JP7443738B2 - Syringe with safety mechanism - Google Patents

Description

The present invention relates to a syringe with a safety mechanism.

For example, European Patent No. 2,376,153 discloses a syringe with a safety mechanism that includes a syringe with a needle, a needle cap, an inner sleeve, and an outer sleeve. In this safety syringe, the needle cap is removed during use.

European Patent No. 2376153

In a syringe with a safety mechanism such as that described in European Patent No. 2,376,153, the outer sleeve may be used as a needle cover to prevent accidental stabbing after use. That is, in the above-mentioned syringe with a safety mechanism, after the syringe is used, the needle cover (outer sleeve) can be relatively displaced (slided) toward the needle with respect to the syringe to a protected position where the needle is surrounded. It is conceivable to configure it as follows. However, if the needle cover slides into the protected position and then returns to the use position where the needle is exposed, mis-sticks and the like may occur.

An object of the present invention is to provide a syringe with a safety mechanism that can prevent a needle cover from being displaced from a protected position to a use position.

A syringe with a safety mechanism according to one aspect of the present invention includes a syringe, a needle connected to a distal end of the syringe, a holder fixed to the syringe, and a surrounding area of the needle from a usage position where the needle is exposed. a needle cover movable relative to the syringe along the axial direction of the syringe toward a protective position surrounding the syringe, the holder configured to hold the needle cover in the use position; The needle cover in the protection position is locked from the inside in the radial direction to the needle cover in the protection position so that the needle cover is locked from the inside in the radial direction of the needle cover in the use position, and the needle cover is held in the protection position. At least one member of the holder and the needle cover has a protrusion that projects toward the other member of the holder and the needle cover, and the other member includes: The needle cover has a regulating portion that abuts on the protruding portion so as to prevent the needle cover from being displaced relative to the syringe along the axial direction of the syringe from the protection position to the use position.

In this syringe with a safety mechanism, at least one member of the holder and the needle cover has a protruding part, and the other member has a regulating part, so that the needle cover moves in the axial direction of the syringe from the protected position to the use position. The protrusion comes into contact with the restriction part when the protrusion is displaced relative to the syringe along the syringe. Therefore, displacement of the needle cover from the protection position to the use position is suppressed.

In the syringe with a safety mechanism, the holder has a guide protrusion that projects toward the needle cover, and the needle cover has a guide protrusion that allows the needle cover to be displaced from the use position toward the protection position. A guide groove for guiding the guide protrusion is sometimes provided, and the guide groove rotates the needle cover about the central axis of the syringe when the needle cover is displaced from the use position to the protection position. a guide surface having a shape, and an abutting surface that abuts the guide protrusion when the needle cover is displaced along the axial direction from the protection position toward the use position, and the guide protrusion is , the protrusion may constitute the protrusion, and the contact surface may constitute the restriction portion.

In this aspect, both stable movement of the needle cover from the use position to the protection position and suppression of displacement of the needle cover from the protection position to the use position are achieved by the guide protrusion.

Alternatively, in the syringe with a safety mechanism, the needle cover has a bulge that bulges toward the holder, and the holder is arranged in the axial direction with respect to the bulge of the needle cover in the protected position. It has a receiving part that faces the protruding part and comes into contact with the protruding part when the needle cover is displaced along the axial direction from the protection position toward the use position, and the protruding part The receiving portion may constitute the regulating portion.

In this case, the holder has a guide projection having a shape that projects toward the needle cover, and the needle cover has a guide protrusion that is disposed on the needle cover when the needle cover is displaced from the use position toward the protection position. A guide groove for guiding the guide protrusion is provided, and the guide groove has a shape that rotates the needle cover around the central axis of the syringe when the needle cover is displaced from the use position to the protection position. The holder has a guide surface, and the holder is formed at a position opposite to the bulged portion of the needle cover in the radial direction of the needle cover in the use position, and the needle cover is located in the protection position from the use position. a first wall portion that allows the needle cover to be displaced while rotating around the central axis of the syringe toward the syringe position; a second wall portion provided at a position adjacent to the first wall portion in the same direction as the direction in which the needle cover rotates around the central axis; It is preferable that the tip portion facing toward the protection position constitutes the receiving portion.

