A syringe for a pump

Abstract

The utility model relates to a kind of syringes for pump, including injection barrel, push rod and piston;Injection barrel top end is equipped with medicine outlet;Piston front end is equipped with recess along circumference, recess is equipped with main seal ring, and main seal ring is set in injection barrel with interference fit;Piston rear end is equipped with pressure-bearing platform along outer wall, the outer wall of pressure-bearing platform is attached to injection barrel inner wall, and the auxiliary pressure chamber is formed between the front end surface of pressure-bearing platform, piston, the rear end surface of main seal ring and injection barrel inner wall;Gas outlet is equipped on the piston between main seal ring and pressure-bearing platform, piston is equipped with gas outlet, push rod is equipped with air inlet, and gas outlet is sequentially communicated with gas outlet, air inlet.The main seal ring in the application is embedded in the annular recess of piston front end, and is tightly attached to the inner wall of injection barrel of syringe, which is the first physical barrier for liquid medicine sealing;The second sealing of liquid medicine is realized through auxiliary pressure chamber 6, to avoid sealing failure leading to large leakage of liquid medicine, and realize long-term reliable operation of the sealing of syringe for pump.

Description

Technical Field

[0001] This utility model relates to a medical device, and more particularly to a pump syringe. Background Technology

[0002] A pump syringe refers to a syringe used in conjunction with an infusion pump. It is widely used in clinical medicine and scientific research experiments due to its advantage of precisely controlling the infusion rate and dosage.

[0003] For example, the patent document with announcement number CN219878850U discloses a disposable pump injection molding machine. In this machine, the sealing performance between the piston and the syringe depends on the rubber elasticity of the piston. The fluidity of high-viscosity liquids (such as fat emulsions) is much lower than that of conventional liquids. When injected, it will generate a lot of viscous resistance. In order to ensure the infusion rate, the injection pump will increase the driving force, which will cause the piston pressure at the sealing contact surface between the syringe and the liquid cavity to rise sharply. The high pressure will squeeze the piston seal of the syringe, causing it to undergo irreversible deformation. For example, the sealing lip will be crushed, the sealing ring will bulge, and gaps will appear on the originally tightly fitted sealing surface. In addition, if the pressure fluctuates violently, it may also impact the joint between the piston seal and the inner wall of the syringe, causing a momentary gap between the two, resulting in seal failure and leakage of liquid to the rear end of the piston, contaminating the drive mechanism. Utility Model Content

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a pump injector.

[0005] The technical solution adopted by this utility model to solve its technical problem is: a pump injector, including an injection barrel, a plunger and a piston; the top of the injection barrel is provided with a drug outlet; The push rod is provided with a piston at its top end, one end of the push rod with the piston is placed inside the injection cylinder, and the other end of the push rod extends out of the injection cylinder; The piston front end is provided with a groove along the circumference, and a main sealing ring is provided in the groove. The main sealing ring is interference-fitted into the injection cylinder. The piston has a pressure-bearing platform along its outer wall at the rear end. The outer wall of the pressure-bearing platform is in contact with the inner wall of the injection cylinder. An auxiliary pressure chamber is formed between the front face of the pressure-bearing platform, the piston, the rear face of the main sealing ring, and the inner wall of the injection cylinder. An air outlet is provided on the piston between the main sealing ring and the pressure plate. An air outlet passage is provided inside the piston. An air inlet passage is provided inside the push rod. The air outlet is connected to the air outlet passage and the air inlet passage in sequence.

[0006] In a preferred embodiment of this utility model, the pressure platform and the piston are integrally formed.

[0007] In a preferred embodiment of this utility model, the main sealing ring is made of medical-grade silicone rubber material, and the outer diameter of the main sealing ring is 0.1-0.3 mm larger than the inner diameter of the syringe barrel.

[0008] In a preferred embodiment of this utility model, the pressure-bearing platform protrudes from the piston, and the outer diameter of the pressure-bearing platform is smaller than the outer diameter of the main sealing ring.

[0009] In a preferred embodiment of the present invention, the groove is provided with wavy fixing teeth on its circumference.

