove for receiving the nose portion 157 and a groove for receiving the anti-rotation projection 119 of the first cylindrical portion. A projection that protrudes upward is formed in the middle portion of the proximal end portion. By providing the projection, it is easy to remove the catheter unit 102 from the inner needle hub 132 and housing 101. Both sides of the tip of the proximal end portion are cut out to form flat surfaces. By forming a flat surface, gripping the outer needle hub 122 becomes easier.

[0071] The valve unit 124, located inside the outer needle hub 122, includes a hemostatic valve 125, a plunger 126 that opens the hemostatic valve 125, and a plunger guide 127 that fixes the hemostatic valve 125 and guides the movement of the plunger 126, as shown in Figures 15 to 17. By providing the valve unit 124, even after the inner needle 131 is withdrawn, blood flow can be prevented until a male connector or the like is connected to the outer needle hub 122, thereby improving safety. Furthermore, in this embodiment, after the male connector is withdrawn, the hemostatic valve 125 closes again to stop blood flow.

[0072] The hemostatic valve 125 is an elastic body such as rubber having an openable and closable slit 181. In this embodiment, the hemostatic valve 125 has a disc-shaped disc portion 182 with the slit 181, a circumferential groove 183 provided on the outer edge of the base end of the disc portion 182, and a circumferential wall portion 184 extending from the disc portion 182 toward the base end.

[0073] As shown in Figure 16, the plunger 126 has a shaft portion 187 of a nearly constant diameter, a tapered tip portion 186 provided on the tip side of the shaft portion 187, and protrusions 188 projecting from both sides of the shaft portion 187 in the width direction. The protrusions 188 are provided on the outer surface of the cylindrical portion of the shaft portion 187. Here, "cylindrical" refers to a structure in which, in a cross section perpendicular to the axial direction of the plunger 126, it is continuous without breaks in the circumferential direction and forms a closed contour. Because the cylindrical portion has high structural rigidity, it is less likely to cause distortion or deflection during molding or connector connection. By providing the protrusions 188 on such a cylindrical portion, displacement of the protrusions 188 during molding or connector connection can be prevented, and the protrusions 188 can reliably exert the expected guiding effect. Note that the entire shaft portion 187 does not need to be cylindrical; it is sufficient if the portion on which the protrusions 188 are provided is formed in a cylindrical shape. For example, even if the shaft portion 187 is composed of a pair of plate-like members provided on both sides in the width direction and not continuous in the circumferential direction, by providing a portion where these plate-like members are bridged and connected in the width direction, that portion can be considered a cylindrical portion, and a protrusion 188 can be provided on the outer surface of that portion.

[0074] Furthermore, the shaft portion 187 has a first plane 187a and a second plane 187b, which are formed by cutting off the upper and lower parts. A stepped portion 189 is formed at the tips of the first plane 187a and the second plane 187b. The normals of the first plane 187a and the second plane 187b are perpendicular to the protruding direction of the convex portion 188.

[0075] As shown in Figure 17, the plunger guide 127 is roughly cylindrical and has a valve fixing portion 191 at the tip and two legs 192 that protrude from the valve fixing portion 191 toward the base end. The two legs 192 of the plunger guide 127 are formed by cutting out a portion of the bottom surface. In addition, notches are formed on both sides so that the convex portion 188 of the plunger 126 can fit between the two legs 192. A housing portion 196 is formed between the two legs 192.

[0076] The outer diameter of the leg portion 192 of the plunger guide 127 is approximately equal to or greater than the inner diameter of the outer needle hub 122, and the plunger guide 127 is fitted and fixed inside the outer needle hub 122. The valve fixing portion 191 of the plunger guide 127 is cylindrical with a smaller diameter than the leg portion 192, and its tip is inserted into the circumferential groove 183 of the hemostatic valve 125, pushing the circumferential wall portion 184 of the hemostatic valve 125 radially outward. As a result, the circumferential wall portion 184 is compressed and fixed between the inner wall surface of the outer needle hub 122 and the outer surface of the valve fixing portion 191. A groove 129 is formed on the inner wall surface of the outer needle hub 122, and a part of the disc portion 182 of the hemostatic valve 125 is located within the groove 129.