In this aspect, both smooth movement of the needle cover from the use position to the protection position and suppression of displacement of the needle cover from the protection position to the use position are achieved.

Furthermore, in this case, the holder further includes a first wall portion different from the first wall portion, and the locking portion is configured to be configured such that when the needle cover is displaced from the use position to the protection position. The needle cover is provided at a position adjacent to the other first wall portion in the same direction as the direction in which the needle cover rotates around the central axis of the syringe, and the bulging portion is formed when the needle cover is in the use position. a first longitudinal rib that faces the first wall portion and the needle cover in the radial direction when the needle cover is in the protected position, and that faces the second wall portion and the axial direction when the needle cover is in the protected position; and when the needle cover is located in the use position, the other first wall portion faces the needle cover in the radial direction, and when the needle cover is located in the protection position, the locking portion and a second vertical rib facing in the axial direction, and a distal end portion of the locking portion in a direction in which the needle cover faces from the use position to the protection position may constitute the receiving portion. preferable.

In this way, displacement of the needle cover from the protection position to the use position is more reliably suppressed.

The guide groove further includes a contact surface that comes into contact with the guide protrusion when the needle cover is displaced from the protection position toward the use position along the axial direction, and the guide protrusion includes: It is preferable that the protruding portion constitutes the above-mentioned protruding portion, and the abutting surface constitutes the restricting portion.

As described above, according to the present invention, it is possible to provide a syringe with a safety mechanism that can suppress displacement of the needle cover from the protection position to the use position.

FIG. 1 is a perspective view of a syringe with a safety mechanism according to an embodiment of the present invention. FIG. 2 is a perspective view of the syringe with safety mechanism shown in FIG. 1 with the cap removed. FIG. 6 is a perspective view of the needle cover in the protected position. FIG. 3 is a perspective view of the guide protrusion in contact with the contact surface. FIG. 2 is a cross-sectional view of the safety mechanism-equipped syringe shown in FIG. 1. FIG. FIG. 6 is a cross-sectional view of FIG. 5 with the cap removed. FIG. 7 is a sectional view showing a state in which the needle cover is slightly displaced from FIG. 6 toward the needle cover protection position. FIG. 3 is a cross-sectional view of the needle cover in the protective position. It is a perspective view of a holder. 5 is a cross-sectional view taken along the line XX shown in FIG. 4. FIG. 5 is a sectional view taken along the line XI-XI shown in FIG. 4. FIG. FIG. 3 is a perspective view of the holder and the needle cover with the needle cover in the use position. 13 is a sectional view taken along line XIII-XIII in FIG. 12. FIG. FIG. 13 is a perspective view showing a state in which the needle cover is slightly displaced toward a protection position from the state shown in FIG. 12; FIG. 3 is a perspective view of the holder and the needle cover with the needle cover in the protected position. FIG. 16 is a perspective view showing a state in which the needle cover is displaced along the axial direction toward a use position from the state shown in FIG. 15;

Embodiments of the invention will be described with reference to the drawings. In addition, in the drawings referred to below, the same numbers are attached to the same or corresponding members.

As shown in FIGS. 1 to 9, the syringe with safety mechanism 1 includes a syringe 100, a needle 200, a needle cap 300, a holder 400, and a needle cover 500. In this syringe 1 with a safety mechanism, the needle cap 300 is removed during use, and after use, the needle cover 500 is moved from the use position (the position shown in FIG. 2) to the protection position (the position shown in FIG. 3). , it is possible to suppress accidental stabbing, etc.

The syringe 100 has a barrel body 110 formed in a cylindrical shape, and a needle holding part 120 connected to the tip (upper end in FIG. 5) of the barrel body 110. Note that in each figure, illustration of the plunger and gasket is omitted.

The needle holder 120 has an outer shape smaller than the outer shape of the barrel body 110. The needle holding section 120 holds the needle 200. As shown in FIGS. 5 to 8 and the like, the tip 122 of the needle holding portion has a shape that projects outward in the radial direction of the barrel body 110.

