A safe syringe suitable for injection of small dose of liquid medicine

Abstract

The application relates to the technical field of medical devices, and particularly discloses a safe syringe suitable for small-dose liquid medicine injection, which comprises a needle cylinder, a needle seat, an injection needle, a ring plug, a push rod, a retraction rod and a compression spring; the piston is detachably connected to the retraction rod which extends from the distal end of a retraction cavity; and the piston is sealed with the inner wall of the inner cavity. The above structure changes the structure form that the piston is arranged on the push rod in the prior art, the piston is arranged on the retraction rod and detachably connected with the retraction rod, after the arrangement, the sealing element between the retraction rod and the push rod is omitted, based on the change of the structure layout, the piston bears multiple actions, one of which is to push the liquid medicine, the second is to realize the sealing between the push rod and the needle cylinder, and the third is to realize the sealing between the push rod and the retraction rod, the function integration degree is higher, the number of parts is smaller, the diameter of the needle cylinder can be smaller, and thus the precise control of the injection of the small-dose liquid medicine is realized.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and more specifically to a safe syringe suitable for injecting small doses of medication. Background Technology

[0002] Syringes are widely used medical devices. If the needle is exposed after injection, it can easily cause accidental injury to non-patients, posing a significant risk of infection. Therefore, the demand for safety syringes with automatically retractable needles after injection is increasing. One type is the self-retracting safety syringe, where the needle automatically retracts into the syringe barrel after injection to prevent exposure.

[0003] For example, Chinese invention patent CN101284154B discloses a self-destructing safety syringe, which is an automatically retractable safety syringe. In this self-destructing safety syringe, after injection, the front end of the retracting rod engages with the rear end of the needle hub. After the elastic rubber ring breaks through the obstruction of the limiting ring, the potential energy of the retracting spring is released. Based on the release of the potential energy of the retracting spring, the assembly consisting of the retracting rod, needle hub, and puncture needle tube retracts into the cylinder of the plunger, thereby protecting the injection needle. In the self-destructing safety syringe disclosed in the above patent, the piston 7 is installed at the distal end of the plunger 2, forming a seal between the plunger and the outer sleeve 1. A leak-proof ring 20 is provided between the retracting rod 9 and the plunger 2, forming a seal between the retracting rod and the plunger.

[0004] In the above structure, two sealing elements (piston 7 and leak-proof ring 20) are spaced apart between the outer sleeve 1, the push cylinder 2, and the retracting rod 9, making the syringe diameter relatively large and suitable for injecting larger doses of medication. When small doses of medication are required (e.g., injections of 1 ml or less), the larger diameter makes it difficult to accurately control the injection dosage. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the technical defect of the self-destructing safety syringe in the prior art that cannot accurately control the injection of small doses of medicine.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a safe syringe suitable for injecting small doses of medication, comprising at least:

[0007] A syringe, wherein the syringe is provided with an inner cavity extending from the proximal end to the distal end and a needle seat cavity communicating with the distal end of the inner cavity, and a stop portion is formed at the junction of the inner cavity and the needle seat cavity.

[0008] The needle hub has an injection needle at its distal end and a first engagement portion at its proximal end. A stop step adapted to the stop portion is provided near the distal end of the needle hub.

[0009] The needle seat has a first annular protrusion at its proximal end. The annular plug is interference-fitted between the first annular protrusion and the inner wall of the inner cavity. An annular cavity for accommodating the annular plug is formed between the first annular protrusion and the distal end of the inner cavity. The annular plug is clearance-fitted with the needle seat and the inner wall of the inner cavity within the annular cavity.

[0010] A push rod, the push rod being located within the inner cavity, and the push rod having a retraction cavity;

[0011] A retractable rod is installed in the retractable cavity. The distal end of the retractable rod is provided with a second engagement portion for adapting to the first engagement portion. A guide limiting structure is provided between the retractable rod and the push rod.

[0012] A compression spring, the compression spring being sleeved on the retraction rod; and

[0013] A piston, which is detachably connected to a retraction rod extending from the distal end of the retraction chamber, and the piston is sealed to the inner wall of the inner chamber.

[0014] In a preferred embodiment, at least two guide grooves are evenly distributed along the circumferential direction on the outer wall of the push rod, extending axially and penetrating into the retraction cavity, and a stop protrusion protruding from the groove wall is provided near the distal end of the guide groove.

[0015] In a preferred embodiment, the proximal end of the retraction rod is provided with a guide block that is adapted to each of the guide grooves. The guide block extends from the retraction cavity along the guide groove and protrudes from the outer wall of the push rod. In the initial state, the guide block is located on the distal side of the stop protrusion.

