Disposable medical injector, dispensing device or medicine dissolving device provided with plastic piston

Abstract

The invention relates to a disposable medical injector, a medicine dispensing device or a medicine dissolving device with a plastic piston, which comprises a needle cylinder, a push rod, a piston connector and a piston, the piston is arranged on the piston connector, the lower end of the piston connector is arranged at the upper end of the push rod, and the piston, the piston connector and the push rod are inserted into the needle cylinder. The piston is composed of a piston head and a piston sleeve which are formed in an injection molding mode, the piston head is in a T shape, the lower end of the piston head is arranged at the upper end of the push rod, an annular groove is formed in the edge of the lower side of the upper face of the piston head, and an annular boss is arranged on the upper face of the piston sleeve. The annular boss on the piston sleeve is inserted into the annular groove in the piston head; according to the technical scheme, the two wedge-shaped inclined planes on the piston head and the piston sleeve are matched, and axial force is converted into partial radial force, so that a better sealing effect is achieved between the piston head and the needle cylinder, the use of a rubber piston is avoided, and the needle cylinder still meets the national current standard requirement after an injection molding piece is adopted.

Description

Technical Field

[0001] This invention relates to a clinical medical device, and more particularly to a disposable medical syringe, dispensing device, or dissolving device equipped with a plastic piston. Background Technology

[0002] In the existing technology, syringes with an injection capacity of less than 10 ml are usually called syringes, while those with an injection capacity of more than 10 ml are called dispensing devices or drug dissolving devices.

[0003] In existing technologies, in order to ensure the sealing effect during the extraction and delivery of drugs in syringes, drug dispensing devices, and drug dissolving devices, most of them use rubber with good elastic sealing effect as the main production material of the piston in syringes, drug dispensing devices, and drug dissolving devices. In addition, silicone oil diluted with hydrochlorofluorocarbon is applied to the outer edge of the piston to ensure that it achieves the desired effect.

[0004] On September 1, 2023, the Ministry of Ecology and Environment of China issued an announcement that the use of hydrochlorofluorocarbons (HCFCs) as silicone oil diluents and cleaning agents will be completely banned in the disposable medical device industry, and a final deadline of December 1, 2023 was set. Summary of the Invention

[0005] In view of this, the main objective of the present invention is to provide a disposable medical syringe, dispensing device or dissolving device equipped with a plastic piston. Through this technical solution, the axial force is converted into a partial radial force by utilizing the cooperation between the two wedge-shaped inclined surfaces on the piston head and the piston sleeve, thereby achieving a better sealing effect between the piston head and the syringe.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A disposable medical syringe, dispensing device, or dissolving device equipped with a plastic piston includes a syringe, a plunger, a piston connector, and a piston. The piston is disposed on the piston connector, and the lower end of the piston connector is disposed on the upper end of the plunger. The piston, piston connector, and plunger are inserted into the syringe. The piston is composed of an injection-molded piston head and a piston sleeve. The piston head is T-shaped, and the lower end of the piston head is disposed on the upper end of the plunger. An annular groove is provided on the upper and lower edges of the piston head. An annular boss is provided on the piston sleeve. The piston sleeve is fitted onto the lower part of the piston head, and the annular boss on the piston sleeve is inserted into the annular groove on the piston head.

[0007] As a further technical solution, the inner side of the annular groove of the piston head is an annular inclined inner surface that tapers inward from bottom to top into the annular groove, and the bottom of the outer side of the annular groove is provided with a first working inner surface that tilts outward from the annular groove. The inner side of the annular boss of the piston sleeve is an annular inclined outer surface that tapers inward from bottom to top into the annular boss, and the top of the outer side of the annular boss is provided with a first working outer surface that tilts outward from the annular boss.

[0008] As a further technical solution, the piston head has a transition inner surface that slopes inward toward the annular groove at the middle of its outer side, and the piston sleeve has a transition outer surface that slopes inward toward the annular boss at the middle of its outer side.

[0009] As a further technical solution, the outer groove of the annular groove of the piston head is provided with a second working inner surface that is inclined outward from the annular groove, and the outer root of the annular boss of the piston sleeve is provided with a second working outer surface that is inclined outward from the annular boss.

[0010] As a further technical solution, a piston mounting seat is provided inside the piston head, and several evenly distributed elastic opening grooves are provided radially on the side wall of the piston head below the piston mounting seat. The upper part of the piston connector head extends into the piston mounting seat by utilizing the elasticity of the elastic opening grooves on the side wall below the piston head.

[0011] As a further technical solution, when the first working inner surface of the annular groove contacts the first working outer surface of the annular boss, the lower end face of the piston sleeve presses against the upper end of the push rod, and a gap of 0.3mm-0.6mm is left between the lower end face of the piston head and the upper end of the push rod.