Needle cap 300 is attached to syringe 100 so as to cover needle 200. Specifically, the open end 310 (see FIG. 5) of the needle cap 300 fits over the tip 122 of the needle holder 120. Needle cap 300 is removable from syringe 100.

The holder 400 is fixed to the needle holding part 120 of the syringe 100. The holder 400 cannot be displaced relative to the barrel body 110 in the axial direction of the barrel body 110, and is rotatable relative to the barrel body 110 around the central axis of the barrel body 110. The holder 400 includes a surrounding tube 410, a neck portion 420, a locking tube 430, and a guide protrusion 440.

The surrounding cylinder 410 surrounds the needle holding part 120. The surrounding cylinder 410 is formed into a cylindrical shape. The surrounding cylinder 410 is rotatable relative to the needle holding part 120 around the central axis of the barrel body 110. As shown in FIG. 9, the surrounding tube 410 is formed with a notch extending in the axial direction of the surrounding tube 410. As shown in FIG.

The neck portion 420 has a shape that projects inward in the radial direction of the surrounding cylinder 410 from the tip (upper end in FIG. 5) of the surrounding cylinder 410. Neck 420 engages tip 122 of needle holder 120 . This prevents the holder 400 from detaching from the barrel body 110.

The locking tube 430 is a portion that locks the needle cover 500. The locking cylinder 430 is formed outside the surrounding cylinder 410 in the radial direction of the surrounding cylinder 410. The locking tube 430 has a shape extending from the outer edge of the neck portion 420 to one side and the other side in the axial direction of the surrounding tube 410. As shown in FIG. 5, locking tube 430 surrounds open end 310 of needle cap 300. As shown in FIG. The open end 310 is press-fitted into the locking cylinder 430. Details of the locking tube 430 will be described later.

The guide protrusion 440 has a shape that projects outward from the outer peripheral surface of the locking cylinder 430 in the radial direction of the surrounding cylinder 410. The guide protrusion 440 is formed into a disk shape or a columnar shape. In this embodiment, the holder 400 has a pair of guide protrusions 440 provided at positions sandwiching the center of the enclosing tube 410 .

The needle cover 500 extends along the axial direction of the syringe 100 from a use position where the needle 200 is exposed (the position shown in FIG. 2) to a protected position where it surrounds the needle 200 (the position shown in FIG. 3). It can be displaced relative to 100. More specifically, the needle cover 500 is movable relative to the barrel body 110 from the use position toward the protection position when the needle cap 300 is removed from the syringe 100. On the other hand, displacement of the needle cover 500 from the protection position toward the use position along the axial direction of the barrel body 110 is restricted. The needle cover 500 includes a cover body 510 and a bulge 520.

The cover main body 510 is formed into a cylindrical shape. The inner diameter of the cover body 510 is set to be the same as or slightly larger than the outer diameter of the barrel body 110. The cover main body 510 surrounds the locking tube 430. The cover main body 510 has a use position engagement part 511, a protection position engagement part 512, and a guide groove 513.

The use position engagement portion 511 is a portion where the cover main body 510 engages with the locking tube 430 in the use position. In this embodiment, the use position engaging portion 511 is configured with a through hole that penetrates the cover body 510 in its radial direction. The use position engaging portion 511 is provided near the tip of the cover body 510 in a direction in which the cover body 510 moves from the use position to the protection position (hereinafter referred to as the "protection direction").

The protection position engagement portion 512 is a portion where the cover body 510 engages with the locking tube 430 in the protection position. In this embodiment, the protection position engaging portion 512 is configured with a through hole that penetrates the cover body 510 in its radial direction. The protection position engagement portion 512 is provided at a portion of the cover body 510 that is spaced apart from the use position engagement portion 511 in the opposite direction to the protection direction.

The guide groove 513 guides the guide protrusion 440 when the cover body 510 is displaced from the use position to the protection position. That is, the guide projection 440 has a shape that projects toward the needle cover 500, and moves within the guide groove 513 when the cover body 510 is displaced from the use position to the protection position. The guide groove 513 is composed of a through hole that penetrates the cover body 510 in its radial direction. The guide groove 513 has a guide surface 513a and a contact surface 513b.

