CN221600901U - Liquid medicine pushing and injecting device and needleless injector - Google Patents

Abstract

The utility model provides a liquid medicine pushing injection device and a needleless injector, comprising: the piston sleeve comprises a first liquid medicine cavity, an injection port and a first piston port, wherein the injection port and the first piston port are respectively positioned at two ends of the first liquid medicine cavity; the first piston head comprises a second liquid medicine cavity, a communication port and a second piston port, wherein the communication port and the second piston port are respectively arranged at two ends of the second liquid medicine cavity, and the first piston head is arranged in the first liquid medicine cavity in a sliding manner in a manner that the communication port faces the injection port and is in sealing connection with the inner side wall of the first liquid medicine cavity; the second piston head is arranged in the second liquid medicine cavity in a sliding manner and is connected with the inner side wall of the second liquid medicine cavity in a sealing manner; the piston rod assembly is used for driving the second piston head to move in the second liquid medicine cavity and driving the first piston head to move in the first liquid medicine cavity, and the first piston head is pushed to move towards the injection port by the piston rod assembly after the piston rod assembly pushes the second piston head to reach a preset position. The utility model can needlelessly inject large doses of medicine to a desired depth.

Description

Liquid medicine pushing and injecting device and needleless injector

Technical Field

The utility model relates to the field of medical tools, in particular to a liquid medicine pushing injection device and a needleless injector.

Background

Needleless jet injection is a technique of injecting a liquid drug through the skin in the form of a narrow jet of greater than 100m/s, which is able to penetrate the epidermis and reach intramuscular depths using only the energy of the flowing liquid.

Experiments have shown that in needleless jet injection, the injection depth is very sensitive to the injection speed and the injection time. For large doses of drug injection, existing needleless injection devices often fail to provide an injection pressure large enough to pierce the skin to the desired depth. If a high dose bolus is achieved by increasing the thrust force, the high thrust force may cause the drug to be injected beyond the desired depth, resulting in discomfort to the recipient.

Disclosure of utility model

The utility model aims to solve the technical problem that large-dose medicines cannot be injected to a preset depth by needleless injection, and provides a liquid medicine pushing injection device and a needleless injector.

The technical scheme for solving the technical problems is that a liquid medicine pushing and injecting device is provided and applied to a needleless injector, and the liquid medicine pushing and injecting device comprises:

The piston sleeve comprises a first liquid medicine cavity, an injection port and a first piston port which are respectively positioned at two ends of the first liquid medicine cavity, and the injection port is communicated with the first liquid medicine cavity;

The first piston head comprises a second liquid medicine cavity, a communication port and a second piston port, wherein the communication port and the second piston port are respectively positioned at two ends of the second liquid medicine cavity, the first piston head is slidably arranged in the first liquid medicine cavity in a mode that the communication port faces the injection port and is in sealing connection with the inner side wall of the first liquid medicine cavity, and the second liquid medicine cavity is communicated with the first liquid medicine cavity through the communication port;

The second piston head is arranged in the second liquid medicine cavity in a sliding manner and is connected with the inner side wall of the second liquid medicine cavity in a sealing manner;

The end part of the piston rod assembly penetrates through the first piston opening and the second piston opening to be connected with the second piston head and is used for driving the second piston head to move in the second liquid medicine cavity and driving the first piston head to move in the first liquid medicine cavity, and the first piston head is pushed to move towards the injection opening by the piston rod assembly after the piston rod assembly pushes the second piston head to reach a preset position.

As a further improvement of the utility model, the aperture of the first piston port and the aperture of the first liquid medicine cavity are respectively matched with the size of the cross section of the first piston head;

The size of the cross section of the second piston head is smaller than that of the cross section of the first piston head, the aperture of the communication port and the aperture of the second liquid medicine cavity are respectively matched with the size of the cross section of the second piston head, and the aperture of the second piston port is smaller than that of the cross section of the second piston head.