[0010] The beneficial effects of this utility model are as follows: The main sealing ring in this application is embedded in the annular groove at the front end of the piston, which is in close contact with the inner wall of the syringe barrel and is located at the critical position between the liquid chamber and the auxiliary pressure chamber. It is the first physical barrier for sealing the liquid. The auxiliary pressure chamber achieves the second sealing of the liquid, avoiding the leakage of a large amount of liquid due to seal failure, and realizing the long-term reliable operation of the pump syringe seal. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 yes Figure 1 Enlarged view of point A in the middle; Figure 3 This is a schematic diagram of the air intake structure; Figure 4 This is a schematic diagram of the groove structure; In the diagram: 1. Injector; 101. Outlet; 2. Push rod; 3. Piston; 301. Main sealing ring; 4. Pressure plate; 5. Auxiliary pressure chamber; 6. Outlet; 7. Outlet channel; 8. Inlet channel; 9. Detailed Implementation

[0012] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0013] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They 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, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0014] like Figures 1 to 4 The pump syringe shown includes a syringe barrel 1, a plunger 2 and a piston 3; the top of the syringe barrel 1 is provided with a drug outlet 101. The push rod 2 is provided with a piston 3 at its top end. One end of the push rod 2 with piston 3 is placed inside the injection cylinder 1, and the other end of the push rod 2 extends out of the injection cylinder 1. The piston 3 has a groove 301 along its circumference at the front end, and a main sealing ring 4 is provided in the groove 301. The main sealing ring 4 is interference-fitted into the syringe 1. In a preferred embodiment, the main sealing ring 4 in this application is made of medical silicone rubber material, and the outer diameter of the main sealing ring 4 is 0.1-0.3 mm larger than the inner diameter of the syringe 1. The piston 3 has a pressure-bearing platform 5 along its outer wall at the rear end. The outer wall of the pressure-bearing platform 5 is in contact with the inner wall of the injection cylinder 1. An auxiliary pressure chamber 6 is formed between the front face of the pressure-bearing platform 5, the outer wall of the piston 3, the rear face of the main sealing ring 4, and the inner wall of the injection cylinder 1. An air outlet 7 is provided on the piston between the main sealing ring 4 and the pressure plate 5. An air outlet 8 is provided inside the piston. An air inlet 9 is provided inside the push rod 2. The air outlet 7 is connected to the air outlet 8 and the air inlet 9 in sequence. The air inlet 9 at one end of the push rod 2 extending out of the syringe is connected to sterile air through a pipe.

[0015] Piston 3 is located inside syringe 1. Piston 3 slides axially along syringe 1 via push rod 2. Piston 3 has a main sealing ring 4 at its front end and an auxiliary pressure chamber 6 in its middle. The piston tail is fixed to the front end of push rod 2 via a threaded or snap-fit ​​structure, ensuring that piston 3 can move synchronously when push rod 2 pushes or pulls. The side wall of piston 3 maintains a very small sliding gap with the inner wall of syringe, which does not affect piston movement and can form a sealed environment with the main sealing ring 4 and auxiliary pressure chamber 6.

[0016] The pump syringe of this application has a plunger 2 extending from the syringe barrel 1, which is rigidly connected to the pump body plunger via a thread or elastic clip. The connection between the plunger 2 of the syringe barrel 1 and the pump body plunger is offset from the air inlet 9, allowing the air inlet 9 to be exposed and connected to sterile air. The pump body pushes the plunger 2 of the syringe barrel 1 to inject the drug in the syringe barrel 1. Before the pump body pushes the plunger 2, a predetermined amount of sterile air is first injected into the auxiliary pressure chamber 6. The sterile air is filtered by a filter element before being injected into the auxiliary pressure chamber 6, and slowly introduced into the air inlet 9. After passing through the air outlet 8 and the air outlet 7, it enters the auxiliary pressure chamber 6 to complete the inflation. At the same time, a miniature pressure gauge can be installed at the interface between the air inlet 9 and the pipeline to monitor the pressure in the auxiliary pressure chamber 6. After reaching the preset pressure, the air valve is closed to complete the inflation. A one-way valve can also be installed in the air inlet to prevent air backflow. A miniature sealing ring is used to seal the interface between the air inlet 9 and the pipeline to prevent air leakage.

