An integrated single-hand bolus device

Abstract

The application provides a one-piece single-hand injection device, which comprises a head cover, a needle cylinder inserted into the head cover from a circular end of the head cover, a guide tube connected with the needle cylinder and comprising a piston and a guide tube straight wall, and a limiting component for limiting the positions of the needle cylinder and the guide tube. The application does not need to be assembled before use, can be used by one hand all the time, has stable discharging, small cross-section projection and is not easy to be hooked, and is convenient to use.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to an integrated single-handed injection device. Background Technology

[0002] Currently, the main methods for treating and stopping bleeding in new wound dressings include the use of drug powders, granules, and expandable sponge granules that can fill wounds. Meanwhile, gels and semi-solid products are also important research directions in the design of next-generation hemostatic products. Besides manual packing, most of these wound dressings are used in the form of pre-filled injectors. Pre-filled injectors typically require assembling the injector rod and tube before use. In the use of traditional pre-filled injectors, due to the need for hemostasis, deeper wounds are required. Therefore, the long syringe and injector usually necessitate separate placement of the injector and syringe. However, separate placement of the injector and syringe increases the lateral projection area of ​​the packaging and makes removal more difficult. Furthermore, built-in injector components are more complex in structure and occupy space within the syringe.

[0003] In related technologies, commercially available products with separate plungers and syringes require removing the piston, opening the syringe tail plug, inserting the piston, and then opening the cap before use. In emergency situations, the contents may spill during assembly and removal of the packaging. The separately placed plunger increases the packaging volume and lateral projection area, making it difficult to remove quickly from the packaging. Furthermore, the assembled plunger is unstable due to its short plunger insertion end, requiring two-handed operation. Summary of the Invention

[0004] To address the aforementioned technical deficiencies in the prior art, this application provides an integrated single-handed injection device that is easy to use and effectively solves the problems in the background art.

[0005] The integrated single-handed injection device provided in this application adopts the following technical solution:

[0006] An integrated one-handed injection device includes:

[0007] Scalp;

[0008] A syringe is inserted into the head cover from one of its circular ends;

[0009] A guide tube, connected to the syringe, includes a piston and a straight wall of the guide tube, the straight wall of the guide tube being sleeved outside the piston;

[0010] The limiting component is used to restrict the position of the syringe and the guide tube.

[0011] In any of the above embodiments, it is preferred that one end of the head cover is closed and the cross-section gradually narrows, while the other end is a circular opening.

[0012] Preferably, in any of the above embodiments, the syringe includes a pointed head and a straight syringe wall;

[0013] The shape of the cavity formed by the inner surface of the head cover matches the shape of the pointed head.

[0014] The straight wall of the syringe is located at the end of the syringe furthest from the cap.

[0015] Preferably, in any of the above embodiments, the pointed head includes an opening flap and an opening slit;

[0016] An opening slit is provided between the two opening lobes.

[0017] In any of the above solutions, the limiting component preferably includes a positioning button, a sliding positioning rod, a sliding button, and a limiting groove;

[0018] The positioning button is disposed on the outer surface of the straight wall of the syringe; the sliding button positioning rod is symmetrically arranged with the positioning button; a sliding button is connected to the sliding button positioning rod;

[0019] The limiting groove is located at the end of the syringe away from the head cap.

[0020] In any of the above embodiments, it is preferred that the piston includes a piston head and a piston rod;

[0021] One end of the piston rod is fixedly connected to the piston head;

[0022] The other end of the piston rod is connected to a piston connecting transverse wall.

[0023] In any of the above embodiments, it is preferred that the straight wall of the guide tube is sleeved outside the piston; the piston connecting transverse wall is fixedly connected to the straight wall of the guide tube.

[0024] In any of the above solutions, it is preferred that the limiting component further includes a transverse guide groove and a longitudinal guide groove;

[0025] The transverse guide groove and the longitudinal guide groove are formed on the straight wall of the guide tube. The transverse guide groove is connected to the longitudinal guide groove. A fixed protrusion is provided in the transverse guide groove. There are two sets of transverse guide grooves and longitudinal guide grooves, which are arranged symmetrically.