As a further improvement of the present utility model, the piston rod assembly includes a first piston rod and a second piston rod coaxially disposed, the first piston rod having a cross-sectional dimension greater than a cross-sectional dimension of the second piston rod, and at least a portion of the second piston rod protruding from a front end face of the first piston rod;

The size of the cross section of the first piston rod is smaller than the aperture of the first piston port and larger than the aperture of the second piston port, and the head end of the first piston rod extends into the first liquid medicine cavity through the first piston port; the size of the cross section of the second piston rod is smaller than the aperture of the second piston port;

The second piston rod is integrated with the second piston head, and the tail end of the second piston rod penetrates through the second piston port to be fixed with the first piston rod; or the head end of the second piston rod passes through the second piston port to be fixed with the second piston head, and the tail end of the second piston rod is fixed with the first piston rod.

As a further improvement of the utility model, the distance between the end face of the first piston rod facing the first piston head and the rear end face of the first piston head is equal to the distance between the front end face of the second piston head and the front end face of the first piston head.

As a further improvement of the utility model, the piston rod assembly comprises a piston rod comprising a first push section and a second push section which are coaxial and integral, and the size of the cross section of the first push section is smaller than the size of the first piston port and larger than the size of the second piston port, and the size of the cross section of the second push section is smaller than the size of the second piston port;

One end of the first pushing section connected with the second pushing section penetrates through the first piston opening to enter the first liquid medicine cavity, and one end of the second pushing section far away from the first pushing section penetrates through the second piston opening to be fixed with a second piston head in the second liquid medicine cavity.

As a further development of the utility model, the distance between the end face of the first push section facing the first piston head and the rear end face of the first piston head is equal to the distance between the front end face of the second piston head and the front end face of the first piston head.

As a further improvement of the utility model, the outer circumferential surface of the first piston head is provided with a plurality of first grooves and a plurality of first rubber rings respectively positioned in the first grooves, each first groove is distributed along the circumferential direction of the first piston head, and the first piston head is in sealing connection with the inner side wall of the first liquid medicine cavity through the first rubber rings.

As a further improvement of the utility model, the outer peripheral surface of the second piston head is provided with a plurality of second grooves and a plurality of second rubber rings respectively positioned in the second grooves, each second groove is distributed along the circumferential direction of the second piston head, and the second piston head is in sealing connection with the inner side wall of the second liquid medicine cavity through the second rubber rings.

As a further improvement of the utility model, the piston sleeve is provided with a plurality of medicine inlets which are respectively communicated with the first medicine liquid cavity;

The liquid medicine pushing and injecting device comprises a first one-way valve and a second one-way valve, the first one-way valve is arranged outside the injection port, and liquid medicine in the first liquid medicine cavity is injected out through the injection port and the first one-way valve; the second one-way valve is arranged outside the medicine inlet, and external medicine liquid enters the first medicine liquid cavity through the second one-way valve and the medicine inlet.

The utility model also provides a needleless injector, which comprises the liquid medicine pushing injection device.

The utility model has the following beneficial effects: the high-dose medicine can be needlelessly injected to the required depth by pushing the second piston head to form high-speed puncture jet to puncture the skin and pushing the first piston head to form low-speed jet to complete the injection of the residual medicine liquid.

Drawings

Fig. 1 is a schematic cross-sectional view of a device for injecting liquid medicine according to an embodiment of the present utility model.

Fig. 2 is an exploded view of a device for injecting liquid medicine according to an embodiment of the present utility model.

Fig. 3 is a graph showing a pressure change of a liquid medicine in a first liquid medicine cavity in a liquid medicine injection process of the liquid medicine injection device according to the embodiment of the utility model.

Fig. 4 is a schematic cross-sectional view of a device for injecting liquid medicine according to another embodiment of the present utility model.

Fig. 5 is a schematic view of a needleless injector provided in an embodiment of the present utility model.

Detailed Description

The present utility model will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present utility model more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.

Those of skill in the art will appreciate that a hardware manufacturer may refer to the same component by different names. The description and claims do not take the form of an element differentiated by name, but rather by functionality. As used throughout the specification and claims, the word "comprise" is an open-ended term, and thus should be interpreted to mean "include, but not limited to. By "substantially" is meant that within an acceptable error range, a person skilled in the art can solve the technical problem within a certain error range, substantially achieving the technical effect.

