JP7722809B2 - indwelling needle - Google Patents

Description

The present invention relates to an indwelling needle that is inserted into a blood vessel and placed therein, and in particular to one that has a safety mechanism.

Indwelling needles have been developed for use in intravenous drips, blood sampling, etc. (see, for example, Patent Document 1).

U.S. Pat. No. 5,779,679

However, in the case of the indwelling needle 1 shown in Patent Document 1, a force is constantly acting from the spring 15 to the needle holding portion 14 in the state shown in Figure 1. Therefore, for example, when the needle holding portion 14 transitions from the state shown in Figure 1 to the state shown in Figure 2, a force constantly acts on the protrusion 40, bending it in a direction toward the central axis of the needle 16. Therefore, it is thought that the extension portion where the U-shaped arm 38 extends from the main body of the needle holding portion 14 will undergo plastic deformation in a direction approaching the central axis.

When the extending portion undergoes plastic deformation in this manner, the state shown in FIG. 1 of Patent Document 1 transitions to the state shown in FIG. 2 of Patent Document 1, and when the protrusion 40 enters the opening 48, it is thought that the protrusion 40 may not fully return in a direction away from the central axis. This is likely to reduce the degree of engagement between the protrusion 40 and the opening 48. In such cases, the protrusion 40 may not be engaged in the opening 48 as desired, and there is a risk that the needle 16 may fall out of the opening 23 of the body 12. As a result, it may be difficult to securely store the needle 16 in the body 12.

The present invention aims to provide technology that improves the accuracy of the operation of a safety mechanism in an indwelling needle that has a safety mechanism that houses the needle exposed from the tip.

To solve the above-mentioned problems, the present invention adopts the following configuration.

That is, an indwelling needle according to one aspect of the present invention comprises a hollow needle; a housing portion which is a substantially tubular member having a hollow portion capable of housing the hollow needle; a movable member which supports the base end of the hollow needle and is disposed inside the housing portion and is capable of moving the hollow portion from a first position where the hollow needle protrudes from an opening of the hollow portion at one end of the housing portion to a second position where the hollow needle is housed in the hollow portion of the housing portion; a spring which biases the movable member in a direction from the first position toward the second position; and an engagement mechanism which causes the movable member to engage with the housing portion at the first position and the second position, wherein the engagement mechanism has an engaging portion which is provided on the movable member and extends in a direction away from the central axis, a first engaged portion which is provided on a side surface of the housing portion and engages with the engaging portion at the first position, and a second engaged portion which engages with the engaging portion at the second position, wherein the distance from the central axis to the second engaged portion is shorter than the distance from the central axis to the first engaged portion.

This configuration reduces the load on the engaging portion at the first position, while ensuring a sufficient amount of engagement when the engaging portion engages with the second engaged portion. Therefore, when the hollow needle moves from the first position, where it protrudes from the opening of the hollow portion, to the second position, where it is housed in the hollow portion, the engaging portion can be more reliably engaged with the second engaged portion, improving the accuracy with which the hollow needle is housed in the housing portion.

In the indwelling needle according to the above aspect, the surface of the second engaged portion facing the base end surface of the engaging portion has a surface that extends in a direction approaching the central axis as it moves toward the tip of the hollow needle, and the base end surface of the engaging portion may engage with the second engaged portion at a second position.

This configuration further reduces the likelihood of the engagement portion moving beyond the second position in the proximal direction.

In the indwelling needle according to the above aspect, the opposing surface of the first engaged portion or the second engaged portion that faces the base end surface of the engaging portion may have a convex portion extending toward the tip, and the engaging portion may have a concave portion on the base end surface of the engaging portion that corresponds to the convex portion.

With this configuration, the engaging portion is fixed by the concave and convex portions, so in the first position, the engaging portion is prevented from deforming in a direction approaching the central axis due to spring pressure. Furthermore, in the second position, the engaging portion is prevented from bending in a direction approaching the central axis and disengaging from the second engaged portion.

In the indwelling needle according to the above aspect, the opposing surface of the first engaged portion that faces the base end surface of the engaging portion may extend in a direction approaching the central axis and toward the tip, and the base end surface of the engaging portion may engage with this opposing surface.

With this configuration, the engaging portion makes surface contact with the first engaged portion, allowing the spring pressure to be received by the surface, reducing damage such as deformation or breakage of the engaging portion due to constant spring pressure.

In the indwelling needle according to the above aspect, the distance between the inner wall of the storage compartment and the central axis between the first and second engaged portions may be at least partially longer than the distance between the first engaged portion and the central axis and may also be longer than the distance between the second engaged portion and the central axis.

This configuration reduces sliding resistance when the engagement portion moves through the storage portion.

In the indwelling needle according to the above aspect, the free end of the engagement portion may have a shape in which the tip side protrudes in a direction away from the central axis.