[0012] The beneficial effects of adopting the above technical solution are as follows: A disposable medical syringe, dispensing device or dissolving device equipped with a plastic piston, through this technical solution, utilizes the cooperation between the two wedge-shaped inclined surfaces on the piston head and piston sleeve to convert axial force into part of radial force, thereby achieving a better sealing effect between the piston head and the syringe, eliminating the use of rubber pistons, and still meeting the requirements of current national standards after using injection molded parts. Attached Figure Description

[0013] Figure 1 This is a schematic cross-sectional view of the overall structure of the dispensing or dissolving apparatus with a volume greater than 10 ml in this invention.

[0014] Figure 2 This is a schematic cross-sectional view of the syringe with a volume of less than 10 ml in this invention.

[0015] Figure 3 This is a schematic cross-sectional view of the overall structure of the residue removal syringe with a volume of less than 10 ml in this invention.

[0016] Figure 4 for Figure 1 A schematic diagram of the enlarged structure in the middle A direction.

[0017] In the figure, 1 is the syringe, 2 is the push rod, 3 is the piston connector, 4 is the piston head, 5 is the piston sleeve, 6 is the annular groove, 7 is the annular boss, 8 is the annular inclined inner surface, 9 is the first working inner surface, 10 is the annular inclined outer surface, 11 is the first working outer surface, 12 is the transition inner surface, 13 is the transition outer surface, 14 is the second working inner surface, 15 is the second working outer surface, 16 is the piston mounting seat, and 17 is the elastic opening groove. Detailed Implementation

[0018] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0019] like Figures 1-4 As shown, the present invention relates to a disposable medical syringe, dispensing device, or dissolving device equipped with a plastic piston, comprising a syringe 1, a push rod 2, a piston connector 3, and a piston. The piston is disposed on the piston connector 3, and the lower end of the piston connector 3 is disposed on the upper end of the push rod 2. The piston, piston connector 3, and push rod 2 are inserted into the syringe 1. The piston is composed of an injection-molded piston head 4 and a piston sleeve 5. The piston head 4 is T-shaped, and the lower end of the piston head 4 is disposed on the upper end of the push rod 2. An annular groove 6 is provided on the upper and lower edges of the piston head 4. An annular boss 7 is provided on the piston sleeve 5. The piston sleeve 5 is fitted onto the lower part of the piston head 4, and the annular boss 7 on the piston sleeve 5 is inserted into the annular groove 6 on the piston head 4.

[0020] As a further embodiment, the inner side of the annular groove 6 of the piston head 4 is an annular inclined inner surface 8 that tapers inward from bottom to top into the annular groove 6, and the bottom of the outer side of the annular groove 6 is provided with a first working inner surface 9 that tilts outward from the annular groove 6. The inner side of the annular boss 7 of the piston sleeve 5 is an annular inclined outer surface 10 that tapers inward from bottom to top into the annular boss 7, and the top of the outer side of the annular boss 7 is provided with a first working outer surface 11 that tilts outward from the annular boss 7.

[0021] As a further embodiment, the piston head 4 has a transition inner surface 12 that is inclined toward the annular groove 6 at the middle of its outer side, and the piston sleeve 5 has a transition outer surface 13 that is inclined toward the annular boss 7 at the middle of its outer side.

[0022] As a further embodiment, the outer groove of the annular groove 6 of the piston head 4 is provided with a second working inner surface 14 that is inclined outward from the annular groove 6, and the outer root of the annular boss 7 of the piston sleeve 5 is provided with a second working outer surface 15 that is inclined outward from the annular boss 7.

[0023] As a further embodiment, a piston mounting seat 16 is provided inside the piston head 4, and several evenly distributed elastic opening grooves 17 are provided radially on the side wall of the piston head 4 below the piston mounting seat 16. The upper part of the piston connector 3 extends into the piston mounting seat 16 by utilizing the elasticity of the elastic opening grooves 17 on the side wall below the piston head 4.

[0024] As a further embodiment, when the first working inner surface 9 of the annular groove 6 contacts the first working outer surface 11 of the annular boss 7, the lower end face of the piston sleeve 5 presses against the upper end of the push rod 2, and a 0.4mm gap is left between the lower end face of the piston head 4 and the upper end of the push rod 2.

[0025] In the technical solution of the present invention, the piston made of rubber material used in the prior art is replaced with piston head 4 and piston sleeve 5 made of injection molding material, which eliminates the need to apply silicone oil diluted with hydrochlorofluorocarbon to the rubber piston, and meets the requirements of the national disposable medical device industry to completely prohibit the use of hydrochlorofluorocarbon as silicone oil diluent and cleaning agent.

[0026] In the technical solution of the present invention, the transition outer surface 13 and the transition inner surface 12 are non-working surfaces, which are designed to create a first working inner surface 9 and a second working inner surface 14 in the annular groove 6 of the piston head 4, and to create a first working outer surface 11 and a second working outer surface 15 on the annular boss 7 of the piston sleeve 5.