[0026] In any of the above embodiments, it is preferred that the positioning button and the sliding button positioning rod are respectively inserted into the two longitudinal guide grooves, and the positioning button and the sliding button positioning rod are respectively fixed in the two transverse guide grooves by two fixing protrusions.

[0027] In any of the above embodiments, it is preferred that the inner diameter of the straight wall of the guide tube is larger than the outer diameter of the syringe; and the outer diameter of the piston head is smaller than the inner diameter of the syringe.

[0028] This application includes at least one of the following beneficial technical effects:

[0029] This application, by setting a limiting component, ensures that all action fulcrums are held by a single hand. When the sliding button is pulled and the syringe is moved towards the guide tube, the guide tube is held in the hand and remains stationary relative to the hand. This process simultaneously pushes the contents and withdraws the syringe. Furthermore, the simple structure of this application simplifies the use of previous pre-filled solid and semi-solid injection devices, and it can be used by users in cases of injury or single-handed disability. Attached Figure Description

[0030] The accompanying drawings are provided to further illustrate the present invention and, together with the embodiments thereof, are used to explain the present invention, but do not constitute a limitation thereof.

[0031] Figure 1 This is an exploded schematic diagram of the integrated single-handed injection device of this application;

[0032] Figure 2 This is a perspective view of the head cover of the integrated single-handed injection device of this application;

[0033] Figure 3 This is a perspective view of the syringe of the integrated single-handed injection device of this application;

[0034] Figure 4 This is a perspective view of the guide tube of the integrated single-handed injection device of this application;

[0035] Figure 5 This is a cross-sectional view of the integrated single-handed injection device of this application when it is not in use;

[0036] Figure 6 This is another cross-sectional view of the integrated single-handed injection device of this application when it is not in use;

[0037] Figure 7 This is a cross-sectional view of the integrated single-handed injection device of this application in use.

[0038] Figure 8 This is another cross-sectional view of the integrated single-handed injection device of this application in use;

[0039] Figure 9 This is a cross-sectional view showing the relationship between the bottom of the syringe and the guide tube after injection is completed using the integrated single-handed injection device of this application;

[0040] Figure 10 This is a perspective view showing the relative relationship between the bottom of the syringe and the guide tube after injection is completed using the integrated single-handed injection device of this application.

[0041] Reference numerals: 100, head cap; 200, syringe; 204, opening flap; 205, opening slit; 206, positioning button; 207, sliding button positioning rod; 208, sliding button; 209, limiting groove; 211, straight wall of syringe; 300, guide tube; 304, piston; 305, piston head; 306, piston rod; 307, transverse guide groove; 308, fixing protrusion; 309, longitudinal guide groove; 310, piston connecting transverse wall; 312, straight wall of guide tube. Detailed Implementation

[0042] To make the technical solutions and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0043] like Figures 1 to 10 As shown, an integrated single-handed injection device includes:

[0044] Headgear 100;

[0045] A syringe 200 is inserted into the head cover 100 from one circular end of the head cover 100;

[0046] A guide tube 300 is connected to the syringe 200 and includes a piston 304 and a guide tube straight wall 312, wherein the guide tube straight wall 312 is sleeved outside the piston 304;

[0047] A limiting component is used to limit the position of the syringe 200 and the guide tube 300.

[0048] In this embodiment of the invention, the cap 100 is fitted over the syringe 200 to protect and seal the syringe 200. One end of the cap 100 is closed and gradually narrows in cross-section, while the other end is a circular opening. The syringe 200 is used to hold contents and is inserted into the wound to release the contents from the tip of the syringe 200. A limiting component is provided at the end of the syringe 200 near the guide tube 300. The piston 304 is inserted into the guide tube 300, and the space formed by the tip and straight wall of the syringe 200 and the upper surface of the piston 304 is for holding... The space for the contents; a limiting component is provided on the straight wall 312 of the guide tube, which cooperates with the limiting component on the syringe 200 to limit the relative position between the syringe 200 and the guide tube 300, simplifying the use of previous pre-filled solid and semi-solid injection devices, and enabling users to use them effectively in cases of injury or single-handed disability; the integrated single-handed injection device is a disposable item, and its material can be one or a combination of two of the following: metal and polymer. Its contents are one or more of the following: granules, powder, solid blocks, and gel.