This configuration reduces the resistance felt when the engagement portion slides within the storage portion.

In the indwelling needle according to the above aspect, the distal wall of the engagement portion may have a shape that protrudes toward the distal end as it moves away from the central axis.

This configuration makes it less likely that the engagement portion will come into contact with the hollow needle and the axis of the moving member when it moves in a direction approaching the central axis.

Furthermore, an indwelling needle according to one aspect of the present invention includes a hollow needle; a housing portion which is a substantially tubular member having a hollow portion capable of housing the hollow needle; a movable member which supports the base end of the hollow needle and is disposed inside the housing portion and is capable of moving the hollow portion from a first position where the hollow needle protrudes from an opening of the hollow portion at one end of the housing portion to a second position where the hollow needle is housed in the hollow portion of the housing portion; a spring which biases the movable member in a direction from the first position to the second position; and an engaging mechanism for engaging the accommodating portion at a first position, the engaging mechanism having an engaging portion that is provided on the movable member and extends in a direction away from the central axis, a first engaged portion that is provided on a side surface of the accommodating portion and engages with the engaging portion at the first position, and a second engaged portion that engages with the engaging portion at the second position, wherein a notch is provided in a side surface of the accommodating portion that is angled with the side surface on which the first engaged portion and the second engaged portion are provided, along a direction from the first position to the second position.

With this configuration, the provision of the notch makes it easier for the wall surface that comes into contact with the moving member when it moves in the storage section to bend in a direction away from the central axis. This reduces the frictional resistance that the moving member experiences from the wall surface of the storage section when the moving member slides. This allows the sliding section to move smoothly from the first position to the second position. It also reduces the biasing force of the spring that biases the moving member in the movement direction. This prevents the engaging section, which is provided on the moving member and engages with the first engaged section and second engaged section of the storage section, from being deformed by constant spring pressure. As a result, it is possible to improve the reliability of operation of the safety mechanism in the indwelling needle.

In the indwelling needle according to the above aspect, at least a portion of the inner wall of the side surface of the storage section against which the engaging portion abuts may have an inclined surface that slopes away from the central axis as it moves from the first position to the second position.

With this configuration, the inner wall of the storage section expands smoothly, reducing the frictional resistance that the moving member experiences from the inner wall of the side surface of the storage section when the moving member moves from the first position to the second position. This allows the sliding section to move smoothly from the first position to the second position. Furthermore, when biasing the moving member in the direction of movement, the biasing force can be reduced.

In the indwelling needle according to the above aspect, the movable member may further have a guide portion that protrudes away from the central axis or is recessed toward the central axis, and the storage portion may further have a guided portion that engages with the guide portion.

With this configuration, when the engaging portion disengages from the first engaged portion and moves to the second engaged portion, the moving member can move smoothly without rattle, ensuring that the engaging portion is reliably guided to the second engaged portion.

In the indwelling needle according to the above aspect, the movable member may further have a rib that prevents the movable member from moving relative to the housing portion in the distal direction when in the first position.

This configuration prevents the movable member from moving relative to the housing portion from the first position toward the distal end without using the engagement portion.

This invention improves the accuracy of device operation when storing the needle exposed from the tip of the indwelling needle within the device.

1 shows an example of an outline of an indwelling needle according to an embodiment. (A) is a schematic front view and a side view of the indwelling needle. (B) is an example of a cross-sectional view taken along the arrows A-A in (A). 2A and 2B are schematic diagrams illustrating an example of an outline of a body. FIG. 2A shows an example of a perspective view of the body. FIG. 2B shows an example of a cross-sectional view of the body taken along the line A-A in FIG. 2A. FIG. 2C shows an example of a cross-sectional view of the body taken along the line B-B in FIG. 2A. FIG. 3 shows an enlarged view of a portion near the engaging portion. Figure 4 shows an overview of the ribs. Figure 4(A) shows a perspective view of the hub on which the ribs are provided. Figure 4(B) shows a top view of the hub on which the ribs are provided. Figure 4(C) shows a cross-sectional view of the hub on which the ribs are provided housed in the body. 5A and 5B show an example of a procedure for releasing the indwelling needle shown in Fig. 1 from its initial state and storing the needle in the body. (A) shows a front view of the indwelling needle. (B) shows a cross-sectional view of (A). 6A and 6B show an example of an outline of the locked state, in which (A) shows a front view of the indwelling needle, and (B) shows a cross-sectional view of (A). 7A and 7B show an example of an outline of an indwelling needle according to a modified example. (A) shows a front view and a side view of the indwelling needle. (B) shows a cross-sectional view along the arrow A-A in (A).

The following describes an embodiment of the present invention. The embodiment described below is an example of an embodiment of the present invention, and does not limit the technical scope of the present invention to the following aspects.