[0016] In a preferred embodiment, the proximal end of the retraction rod is provided with a plurality of elastic arms, and the guide block is disposed at the free end of the elastic arms.

[0017] In a preferred embodiment, the compression spring is located between the guide block and the distal end of the retraction cavity.

[0018] In a preferred embodiment, a second annular boss for mounting a piston is provided near the distal end of the retraction rod, and an annular groove adapted to the second annular boss is provided on the inner side of the piston.

[0019] In a preferred embodiment, the proximal end of the needle hub is provided with a fluid flow hole that axially penetrates the first joint, and the fluid flow hole communicates with the injection needle.

[0020] In a preferred embodiment, the needle seat has at least one fluid flow groove along the circumferential direction near the proximal end, the fluid flow groove is located on the distal side of the first joint, and the needle seat has a fluid flow hole that extends axially into the fluid flow groove.

[0021] In a preferred embodiment, the needle hub is provided with a mounting hole for mounting an injection needle, the diameter of which is larger than the diameter of the fluid flow hole.

[0022] The safe syringe used in this embodiment for injecting small doses of medication has the following advantages compared to the prior art:

[0023] (1) The structure of the piston being set on the push rod in the prior art has been changed. The piston is set on the retraction rod and is detachably connected to the retraction rod. With this setting, the sealing element between the retraction rod and the push rod is omitted. Based on the change in structural layout, the piston can perform multiple functions, namely, pushing the liquid medicine, sealing the push rod and the syringe, and sealing the push rod and the retraction rod.

[0024] (2) Based on the above structural layout changes, the number of parts is reduced, which makes the diameter of the syringe smaller, thus achieving precise control of injecting smaller doses of drug solution.

[0025] (3) The push rod is provided with a guide groove, and a stop protrusion is provided on the groove wall of the guide groove. The retraction rod is provided with a guide block extending from the guide groove. In the initial state, the guide block is restricted to the far end by the stop protrusion. The compression spring is provided between the piston mounting part and the guide block. The premise for the release of the potential energy of the compression spring is that the guide block breaks through the restriction of the stop protrusion. During the breakthrough process, the stop protrusion, the guide groove and the push rod wall need to be deformed as a whole. The breakthrough force required is large, and the possibility of false triggering is almost non-existent. The reliability is far superior to the existing technology.

[0026] (4) The guide groove and guide block play a guiding role during the retraction of the retraction rod. The resistance encountered by the retraction rod during the retraction process is smaller, the potential energy utilization efficiency of the compression spring is higher, and the retraction speed is faster. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a safety syringe suitable for injecting small doses of medication in this embodiment;

[0028] Figure 2 for Figure 1 The diagram shows the structure of the safety syringe in its explosive state.

[0029] Figure 3 This is a schematic diagram of the syringe structure in this embodiment;

[0030] Figure 4This is a schematic diagram of the combined state of the push rod and the retraction rod in this embodiment;

[0031] Figure 5 This is a schematic diagram of the push rod structure in this embodiment;

[0032] Figure 6 This is a schematic diagram of the combined state of the retraction rod and piston in this embodiment;

[0033] Figure 7 for Figure 6 A cross-sectional view of the structure shown;

[0034] Figure 8 This is a schematic diagram of the combined state of the needle hub and injection needle in the first embodiment of this example;

[0035] Figure 9 This is a schematic diagram of the needle seat structure according to the second embodiment in this example;

[0036] Figure 10 for Figure 9 A schematic cross-sectional view of the needle hub shown.

[0037] Figure 11 This is a cross-sectional view of the safety syringe for injecting small doses of medication in this embodiment, in its initial state.

[0038] Figure 12 This is a cross-sectional view of the safety syringe used for injecting small doses of medication in this embodiment after it has absorbed the medication.

[0039] Figure 13 This is a cross-sectional view of the safety syringe used in this embodiment for injecting small doses of medication, in the state where the injection is completed and the needle hub and injection needle are about to retract.

[0040] Figure 14 This is a cross-sectional view of the needle hub and injection needle in the retracted state after the injection of a safe syringe suitable for injecting small doses of medication in this embodiment. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0042] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an integral connection, or a detachable connection; they can refer to the internal connection of two components; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] In the description of this invention, it should be noted that the end of the syringe closer to the user is defined as the proximal end, and the end closer to the patient is defined as the distal end.