[0049] like Figures 1 to 10As shown, one end of the head cover 100 is closed and the cross-section gradually narrows, while the other end is a circular opening; the syringe 200 includes a pointed head and a straight syringe wall 211; the shape of the cavity formed by the inner surface of the head cover 100 matches the shape of the pointed head; the straight syringe wall 211 is located at the end of the syringe 200 away from the head cover 100; the pointed head includes an opening flap 204 and an opening slit 205; an opening slit 205 is provided between the two opening flaps 204.

[0050] In this embodiment of the invention, the contents of the syringe 200 are released from the pointed tip formed by the opening flap 204 and the opening slit 205; the cavity shape formed by the inner surface of the cap 100 matches the shape of the pointed tip of the syringe 200, allowing the cap 100 to be fitted onto the syringe tip; the straight wall 211 of the syringe is used to store the contents and is connected to the guide tube 300, which can be inserted into the straight wall 211, allowing the contents to be released from the opening flap 204 by compression; when not in use, the cap 100 can be closed on the syringe 200, protecting the opening flap 204 and sealing the opening slit 205. Simultaneously, the cap 100... The opening flap 204 is restricted from moving, and the opening slit 205 is closed to prevent the contents from leaking out of the tip of the syringe 200. When needed, the operator can remove the cap 100 from the syringe 200 with one hand, so that the opening flap 204 can release the contents. This can be done with one hand, making the operation convenient. The diameter of the opening end of the cap 100 should be greater than the outer diameter of the syringe straight wall 211 of the syringe 200, and the difference must be less than 3% of the outer diameter of the syringe straight wall 211 to ensure the fitting and sealing of the cap 100. The cross-sectional shape of the cap 100 can be circular, elliptical, or a polygon containing two symmetrical arcs.

[0051] like Figures 1 to 10 As shown, the limiting assembly includes a positioning button 206, a sliding button positioning rod 207, a sliding button 208, and a limiting groove 209; the positioning button 206 is disposed on the outer surface of the straight wall 211 of the syringe; the sliding button positioning rod 207 is symmetrically arranged with the positioning button 206; the sliding button positioning rod 207 is connected to the sliding button 208; the limiting groove 209 is disposed at one end of the syringe 200 away from the head cover 100, and there are four of them.

[0052] In this embodiment of the invention, both the sliding button positioning rod 207 and the positioning button 206 are protruding short rods extending from the outer wall of the syringe straight wall 211. The length of the positioning button 206 and the sliding button positioning rod 207 perpendicular to the syringe straight wall 211 needs to be greater than the outer diameter of the guide tube 300, so that the positioning button 206 and the sliding button positioning rod 207 protrude from the outer surface of the guide tube 300, providing a stable limiting function, and the protrusion makes it convenient for the operator to use. The sliding button positioning rod 207 is connected to a sliding button 208 that can be pushed by the operator. The operator can push the sliding button 208 with one hand to complete the pushing operation of the contents, making the operation more convenient. The limiting groove 209 is used to limit the movement of the syringe 200 in the guide tube 300. When the syringe 200 abuts against the limiting groove 209, it means that the injection operation of the contents is completed.

[0053] like Figures 1 to 10 As shown, the piston 304 includes a piston head 305 and a piston rod 306; one end of the piston rod 306 is fixedly connected to the piston head 305; the other end of the piston rod 306 is connected to a piston connecting transverse wall 310, and the guide tube straight wall 312 is sleeved on the outside of the piston 304; the piston connecting transverse wall 310 is fixedly connected to the guide tube straight wall 312.

[0054] In this embodiment of the invention, the piston 304 is inserted into the syringe 200, and the straight wall 312 of the guide tube is sleeved outside the syringe 200, allowing the straight wall 211 of the syringe to enter the space enclosed by the piston 304 and the straight wall 312 of the guide tube. This provides stable support for the relative movement between the syringe 200 and the guide tube 300, avoiding instability due to a short insertion section of the push rod and the need for two-handed operation. The space formed by the opening flap 204, the straight wall of the syringe 200, and the upper surface of the piston head 305 is a space for accommodating the contents. When the piston head 305 enters the syringe 200, the syringe 200... The contents of syringe 200 are released from the opening flap 204 under the squeezing action of piston 305. Since piston 304 is fixedly connected to the straight wall 312 of guide tube, when the contents of syringe 200 need to be released, simply push the straight wall 312 of guide tube to drive piston rod 306 and piston head 305 to push the contents and open the opening flap 204, thus releasing the contents. The piston 204 continues to move towards the opening flap 204 in syringe 200 until it contacts the piston connecting transverse wall 310 by limiting groove 209, preventing guide tube 300 from continuing to move longitudinally, thus completing the injection.