<Equipment configuration>
FIG. 1 shows an example of the configuration of an indwelling needle 51 according to an embodiment of the present invention. FIG. 1(A) shows a front view and a side view of the indwelling needle 51. FIG. 1(B) shows a cross-sectional view along the arrow A-A in FIG. 1(A). As shown in FIG. 1, the indwelling needle 51 includes a hollow needle 52, a body 53 that houses the needle 52, and a hub 55 that is disposed inside the body 53 and holds the base end of the needle 52. Herein, the body 53 is an example of a "housing portion" in the present invention. The hub 55 is an example of a "moving member" in the present invention. Hereinafter, the left side of the indwelling needle 51 in FIG. 1 will also be referred to as the tip side, and the right side as the rear side. The up and down directions in FIG. 1(B) will also be referred to as the upper side and the lower side, respectively. The side perpendicular to the plane of the paper in FIG. 1 will also be referred to as the right side, and the side perpendicular to the plane of the paper will also be referred to as the left side. The state of the indwelling needle during use in FIG. 1 will also be referred to as the initial state. Furthermore, the state in which the needle 52 is housed in the body 53 after the initial state shown in FIG. 5 (described later) is released will hereinafter also be referred to as a locked state.

2A and 2B are schematic diagrams illustrating an example of the outline of the body 53 forming the indwelling needle 51. Fig. 2A shows a perspective view of the body 53. Fig. 2B shows an example of a cross-sectional view of the body 53, taken along the arrows A-A in Fig. 2A. Fig. 2C shows an example of a cross-sectional view of the body 53, taken along the arrows B-B in Fig. 2A. As shown in Fig. 2A, the body 53 is formed from a cylindrical distal end portion 53A and a main body portion 53B located rearward of the distal end portion 53A and having a hollow portion communicating with the hollow portion of the distal end portion 53A. The main body portion 53B is a cylindrical portion having a cross section that is approximately rectangular with rounded corners when viewed axially. When the indwelling needle 51 is used, the body 53 is fixed to the patient's skin so that the lower portion of the body 53 in Fig. 2C comes into contact with the skin. By fixing the body 53 in this manner, the difference in level between the needle and the skin when the body 53 is fixed to the skin can be reduced, reducing the adverse effects of the metal needle on blood vessels. Furthermore, as shown in FIG. 2(C), the flat underside of the body 53 contributes to stabilizing the body 53 when it is fixed to the skin. Furthermore, the curved (rounded) sides of the body 53 prevent damage to the skin. Furthermore, the body 53 has openings on both ends along the central axis 60. Of the openings at both ends, the tip-side opening 54 is large enough to allow the needle 52 and the tip portion 55A of the hub 55 that holds the base end of the needle 52 to pass through.

The body 53 also includes a first engagement hole 58 that engages with an engagement portion 57 (described later) of the hub 55 to hold the needle 52 stationary when the needle 52 protrudes from the opening 54. The first engagement hole 58 is provided on the distal end side of the main body portion 53B, on the upper and lower surfaces relative to the central axis 60. As shown in FIG. 2B , a base-end surface 70 forming the first engagement hole 58 extends toward the central axis 60 and toward the distal end of the body 53. The base-end surface 70 also includes a protrusion 72 extending toward the distal end of the body 53. The base-end surface 70 is an example of a "first engaged portion" of the present invention, and the first engagement hole 58 includes the "first engaged portion" of the present invention. The portion facing the proximal end surface of the engaging portion may be formed by providing a protrusion, or the portion facing the proximal end surface of the engaging portion may be formed by providing a groove. The base-end surface 70 is also an example of a "facing surface of the first engaged portion facing the proximal end surface of the engaging portion" of the present invention.

The body 53 also has a second engagement hole 61 on the movement direction side of the first engagement hole 58. The base end surface 73 that forms the second engagement hole 61 extends in the direction of the central axis 60 toward the tip of the body 53. The base end surface 73 may also be provided with a convex portion similar to the convex portion 72 provided on the base end surface 70. Here, the base end surface 73 is an example of a "second engagement portion" in the present invention, and the second engagement hole 61 includes a "second engaged portion" in the present invention. The base end surface 73 is also an example of a "surface of the second engaged portion facing the engaging portion base end surface" in the present invention.

More specifically, the second engagement holes 61 are provided on the rear end of the main body portion 53B, on the upper and lower surfaces relative to the central axis 60. The first engagement holes 58 and second engagement holes 61 penetrate the upper and lower walls of the body 53. Furthermore, the first engagement holes 58 and second engagement holes 61 are provided so that the distance X between the second engagement holes 61 and the central axis 60 is shorter than the distance Y between the first engagement holes 58 and the central axis 60.