[0027] In the three embodiments of the technical solution of the present invention, the first embodiment is a drug dispensing device or drug dissolving device with a flat piston head and biased needle for a volume greater than 10 ml; the second embodiment is a syringe with a conical piston head for a volume less than 10 ml; and the third embodiment is a syringe with a flat piston head for a volume less than 10 ml and a residue removal function.

[0028] In the technical solution of the present invention, for syringes with a capacity of less than 10ml, the piston head and the plunger can also be connected by a thread.

[0029] The technical solution of the present invention involves two steps in use: first, extracting the liquid medicine, and second, pushing the liquid medicine.

[0030] When the liquid medication is pushed into the syringe 1 by the push rod 2, the piston head 4 forms a certain resistance under the action of the liquid medication and the syringe 1 wall. Since there is a 0.4mm gap between the bottom of the piston head 4 and the top of the push rod 2, and the piston sleeve 5 presses against the push rod 2, the push rod 2 first pushes the piston sleeve 5, so that the annular boss 7 of the piston sleeve 5 presses tightly against the annular groove 6 of the piston head 4, and the first working inner surface 9 and the second working inner surface 14 press down on the first working outer surface 11 and the second working outer surface 15 respectively, forcing the outer edge of the piston head 4 to expand radially. While maintaining this state, the push rod 2 drives the piston connecting head 3 to push the piston head 4 to overcome the resistance of the liquid medication and the syringe 1 wall to push the liquid medication. At the same time, the piston sleeve 5 and the push rod 2 move synchronously to maintain the radial expansion of the outer edge of the piston head 4, forming the best sealing effect between the syringe 1 and the piston head 4.

[0031] When the liquid medicine is drawn out, as the push rod 2 is pulled out from the syringe 1, the piston sleeve 5 presses against the push rod 2. Because there is a 0.4mm gap between the bottom of the piston head 4 and the top of the push rod 2, the piston connector 3 drives the piston head 4 to move slightly downward, causing the annular groove 6 of the piston head 4 to press tightly against the annular boss 7 of the piston sleeve 5. The first working inner surface 9 and the second working inner surface 14 press down on the first working outer surface 11 and the second working outer surface 15 respectively, forcing the outer edge of the piston head 4 to expand radially, thus achieving the best sealing effect between the syringe 1 and the piston head 4 when drawing out the liquid medicine.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A disposable medical syringe, dispensing device, or dissolving device equipped with a plastic piston, comprising a syringe barrel, a plunger, a piston connector, and a piston, wherein the piston is disposed on the piston connector, the lower end of the piston connector is disposed on the upper end of the plunger, and the piston, piston connector, and plunger are inserted into the syringe barrel, characterized in that, The piston is composed of an injection-molded piston head and a piston sleeve. The piston head is T-shaped, with its lower end set on the upper end of the push rod. An annular groove is provided on the upper and lower edges of the piston head. An annular boss is provided on the piston sleeve. The piston sleeve is fitted onto the lower part of the piston head, and the annular boss on the piston sleeve is inserted into the annular groove on the piston head.

2. The disposable medical syringe, dispensing device, or dissolving device equipped with a plastic piston according to claim 1, characterized in that, The inner side of the annular groove of the piston head is an annular inclined inner surface that tapers inward from bottom to top into the annular groove. The bottom of the outer side of the annular groove is provided with a first working inner surface that tilts outward from the annular groove. The inner side of the annular boss of the piston sleeve is an annular inclined outer surface that tapers inward from bottom to top into the annular boss. The top of the outer side of the annular boss is provided with a first working outer surface that tilts outward from the annular boss.

3. The disposable medical syringe, dispensing device, or dissolving device equipped with a plastic piston according to claim 1 or 2, characterized in that, The piston head has a transition inner surface that slopes inward toward the annular groove at the middle of its outer side, and the piston sleeve has a transition outer surface that slopes inward toward the annular boss at the middle of its outer side.

4. The disposable medical syringe, dispensing device, or dissolving device equipped with a plastic piston according to claim 1 or 2, characterized in that, The piston head has a second working inner surface that is inclined outward from the annular groove on the outer side of the groove, and the piston sleeve has a second working outer surface that is inclined outward from the annular boss on the outer side of the root.

5. The disposable medical syringe, dispensing device, or dissolving device equipped with a plastic piston according to claim 1, characterized in that, The piston head is provided with a piston mounting seat. Several evenly distributed elastic opening grooves are provided radially on the side wall of the piston head below the piston mounting seat. The upper part of the piston connector head extends into the piston mounting seat by utilizing the elasticity of the elastic opening grooves on the side wall below the piston head.

6. The disposable medical syringe, dispensing device, or dissolving device equipped with a plastic piston according to claim 1 or 2, characterized in that, When the first working inner surface of the annular groove contacts the first working outer surface of the annular boss, the lower end face of the piston sleeve presses against the upper end of the push rod, and a gap of 0.3mm-0.6mm is left between the lower end face of the piston head and the upper end of the push rod.

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