[0077] The plunger 126 has its tip 186 inserted into the housing 196, and when the plunger 126 is in the valve closed position at the base end, the stepped portion 189 abuts against the front side surface 194 of the bottom surface of the housing 196. Therefore, the plunger 126 does not move beyond the valve closed position towards the base end. When the male connector is inserted from the base end of the outer needle hub 122, the male connector moves the plunger 126 to the valve open position at the tip end. This causes the tip 186 of the plunger 126 to push open the slit of the hemostatic valve 125. Alternatively, when the plunger 126 is in the valve open position, the front surface of the protrusion 188 may abut against the side surface of the plunger guide 127. This prevents the plunger 126 from moving beyond the valve open position towards the tip end. When the male connector is removed, the hemostatic valve 125's elastic force returns the plunger 126 to the valve closed position, and the hemostatic valve 125 closes. Furthermore, various methods such as a coil spring can be used to return the plunger so that the hemostatic valve 125 closes again after the male connector is removed. It is also possible to configure the valve to remain open even after the male connector is removed, once it has been opened.

[0078] The two legs 192 of the plunger guide 127 have guide planes 197 that face the upper first plane 187a and the lower second plane 187b of the plunger 126, and the distance between the opposing guide planes 197 is slightly greater than the distance between the first plane 187a and the second plane 187b. That is, the first plane 187a and the second plane 187b each face the guide plane 197 and are in extremely close proximity, although they do not touch. As a result, the plunger 126 can move within the housing 196 with almost no vertical wobble. The gap between the guide plane 197 and the first plane 187a or the second plane 187b is preferably 0.035 mm or more and 0.01 mm or less, but is not limited to this range. Since the guide plane 197, the first plane 187a, and the second plane 187b are all planes, vertical wobble is less likely to occur, and movement is smooth. Furthermore, it becomes easier to mold with high precision. The protrusions 188 that project from both sides of the shaft portion 187 of the plunger 126 have their protruding end faces facing the inner circumferential surface of the outer needle hub 122 with a small gap between them. That is, the protrusions 188 that project from both sides in the width direction from the shaft portion 187 of the plunger 126 are in extremely close proximity to the inner surface of the outer needle hub 122, although they do not make contact. This makes it possible to reduce the widthwise (left-right) wobble of the plunger 126. From the viewpoint of suppressing plunger wobble, it is preferable that the gap between the protrusions 188 of the plunger 126 and the inner surface of the outer needle hub 122 be between 0.07 mm and 0.15 mm over the entire range in which the plunger 126 moves. However, it is not limited to this range. In addition, the protrusions 188, being sandwiched between the two leg portions 192, also contribute to reducing vertical wobble. The relationship between the first plane 187a and the second plane 187b and the guide plane 197, as well as the relationship between the convex portion 188 and the slit between the two legs 192, can also be used to restrict the rotation of the plunger 126.

[0079] In this example, a notch is provided between the two legs 192 of the plunger guide 127, and the convex portion of the plunger 126 is guided by being sandwiched between the two legs 192. However, the housing can also be formed by a cylindrical member without a notch. In this case, the protruding end face of the convex portion 188 can be positioned to face the inner surface of the housing of the plunger guide 127 with a small gap between them. Alternatively, a groove can be formed on the inner surface of the cylindrical member so that the convex portion 188 is guided by the groove. Furthermore, a configuration without the convex portion 188 is also possible.

[0080] In this embodiment, the protrusion 188 of the plunger 126 has a recess 188a on its tip side. Since the plunger 126 is formed with a gate at the position of the recess 188a, it is possible to prevent the gate burr from protruding beyond the outer diameter of the protrusion 188. This enables smoother movement of the plunger 126. However, the gate position of the plunger 126 is not limited to this position and can be selected as appropriate.