[0055] like Figures 1 to 10As shown, the limiting component also includes a transverse guide groove 307 and a longitudinal guide groove 309; the transverse guide groove 307 and the longitudinal guide groove 309 are formed on the straight wall 312 of the guide tube, the transverse guide groove 307 is connected to the longitudinal guide groove 309, and a fixing protrusion 308 is provided in the transverse guide groove 307; both the transverse guide groove 307 and the longitudinal guide groove 309 have two sets and are symmetrically arranged.

[0056] In this embodiment of the invention, the transverse guide groove 307 and the longitudinal guide groove 309 are perpendicular to each other. The direction of the longitudinal guide groove 309 is the same as the direction of the piston rod 306, and the upper end of the longitudinal guide groove 309 is open. The width of the transverse guide groove 307 and the longitudinal guide groove 309 matches the diameter of the positioning button 206 and the sliding positioning rod 207, so as to facilitate the entry of the positioning button 206 and the sliding positioning rod 207 on the syringe 200. The function of the transverse guide groove 307 and the longitudinal guide groove 309 is to guide or restrict the movement of the syringe 200 in the guide tube 300. The combined design of the transverse guide groove 307 and the longitudinal guide groove 309 can provide transverse and longitudinal guidance for the syringe 200, so that the syringe 200 moves in the guide tube 300 following the trajectory of the transverse guide groove 307 and the longitudinal guide groove 309. The fixed protrusion 308 is used to limit the movement range of the object in the transverse guide groove 307, and plays a limiting role.

[0057] like Figures 1 to 10 As shown, the positioning button 206 and the sliding button positioning rod 207 are respectively inserted into the two longitudinal guide grooves 309, and the positioning button 206 and the sliding button positioning rod 207 are respectively fixed in the two transverse guide grooves 207 by two fixing protrusions 308.

[0058] In this embodiment of the invention, the transverse guide groove 307 and the longitudinal guide groove 309 are used in conjunction with the positioning button 206 and the sliding positioning rod 207. The positioning button 206 and the sliding positioning rod 207 restrict the horizontal movement of the syringe 200 relative to the guide tube 300. Simultaneously, the positioning button 206 and the sliding positioning rod 207 are fixed within the transverse guide groove 307 by a fixing protrusion 308, which fixes the relative position of the guide tube 300 and the syringe 200, restricting the vertical movement and rotation of the syringe 200 relative to the guide tube 300 around the horizontal direction. In the unused state, because the relative position between the syringe 200 and the guide tube 300 is fixed, the piston 304 will not push the contents of the syringe 200 under longitudinal force, ensuring that the contents do not leak. Upon initial use, the sliding button 208, under external force, causes the positioning button 206 and the sliding positioning rod 207 to disengage from the fixing protrusion 308 in the transverse guide groove. The syringe 200 is rotated into the longitudinal guide groove 309 through the groove 307. At this time, the syringe 200 can move longitudinally along the longitudinal guide groove 309. During this process, the syringe 200 is further nested inside the straight wall 312 of the guide tube and wrapped by the inner surface of the guide tube 300. The relative position of the piston head 305 inside the syringe gradually moves towards the tip of the syringe 200 and pushes the contents towards the tip of the syringe 200. After the piston head 305 enters the range of the opening flap 204, the opening flap 204 is gradually opened because the diameter of the piston head 305 gradually exceeds the inner diameter of the opening flap 204, so that it opens along the opening seam 205 and releases the contents. The length of the piston head 305, piston rod 306 and piston connecting transverse wall 310 added together must be greater than the length of the straight wall 312 of the guide tube and also greater than the length of the syringe 200, so that the piston 304 can be fully inserted into the syringe 200 and the contents can be completely squeezed out without waste.

