Connecting structure of piston rod and push rod and needleless injector thereof

Abstract

The utility model relates to the technical field of needleless injectors, in particular to a connecting structure of a piston rod and a push rod and a needleless injector thereof, the connecting structure comprises the piston rod and the push rod, the piston rod comprises a first rod body and a first clamping part located at the end of the first rod body, and the first clamping part comprises a plurality of clamping jaws. The push rod comprises a second rod body and a second clamping part located at the end of the second rod body, the second clamping part comprises an inner limiting body and an outer limiting body located on the periphery of the inner limiting body, and an annular limiting cavity allowing the clamping jaws to be clamped in so as to fix the clamping jaws is formed between the inner limiting body and the outer limiting body; according to the utility model, the inner limiting body and the outer limiting body on the push rod are utilized to form the annular limiting cavity in which the clamping jaws are clamped to fix the clamping jaws, and the outer limiting body surrounds the outer sides of the plurality of clamping jaws to limit the outward bending degree of the clamping jaws, so that the clamping jaws are prevented from being separated from the push rod; the inner limiting bodies are supported on the inner sides of the clamping jaws to limit the inward bending degree of the clamping jaws, so that the breaking phenomenon caused by excessive bending of the clamping jaws is avoided.

Description

Technical Field

[0001] This utility model relates to the field of needleless injector technology, and in particular to a connection structure of piston rod and push rod and its needleless injector. Background Technology

[0002] Needle-free injectors typically use a push mechanism with a piston assembly to pressurize the liquid medication inside the tube, rapidly pushing the medication out to form a high-speed airflow that penetrates the skin and enters the body.

[0003] The pushing mechanism generally includes a push rod, and the piston assembly includes a piston rod and a piston fixed to the end of the piston rod. Existing piston rod and push rod connection structures are as follows: Figure 1 As shown, several claws on the piston rod engage with the slots inside the push rod. However, in order to allow the claws to have a certain elastic deformation to engage with the slots, the structural strength of the claws is relatively small, and they may break during the process of engaging with the slots. Utility Model Content

[0004] The technical problem to be solved by this utility model is: in order to solve the problem that in the prior art, the connection structure of the piston rod and push rod of the needle-free injector is that the claws are inserted into the slot, but the structural strength of the claws is small and they may break during the insertion process. The present invention provides a connection structure of piston rod and push rod and a needle-free injector.

[0005] To solve the above-mentioned technical problems, this utility model adopts the following technical solution: a connection structure for a piston rod and a push rod, comprising:

[0006] A piston rod includes a first rod body extending axially and a first engaging portion located at the end of the first rod body, the first engaging portion including a plurality of claws arranged circumferentially along the first rod body;

[0007] The push rod includes a second rod extending axially and a second locking part located at the end of the second rod and cooperating with the first locking part. The second locking part includes an inner limiting body and an outer limiting body located around the inner limiting body. An annular limiting cavity is formed between the outer peripheral wall of the inner limiting body and the inner peripheral wall of the outer limiting body for the locking claw to be engaged and fixed.

[0008] Furthermore, the claw includes a rod extending axially along the first rod body and a hook portion located at one end of the rod portion away from the first rod body and bent inward toward the inner limiting body, wherein the inner limiting body protrudes radially to form a protrusion for engaging with the hook portion.

[0009] Furthermore, several pawls gradually move closer together along the piston rod towards the push rod.

[0010] Furthermore, the cross-sectional area of ​​the protrusion gradually decreases along the direction from the push rod to the piston rod.

[0011] Furthermore, the outer limiting body has a guide slope at one end near the piston rod.

[0012] A needle-free injector includes the connection structure of the piston rod and the push rod described above.

[0013] Furthermore, it also includes a piston installed at one end of the first rod away from the first engaging portion and an injection tube sleeved outside the piston rod. The first rod protrudes radially and has an annular protrusion for abutting against the injection tube to limit the position of the piston rod.

[0014] The beneficial effects of this utility model are as follows: This utility model utilizes the inner and outer limiting bodies on the push rod to form an annular limiting cavity for the pawls to be engaged and fixed. The outer limiting body surrounds the outer side of several pawls to limit the degree of outward bending of the pawls, thereby preventing the pawls from detaching from the push rod. The inner limiting body supports the inner side of several pawls to limit the degree of inward bending of the pawls, thereby preventing breakage caused by excessive bending of the pawls. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] Figure 1 This is a structural diagram of existing technology;

[0017] Figure 2 This is a three-dimensional schematic diagram of the present invention;

[0018] Figure 3 This is a cross-sectional view of the present invention;

[0019] Figure 4 This is an exploded view of this utility model;

[0020] 1. Piston rod; 101. First rod body; 1011. Annular protrusion; 102. Claw; 1021. Rod part; 1022. Hook part;

[0021] 2. Push rod; 201. Second rod body; 202. Inner limiting body; 2021. Protrusion; 203. Outer limiting body; 2031. Guide slope; 204. Annular limiting cavity;

[0022] 3. Piston;

[0023] 4. Injection tube; 401. Spray nozzle. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention. Therefore, they only show the components relevant to the present invention. Orientations and references (e.g., up, down, left, right, etc.) are only used to aid in the description of the features in the drawings. Therefore, the following specific embodiments are not intended to be restrictive, and the scope of the claimed subject matter is defined solely by the appended claims and their equivalents.