In the description of the present application, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "horizontal," and the like indicate an orientation or a positional relationship based on that shown in the drawings, and are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the apparatus or element to be referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

In the description of the present application, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance unless explicitly specified or limited otherwise; the term "plurality" refers to two or more than two; unless specified or indicated otherwise, the terms "coupled," "fixed," and the like are to be construed broadly and are, for example, capable of being coupled either permanently or detachably, or integrally or electrically; "coupled" may be directly coupled or indirectly coupled through intermediaries. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

As shown in fig. 1 and 2, the present utility model provides a schematic structure of a liquid medicine injection device, which is applicable to a needleless injector, and in particular, can be assembled to a front end portion of the needleless injector and used for forming a high-speed puncture jet and a low-speed jet for needleless injection. The liquid medicine pushing and injecting device comprises a piston sleeve 10, a first piston head 20, a second piston head 30 and a piston rod assembly 40, wherein the first piston head 20 is arranged in the piston sleeve 10, the second piston head 30 is arranged in the first piston head 20, and the first piston head 20 and the second piston head 30 are driven to reciprocate by the piston rod assembly 40.

The piston sleeve 10 may be made of hard materials such as metal and plastic, and the piston sleeve 10 includes a first liquid medicine chamber 11, an injection port 12 and a first piston port 13, wherein the first liquid medicine chamber 11 is used for temporarily storing the liquid medicine to be injected, and the injection port 12 and the first piston port 13 are respectively located at two ends of the first liquid medicine chamber 11 and are respectively communicated with the first liquid medicine chamber 11. The diameter of the injection port 12 is much smaller than the aperture of the first medical fluid chamber 11, for example, the aperture of the injection port 12 is smaller than 1mm, so that high-speed jet flow can be formed at the injection port 12 when the medical fluid in the first medical fluid chamber 11 is pressurized greatly; the size of the first piston port 13 may then be adapted to the bore diameter of the first medical fluid chamber 11 (e.g. the size of the first piston port 13 is the same or substantially the same as the bore diameter of the first medical fluid chamber 11). Specifically, like the conventional syringe, the piston sleeve 10 may have a cylindrical shape (leaving only the injection port 12) with one end open (the opening constituting the first piston port 13) and the other end close to be closed, and in practical use, the injection port 12 may be constituted by a through hole provided in a partition plate radially disposed inside the cylinder. The first medical fluid chamber 11 is constituted by a hollow portion of a cylinder, and the shape and the size of each cross section of the first medical fluid chamber 11 in the axial direction are unchanged.

The first piston head 20 is slidably disposed in the first medical fluid chamber 11 (the first piston port 13 and the injection port 12 are located at two sides of the first piston head 20 respectively), that is, the first piston head 20 can move along the axial direction of the first medical fluid chamber 11 under the driving of external force after being mounted in the first medical fluid chamber 11. The outer side wall of the first piston head 20 is in sealing connection with the inner side wall of the first liquid medicine cavity 11, and the outer side wall of the first piston head 20 is kept sealed with the inner side wall of the first liquid medicine cavity 11 during the process of moving the first piston head 20 along the first liquid medicine cavity 11, so that the liquid medicine in the first liquid medicine cavity 11 cannot flow out from between the first piston ports 13 at the rear side of the first piston head 20, but only flows out from the injection ports 12 at the front side of the first piston head 20. The first piston head 20 further includes a second liquid medicine cavity 21, a communication port, and a second piston port 23, where the communication port and the second piston port 23 are located at two ends of the second liquid medicine cavity 21, respectively, and the first piston head 20 is installed in the first liquid medicine cavity 11 in such a way that the communication port faces the injection port 12, and the second liquid medicine cavity 21 is communicated with the first liquid medicine cavity 11 through the communication port. The diameter of the communication port is matched with the aperture of the second liquid medicine cavity 21 (for example, the size of the communication port is the same as or basically the same as the aperture of the second liquid medicine cavity 21), so that the liquid medicine in the first liquid medicine cavity 11 can conveniently enter the second liquid medicine cavity 21, and the liquid medicine in the second liquid medicine cavity 21 can conveniently flow out to the first liquid medicine cavity 11; the second piston port 23 is smaller in size than the bore diameter of the second medical fluid chamber 21. Specifically, the first piston head 20 may have a cylindrical shape with one end open (the opening constituting the communication port) and the other end having an opening (the opening constituting the second piston port 23), the second medical fluid chamber 21 may be constituted by a hollow portion of the cylinder, and the shape and the size of each cross section of the second medical fluid chamber 21 in the axial direction may be unchanged.