[0059] like Figures 1 to 10 As shown, the inner diameter of the guide tube 300's straight wall 312 is larger than the outer diameter of the syringe 200; the outer diameter of the piston head 305 is smaller than the inner diameter of the syringe 200.

[0060] In this embodiment of the invention, the inner diameter of the guide tube 300's straight wall 312 is larger than the outer diameter of the syringe 200, and the outer diameter of the piston head 305 is smaller than the inner diameter of the syringe 200, with the difference being less than 3% of the inner diameter of the syringe straight wall 211. The cross-sectional shape of the piston head 305 and the guide tube straight wall 312 of the guide tube 300 can be circular or elliptical, or a polygon containing two symmetrical arcs. This allows the syringe straight wall 211 to enter the space enclosed by the piston 304 and the guide tube 300 straight wall, avoiding instability of the syringe straight wall 211 when entering the guide tube 300. At the same time, the piston head 305 and the syringe straight wall fit together to seal the space where the contents are located, preventing leakage of the contents.

[0061] This application simplifies the use of previous pre-filled solid and semi-solid injection devices, enabling users to use them effectively in situations such as injury or single-handed disability. The integrated single-handed injection device is a disposable item, and its material can be one or a combination of two major or two types of materials, such as metal or polymer. Its contents are one or more of granules, powders, solid blocks, and gels. In this application, because the positioning button 206 and the sliding positioning rod 207 can move in the transverse guide groove 307 and the longitudinal guide groove 309, the assembly composed of the guide tube 300 and the syringe 200 has two relatively stable positions.

[0062] The first stable position is the state of the integrated single-handed injection device when it contains contents and is not in use. The positioning button 206 and the sliding button positioning rod 207 are fixed by the fixed protrusion 308 in the transverse guide groove 307, which can fix the relative position of the guide tube 300 and the syringe 200, so that the syringe 200 and the guide tube 300 will not move longitudinally relative to each other due to external force during storage and transportation, and the piston will not push the contents under longitudinal force. This state is the state when the injection device is not in use. In this state, the circular opening end of the head cover 100 completely covers the pointed head of the syringe 200, which includes the opening flap 204 and the opening slit 205, which together form a non-integral structure.

[0063] The second stable position is the state of the integrated single-handed injection device during use. First, remove the head cover 100. The user pushes the sliding button 208 by hand. Under the external force, the sliding button 208 drives the positioning button 206 and the sliding button positioning rod 207 to disengage from the fixing protrusion 308, causing the syringe 200 to rotate along the transverse guide groove 307 into the longitudinal guide groove 309. Then, the user uses the bottom of the guide tube 300 as a fulcrum and slides the sliding button 208 towards the piston connecting transverse wall 310 end of the guide tube 300 to move longitudinally along the longitudinal guide groove, causing the syringe 200 to enter the guide tube 300. The piston 304 enters the syringe 200, pushes out the contents, and pushes... When the opening flap 204 is opened, the straight wall of the syringe 200 enters the space enclosed by the piston 304 and the straight wall of the guide tube 300. The relative position of the piston head 305 inside the syringe gradually moves towards the tip of the syringe 200, pushing the contents towards the tip of the syringe 200. After the piston head 305 enters the range of the opening flap 204, the opening flap 204 is gradually opened because the diameter of the piston head 305 gradually becomes larger than the inner diameter of the opening flap 204, so that it opens along the opening seam 205 to release the contents. Until the limiting groove 209 contacts the piston connecting transverse wall 310, the syringe 200 and the guide tube 300 can no longer move longitudinally relative to each other, thus completing the injection.