The body 53 also has notches 65 formed along the movement direction between the first engagement holes 58 and the second engagement holes 61. As shown in Figure 2 (C), a total of four notches 65 are provided, located on both sides of the two first engagement holes 58 and the two second engagement holes 61 (on the left and right sides of the body 53).

In addition, in this embodiment, the first engagement hole 58 and the second engagement hole 61 are provided so as to open in the vertical direction on the arc-shaped surface of the rounded rectangular outer shape of the main body portion 53B, while the notch 65 is provided on a surface that has an angle (angle around the central axis of the body 53) with the surface on which the first engagement hole 58 and the second engagement hole 61 are provided. More specifically, the notch 65 is provided on the arc-shaped surface that sandwiches the surface on which the first engagement hole 58 and the second engagement hole 61 are provided (opening), and is closer to the portion having the linear outer shape. Furthermore, the notch 65 may open so that its axis is perpendicular to the outer shape of the main body portion 53B, or it may open so that its axis is perpendicular to the normal to the first engagement hole 58 and the second engagement hole 61.

In Figure 2 (A), the first engagement hole 58 and the second engagement hole 61 appear to be located on different surfaces of the exterior of the body 53, but they both open in the vertical direction in Figure 1 and are located on the same surface. However, in the present invention, the surfaces on which the first engagement hole and the second engagement hole are located do not have to be exactly the same surface; if they are located on slightly different surfaces, the surfaces on which the first engagement hole and the second engagement hole are located refer to surfaces that are included in the area defined by these two surfaces.

The body 53 also includes a pressing arm 66 that branches off from the main body and presses the engagement portion 57 in a direction toward the central axis 60 of the body 53. The pressing arm 66 is an example of a "pressing member" in the present invention, and can be bent in a direction toward the central axis 60, with the connection portion 62 with the body 53 as a fixed end. The tip of the pressing arm 66 is provided with a pressing portion 64 that protrudes in a direction toward the central axis 60. The pressing portion 64 is displaced in a direction toward the central axis 60 as the pressing arm 66 bends in a direction toward the central axis 60.

Furthermore, when the engagement portion 57 moves, it abuts against the inner surface 68 of the main body portion 53B of the body 53 (details will be described later), and a sloped surface 67 is formed in a portion of the tip side of the inner surface 68, sloping away from the central axis 60 as it moves in the direction of movement. The distance between the central axis 60 and the inner surface 68 is longer than the distance between the base end wall of the first engagement hole 58 and the central axis 60 and the distance between the base end wall of the second engagement hole 61 and the central axis 60. Furthermore, the shape of the body 53 may be such that the distance between the central axis 60 and a portion of the inner surface 68 is longer than the distance between the first engagement hole 58 and the central axis 60 and the distance between the second engagement hole 61 and the central axis 60.

On the other hand, as shown in FIG. 1, the hub 55 is a hollow member that extends in the direction of movement and is open at both ends in that direction. The hub 55 is formed from a tip portion 55A located at the tip side and supporting the needle 52, a main body portion 55B located rearward of the tip portion 55A, and a rear end portion 55C located further rearward from the main body portion 55B. The needle 52 is fixed to the hub 55 with its base end inserted into the opening of the tip portion 55A of the hub 55. In other words, the hollow portion of the hub 55 and the hollow portion of the needle 52 are in communication. By connecting the needle 52 and the hub 55 in this way, for example, by supplying a medicinal solution from the rear end portion 55C of the hub 55, the medicinal solution can be supplied into the patient's body via the hollow portions of the hub 55 and needle 52.

The hub 55 also has a flexible extension portion 56 that branches off from the main body portion 55B and extends toward the tip. The tip of the extension portion 56 is provided with an engagement portion 57 that protrudes away from the central axis 60 and is engageable with the first engagement hole 58 and the second engagement hole 61. The engagement portion 57 can be positioned farther away from the inner surface 68 of the body 53 when viewed from the central axis 60, and engages with the first engagement hole 58 and the second engagement hole 61. In this embodiment, the position of the hub 55 when the engagement portion 57 is engaged with the first engagement hole 58 corresponds to the first position. The position of the hub 55 when the engagement portion 57 is engaged with the second engagement hole 61 corresponds to the second position.

Figure 3 also illustrates an enlarged partial view of the vicinity of the engaging portion 57 of the main body portion 55B. As shown in Figure 3, the free end of the engaging portion 57 has a distal end surface 74 that protrudes in a direction away from the central axis 60. The proximal end surface 75 of the engaging portion 57 has a recess 76 that recesses toward the distal end. In the initial state, the proximal end surface 75 engages in surface contact with the proximal end surface 70 of the first engaging hole 58. During engagement, the recess 76 engages with the protrusion 72 provided on the proximal end surface 70. In the locked state, the proximal end surface 75 engages in surface contact with the proximal end surface 73 of the second engaging hole 61. The proximal end surface 75 is an example of the "engaging portion proximal end surface" of the present invention.