The guide surface 513a has a shape that allows the cover body 510 to rotate around the central axis of the barrel body 110 when the cover body 510 is displaced from the use position to the protection position. In this embodiment, the guide surface 513a has a shape that rotates the cover body 510 by 45 degrees around the central axis of the barrel body 110 when the cover body 510 is displaced from the use position to the protection position.

As shown in FIGS. 4 and 10, the contact surface 513b contacts the guide protrusion 440 when the cover main body 510 is displaced along the axial direction of the barrel main body 110 from the protection position toward the use position. Therefore, displacement of the cover body 510 from the protection position toward the use position along the axial direction of the barrel body 110 is restricted. That is, the guide protrusion 440 constitutes a protrusion that protrudes toward the needle cover 500, and the abutment surface 513b is formed as the cover body 510 moves along the axial direction of the barrel body 110 from the protection position to the use position. It constitutes a regulating portion that regulates relative displacement with respect to the barrel body 110. In the state where the guide protrusion 440 is in contact with the contact surface 513b (the state shown in FIGS. 4, 10, and 11), the needle 200 is surrounded by the needle cover 500.

The bulging portion 520 has a shape that bulges inward from the inner peripheral surface of the cover body 510 in the radial direction of the cover body 510. The bulging portion 520 has a first vertical rib 521 and a second vertical rib 522.

As shown in FIG. 10, the first vertical rib 521 is provided at a position spaced apart from the contact surface 513b in the protection direction (upward in FIG. 10). The first vertical rib 521 has a shape extending along the axial direction of the cover body 510. As shown in FIGS. 10 and 13, the bulging portion 520 has a pair of first vertical ribs 521 provided at positions sandwiching the central axis of the cover body 510. As shown in FIGS.

As shown in FIG. 11, the second vertical rib 522 is provided at a position spaced apart from the protection position engaging portion 512 in the protection direction (upward in FIG. 11). The second vertical rib 522 has a shape extending along the axial direction of the cover body 510. The second vertical rib 522 is provided at a position rotated 90 degrees from the first vertical rib 521 in the circumferential direction of the cover main body 510. As shown in FIGS. 11 and 13, the bulging portion 520 has a pair of second vertical ribs 522 provided at positions sandwiching the central axis of the cover body 510. As shown in FIGS.

Here, the locking tube 430 will be explained. As shown in FIG. 9, the locking tube 430 includes a first wall portion 432, a second wall portion 431, and a locking portion 433.

The first wall portion 432 is formed at a position radially opposite to the bulging portion 520 and the needle cover 500 in the use position. In this embodiment, the locking cylinder 430 has four first walls 432 provided at 90 degree intervals along the circumferential direction of the surrounding cylinder 410. Hereinafter, the first vertical rib 521 of the needle cover 500 in the use position and the first wall part 432 facing in the radial direction of the needle cover 500 will be referred to as "first wall part 432A", and the second wall part 432 of the needle cover 500 in the use position The first wall portion 432 that faces the vertical rib 522 in the radial direction of the needle cover 500 may be referred to as a “first wall portion 432B”.

Each first wall portion 432 allows the needle cover 500 to be displaced from the use position toward the protection position while rotating about the central axis of the barrel body 110. The outer surface of each first wall portion 432 is formed flat. As shown in FIG. 13, a gap is formed between the first vertical rib 521 of the needle cover 500 in the use position and the opposing first wall portion 432A. A gap is formed between the second vertical rib 522 of the needle cover 500 in the use position and the opposing first wall portion 432B. Therefore, as shown in FIGS. 12 to 15, the needle cover 500 is allowed to rotate around the central axis of the barrel body 110 while being displaced from the use position toward the protection position. Note that in FIGS. 12, 14, and 15, only the first vertical rib 521 of the bulge portion 520 is shown. Further, in FIG. 14, illustration of the locking protrusion 435 is omitted.