[0064] The above are merely preferred embodiments of this application and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An integrated single-handed injection device, characterized in that, include: Headgear (100); A syringe (200) is inserted into the head cover (100) from one circular end; A guide tube (300) is connected to the syringe (200) and includes a piston (304) and a guide tube straight wall (312), wherein the guide tube straight wall (312) is sleeved outside the piston (304); A limiting component is used to limit the position of the syringe (200) and the guide tube (300); The syringe (200) includes a pointed head and a straight syringe wall (211). The cavity shape formed by the inner surface of the head cover (100) matches the shape of the pointed head. The straight wall (211) of the syringe is located at the end of the syringe (200) away from the head cap (100); The pointed head includes an opening flap (204) and an opening slit (205). An opening slit (205) is provided between the two opening lobes (204); The limiting component includes a positioning button (206), a sliding positioning rod (207), a sliding button (208), and a limiting groove (209). The positioning button (206) is disposed on the outer surface of the straight wall (211) of the syringe; the sliding positioning rod (207) is symmetrically disposed with the positioning button (206); a sliding button (208) is connected to the sliding positioning rod (207). The limiting groove (209) is disposed at one end of the syringe (200) away from the head cap (100); The piston (304) includes a piston head (305) and a piston rod (306). One end of the piston rod (306) is fixedly connected to the piston head (305); The other end of the piston rod (306) is connected to a piston connecting transverse wall (310). The piston connecting transverse wall (310) is fixedly connected to the guide tube straight wall (312); The limiting component also includes a transverse guide groove (307) and a longitudinal guide groove (309). The transverse guide groove (307) and the longitudinal guide groove (309) are formed on the straight wall (312) of the guide tube. The transverse guide groove (307) and the longitudinal guide groove (309) are connected and perpendicular to each other. A fixed protrusion (308) is provided in the transverse guide groove (307) to limit the movement range of the object in the transverse guide groove (307). The direction of the longitudinal guide groove (309) is the same as the direction of the piston rod (306), and the upper end of the longitudinal guide groove (309) is open. Both (307) and the longitudinal guide groove (309) have two sets and are symmetrically arranged to guide or restrict the movement of the syringe (200) in the guide tube (300), so that the syringe (200) moves in the guide tube (300) following the trajectory of the transverse guide groove (307) and the longitudinal guide groove (309); the width of the transverse guide groove (307) and the longitudinal guide groove (309) matches the diameter of the positioning button (206) and the sliding positioning rod (207), so as to facilitate the entry of the positioning button (206) and the sliding positioning rod (207) on the syringe (200); The positioning button (206) and the sliding positioning rod (207) are respectively inserted into the two longitudinal guide grooves (309), and the positioning button (206) and the sliding positioning rod (207) are respectively fixed in the two transverse guide grooves (307) by two fixed protrusions (308), thereby restricting the movement of the syringe (200) relative to the guide tube (300) in the horizontal direction; the positioning button (206) and the sliding positioning rod (207) are fixed in the transverse guide grooves (307) by the fixed protrusions (308), thereby fixing the relative position of the guide tube (300) and the syringe (200), thereby restricting the movement of the syringe (200) relative to the guide tube (300) in the vertical direction and the rotation around the horizontal direction; In the unused state, the relative positions between the syringe (200) and the guide tube (300) are fixed, and the piston (304) is relatively stationary with respect to the contents of the syringe (200), ensuring that the contents will not leak. After use, the sliding button (208) is pushed by external force to drive the positioning button (206) and the sliding button positioning rod (207) to disengage from the fixed protrusion (308), and drive the syringe (200) to rotate into the longitudinal guide groove (309) in the transverse guide groove (307). At this time, the syringe (200) moves longitudinally along the longitudinal guide groove (309), and the syringe (200) is further nested inside the straight wall (312) of the guide tube, and is wrapped by the inner surface of the guide tube (300), while the piston head (304) is... 05) The piston head (305) moves gradually toward the tip of the syringe (200) in the relative position inside the syringe and pushes the contents toward the tip of the syringe (200). After the piston head (305) enters the range of the opening flap (204), the opening flap (204) is gradually opened because the diameter of the piston head (305) is gradually larger than the inner diameter of the opening flap (204), so that it opens along the opening seam (205) and releases the contents. The length of the piston head (305), piston rod (306) and piston connecting transverse wall (310) added together must be greater than the length of the guide tube straight wall (312) and also greater than the length of the syringe (200) so that the piston (304) can be fully inserted into the syringe (200) so that all the contents are squeezed out.

2. The integrated single-handed injection device according to claim 1, characterized in that: The head cover (100) is closed at one end and gradually narrows in cross-section, while the other end is a circular opening.

3. The integrated single-handed injection device according to claim 1, characterized in that: The inner diameter of the straight wall (312) of the guide tube (300) is greater than the outer diameter of the syringe (200); the outer diameter of the piston head (305) is smaller than the inner diameter of the syringe (200).

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