Furthermore, when the engagement portion 57 is pressed, for example, from a direction away from the central axis 60 to a direction toward the central axis 60, the extension portion 56 bends toward the central axis 60, with the connection portion 63 with the main body of the hub 55 serving as the fixed end. This allows the engagement portion 57 to move toward the central axis 60 and disengage from the first engagement hole 58 and the second engagement hole 61.

The hub 55 also includes a rib 69 on its main body 55B that protrudes away from the central axis 60. FIG. 4 shows an overview of the rib 69. FIG. 4(A) shows a perspective view of the hub 55 when the rib 69 protrudes upward. FIG. 4(B) shows a top view of the hub 55 when the rib 69 protrudes upward. FIG. 4(C) is a cross-sectional view of the hub 55 along the arrows X-X in FIG. 4(B), showing the hub 55 housed in the body 53. As shown in FIG. 4, the rib 69 protrudes away from the central axis 60. The rib 69 is arranged along the central axis 60. While the rib 69 is provided on the top surface of the hub, it can also be provided on the bottom surface of the hub. Meanwhile, a groove 79 that guides the rib 69 is formed on the inner surface of the main body 53B of the body 53. The rib 69 and the groove 79 abut against each other. A tip wall 80 is provided at the tip of the groove 79, perpendicular to the direction of movement. The tip of the rib 69 abuts against the tip wall 80. Therefore, when the hub 55 moves in the direction of movement, the hub 55 is guided by the groove 79 and the rib 69 formed on the inner surface of the main body portion 53B of the body 53. This ensures that the engaging portion 57 is guided into the second engaging hole 61. Furthermore, because the tip of the rib 69 abuts against the tip wall 80, relative movement of the hub 55 relative to the body 53 is prevented from moving distally from the initial state. Note that the tip wall 80 may be located a predetermined distance distally from the tip position of the rib 69 in the initial state. In such a structure, the hub 55 is allowed to move distally relative to the body 53 from the initial state, but it is preferable that the tip surface 74 of the engaging portion 57 does not or is unlikely to hit the body. This prevents the engaging portion 57 from hitting the body, resulting in deformation or damage. Here, the rib 69 is an example of a "guide portion" in the present invention. 4C , holes penetrating in a direction approaching the central axis 60 may be provided instead of the grooves 79. Alternatively, grooves may be provided on the outer surface of the hub 55, and protrusions may be provided on the inner surface of the body 53.

The indwelling needle 51 also includes a coil spring 59 that biases the hub 55 in the direction of movement. In other words, the engagement portion 57 is biased in the direction of movement by the coil spring 59.

<Explanation of accommodation flow>
Next, the process of storing the needle 52 of the indwelling needle 51 in the body 53 will be described. Figure 5 shows an example of the procedure for releasing the initial state of the indwelling needle 51 shown in Figure 1 and storing the needle 52 in the body 53 to transition to a locked state. Figure 5(A) shows an example of a front view and a side view of the indwelling needle 51. Figure 5(B) shows a cross-sectional view of Figure 5(A).

As shown in FIG. 5 , first, the user applies force to the pressing arm 66 in a direction toward the central axis 60, causing the pressing arm 66 to bend, and the pressing portion 64 and the engagement portion 57 to come into contact. The engagement portion 57 is then pressed by the pressing portion 64 in a direction toward the central axis 60. At this time, the recess 76 of the engagement portion 57 and the protrusion 72 of the body 53 are engaged. Therefore, unless a force greater than a predetermined value acts on the engagement portion 57 in a direction toward the central axis 60, the protrusion 72 will not disengage from the recess 76. When a force greater than a predetermined value acts on the engagement portion 57 in a direction toward the central axis 60, the protrusion 72 disengages from the recess 76, and the extension portion 56 bends in a direction toward the central axis 60, with the coupling portion 63 as the fixed end. The entire engagement portion 57 then disengages from the first engagement hole 58. When the engaging portion 57 disengages from the first engaging hole 58, the tip surface 74 of the engaging portion 57 is inclined toward the tip as it moves away from the central axis 60, thereby preventing contact with the main body portion 55B of the hub 55. Furthermore, because the hub 55 is biased in the movement direction by the coil spring 59, when the engaging portion 57 disengages from the first engaging hole 58, the hub 55 moves from the tip to the rear end. At this time, an elastic force acts on the engaging portion 57, restoring it in the direction away from the central axis 60, so the engaging portion 57 moves in the movement direction while abutting against the inner surface of the body 53.