The second piston head 30 is slidably disposed in the second liquid medicine cavity 21 (the second piston port 23 and the communication port are located at two sides of the second piston head 30 respectively), that is, the second piston head 30 can move along the axial direction of the second liquid medicine cavity 21 under the driving of external force after being mounted in the second liquid medicine cavity 21. The outer side wall of the second piston head 30 is in sealing connection with the inner side wall of the second liquid medicine cavity 21, and the outer side wall of the second piston head 30 is kept sealed with the inner side wall of the second liquid medicine cavity 21 in the process that the second piston head 30 moves along the second liquid medicine cavity 21, so that the liquid medicine in the second liquid medicine cavity 21 cannot flow out from the second piston port 23 at the rear side of the second piston head 30, but only flows out from the communication port at the front side of the second piston head 30.

The end of the piston rod assembly 40 passes through the first piston port 13 and the second piston port 23 to be connected with the second piston head 30, and is used for driving the second piston head 30 to move in the second liquid medicine cavity 21 and driving the first piston head 20 to move in the first liquid medicine cavity 11, namely, during the process of filling the liquid medicine into the first liquid medicine cavity 11 and the second liquid medicine cavity 21, the piston rod assembly 40 drives the first piston head 20 and the second piston head 30 to move in the direction away from the injection port 12; during injection of the medical fluid, the piston rod assembly 40 drives the first and second piston heads 20, 30 toward the injection port 12. In the process of injecting the liquid medicine, the piston rod assembly 40 pushes the second piston head 30 to move in the direction of the communication port (i.e., the direction of the injection port 12) in the second liquid medicine cavity 21 to pressurize the liquid medicine in the second liquid medicine cavity 21, and after the second piston head 30 reaches the preset position, the piston rod assembly 40 pushes the first piston head 20 again to move along with the second piston head in the direction of the injection port 12.

As shown in fig. 3 (time on the horizontal axis and pressure of the liquid medicine in the first liquid medicine chamber 11 on the vertical axis), when the liquid medicine injection device is used for needleless injection of the liquid medicine, the piston rod assembly 40 pushes the second piston head 30 to move toward the injection port 12 at time T1, pushes out the liquid medicine in the second liquid medicine chamber 21, and forms a high-speed puncture jet to pierce the skin at the injection port 12 (injection puncture stage); at time T2, the bolus injection of the drug solution in the second drug solution chamber 21 is completed, and the piston rod assembly 40 pushes the first piston head 20 (together with the second piston head 30) to form a low-velocity jet to complete the injection of the remaining drug solution (dispersion stage), until time T3, a large dose of drug is needlelessly injected to a desired depth. By the mode, the problem of insufficient pressure during needleless injection of large-dose medicines is solved under the condition of the same pressure.

In one embodiment of the present utility model, the aperture of the first piston port 13 and the aperture of the first medical fluid chamber 11 are respectively matched with the size of the cross section of the first piston head 20 (it is understood that the cross section of the first piston port 13 and the cross section of the first medical fluid chamber 11 are respectively the same as the cross section of the first piston head 20), so as to facilitate the first piston head 20 to be installed into the first medical fluid chamber 11 from the first piston port 13 and slide in the first medical fluid chamber 11.

Accordingly, the size of the cross section of the second piston head 30 is smaller than the size of the cross section of the first piston head 20, the aperture of the communication port and the aperture of the second liquid medicine chamber 21 are respectively matched with the size of the cross section of the second piston head 30 (it is understood that the shapes of the cross sections of the communication port and the second liquid medicine chamber 21 are respectively the same as the shape of the cross section of the second piston head 30), and the aperture of the second piston port 23 is smaller than the size of the cross section of the second piston head 30, so that the second piston head 30 is conveniently installed into the second liquid medicine chamber 21 from the communication port and slides in the second liquid medicine chamber 21, and the second piston head 30 can drive the first piston 20 to move towards the direction opposite to the injection port 12, so that the liquid medicine is conveniently injected into the first liquid medicine chamber 11 and the second liquid medicine chamber 21.

In one embodiment of the present utility model, the piston rod assembly 40 includes a first piston rod 41 and a second piston rod 42, the first piston rod 41 and the second piston rod 42 are coaxially disposed, and a cross-section of the first piston rod 41 is larger than a cross-section of the second piston rod 42, and at least a portion of the second piston rod 42 protrudes from an end of the first piston rod 41. Specifically, the first piston rod 41 and the second piston rod 42 may each have a cylindrical shape.

