CN103656804A - Piston for injector - Google Patents

Abstract

The invention relates to a piston for an injector. The piston for the injector comprises a piston top part and a piston body, wherein the piston body is a hollow cylinder with an opening in the bottom; the lower part of the hollow cylinder is connected with a push rod of the injector; the upper part of the hollow cylinder and the piston top part form a piston contraction cavity; a sealing ring is arranged on the outer part of the piston body; the piston top part is of a conical structure with a thin wall; and the tail end of the conical surface of the piston top part and the upper edge of the sealing ring on the top part of the piston body form an annular plane boss. Due to the plane boss and the piston contraction cavity structure on the top part of the piston, the sealing performance and the blood return preventing performance of the injector can be improved, and the safety in use is enhanced.

Description

plunger for syringe

technical field

The invention relates to a piston, in particular to a piston for a medical syringe.

Background technique

At present, the syringes used clinically at home and abroad are composed of an outer cylinder, a push rod, and a piston. The purpose of pumping liquid is realized by pushing and pulling the piston through the push rod, and the function of the syringe is realized. The piston structure is closely related to the sealing performance and anti-bleeding performance of the syringe. Chinese invention patent application CN103170035A, a pre-filled syringe with anti-bleeding type. There is a piston contraction chamber between the top of the piston and the push rod. The top of the piston is a thin-walled structure. The top of the piston is deformed to prevent the top of the piston from entering the hollow channel. Avoid bleeding. But the top of this piston and the sealing ring of piston body top have adopted the tangential structure. When the top of the piston is deformed and shrinks inwardly under the pressure of the flushing tube, it will drive the sealing ring that is tangent to it to shrink inwardly, resulting in a reduction in the contact area between the sealing ring and the syringe sleeve, and a decrease in sealing performance.

Contents of the invention

The object of the present invention is to overcome the above defects and provide a piston with good sealing performance and anti-bleeding.

The technical scheme that the present invention solves technical problem adopts is:

A plunger for a syringe, comprising a top of the piston and a main body of the piston, the main body of the piston is a hollow cylinder with an open bottom, the lower part of the hollow cylinder can be connected with the push rod of the syringe, and the upper part of the hollow cylinder and the top of the piston form a piston contraction chamber, its features The outer part of the piston main body is provided with a sealing ring, the top of the piston is a thin-walled conical structure, and the end of the conical surface of the piston top and the upper edge of the top sealing ring of the piston main body form a circular planar boss.

As a preferred method, three seal rings are arranged on the outer surface of the piston body, the first seal ring is located at the lowermost end of the piston body, the third seal ring is the top seal ring of the piston body, and the second seal ring is located between the first seal ring and the third seal ring. Between the sealing rings, it occupies 1/2-3/4 of the distance between the third sealing ring and the first sealing ring, which makes the upper part of the piston easier to deform and prevent blood return. There is a piston thread inside the hollow cylinder of the piston body, and the piston thread will The piston body is connected to the syringe push rod.

In the present invention, the end of the conical surface of the top of the piston and the upper edge of the top sealing ring of the piston body form an annular plane boss, rather than a tangent structure, and the top of the piston has a piston shrinkage cavity, which can ensure that when the top of the piston is flushed When the pressure deforms and shrinks inwardly to the piston shrinkage cavity, it will not drive the third sealing ring to shrink inwardly together, thereby avoiding the reduction of the sealing performance caused by the reduction of the contact area with the syringe sleeve. The boss makes the conical surface not affected by the deformation of the sealing ring, and it is easier to deform the thin-walled structure of the entire conical surface so as to effectively prevent blood return. Therefore, the syringe plunger with this structure can effectively prevent blood return and enhance the safety of use.

Description of drawings

Fig. 1 is the front view of the plunger for the syringe of the present invention.

Fig. 2 is a schematic diagram of the structure of the plunger used in the syringe of the present invention.

Fig. 3 is a sectional view of the plunger for the syringe of the present invention.

Among the figure, 1 piston top, 2 piston main body, 21 piston shrink chamber, 22 piston thread, 23 first sealing ring, 24 second sealing ring, 25 piston main body top sealing ring, 26 plane boss.

Detailed ways

As shown in Figures 1-3, a piston for a syringe includes a piston top 1 and a piston body 2, the piston body 2 is a hollow cylinder with an open bottom, the lower part of the hollow cylinder can be connected with the push rod of the syringe, and the hollow cylinder The upper part of the piston and the piston top 1 form a piston contraction cavity 21, and a sealing ring is provided outside the piston body. As a preferred method, three sealing rings are provided on the outer surface of the piston body, the first sealing ring 23 is located at the lowermost end of the piston body 2, and the third sealing ring The ring is the top seal ring 25 of the piston body, the second seal ring 24 is located between the first seal ring 25 and the third seal ring 23, and the distance between the first seal ring 23 and the top seal ring 25 of the piston body is 1/2-3/4 There are piston threads 22 inside the hollow cylinder of the piston main body 2. The piston threads 22 connect the piston body 2 to the syringe push rod. The upper edge of the upper edge forms a circular plane boss 26.

Claims (2)

1. A piston for a syringe, comprising a piston top and a piston main body, the piston main body is a hollow cylinder with an open bottom, the bottom of the hollow cylinder can be connected with the push rod of the syringe, and the top of the hollow cylinder and the top of the piston form a piston contraction chamber, It is characterized in that a sealing ring is provided outside the piston main body, the top of the piston is a thin-walled conical structure, and the end of the conical surface of the piston top and the upper edge of the sealing ring on the top of the piston main body form a circular planar boss. 2. The syringe piston according to claim 1, characterized in that: three sealing rings are arranged on the outer surface of the piston main body, the first sealing ring is located at the lowermost end of the piston main body, the third sealing ring is the top sealing ring of the piston main body, and the third sealing ring is the top sealing ring of the piston main body. The second sealing ring is located between the first sealing ring and the third sealing ring, accounting for 1/2-3/4 of the distance between the third sealing ring and the first sealing ring. There is a piston thread inside the hollow cylinder of the piston body, and the piston thread connects the piston The body is connected to the plunger of the syringe.

Images