When the engaging portion 57 moves in the direction of movement while abutting against the inner surface of the body 53, the engaging portion 57 first slides along the inclined surface 67 of the body 53. As shown in FIG. 2(B), the inclined surface 67 is inclined away from the central axis 60 as it moves in the direction of movement. Therefore, as the engaging portion 57 slides along the inclined surface 67, the frictional force applied to the engaging portion 57 by the inclined surface 67 gradually decreases. The engaging portion 57 then moves while abutting against the inner surface 68 (see FIGS. 2(B) and 2(C)) located rearward of the inclined surface 67, and reaches the second engaging hole 61. When the engaging portion 57 reaches the second engaging hole 61, the restoring force of the bent extension portion 56 causes the engaging portion 57 to fit into the second engaging hole 61, thereby locking the engaging portion 57 into the second engaging hole 61.

The indwelling needle 51 also has a notch 65 formed along the direction of movement on a surface sandwiching the surface of the main body 53B where the first engagement hole 58 and the second engagement hole 61 are formed. When the engagement portion 57 slides over the inner surface 68, including the inclined surface 67, of the body 53, the inner surface 68, including the inclined surface 67, bends so as to bulge in a direction away from the central axis 60 (as indicated by the arrow in Figure 5(B)). This also reduces the frictional force applied to the engagement portion 57 from the inner surface 68 when the engagement portion 57 slides over it. The notch 65 is formed in a position sufficiently close to the first engagement hole 58 and the second engagement hole 61 so that the inner surface 68 can easily bend when the engagement portion 57 slides over the inner surface 68, including the inclined surface 67 of the body 53.

Figure 6 shows an example of an outline of the locked state. Figure 6(A) shows a front view and a side view of the indwelling needle 51. Figure 6(B) shows a cross-sectional view of Figure 6(A). As shown in Figure 6, in the locked state, the needle 52 is housed inside the body 53.

Even in the locked state, the hub 55 is biased in the direction of movement by the coil spring 59. However, the second engagement hole 61 is arranged so that the distance X between the second engagement hole 61 and the central axis 60 is shorter than the distance Y between the first engagement hole 58 and the central axis 60. This increases the engagement between the engagement portion 57 and the second engagement hole 61, preventing the engagement portion 57 from disengaging from the second engagement hole 61 in the locked state.

[Actions and Effects]
In the indwelling needle 51 described above, the extension portion 56 provided on the hub 55 bends toward the central axis 60, causing the engagement portion 57 to disengage from the first engagement hole 58. The hub 55 then moves in the movement direction due to the biasing force of the coil spring 59 in the movement direction. The disengaged engagement portion 57 moves while abutting against the inner surface 68 of the body 53, reaches the second engagement hole 61, and engages with the second engagement hole 61. Here, the distance X between the second engagement hole 61 and the central axis 60 is shorter than the distance Y between the first engagement hole 58 and the central axis 60. Therefore, in the first position, the extension portion 56 is in a natural state or is slightly bent toward the central axis 60 due to the pressure of the coil spring 59. Meanwhile, in the second position, the extension portion 56 is more bent toward the central axis 60 than in the first position. In other words, in the first position, the extension portion 56 is not excessively bent, and the load on the engagement portion 57 is suppressed. Therefore, the user does not need to press the engaging portion 57 excessively to disengage it from the first engaging hole 58, making it relatively easy to transition the needle 52 to the locked state. On the other hand, once the engaging portion 57 engages with the second engaging hole 61, a stronger restoring force acts on the engaging portion 57 in a direction away from the central axis 60 than when the engaging portion 57 engages with the first engaging hole 58. This prevents the engaging portion 57 from easily disengaging from the second engaging hole 61. This improves the reliability with which the needle 52 and hub 55 are accommodated in the body 53 when transitioning from the initial state to the locked state. It is preferable that the engaging portion be accommodated within the second engaging hole 61 in the second position. If the engaging portion extends outside the second engaging hole 61, the engaging portion can be pressed from the outside, which is undesirable from a safety perspective.

Furthermore, with the indwelling needle 51 described above, even if the engaging portion 57 or the extending portion 56 is plastically deformed in a direction approaching the central axis 60 due to the long-term biasing force exerted by the coil spring 59 in the initial state, the engagement between the engaging portion 57 and the second engaging hole 61 is large, preventing the engaging portion 57 from disengaging from the second engaging hole 61. This improves the reliability with which the needle 52 and hub 55 are housed in the body 53.

Furthermore, with the indwelling needle 51 as described above, the recess 76 of the engaging portion 57 and the protrusion 72 of the hub 55 are engaged in the initial state. Therefore, even if the user accidentally presses the engaging portion 57 in a direction approaching the central axis 60 without intending to insert the needle 52 into the body 53,
The engaging portion 57 is prevented from coming off the first engaging hole 58. Furthermore, the engagement between the recessed portion 76 and the protruding portion 72 prevents the engaging portion 57 from being deformed in a direction approaching the central axis 60 due to the spring pressure of the coil spring 59.