[0017] A patch sensor is installed on the side of the piston facing the liquid chamber. The patch sensor is connected to a controller, which can be externally mounted. The patch sensor collects the pressure signal of the liquid flow in real time. The signal is converted from analog to digital and transmitted to the controller, which directly displays the pressure value. A miniature pressure sensor is installed on the outer wall of the piston in the auxiliary pressure chamber 6. The miniature pressure sensor is also connected to the controller, which is connected to an alarm. The miniature pressure sensor monitors the pressure in the auxiliary pressure chamber in real time, always maintaining the pressure in the auxiliary pressure chamber 0.05-0.1 MPa higher than the pressure in the liquid chamber. Under normal operating conditions, the positive pressure in the auxiliary pressure chamber 6 forms a reverse support force on the rear end of the main sealing ring 4, offsetting part of the pressure of the liquid on the main sealing ring 4 and reducing the permanent deformation of the main sealing ring 4. If the main sealing ring 4 develops tiny gaps due to wear, aging, or erosion by high-viscosity liquid, the liquid will be reversed and suppressed in the liquid chamber due to the pressure difference between the liquid chamber pressure and the auxiliary chamber pressure, preventing it from continuing to permeate to the rear end of the piston and avoiding liquid contamination of the pump drive mechanism or external leakage. The pump body injects sterile air into the auxiliary pressure chamber through the air inlet 9, and always maintains the pressure inside the chamber slightly higher than the pressure inside the drug liquid chamber.

[0018] A miniature pressure sensor monitors the air pressure in the auxiliary pressure chamber in real time. When the leakage of the main sealing ring increases, air in the auxiliary pressure chamber will flow out along with the liquid seepage, causing a drop in pressure within the chamber. When the pressure falls below a preset threshold, the miniature pressure sensor immediately sends an electrical signal to the pump controller, triggering an alarm. At this point, the operator can promptly stop the machine for inspection or replace the piston, preventing seal failure and subsequent large-scale liquid leakage, thus ensuring long-term reliable operation of the pump syringe seal.

[0019] In this application, a groove 301 is provided along the circumference of the piston front end. Specifically, the groove depth can be 2-3 mm and the width 1-2 mm. A main sealing ring 4 is provided in the groove, and the groove 301 achieves radial limiting and axial positioning of the main sealing ring 4. The inner wall of the groove 301 restricts excessive expansion of the main sealing ring, ensuring that the interference fit between the outer ring of the main sealing ring and the inner wall of the syringe barrel is always within the optimal range, that is, the outer diameter of the main sealing ring is 0.1-0.3 mm larger than the inner diameter of the syringe barrel 1. The front and rear end faces of the groove 301 prevent the sealing ring from moving, ensuring that the main sealing ring is always aligned with the critical position between the liquid cavity and the auxiliary pressure cavity, avoiding sealing surface misalignment. When the push rod pushes the liquid, when the liquid pressure acts on the front end face of the main sealing ring, the main sealing ring is squeezed towards the rear end face of the groove. At the same time, the liquid will further push the outer ring of the main sealing ring towards the inner wall of the syringe barrel through the tiny gap between the main sealing ring and the inner wall of the groove, achieving a self-reinforcing seal where the greater the pressure, the tighter the fit.

[0020] The groove in this application provides rigid support for the sealing ring, reducing the elastic deformation of the main sealing ring during sliding and lowering the wear rate. Medical-grade grease (compatible with the sealing ring and medication) can be applied to the bottom of the groove to form an oil film lubrication, reducing friction between the inner ring of the main sealing ring and the groove, while also preventing cracking and aging of the main sealing ring due to dry friction. Without the groove structure, the main sealing ring is prone to radially disordered deformation under stress, failing to generate directional expansion force, which may lead to leakage under high pressure due to the sealing ring turning outwards.

[0021] As a preferred embodiment, the pressure platform 5 and the piston 3 are integrally formed, which helps to improve the integrity and structural strength of the pressure platform 5 and the piston 3.

[0022] In a preferred embodiment, the pressure plate 5 in this application protrudes from the piston 3, and the outer diameter of the pressure plate 5 is smaller than the outer diameter of the main sealing ring 4, thereby reducing the friction between the pressure plate 5 and the injection cylinder and ensuring stable injection of the drug by the push rod.

[0023] The groove 301 is provided with a wave-shaped fixing tooth 3011 on its circumference. The wave-shaped fixing tooth 3011 structure enhances the axial positioning of the main sealing ring 4 and the groove 301, further increases the resistance of the liquid flow, blocks the internal leakage channel, and prevents the main sealing ring 4 from sliding.