[0045] This embodiment provides a safety syringe, such as... Figure 1-2 As shown, the device includes a syringe 10, a plunger 20, a needle holder 30, a retraction rod 40, an injection needle 50, a compression spring 60, and a protective cap 90. The injection needle 50 is fixedly mounted at the distal end of the needle holder 30, as shown... Figure 3 As shown, the distal end of the syringe 10 is provided with a cap coupling seat 13 for cooperating with the cap 90. In the initial state, the cap 90 is sleeved on the outside of the injection needle 50 and is connected to the cap coupling seat 13 to protect the injection needle 50.

[0046] In this embodiment, as Figure 3 As shown, the syringe 10 has an inner cavity 11 extending from the proximal end to the distal end, and the push rod 20 is installed in the inner cavity 11. The cap coupling 13 has a needle seat cavity 17 that penetrates and communicates with the inner cavity 11. The diameter of the needle seat cavity 17 is smaller than the diameter of the inner cavity 11, and a stop portion 12 is formed at the junction of the inner cavity 11 and the needle seat cavity 17.

[0047] like Figure 11 As shown, the needle hub 30 enters from the proximal end of the inner cavity 11 and is then constrained to its initial position by the ring plug 70. Specifically, as... Figure 8-10 As shown, the proximal end of the needle holder 30 is provided with a first annular protrusion 31, such as... Figure 11As shown, the ring plug 70 is interference-fitted between the first annular boss 31 and the inner wall of the inner cavity 11. It should be noted that the ring plug has a certain degree of elasticity and can undergo axial displacement under external force. Specifically, in this embodiment, an annular cavity 16 is formed between the first annular boss 31 and the distal end of the inner cavity 11 to accommodate the ring plug 70, and the ring plug 70 is clearance-fitted with the needle seat 30 and the inner wall of the inner cavity 11 within the annular cavity 16.

[0048] As a preferred option, such as Figure 3 As shown, in this embodiment, the inner wall of the inner cavity 11 is provided with an annular groove 15. In the initial state, the outer side of the ring plug 70 is installed in the annular groove 15 to prevent the ring plug from axially moving when it is not subjected to external force or the external force received is small.

[0049] In this embodiment, a handheld operating part 15 is provided near the proximal end of the syringe 10, which is a conventional structure of a syringe.

[0050] like Figure 8 As shown, in this embodiment, the needle hub 30 of the first structural form has a mounting section 32 at its distal end that is adapted to the needle hub cavity 17. The mounting section 32 is detachably mounted in the needle hub cavity 17. A stop step 33 adapted to the stop portion 12 is provided at the proximal end of the mounting section 32 to prevent the needle hub from separating from the syringe barrel from the distal end of the syringe barrel.

[0051] In this embodiment, the proximal end face of the needle holder 30 is provided with a first engagement portion 34, and correspondingly, as shown... Figure 7 As shown, the distal end of the retraction rod 40 is provided with a second engagement portion 43 for fitting with the first engagement portion 34. After the first engagement portion 34 and the second engagement portion 43 are engaged, the needle seat 30 and the retraction rod 40 form a component that is difficult to separate easily.

[0052] Preferably, in this embodiment, the proximal end of the needle hub is provided with a fluid flow hole 36 that axially penetrates the first joint portion 34, and the fluid flow hole 36 communicates with the injection needle 50.

[0053] Preferably, in this embodiment, the first joint portion 34 is a joint protrusion protruding from the proximal end face of the needle seat, and the second joint portion 43 is a joint groove recessed inward from the distal end face of the retraction rod 40. The joint protrusion has an annular boss, and the joint groove has an annular protrusion. After the annular boss passes over the annular protrusion, the annular protrusion prevents the annular boss from disengaging from the joint groove. It should be noted that since the needle seat and the retraction rod are usually injection molded parts, they can undergo a certain degree of deformation. Based on the deformation under external force, the annular boss can pass over the annular protrusion and enter the joint groove.

[0054] It should be noted that the specific structures of the first and second joints given in this embodiment are preferred embodiments of this embodiment, and the joint structure of the two can also use any suitable joint structure in the prior art.

[0055] The second structural form of the needle holder 30 in this embodiment is as follows: Figures 9-10 As shown, the needle holder 30 has a radially penetrating fluid channel 35 near its proximal end, located on the distal side of the first joint. The needle holder 30 also has a fluid channel 36 extending axially into the fluid channel 35. This fluid channel 36 communicates with a mounting hole 37 inside the needle holder for mounting an injection needle. The diameter of the mounting hole 37 is larger than the diameter of the fluid channel 36.