Furthermore, with the indwelling needle 51 described above, when the engaging portion 57 is engaged with the first engaging hole 58 in the initial state, the base end surface 70 of the first engaging hole 58 is in surface contact with the base end surface 75 of the body 53. This allows the biasing force of the coil spring 59 to be received by the base end surface 75, reducing damage such as breakage of the engaging portion 57 due to the constant pressure of the coil spring 59.

Furthermore, with the indwelling needle 51 described above, the notch 65 is provided along the direction of movement on a surface sandwiching the surface on which the first engagement hole 58 and the second engagement hole 61 are provided. Therefore, when the hub 55 slides on the inner surface 68 of the body 53, the inclined surface 67 or the inner surface 68 is more likely to bend in a direction away from the central axis 60. This reduces the frictional resistance that the engagement portion 57 of the hub 55 experiences from the inclined surface 67 or the inner surface 68 of the body 53.

Furthermore, by reducing the frictional resistance that the engaging portion 57 of the hub 55 experiences from the inclined surface 67 or inner surface 68 of the body 53, the biasing force of the coil spring 59 can be reduced, and plastic deformation of the engaging portion 57 or extension portion 56 in a direction approaching the central axis 60 can be suppressed. This also prevents the engaging portion 57, once engaged with the second engaging hole 61, from disengaging from the second engaging hole 61, improving the accuracy with which the needle 52 and hub 55 are housed in the body 53.

In addition, the distance between the central axis 60 and the inner surface 68 is longer than the distance between the first engagement hole 58 and the central axis 60 and the distance between the second engagement hole 61 and the central axis 60. Therefore, when the engagement portion 57 disengages from the first engagement hole 58, it initially bends toward the central axis 60, but the amount of bending is reduced when it is in contact with the inner surface 68. In other words, the degree to which the biasing force acting on the engagement portion 57 in the direction away from the central axis 60 is reduced. This also reduces the frictional resistance acting on the engagement portion 57 from the inner surface 68 when the engagement portion 57 moves in the movement direction.

Furthermore, because the engagement portion 57 is a free end, when the hub 55 moves in the movement direction inside the body 53, the engagement portion 57 moves smoothly along the inner surface 68. This prevents the engagement portion 57 from rattling, reducing the distance required to move the needle 52 and hub 55. Furthermore, the tip surface 74 of the engagement portion 57 has a shape that protrudes away from the central axis. Therefore, as shown in FIG. 6, in the locked state, the engagement portion 57 and the tip wall 78 of the second engagement hole 61 face each other. Therefore, even if a force acting to move the hub 55 in the distal direction acts on the hub 55 in the locked state, the hub 55 comes into contact with the tip wall 78, thereby preventing the hub 55 from moving in the distal direction.

Furthermore, with the indwelling needle 51 described above, the proximal end surface 73 forming the second engagement hole 61 extends in a direction approaching the central axis 60 and toward the distal end of the body 53. This prevents the engagement portion 57 from disengaging from the second engagement hole 61 in the locked state. This prevents the needle 52 and hub 55 from moving in the proximal direction and falling out of the opening in the body 53 located in that proximal direction.

Furthermore, in the above embodiment, the tip portion 53A of the body 53 has a cylindrical shape, and the main portion 53B is a tubular member having a vertically elongated rounded rectangular cross section, but the shape of the body 53 is not limited to this. The body 53 may have any shape, as long as the tip portion 53A and the main portion 53B have hollow portions capable of accommodating the needle 52 and the hub 55, such as a rectangular or elliptical shape with chamfered corners. The number of notches 65 is not limited. The notches 65 may be positioned so that the inclined surface 67 or the inner surface 68 of the body 53 bends away from the central axis 60 when the hub 55 slides over the inner surface 68 of the body 53.

<Modification>
FIG. 7 shows an overview of an indwelling needle 51A according to a modified example. FIG. 7(A) is a front view and a side view of the indwelling needle 51A. FIG. 7(B) is a cross-sectional view along the arrows A-A in FIG. 7(A). The hub 55 of the indwelling needle 51A does not have the rib 69 shown in FIG. 4. With this indwelling needle 51A, if the engaging portion 57 is unintentionally pushed toward the central axis 60, the engaging portion 57 may strike the distal wall of the first engaging hole 58 with force, potentially damaging the engaging portion 57. In this case, when the hub 55 is returned to its initial position by the coil spring 59, the protruding portion 72 may not engage with the recessed portion 76, potentially compromising the stability of the engaging portion 57 in its initial position. Therefore, in the indwelling needle 51A, a portion of the outer surface of the distal wall 81 of the first engaging hole 58 is cut out. With this indwelling needle 51A, the engaging portion 57 is prevented from coming into contact with the distal wall 81 of the first engaging hole 58 when the engaging portion 57 is pressed in a direction approaching the central axis 60. Therefore, even when the engaging portion 57 is moved from the initial position toward the distal end and then returned to the initial position, the engagement between the recessed portion 76 of the engaging portion 57 and the protruding portion 72 is stably performed. From the viewpoint of formability, the partial cutout on the outer surface of the distal wall 81 of the first engaging hole 58 may be tapered so that the outer surface tapers in a direction approaching the central axis toward the base end.