The second wall portion 431 is provided between the first wall portions 432 adjacent to each other. That is, the locking cylinder 430 has a pair of second walls 431 that sandwich the center of the surrounding cylinder 410 . More specifically, each second wall portion 431 rotates the first wall in the same direction as the direction in which the needle cover 500 rotates around the central axis of the barrel body 110 when the needle cover 500 is displaced from the use position to the protection position. It is provided at a position adjacent to the portion 432A (the first wall portion 432 radially facing the first vertical rib 521 in the use position). Each second wall portion 431 has a thickness greater than the thickness of the first wall portion 432.

Each second wall portion 431 has a receiving portion 431a formed at the tip in the protection direction. The receiving portion 431a is axially opposed to the first vertical rib 521 of the needle cover 500 in the protection position, and the receiving part 431a is axially opposed to the first vertical rib 521 of the needle cover 500 when the needle cover 500 is displaced from the protection position toward the use position. 521. In other words, the first vertical rib 521 constitutes a protruding part that protrudes toward the holder 400, and the receiving part 431a is formed so that the needle cover 500 moves toward the barrel body 110 from the protection position to the use position. It constitutes a regulating part that regulates relative displacement along the axial direction.

The locking portion 433 locks the needle cover 500 from the inside of the needle cover 500 in the radial direction. Locking portion 433 holds needle cover 500 in the use position. Specifically, the locking portion 433 engages with the use position engagement portion 511 of the needle cover 500 in the use position. The locking portion 433 also holds the needle cover 500 in the protected position. Specifically, the locking portion 433 engages with the protection position engagement portion 512 of the needle cover 500 in the protection position.

The locking portion 433 is provided between the first wall portions 432 adjacent to each other. That is, the locking cylinder 430 has a pair of locking parts 433 that sandwich the center of the surrounding cylinder 410. More specifically, each locking portion 433 rotates the first wall portion in the same direction as the direction in which the needle cover 500 rotates around the central axis of the barrel body 110 when the needle cover 500 is displaced from the use position to the protection position. 432B (the first wall portion 432 radially facing the second vertical rib 522 in the use position).

A pair of slits S are formed on both sides of each locking portion 433 of the locking tube 430 . This allows each locking portion 433 to bend inward in the radial direction of the surrounding cylinder 410. The locking portion 433 includes a flexible piece 434 and a locking protrusion 435.

The flexible piece 434 is sandwiched between a pair of slits S and is formed into a plate shape.

The locking projection 435 has a shape that projects outward in the radial direction from the outer surface of the flexible piece 434. The locking protrusion 435 engages with the use position engagement portion 511 and the protection position engagement portion 512 from inside the needle cover 500 in the radial direction. The locking protrusion 435 is provided on the outer surface of the tip of the flexible piece 434 in the protection direction.

The flexible piece 434 is elastically deformable so that the locking protrusion 435 is displaced between an engaged position and a disengaged position. The engagement position is a position where the locking protrusion 435 engages with the use position engagement portion 511 when the needle cover 500 is in the use position (the position shown in FIG. 6). The detached position is a position (the position shown in FIG. 7) where the locking protrusion 435 separates radially inward from the use position engagement portion 511 when the needle cover 500 is displaced from the use position to the protection position.

As shown in FIGS. 9 to 11, the flexible piece 434 has a receiving portion 434a formed at the tip in the protection direction. The receiving portion 434a axially faces the second vertical rib 522 of the needle cover 500 in the protection position, and the second vertical rib 522 when the needle cover 500 is displaced from the protection position toward the use position. 522. In other words, the second vertical rib 522 constitutes a protruding part that protrudes toward the holder 400, and the receiving part 434a is formed so that the needle cover 500 moves toward the barrel body 110 from the protection position to the use position. A regulating portion is configured to regulate relative displacement along the axial direction.

As shown in FIG. 5, when the needle cap 300 is attached to the syringe 100, the open end 310 of the needle cap 300 is press-fitted between the tip 122 of the needle holder 120 and the flexible piece 434. ing. In other words, the open end portion 310 constitutes a support portion that supports the locking portion 433 from inside in the radial direction so as to prevent the locking portion 433 from deflecting inward in the radial direction.