[0056] In this embodiment, the liquid flows radially from the liquid flow groove 35 to the injection needle 50, which changes the traditional needle seat structure. This structure can increase the piston's limit stroke, resulting in less liquid residue in the liquid chamber.

[0057] The structure of the push rod 20 in this embodiment is as follows: Figure 4-5 As shown, it has a retraction cavity 21 inside, a plug 27 at its proximal end, and a retraction through hole 25 at its distal end to accommodate the retraction rod extending out. A stepped surface 26 is provided at the position where the retraction through hole 25 connects with the retraction cavity 21.

[0058] As a special feature of this embodiment, two guide grooves 22 are evenly distributed along the circumferential direction on the outer wall of the push rod 20, extending axially and penetrating into the retraction cavity 21. A stop protrusion 23 protruding from the groove wall is provided near the distal end of each guide groove 22. Preferably, in this embodiment, the stop protrusions 23 are a pair and arranged opposite to each other.

[0059] The structure of the retraction rod 40 in this embodiment is as follows: Figure 6-7 As shown, two elastic arms 41 are provided at the proximal end of the push rod 20, and the free end of each elastic arm 41 is provided with a guide block 42 that is adapted to the guide groove 22. The guide block 42 extends from the retraction cavity 21 along the guide groove 22 and protrudes from the outer wall of the push rod 20. In the initial state, the guide block 42 is located at the initial position 24 on the distal side of the stop protrusion 23, thereby restricting the retraction rod to the distal position of the retraction cavity.

[0060] In this embodiment, the guide groove 22, the guide block 42, and the stop protrusion 23 constitute a guide and limiting structure between the push rod and the retracting rod. It should be noted that the guide and limiting structure shown in this embodiment is a preferred embodiment, but other suitable guide and limiting structures can also be used.

[0061] As a special feature of this embodiment, such as Figure 11As shown, the compression spring 60 is sleeved on the retraction rod 40 and located between the stepped surface 26 and the guide block 42.

[0062] As a preferred option, such as Figure 7 As shown, the distal end of the guide block 42 is provided with an inwardly inclined slope 45. The purpose of this arrangement is to prevent the compression spring 60 from falling off the guide block 42.

[0063] As a preferred option, such as Figure 7 As shown, a guide ramp 46 is provided on the proximal side of the guide block 42, which serves to guide the deformation of the elastic arm 41 when the guide block 42 is installed from the distal end of the push rod 20 into the retraction cavity.

[0064] As a special feature of this embodiment, such as Figure 6-7 As shown, the piston 80 is detachably connected to the retraction rod 40 extending from the distal end of the retraction cavity, and the piston 80 is sealed to the inner wall of the inner cavity 11. Specifically, in this embodiment, a second annular boss 44 for mounting the piston is provided near the distal end of the retraction rod 40, and an annular groove 81 adapted to the second annular boss is provided on the inner side of the piston. Since the piston is an elastic structure, it can be mounted on the retraction rod by deformation, and can also be separated from the retraction rod under the action of external force.

[0065] A unique feature of this embodiment is that the piston 80 serves both as a drive structure for adsorbing and propelling the drug solution and as a sealing element. Furthermore, it is sealed by simultaneously sealing the gaps between the drug solution chamber and the push rod and syringe, as well as the gaps between the drug solution chamber and the push rod and the retraction rod. Compared to existing technologies, fewer seals are required, allowing for a smaller syringe diameter, which is suitable for precise control of small-dose drug injections.

[0066] The working principle of the safety syringe in this embodiment is as follows:

[0067] (1) Figure 1 As shown in the initial state, with the protective cap 90 removed, its internal structure is as follows: Figure 11 As shown, the distal end of piston 80 contacts the proximal end of needle seat.

[0068] (2) Pull the push rod 20. The state after adsorbing the medicine is as follows: Figure 12 As shown.

[0069] (3) Push the push rod 20. The state of the drug injection is as follows: Figure 13 As shown, at this time, the distal end of the piston 80 contacts the proximal end of the ring plug 70. Continuing to push the push rod causes the second engagement of the retraction rod 40 to engage with the first engagement of the needle seat. During this process, the distal end of the piston acts on the proximal end face of the ring plug, driving the ring plug to move into the annular cavity 16.

[0070] (4) After the second joint of the retraction rod 40 engages with the first joint of the needle seat, the push rod 20 continues to be pushed. At this time, the position of the retraction rod 40 is relatively fixed. During the process of the push rod continuing to move, the ring plug is pushed into the annular cavity 16. At this time, the ring plug releases the interference fit between the needle seat and the inner cavity. During this process, the end face of the push rod acts on the piston 80. When the position of the retraction rod 40 is fixed, the piston separates from the retraction rod under the pushing force of the push rod.