[0024] The main sealing ring in this application is embedded in the annular groove at the front end of the piston, tightly fitting against the inner wall of the syringe barrel. Located at the critical position between the drug chamber and the auxiliary pressure chamber, it serves as the first physical barrier for sealing the drug. The main sealing ring 4, made of medical-grade silicone rubber, is inherently elastic. After installation, its outer diameter is slightly larger than the inner diameter of the syringe barrel, allowing it to form a tight seal with the inner wall of the syringe barrel through its own deformation. Without additional connecting parts, it remains relatively fixed by structural engagement and material elasticity. After the piston is assembled, when the pump uses the syringe to draw the drug, the cavity containing the drug becomes the drug chamber. The main sealing ring 4, due to interference fit, is squeezed by the inner wall of the syringe barrel, causing elastic deformation and forming an annular sealing surface tightly against the inner wall, completely blocking the connection between the drug chamber and the auxiliary pressure chamber. When the pump pushes the piston to inject the drug, the drug pressure acts on the front end of the main sealing ring, further compressing the sealing ring against the inner wall, achieving a pressure-reinforced seal. The greater the drug pressure, the tighter the sealing ring fits, and the more reliable the basic sealing effect. When the pump uses a syringe to push or draw the medication, the medication in the medication chamber exerts forward or backward pressure on the main sealing ring. This pressure further compresses the main sealing ring, making it fit more closely to the inner wall of the syringe barrel, thus preventing the medication from seeping into the rear end of the piston and completing the first seal. If the main sealing ring 4 develops tiny gaps due to wear, aging, or erosion by high-viscosity medication, and the medication is about to break through the main sealing ring and seep backward, the pressure in the auxiliary pressure chamber 6 is 0.05-0.1 MPa greater than the medication pressure. For example, when the medication pressure is 0.3 MPa, the auxiliary chamber pressure is 0.35-0.4 MPa, achieving a second seal for the medication through the auxiliary pressure chamber 6.

[0025] The pressure-bearing platform, as one of the rigid enclosing walls of the auxiliary pressure chamber, has its front end face tightly fitted with the rear end face of the main sealing ring, while its rear end face, together with the side wall of the piston body, forms the chamber boundary. During inflation, the rigid structure of the pressure-bearing platform resists the pressure of the air inside the chamber, preventing radial expansion or deformation of the chamber and providing a stable chamber space for the inflation process. Simultaneously, the coaxial integrated design of the pressure-bearing platform and the piston ensures uniform pressure distribution within the chamber during inflation, preventing excessively high local pressure due to chamber misalignment. This protects the main sealing ring, ensuring it remains in a stable sealing state and preventing air leakage from the gap between the sealing ring and the cylinder wall.

[0026] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0027] In summary, although the present invention has been disclosed above with reference to preferred embodiments, the above preferred embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. A pump syringe, characterized in that, It includes an injection cylinder (1), a push rod (2) and a piston (3); the top of the injection cylinder (1) is provided with a drug outlet (101). The push rod (2) is provided with a piston (3) at the top end. One end of the push rod (2) with piston (3) is placed inside the injection cylinder (1), and the other end of the push rod (2) extends out of the injection cylinder (1). The piston (3) has a groove (301) along its circumference at the front end, and a main sealing ring (4) is provided in the groove (301). The main sealing ring (4) is interference-fitted into the injection cylinder (1). The piston (3) has a pressure plate (5) along its outer wall at the rear end. The outer wall of the pressure plate (5) is attached to the inner wall of the injection cylinder (1). An auxiliary pressure chamber (6) is formed between the front end face of the pressure plate (5), the piston (3), the rear end face of the main sealing ring (4), and the inner wall of the injection cylinder (1). An air outlet (7) is provided on the piston between the main sealing ring (4) and the pressure plate (5). An air outlet (8) is provided inside the piston. An air inlet (9) is provided inside the push rod (2). The air outlet (7) is connected to the air outlet (8) and the air inlet (9) in sequence.

2. The syringe for pumps according to claim 1, characterized in that, The pressure plate (5) and the piston (3) are integrally formed.

3. The syringe for pumps according to claim 1, characterized in that, The main sealing ring (4) is made of medical silicone rubber material, and the outer diameter of the main sealing ring (4) is 0.1-0.3 mm larger than the inner diameter of the syringe (1).

4. The syringe for pumps according to claim 1, characterized in that, The pressure plate (5) protrudes from the piston (3), and the outer diameter of the pressure plate (5) is smaller than the outer diameter of the main sealing ring (4).

5. The syringe for pumps according to claim 1, characterized in that, The groove (301) is provided with a wave-shaped fixing tooth (3011) on its circumference, and the fixing tooth (3011) has a height of 0.1mm.

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