[0025] like Figures 2-4 As shown, a connection structure for a piston rod and a push rod includes a piston rod 1 and a push rod 2;

[0026] The piston rod 1 is movably disposed in the injection tube 4, and includes a first rod body 101 extending axially and a first snap-fit ​​portion located at the end of the first rod body 101. The other end of the first rod body 101 is formed with a mounting portion for mounting the piston 3.

[0027] The first rod 101 is a cylindrical slender component with several grooves on its outer peripheral wall along its circumference. Each groove extends along the axial direction of the first rod 101 but does not penetrate the two end faces of the first rod 101 along its axial direction. The grooves can reduce the contact area between the outer peripheral wall of the first rod 101 and the inner peripheral wall of the injection tube 4, thereby reducing the pushing force applied to it by the push rod 2. The shape of the grooves can be, but is not limited to, arc or square. At the same time, when the piston 3 fails, the grooves can be used to contain the liquid medicine leaking from the piston 3, preventing the liquid medicine from entering other parts of the needleless injector.

[0028] The first latching part includes a plurality of latches 102 arranged circumferentially along the first rod 101. The plurality of latches 102 are spaced apart and have a certain elastic deformation capability. The number of latches 102 can be, but is not limited to, two, three or four.

[0029] The push rod 2 includes a second rod body 201 extending axially and a second locking part located at the end of the second rod body 201 and cooperating with the first locking part. The second rod body 201 is also a cylindrical slender member. The second locking part includes an inner limiting body 202 and an outer limiting body 203 located around the inner limiting body 202. A space is formed between the outer peripheral wall of the inner limiting body 202 and the inner peripheral wall of the outer limiting body 203 for the locking claw 102 to be engaged and fixed. Annular limiting cavity 204; During installation, the claws 102 are inserted into the annular limiting cavity 204 and locked inside it. At the same time, the outer limiting body 203 surrounds the outer side of the claws 102 to limit the degree of outward bending of the claws 102, so as to prevent the claws 102 from disengaging from the second locking part. The inner limiting body 202 supports the inner side of the claws 102 to limit the degree of inward bending of the claws 102, so as to avoid the breakage caused by excessive bending of the claws 102.

[0030] In some examples, such as Figure 3 and Figure 4 As shown, the pawl 102 includes a rod portion 1021 extending axially along the first rod body 101 and a hook portion 1022 located at one end of the rod portion 1021 away from the first rod body 101 and bent toward the inner limiting body 202. The inner limiting body 202 has a protruding portion 2021 that mates with the hook portion 1022 in its radial direction. A limiting step is formed between the protruding portion 2021 and the inner limiting body 202. After the pawl 102 enters the annular limiting cavity 204, it hooks with the limiting step, thereby limiting the pawl 102 within the annular limiting cavity 204.

[0031] In some examples, such as Figure 3 As shown, the rod portions 1021 of the several claws 102 gradually move closer together along the piston rod 1 toward the push rod 2, forming a centering effect. This makes it easier for the claws 102 to enter the annular limiting cavity 204 and avoid collision with the outer limiting body 203 during installation. Furthermore, the inclined rod portions 1021 bring the hook portions 1022 at their ends closer to the protrusions 2021, thereby improving the connection strength when the claws 102 and the protrusions 2021 are hooked together.

[0032] In some examples, such as Figure 3 As shown, the cross-sectional area of ​​the protrusion 2021 gradually decreases along the direction from the push rod 2 to the piston rod 1, that is, it has a conical structure with a smaller front and a larger rear. The protrusion 2021 cooperates with the inclined claw 102 to make it easier for the claw 102 to enter the annular limiting cavity 204. The end face of the protrusion 2021 near the piston rod 1 is provided with a rounded corner, which further facilitates the entry of the claw 102. As the claw 102 gradually enters the annular limiting cavity 204, the inner limiting body 202 located inside the claw 102 gradually opens the claw 102, causing it to undergo elastic deformation until the hook part 1022 of the claw 102 passes over the protrusion 2021. Then the claw 102 resets and abuts against the limiting step to fix the claw 102.