The embodiments and variations disclosed above can be combined with each other.

1: Indwelling needle; 2: Needle; 3: Body; 3B: Main body; 4: Opening; 5: Hub; 5A: Tip; 5B: Main body; 6: Extension; 7: Engagement portion; 8: First engagement hole; 9: Coil spring; 10: Central shaft; 11: Second engagement hole; 14: Pressing portion; 15: Pressing arm; 16: Inner surface; 51: Indwelling needle; 52: Needle; 53: Body; 53A: Tip; 53B: Main body; 54: Opening; 55: Hub; 55A: Tip; 55B: Main body 55C: Rear end; 56: Extension; 57: Engagement portion; 58: First engagement hole; 59: Coil spring; 60: Center axis; 61: Second engagement hole; 62: Connecting portion; 63: Connecting portion; 64: Pressing portion; 65: Notch; 66: Pressing arm; 67: Inclined surface; 68: Inner surface; 69: Rib; 70: Base end surface; 72: Convex portion; 73: Base end surface; 74: Distal end surface; 75: Base end surface; 76: Recess; 78: Distal end wall; 79: Groove; Distal end wall 80; Distal end wall 81

Claims (11)

A hollow needle,
a housing portion that is a substantially cylindrical member having a hollow portion capable of housing the hollow needle;
a moving member that supports the base end of the hollow needle and is disposed inside the housing portion, and that is capable of moving the hollow portion from a first position where the hollow needle protrudes from an opening of the hollow portion at one end of the housing portion to a second position where the hollow needle is housed in the hollow portion of the housing portion;
a spring that biases the moving member in a direction from the first position toward the second position;
an engagement mechanism that engages the moving member with the accommodation portion at the first position and the second position,
The engagement mechanism includes:
an engaging portion provided on the moving member, extending in a direction away from the central axis, and movable in the direction of the central axis when pressed;
a first engaged portion provided on a side surface of the accommodation portion and engaging with the engaging portion at the first position;
a second engaged portion that engages with the engaging portion at the second position,
a distance from the central axis to the second engaged portion is shorter than a distance from the central axis to the first engaged portion;
the engaging portion prevents the moving member from moving in a proximal direction at the first position and the second position;
Indwelling needle. a surface of the second engaged portion facing the base end surface of the engaging portion has a surface that extends in a direction approaching the central axis as it moves toward the distal end of the hollow needle, and the base end surface of the engaging portion engages with the second engaged portion at the second position;
The indwelling needle according to claim 1. a surface of the first engaged portion or the second engaged portion facing the base end surface of the engaging portion has a protrusion extending toward a distal end direction,
The engaging portion has a recess corresponding to the protrusion on a base end surface of the engaging portion.
The indwelling needle according to claim 2. an opposing surface of the first engaged portion that faces the engaging portion base end surface extends toward the central axis and toward the tip end, and the engaging portion base end surface of the engaging portion engages with the opposing surface;
The indwelling needle according to claim 2 or 3. a distance between an inner wall of the accommodating portion and the central axis between the first engaged portion and the second engaged portion is at least partially longer than a distance between the first engaged portion and the central axis and a distance between the second engaged portion and the central axis;
The indwelling needle according to any one of claims 1 to 4. The free end of the engagement portion has a shape such that the tip side thereof protrudes in a direction away from the central axis.
The indwelling needle according to any one of claims 1 to 5. The distal end wall of the engagement portion has a shape that protrudes toward the distal end as it moves in a direction away from the central axis.
The indwelling needle according to any one of claims 1 to 6. a notch is provided in a side surface of the accommodation portion that is angled with a side surface on which the first engaged portion and the second engaged portion are provided, along a direction from the first position to the second position;
The indwelling needle according to claim 1. In the accommodation portion, at least a part of an inner wall of the side surface with which the engaging portion abuts has an inclined surface that inclines in a direction away from the central axis as it moves from the first position to the second position.
The indwelling needle according to claim 8. the moving member further includes a guide portion that protrudes in a direction away from the central axis or that is recessed in a direction toward the central axis,
The accommodation portion further includes a guided portion that engages with the guide portion.
The indwelling needle according to claim 8 or 9. The moving member further includes a rib that prevents the moving member from moving relative to the accommodating portion in a distal direction when the moving member is at the first position.
The indwelling needle according to claim 10.