[0081] While the description shows a configuration in which protrusions 188 are provided on both sides in the width direction of the shaft portion 187 of the plunger 126, forming a first plane 187a and a second plane 187b in the vertical direction, it is also possible to have a configuration in which the first plane 187a and the second plane 187b are provided on both sides in the width direction, and protrusions 188 are provided on both sides in the vertical direction. In this case, the plunger guide 127 is positioned so that the guide plane 197 faces the first plane 187a and the second plane 187b of the plunger 126. This allows the guide plane 197 and the first plane 187a and the second plane 187b to suppress the width direction wobble of the plunger 126, while the inner surface of the outer needle hub and the protrusions 188 suppress the vertical direction wobble of the plunger 126.

[0082] The inner needle 131 is a hollow needle with a sharp blade surface 133 at its tip, and can be made of stainless steel, aluminum, titanium, or their alloys. The inner needle 131 can also be a solid needle. The hub body 135 of the inner needle hub 132 can be made of a hard synthetic resin material such as polypropylene. The inner needle fixing part 136 has a lumen whose inner diameter is approximately equal to or slightly larger than the outer diameter of the inner needle 131, except at the base end, and the inner diameter at the base end is smaller than the outer diameter of the inner needle 131 so that the inner needle 131 does not penetrate the inner needle fixing part 136. The inner needle 131 inserted into the inner needle fixing part 136 can be fixed by adhesive or the like. Various methods can be used to fix the inner needle 131.

[0083] A sliding part fixing portion 138 with a large inner diameter is formed at the base end of the hub body 135. The cylindrical portion 141 of the sliding part 140 can be fitted and fixed into the sliding part fixing portion 138. Various methods can be used to fix the sliding part 140.

[0084] An intermediate section 137 is formed between the inner needle fixing section 136 and the sliding section fixing section 138. The inner diameter of the intermediate section 137 is larger than that of the inner needle fixing section 136 and smaller than that of the sliding section fixing section 138. A ventilation filter 146 is installed between the intermediate section 137 and the sliding section fixing section 138. The ventilation filter 146 is attached to the intermediate section 137 by heat welding, but various methods can be used to attach the ventilation filter 146.

[0085] A ventilation filter 146 is attached to the middle section 137 of the hub body 135. Although the space is separated by the ventilation filter 146 and liquid cannot pass through, air can move in the space from the tip of the inner needle 131 to the base opening of the hub body 135. Therefore, when the inner needle 131 punctures a blood vessel, blood can flow into the hub body 135. By making the housing 101 and the hub body 135 transparent or translucent, the lumen of the middle section 137 can be used as a flashback space to confirm puncture of a blood vessel. Furthermore, the configuration for confirming flashback may be provided as needed, or it may be omitted. [Industrial applicability]

[0086] The indwelling needle assembly described herein offers improved operability and is useful as a medical device. [Explanation of Symbols]

[0087] 101 Housing, 102 Catheter unit, 103 Inner needle unit, 105 Safety mechanism, 111 First tube section, 112 Second tube section, 114, 114A, 114B Ribs, 115 End face, 117 Insertion section, 118 Cover section, 119 Anti-rotation projection, 121 Outer needle, 122 Outer needle hub, 124 Valve unit, 125 Hemostatic valve, 126 Plunger, 127 Plunger guide, 128 Rim, 129 Groove, 131 Inner needle, 132 Inner needle hub, 133 Blade surface, 135 Hub body, 136 Inner needle fixing section, 137 Intermediate section, 138 Sliding section fixing section, 139 Spring seat, 140 Sliding section, 141 Tube section, 142 Flange section, 144 145 Sliding surface, 146 Tapered surface, 146 Ventilation filter, 147 Engaging recess, 147a Engaging protrusion, 148 Small diameter section, 149 Notch, 151 Spring, 152, 152A Locking section, 155 Ring section, 155a Lumen, 156, 156A Operating button, 157 Nose section, 161 Lower part of peripheral wall, 161a Engaging groove, 162 Projection, 171 Inner flange, 173 Ring section insertion slot, 174 Operating button receiving section, 176 Projection, 178 Nose section engagement groove, 181 Slit, 182 Disc section, 183 Peripheral groove, 184 Peripheral wall section, 186 Tip section, 187 Shaft section, 187a First plane, 187b Second plane, 188 Protrusion, 188a Recess, 189 Stepped section, 191 Valve fixing section, 192 Leg section, 194 Side of tip, 196 Housing section, 197 Guide plane