Next, the procedure for using the syringe 1 with a safety mechanism will be explained. First, before using the syringe 1 with a safety mechanism, the needle cap 300 is attached to the syringe 100, as shown in FIGS. 1 and 5. In this state, the open end (supporting part) 310 of the needle cap 300 supports the locking part 433 from the inside in the radial direction, so that the locking part 433 is prevented from deflecting inward in the radial direction. Ru. Therefore, while the needle cap 300 is attached to the syringe 100, the needle cover 500 is held in the use position. In other words, in this syringe 1 with a safety mechanism, displacement of the needle cover 500 to the protection position is restricted before the needle cap 300 is removed.

When using the syringe 1 with a safety mechanism, the needle cap 300 is removed. This exposes the needle 200.

After use, the needle cover 500 is moved relative to the barrel body 110 from the use position to the protection position. At the start of this movement, since the locking portion 433 is not supported by the open end 310 of the needle cap 300, the locking protrusion 435 is pressed by the cover body 510, causing the flexible piece 434 to move inward in the radial direction. bend. Therefore, movement of the needle cover 500 in the protection direction is allowed. The needle cover 500 moves to the protection position while rotating around the central axis of the barrel body 110 along the guide groove 513. When the needle cover 500 moves with rotation, the first vertical rib 521 is maintained apart from the first wall 432A, and the second vertical rib 522 is maintained separated from the first wall 432B. Ru.

Then, when the needle cover 500 reaches the protection position, the flexible piece 434 returns so that the locking protrusion 435 engages with the protection position engagement portion 512. Therefore, the needle cover 500 is held in a protected position. At this time, as shown in FIG. 15, the first vertical rib 521 faces the receiving portion 431a of the second wall portion 431 in the axial direction. Further, the second vertical rib 522 faces the receiving portion 434a of the flexible piece 434 in the axial direction.

Here, when an external force acts on the needle cover 500 to move the needle cover 500 from the protection position to the use position along the axial direction of the barrel body 110, as shown in FIGS. 4, 10, and 16, The guide protrusion 440 contacts the contact surface 513b, the first vertical rib 521 contacts the receiving portion 431a of the second wall portion 431, and the second vertical rib 522 contacts the receiving portion 434a of the flexible piece 434. Therefore, the needle cover 500 is prevented from further displacing along the axial direction of the barrel body 110 in the direction opposite to the protection direction. Note that in FIG. 16, illustration of the second vertical rib 522 is omitted.

In this way, in a state where the protruding parts (guide protrusion 440, first vertical rib 521, second vertical rib 522) are in contact with the regulating part (contact surface 513b, receiving part 431a, receiving part 434a), the needle 200 is , surrounded by a needle cover 500. Therefore, occurrence of accidental pricking after use is suppressed.

Furthermore, in this embodiment, the locking portion 433 has a function of locking the needle cover 500 in the use position or the protection position, and cooperates with the second vertical rib 522 to direct the needle cover 500 from the protection position to the use position. It also has the function of regulating displacement along the axial direction.

Note that the embodiments disclosed herein are illustrative in all respects and should not be considered restrictive. The scope of the present invention is indicated by the claims rather than the description of the embodiments described above, and includes all changes within the meaning and range equivalent to the claims.

For example, the displacement of the needle cover 500 relative to the syringe 100 from the protective position to the use position along the axial direction can be regulated by a regulation mechanism consisting of a single protrusion and a single regulation part, so the guide Any one of the regulating mechanism consisting of the protrusion 440 and the contact surface 513b, the regulating mechanism consisting of the first vertical rib 521 and the receiving part 431a, and the regulating mechanism consisting of the second vertical rib 522 and the receiving part 434a, Alternatively, any two may be omitted.