[0071] (5) While step (4) is being performed, based on the relative movement of the push rod and the retraction rod, the guide block 42 drives the stop protrusion 23 to deform, thereby releasing the restriction on the guide block 42 and causing the guide block 42 to move to the proximal side of the stop protrusion 23.

[0072] (6) After the stop protrusion 24 releases its restriction on the guide block 46, the potential energy of the compression spring 60 is released, driving the assembly consisting of the retraction rod, needle seat, and injection needle into the retraction cavity, until... Figure 14 The state shown indicates that automatic protection of the injection needle is achieved.

[0073] In summary, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A safe syringe suitable for injecting small doses of medication, characterized in that, At least including: The syringe (10) has an inner cavity (11) extending from the proximal end to the distal end and a needle seat cavity (17) communicating with the distal end of the inner cavity (11). The junction of the inner cavity (11) and the needle seat cavity (17) forms a stop (12). The needle hub (30) has an injection needle (50) at its distal end and a first joint (34) at its proximal end. A stop step (33) adapted to the stop part (12) is provided near the distal end of the needle hub. The ring plug (70) is provided with a first annular boss (31) at the proximal end of the needle seat. The ring plug is interference-fitted between the first annular boss and the inner wall of the inner cavity. An annular cavity (16) for accommodating the ring plug is formed between the first annular boss and the distal end of the inner cavity. The ring plug is clearance-fitted with the needle seat and the inner wall of the inner cavity within the annular cavity. Push rod (20), the push rod is located in the inner cavity (11), and the push rod is provided with a retraction cavity (21). A retractable rod (40) is installed in the retractable cavity. The distal end of the retractable rod is provided with a second joint (43) for adapting to the first joint (34). A guide limiting structure is provided between the retractable rod and the push rod. Compression spring (60), the compression spring being sleeved on the retraction rod; and A piston (80) is detachably connected to a retraction rod extending from the distal end of the retraction cavity, and the piston is sealed to the inner wall of the inner cavity (11). After the second joint of the retracting rod engages with the first joint of the needle seat, the push rod continues to be pushed. At this time, the position of the retracting rod is relatively fixed. As the push rod continues to move, the ring plug is pushed into the annular cavity. At this time, the ring plug releases the interference fit between the needle seat and the inner cavity. During this process, the end face of the push rod acts on the piston. When the position of the retracting rod is fixed, the piston separates from the retracting rod under the pushing force of the push rod.

2. The safety syringe according to claim 1, characterized in that, At least two guide grooves (23) are evenly distributed along the circumferential direction on the outer wall of the push rod, extending axially and penetrating into the retraction cavity. A stop protrusion (24) protruding from the groove wall is provided near the far end of the guide groove.

3. The safety syringe according to claim 2, characterized in that, The proximal end of the retraction rod is provided with a guide block (42) that is adapted to the guide groove. The guide block extends from the retraction cavity along the guide groove and protrudes from the outer wall of the push rod. The guide groove, the stop protrusion and the guide block constitute the guide limiting structure. In the initial state, the guide block is located on the far end side of the stop protrusion.

4. The safety syringe according to claim 3, characterized in that, The retraction rod has a plurality of elastic arms (41) at its proximal end, and the guide block is located at the free end of the elastic arms.

5. The safety syringe according to claim 3, characterized in that, The compression spring is located between the guide block (42) and the far end of the retraction cavity (21).

6. The safety syringe according to claim 1, characterized in that, The retraction rod is provided with a second annular boss (44) for mounting the piston near its distal end, and the piston is provided with an annular groove (81) that matches the second annular boss on its inner side.

7. The safety syringe according to any one of claims 1-6, characterized in that, The proximal end of the needle hub is provided with a fluid flow hole (36) that axially penetrates the first joint (34), and the fluid flow hole is in communication with the injection needle.

8. The safety syringe according to any one of claims 1-6, characterized in that, The needle seat has at least one fluid groove (35) arranged in the circumferential direction near the proximal end. The fluid groove is located on the distal side of the first joint. The needle seat is provided with a fluid hole (36) that extends axially into the fluid groove.

9. The safety syringe according to claim 8, characterized in that, The needle hub is provided with a mounting hole (37) for mounting an injection needle, and the diameter of the mounting hole (37) is larger than the diameter of the liquid flow hole.

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