The cross section of the first piston rod 41 is smaller than the aperture of the first piston opening 13 and larger than the aperture of the second piston opening 23, and the head end of the first piston rod 41 extends into the first liquid medicine cavity through the first piston opening 13; the cross-sectional dimension of the second piston rod 42 is smaller than the bore diameter of the second piston port 23. In particular, the cross-sectional shape of the second piston rod 42 may be the same as the shape of the second piston port 23, and the size of the cross-section of the second piston rod 42 is slightly smaller than the aperture of the second piston port 23, so that the second piston rod 42 may be guided in the sliding direction through the second piston port 23. With the above structure, after the second piston rod 42 pushes the second piston head 30 to push out the liquid medicine in the second liquid medicine chamber 21, the first piston rod 41 pushes the first piston head 20 to move, so that the liquid medicine in the first liquid medicine chamber 11 is continuously ejected through the ejection port 12.

The second piston rod 42 and the second piston head 30 may be integrally formed, and the tail end of the second piston rod 42 passes through the second piston opening 23 to be fixed with the first piston rod 41, which is beneficial to reducing components and improving the connection strength between the second piston rod 42 and the second piston head 30. Of course, in practical applications, the second piston rod 42 and the second piston head 30 may also adopt a split structure, where the head end of the second piston rod 42 passes through the second piston opening 23 to be fixed with the second piston head 30 in the second liquid medicine cavity 21, and the tail end of the second piston rod 42 is fixed with the first piston rod 41.

In order to ensure smooth sliding of the second piston head 30 in the second medical fluid chamber 21 and at the same time ensure the penetration effect of the injection penetration stage, in one embodiment of the present utility model, the distance between the end surface of the first piston rod 41 facing the first piston head 20 (i.e., the front end surface) and the rear end surface of the first piston head 20 is equal to the distance between the front end surface of the second piston head 30 and the front end surface of the first piston head 20, so that the front end of the second piston head 30 is flush with the front end of the first piston head 20 during the injection penetration stage.

In one embodiment of the utility model, as shown in connection with fig. 4, the piston rod assembly 40 comprises a piston rod comprising a first push section 43 and a second push section 44 which are coaxial, i.e. the first push section 43 and the second push section 44 are of a unitary construction. The cross-sectional dimension of the first push section 43 is smaller than the dimension of the first piston port 13 and larger than the dimension of the second piston port 23, and the cross-sectional dimension of the second push section 44 is smaller than the dimension of the second piston port 23. Similar to the embodiment of fig. 1 and 2, the end of the first pushing section 43 connected to the second pushing section 44 passes through the first piston opening and enters the first liquid medicine cavity 11, and the end of the second pushing section 44 remote from the first pushing section 43 passes through the second piston opening 23 and is fixed to the second piston head 30 in the second liquid medicine cavity 21. With the above structure, after the second pushing section 44 pushes the second piston head 30 to push out the liquid medicine in the second liquid medicine chamber 21, the first pushing section 43 pushes the first piston head 20 to move, so that the liquid medicine in the first liquid medicine chamber 11 is continuously ejected through the ejection port 12.

Similarly, the distance between the end face of the first push section 43 facing the first piston head 20 and the rear end face of the first piston head 20 is equal to the distance between the front end face of the second piston head 30 and the front end face of the first piston head 20.

In one embodiment of the present utility model, the main body portion of the first piston head 20 is made of a hard material such as metal, plastic, etc., and accordingly, the first piston head 20 may be sealingly connected with the inner side wall of the first medical fluid chamber 11 by: the outer peripheral surface of the first piston head 20 is provided with a plurality of first grooves 26 and a plurality of first rubber rings respectively positioned in the first grooves 26, each first groove 26 is distributed along the circumferential direction of the first piston head 20, and the first piston head 20 is in sealing connection with the inner side wall of the first liquid medicine cavity 11 through the first rubber rings. Of course, in practice, the first piston head 20 may be formed of an elastic material, but this is disadvantageous for sliding the second piston head 30 in the second medical fluid chamber 21.