[0033] In some examples, such as Figure 3 and Figure 4 As shown, the outer limiting body 203 has a guide slope 2031 at one end near the piston rod 1 to guide the movement of the pawl 102 and make it easier for the pawl 102 to enter the annular limiting cavity 204.

[0034] In some examples, a needle-free injector includes the aforementioned connection structure of the piston rod and push rod.

[0035] In some examples, such as Figures 2-4As shown, the needle-free injector also includes a piston 3 installed at one end of the first rod 101 away from the first snap-fit ​​portion and an injection tube 4 sleeved outside the piston rod 1. The piston 3 and the piston rod 1 are snapped together to form a piston assembly. The piston assembly can slide back and forth in the inner cavity of the injection tube 4 under the action of the push rod 2. The inner cavity of the injection tube 4 includes a variable diameter section at the front end and a constant diameter section at the rear end. The variable diameter section gradually decreases from the rear to the front. The piston 3 and the inner peripheral wall of the injection tube 4 enclose a drug cavity for containing the drug solution.

[0036] The injection tube 4 has a spray hole 401 at one end (i.e., the front end) away from the push rod 2. The diameter of the spray hole 401 can be, but is not limited to, 0.14 mm. The push rod 2 drives the piston assembly to move in the direction of the spray hole 401 to push the liquid in the medicine chamber out of the spray hole 401 and form a high-speed airflow to penetrate the skin.

[0037] The rear end of the first rod 101 protrudes radially to form an annular protrusion 1011 for contacting the injection tube 4. When the annular protrusion 1011 contacts the rear end of the injection tube 4, this is the maximum displacement of the piston 3 assembly moving forward.

[0038] Working principle:

[0039] During installation, the claw 102 is inserted into the annular limiting cavity 204. Initially, the guide slope 2031 on the outer limiting body 203 provides guidance for the movement of the claw 102. Then, as the claw 102 penetrates deeper into the annular limiting cavity 204, the inner limiting body 202 located inside the claw 102 gradually expands the claw 102, causing it to undergo elastic deformation until the hook portion 1022 of the claw 102 passes over the protrusion 2021. Then, the claw 102 resets and abuts against the limiting step to confine the claw 102 within the annular limiting cavity 204. At the same time, the outer limiting body 203 surrounds the outer side of several claws 102 to limit the degree of outward bending of the claws 102, so as to prevent the claws 102 from disengaging from the second engaging portion. The inner limiting body 202 supports the inner side of several claws 102 to limit the degree of inward bending of the claws 102, so as to avoid breakage caused by excessive bending of the claws 102.

[0040] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A connection structure for a piston rod and a push rod, characterized in that: include: The piston rod (1) includes a first rod body (101) extending axially and a first locking portion located at the end of the first rod body (101). The first locking portion includes a plurality of claws (102) arranged circumferentially along the first rod body (101). The push rod (2) includes a second rod body (201) extending axially and a second locking part located at the end of the second rod body (201) and cooperating with the first locking part. The second locking part includes an inner limiting body (202) and an outer limiting body (203) located around the inner limiting body (202). An annular limiting cavity (204) is formed between the outer peripheral wall of the inner limiting body (202) and the inner peripheral wall of the outer limiting body (203) for the locking claw (102) to be engaged and fixed.

2. The connection structure of the piston rod and push rod according to claim 1, characterized in that: The claw (102) includes a rod portion (1021) extending axially along the first rod body (101) and a hook portion (1022) located at one end of the rod portion (1021) away from the first rod body (101) and bent toward the inner limiting body (202). The inner limiting body (202) protrudes radially to form a protrusion (2021) for engaging with the hook portion (1022).

3. The connection structure of the piston rod and the push rod according to claim 2, characterized in that: Several pawls (102) have several rods (1021) that gradually move closer together along the piston rod (1) toward the push rod (2).

4. The connection structure of the piston rod and the push rod according to claim 2, characterized in that: The cross-sectional area of ​​the protrusion (2021) gradually decreases along the direction from the push rod (2) to the piston rod (1).

5. The connection structure of the piston rod and push rod according to claim 1, characterized in that: The outer limiting body (203) has a guide slope (2031) at one end near the piston rod (1).

6. A needle-free injector, characterized in that: It includes the connection structure of the piston rod and push rod as described in any one of claims 1-5.

7. A needle-free injector according to claim 6, characterized in that: The needleless injector also includes a piston (3) installed on the end of the first rod (101) away from the first snap-fit ​​portion and an injection tube (4) sleeved on the outside of the piston rod (1). The first rod (101) protrudes radially and has an annular protrusion (1011) for abutting against the end of the injection tube (4).

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