Claims

1. Housing and A catheter unit having an outer needle and an outer needle hub is positioned at the tip of the housing, An inner needle unit having an inner needle and an inner needle hub inserted through the outer needle, The system includes a safety mechanism that moves the inner needle hub from a use position in which the inner needle protrudes from the tip of the outer needle and is capable of puncturing, to a retracted position in which the inner needle is housed within the housing, The safety mechanism includes a spring that biases the inner needle hub toward the base end, an inner needle hub engaging portion that releasably holds the inner needle hub in the operating position against the biasing force of the spring, and an operating portion that releases the holding of the inner needle hub by the inner needle hub engaging portion in order to move the inner needle hub to the retracted position. The housing has a plurality of ribs that protrude radially inward and extend axially, The inner needle hub has a sliding portion that slides while in contact with the rib from the usage position to the retracted position, An indwelling needle assembly wherein the rib has a portion configured such that the frictional force generated between it and the sliding portion decreases in the direction of movement from the use position to the retraction position.

2. The indwelling needle assembly according to claim 1, wherein the surface of the rib facing the sliding portion is a curved surface that is concave radially outward, and the sliding portion has a curved surface that is complementary to the curved surface.

3. The operating part is an operating button, the operating button has a finger rest formed by a recess, and the inner needle hub engaging part is located directly below the recess. The indwelling needle assembly according to claim 1, wherein pressing the operation button causes the inner needle hub engaging portion to move in a direction perpendicular to the axis of the housing, thereby releasing the retention of the inner needle hub.

4. The outer needle hub has a valve unit located inside, The valve unit comprises a hemostatic valve, a plunger that opens the hemostatic valve, and a plunger guide that guides the movement of the plunger. The plunger has a tip that gradually tapers towards the front and a shaft provided at the base end of the tip. The shaft portion has protrusions projecting to both sides, and a first plane and a second plane extending in the axial direction. The normals of the first plane and the second plane are perpendicular to the protruding direction of the convex portion. The aforementioned protrusion is provided on the cylindrical portion of the shaft, The protruding end face of the convex portion faces the inner surface of the outer needle hub or the inner surface of the plunger guide. The indwelling needle assembly according to claim 1, wherein the first plane and the second plane face a guide plane provided on the plunger guide.

5. Housing and A catheter unit having an outer needle and an outer needle hub is positioned at the tip of the housing, An inner needle unit having an inner needle and an inner needle hub inserted through the outer needle, The system includes a safety mechanism that moves the inner needle hub from a use position in which the inner needle protrudes from the tip of the outer needle and is capable of puncturing, to a retracted position in which the inner needle is housed within the housing, The aforementioned safety mechanism is A spring that biases the aforementioned inner needle hub toward the base end, An inner needle hub engaging portion that releasably holds the inner needle hub in the operating position against the biasing force of the spring, It has an operating button connected to the inner needle hub engagement portion and exposed to the outside of the housing, The aforementioned operation button has a finger rest formed by a recess, The inner needle hub engaging portion is located directly below the recess, An indwelling needle assembly in which, by pressing the aforementioned operating button, the inner needle hub engaging portion moves in a direction perpendicular to the axis of the housing, thereby releasing the retention of the inner needle hub.

6. A catheter unit having an outer needle and an outer needle hub, The unit comprises an inner needle unit having an inner needle inserted through the outer needle and an inner needle hub, The outer needle hub has a valve unit located inside, The valve unit comprises a hemostatic valve, a plunger that opens the hemostatic valve, and a plunger guide that guides the movement of the plunger. The plunger has a tip that gradually tapers towards the front and a shaft provided at the base end of the tip. The shaft portion has protrusions projecting to both sides, and a first plane and a second plane extending in the axial direction. The normals of the first plane and the second plane are perpendicular to the protruding direction of the convex portion. The aforementioned protrusion is provided on the cylindrical portion of the shaft, The protruding end face of the convex portion faces the inner circumferential surface of the outer needle hub or the inner circumferential surface of the plunger guide. The indwelling needle assembly wherein the first plane and the second plane face the guide plane provided on the plunger guide.

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