Similarly, the main body portion of the second piston head 30 is made of a hard material such as metal, plastic, etc., and accordingly, the second piston head 30 may be sealingly connected with the inner side wall of the second medical fluid chamber 21 by: the outer peripheral surface of the second piston head 30 is provided with a plurality of second grooves 36 and a plurality of second rubber rings respectively positioned in the second grooves 36, each second groove 36 is distributed along the circumferential direction of the second piston head 30, and the second piston head 30 is in sealing connection with the inner side wall of the second liquid medicine cavity 21 through the second rubber rings. Of course, in practice, the second piston head 30 may also be machined from an elastomeric material.

In one embodiment of the present utility model, the piston sleeve 10 has a plurality of drug inlets 15 respectively communicating with the first drug solution chamber 11; correspondingly, the liquid medicine pushing and injecting device further comprises a first one-way valve 51 and a second one-way valve 52, wherein the first one-way valve 51 is arranged outside the injection port 12, and the liquid medicine in the first liquid medicine cavity 11 is injected through the injection port 12 and the first one-way valve 51; the second check valve 52 is disposed outside the drug inlet 15, and external liquid medicine enters the first liquid medicine cavity 11 through the second check valve 52 and the drug inlet 15. Thus, when the liquid medicine is injected into the first liquid medicine chamber 11, the first piston head 20 and the second piston head 30 are moved away from the injection port 12 only by the piston rod assembly 40, and the liquid medicine in the liquid medicine container connected to the second check valve 52 is introduced into the first liquid medicine chamber 11 and the second liquid medicine chamber 21 through the second check valve 52 and the medicine inlet 15 by the negative pressure (at this time, the first check valve 51 is closed); when the injection of the medical fluid is performed, the piston rod assembly 40 pushes the first piston head 20 and the second piston head 30 to move in the direction of the injection port 12, and the medical fluid in the first medical fluid chamber 11 and the second medical fluid chamber 21 is injected through the injection port 12 and the first check valve 51 under pressure (at this time, the second check valve 52 is closed). Through the structure, the filling and injection of the liquid medicine can be conveniently realized.

In particular, the above-mentioned device for injecting a liquid medicine further comprises a sleeve 60, and accordingly, the outer circumference of the piston sleeve 10 has circumferentially distributed grooves, and the medicine inlet 15 is located at the bottom of the grooves. The sleeve 60 is sleeved outside the piston sleeve 10 and covers the groove, so that an annular cavity is formed between the outer periphery of the piston sleeve 10 and the inner wall of the sleeve 60, and the liquid medicine injected by the second one-way valve 52 enters the first liquid medicine cavity 11 and the second liquid medicine cavity 21 through the annular cavity and the medicine inlet 15, so that the liquid medicine filling speed is improved.

Fig. 5 is a schematic structural view of a needleless injector according to an embodiment of the present utility model, which can be used to inject a medical fluid, such as a vaccine, an antibiotic, etc., into an animal. The needleless injector of the present embodiment includes a main housing 70, a jet head 71, a push module, and a medical fluid injection device as described above. The main housing 70 may be made of metal or hard plastic, a main mounting cavity is formed in the main housing 70, the pushing module and the liquid medicine injection device are both installed in the main mounting cavity, the piston rod assembly 40 is driven by the pushing module, and the injection head 71 is installed at the front end of the piston sleeve 10. The pushing module can be assembled by a plurality of parts and can be matched with the components to realize needleless injection of liquid medicine. In particular, the pushing module can use any existing structure and be assembled with the liquid medicine pushing device by using an existing mode.

The present utility model is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present utility model are intended to be included in the scope of the present utility model. Therefore, the protection scope of the present utility model should be subject to the protection scope of the claims.