1 Syringe with safety mechanism, 100 Syringe, 110 Barrel body, 120 Needle holding part, 122 Tip part, 200 Needle, 300 Needle cap, 310 Open end part (support part), 400 Holder, 410 Surrounding cylinder, 420 Neck part, 430 Connection Stop tube, 431 Second wall portion, 431a Receiving portion (regulating portion), 432 First wall portion, 432A First wall portion, 432B First wall portion, 433 Locking portion, 434 Flexible piece, 434a Receiving portion (regulating portion) ), 435 locking protrusion, 440 guide protrusion (protrusion), 500 needle cover, 510 cover body, 511 use position engagement part, 512 protection position engagement part, 513 guide groove, 513a guide surface, 513b contact surface (Regulating portion), 520 bulging portion (protruding portion), 521 first vertical rib (protruding portion), 522 second vertical rib (protruding portion).

Claims (4)

syringe and
a needle connected to the tip of the syringe;
a holder fixed to the syringe;
a needle cover that is movable relative to the syringe along the axial direction of the syringe from a use position where the needle is exposed to a protection position where the needle is surrounded;
The holder locks onto the needle cover in the use position from the inside of the needle cover in a radial direction so that the needle cover is held in the use position, and the needle cover is held in the protection position. a locking portion that locks the needle cover in the protection position from the inside in the radial direction,
At least one member of the holder and the needle cover has a protrusion that projects toward the other member of the holder and the needle cover, and the other member is configured to move the needle cover from the protected position to the use position. a regulating part that abuts on the protruding part so as to regulate relative displacement of the syringe along the axial direction toward the syringe ;
The needle cover has a bulge that bulges toward the holder,
The holder faces the bulge of the needle cover in the protection position in the axial direction, and when the needle cover is displaced along the axial direction from the protection position toward the use position. It has a receiving part that comes into contact with the bulging part,
The bulging part constitutes the protruding part, the receiving part constitutes the regulating part,
The holder has a guide projection having a shape that projects toward the needle cover,
The needle cover is provided with a guide groove that guides the guide protrusion when the needle cover is displaced from the use position toward the protection position,
The guide groove has a guide surface having a shape that rotates the needle cover around the central axis of the syringe when the needle cover is displaced from the use position to the protection position,
The holder is
The swollen portion of the needle cover in the use position is formed at a position opposite to the needle cover in the radial direction, and the needle cover moves toward the central axis of the syringe from the use position to the protection position. a first wall portion that allows displacement while rotating around the first wall portion;
A second wall provided at a position adjacent to the first wall portion in the same direction as the direction in which the needle cover rotates around the central axis of the syringe when the needle cover is displaced from the use position to the protection position. having a wall portion;
A syringe with a safety mechanism , wherein a distal end portion of the second wall portion in a direction in which the needle cover faces from the use position to the protection position constitutes the receiving portion . The holder has a guide projection having a shape that projects toward the needle cover,
The needle cover is provided with a guide groove that guides the guide protrusion when the needle cover is displaced from the use position toward the protection position,
The guide groove is
a guide surface having a shape that rotates the needle cover around a central axis of the syringe when the needle cover is displaced from the use position to the protection position;
a contact surface that comes into contact with the guide protrusion when the needle cover is displaced along the axial direction from the protection position toward the use position;
The syringe with a safety mechanism according to claim 1, wherein the guide protrusion constitutes the protrusion, and the contact surface constitutes the restriction part. The holder further includes a first wall portion different from the first wall portion,
The locking portion is adjacent to the other first wall portion in the same direction as the direction in which the needle cover rotates around the central axis of the syringe when the needle cover is displaced from the use position to the protection position. It is located in a position where
The bulge is
When the needle cover is in the use position, the first wall faces the needle cover in the radial direction, and when the needle cover is in the protection position, the second wall faces the shaft. a first vertical rib facing in the direction;
When the needle cover is located in the use position, the other first wall portion faces the needle cover in the radial direction, and when the needle cover is located in the protection position, the locking portion and the a second vertical rib facing in the axial direction;
The syringe with a safety mechanism according to claim 1 or 2 , wherein a distal end portion of the locking portion in a direction in which the needle cover faces from the use position to the protection position constitutes the receiving portion. The guide groove further includes a contact surface that comes into contact with the guide protrusion when the needle cover is displaced from the protection position toward the use position along the axial direction,
The syringe with a safety mechanism according to any one of claims 1 to 3, wherein the guide protrusion constitutes the protrusion, and the contact surface constitutes the restriction part.

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