Claims (10)

1. A medical fluid bolus device for use with a needleless injector, the medical fluid bolus device comprising:

The piston sleeve comprises a first liquid medicine cavity, an injection port and a first piston port which are respectively positioned at two ends of the first liquid medicine cavity, and the injection port is communicated with the first liquid medicine cavity;

The first piston head comprises a second liquid medicine cavity, a communication port and a second piston port, wherein the communication port and the second piston port are respectively positioned at two ends of the second liquid medicine cavity, the first piston head is slidably arranged in the first liquid medicine cavity in a mode that the communication port faces the injection port and is in sealing connection with the inner side wall of the first liquid medicine cavity, and the second liquid medicine cavity is communicated with the first liquid medicine cavity through the communication port;

The second piston head is arranged in the second liquid medicine cavity in a sliding manner and is connected with the inner side wall of the second liquid medicine cavity in a sealing manner;

The end part of the piston rod assembly penetrates through the first piston opening and the second piston opening to be connected with the second piston head and is used for driving the second piston head to move in the second liquid medicine cavity and driving the first piston head to move in the first liquid medicine cavity, and the first piston head is pushed to move towards the injection opening by the piston rod assembly after the piston rod assembly pushes the second piston head to reach a preset position.

2. The medical fluid bolus device according to claim 1, wherein the aperture of the first piston port and the aperture of the first medical fluid chamber are respectively adapted to the size of the cross section of the first piston head;

The size of the cross section of the second piston head is smaller than that of the cross section of the first piston head, the aperture of the communication port and the aperture of the second liquid medicine cavity are respectively matched with the size of the cross section of the second piston head, and the aperture of the second piston port is smaller than that of the cross section of the second piston head.

3. The medical fluid bolus device according to claim 1, wherein the piston rod assembly includes a first piston rod and a second piston rod coaxially disposed, the first piston rod having a cross-sectional dimension that is greater than a cross-sectional dimension of the second piston rod, and at least a portion of the second piston rod protruding from a front face of the first piston rod;

The size of the cross section of the first piston rod is smaller than the aperture of the first piston port and larger than the aperture of the second piston port, and the head end of the first piston rod extends into the first liquid medicine cavity through the first piston port; the size of the cross section of the second piston rod is smaller than the aperture of the second piston port;

The second piston rod is integrated with the second piston head, and the tail end of the second piston rod penetrates through the second piston port to be fixed with the first piston rod; or the head end of the second piston rod passes through the second piston port to be fixed with the second piston head, and the tail end of the second piston rod is fixed with the first piston rod.

4. A device according to claim 3, wherein the distance between the end face of the first piston rod facing the first piston head and the rear end face of the first piston head is equal to the distance between the front end face of the second piston head and the front end face of the first piston head.

5. The medical fluid bolus device of claim 1, wherein the piston rod assembly includes a piston rod including a first push segment and a second push segment that are coaxial and integral, and wherein a cross-sectional dimension of the first push segment is smaller than a dimension of the first piston port and larger than a dimension of the second piston port, and wherein a cross-sectional dimension of the second push segment is smaller than a dimension of the second piston port;

One end of the first pushing section connected with the second pushing section penetrates through the first piston opening to enter the first liquid medicine cavity, and one end of the second pushing section far away from the first pushing section penetrates through the second piston opening to be fixed with a second piston head in the second liquid medicine cavity.

6. The medical fluid bolus device of claim 5, wherein a distance between an end face of the first pushing section facing the first piston head and a rear end face of the first piston head is equal to a distance between a front end face of the second piston head and a front end face of the first piston head.

7. The device of any one of claims 1-6, wherein the outer circumferential surface of the first piston head has a plurality of first grooves and a plurality of first rubber rings respectively positioned in the first grooves, each of the first grooves is distributed along the circumferential direction of the first piston head, and the first piston head is in sealing connection with the inner side wall of the first liquid medicine cavity through the first rubber rings.

8. The device of any one of claims 1-6, wherein the outer circumferential surface of the second piston head has a plurality of second grooves and a plurality of second rubber rings respectively positioned in the second grooves, each of the second grooves is distributed along the circumferential direction of the second piston head, and the second piston head is in sealing connection with the inner side wall of the second liquid medicine cavity through the second rubber rings.

9. The medical fluid bolus device according to any one of claims 1-6, wherein the piston sleeve has a plurality of inlet ports in communication with the first medical fluid chamber, respectively;

The liquid medicine pushing and injecting device comprises a first one-way valve and a second one-way valve, the first one-way valve is arranged outside the injection port, and liquid medicine in the first liquid medicine cavity is injected out through the injection port and the first one-way valve; the second one-way valve is arranged outside the medicine inlet, and external medicine liquid enters the first medicine liquid cavity through the second one-way valve and the medicine inlet.

10. A needleless injector comprising the medical fluid bolus device of any one of claims 1-9.