CN111558112B

CN111558112B - Injection head of needleless injector, needleless injector body and needleless injector

Info

Publication number: CN111558112B
Application number: CN202010366995.9A
Authority: CN
Inventors: 张明
Original assignee: Beijing Qs Medical Technology Co ltd
Current assignee: Beijing Qs Medical Technology Co ltd
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2021-09-24
Anticipated expiration: 2040-04-30
Also published as: CN111558112A

Abstract

The invention relates to an injection head of a needleless injector, a needleless injector body and the needleless injector. The injection head comprises a medicine tube and a piston rod. The rear end of the medicine tube is opened and the front end is provided with an injection micropore. The piston of the piston rod can move back and forth in the cavity, and the side wall and the front wall of the piston and the medicine tube jointly define a liquid medicine containing cavity; a liquid medicine channel is arranged in the piston rod. The injection head and the medicine storage bottle can be installed on the needleless injector main body together, the medicine liquid can enter the medicine liquid containing cavity through the medicine liquid channel, and the piston rod can push the medicine liquid in the medicine liquid containing cavity to be ejected outwards through the injection micropores. According to the scheme provided by the invention, the medicine storage bottle such as a cassette bottle can be accommodated in the needleless injector main body, the injection head can suck medicine from the medicine storage bottle and complete injection each time the needleless injector is used, the operation process can be efficiently and laborsavingly completed, and the whole process does not need to take out the medicine storage bottle or separate the medicine tube from the medicine storage bottle.

Description

Injection head of needleless injector, needleless injector body and needleless injector

Technical Field

The present invention relates to a medical device for injecting a liquid drug. More particularly, the present invention relates to an injector head for a needle-free injector, and a needle-free injection assembly.

Background

The needleless injector does not need to use a needle, but is a medical device which can inject liquid medicine into the subcutaneous part of a patient through micropores at the end part by applying high pressure to the liquid medicine, thereby being capable of preventing the patient from suffering from acupuncture. Needleless injectors generally comprise a cartridge and a pusher. The function of the cartridge is to contain the liquid drug.

Generally, when a needleless injector is used, a medicine tube is firstly installed on the needleless injector, then medicine is extracted from a medicine storage bottle through a needle head at the front end of the medicine tube, and the medicine can be injected after the medicine tube and the medicine storage bottle are separated after the medicine extraction is finished. It can be seen that the operation of getting it filled is comparatively loaded down with trivial details.

In order to solve the problem, the existing solution is to combine the medicine tube and the medicine storage bottle into one and use the medicine tube and the medicine storage bottle once, but the cost of the method is high, and the material of the two-in-one medicine tube/medicine storage bottle generally cannot meet the safety requirement of long-term contact with the medicine.

Accordingly, there is a need to provide an injector head, a needle-free injector body, and a needle-free injection assembly for a needle-free injector that at least partially address the above-mentioned problems.

Disclosure of Invention

In order to overcome the defects, the invention provides an injection head of a needleless injector, a needleless injector body and a needleless injector. According to the scheme provided by the invention, the medicine storage bottle such as a cassette bottle can be accommodated in the needleless injector, medicine suction and injection can be completed in each use, the operation process can be completed efficiently and in a labor-saving manner, and the whole process does not need to take out the medicine storage bottle or separate the medicine tube from the medicine storage bottle. And the medicine storage bottle is accommodated in the needleless injector, so that the problems of the medicine storage bottle, such as loss, pollution and the like, can be avoided.

According to one aspect of the present invention there is provided an injector head for a needle-free injector body for use with a drug storage vial in the needle-free injector body, the injector head comprising:

the medicine tube is internally provided with a cavity with an opening at the rear end, and the front end of the medicine tube is provided with an injection micropore for communicating the cavity with the outside;

a piston rod, the piston rod comprising:

the piston is positioned in the cavity and can move back and forth in the cavity, and the piston and the side wall and the front wall of the medicine tube can jointly define a liquid medicine containing cavity;

a rod part fixedly connected to a rear end of the piston,

wherein, when in use, the rear end of the rod part of the injection head can be inserted into a medicine storage bottle and extends into the medicine storage bottle, and a medicine liquid channel which is communicated with the medicine liquid accommodating cavity and the medicine storage bottle is arranged in the piston rod,

the injection head and the medicine storage bottle can be mounted on the needleless injector main body together, and the piston rod can move backwards relative to the medicine tube so that the medicine liquid in the medicine storage bottle can enter the medicine liquid accommodating cavity through the medicine liquid channel and can move forwards relative to the medicine tube so as to push the medicine liquid in the medicine liquid accommodating cavity to be ejected outwards through the injection micropores.

In one embodiment, the medical fluid passage extends in an axial direction of the piston rod, and a front end of the piston rod is provided with a check valve that allows only medical fluid to enter the medical fluid-accommodating chamber from the drug storage bottle.

In one embodiment, the one-way valve includes a valve element capable of being embedded in the piston and capable of moving back and forth with respect to the piston by a small amplitude, and the liquid medicine from the medicine storage bottle has to flow through a gap between the valve element and the piston and enter the liquid medicine accommodating chamber.

In one embodiment, the valve core is a ball-shaped structure; or

The front part of the valve core is of a conical structure, the rear part of the valve core is of a cylindrical structure, the cylindrical structure is connected to the bottom surface of the conical structure, and the diameter of the bottom surface of the conical structure is larger than that of the cylindrical structure.

In one embodiment, the piston is provided with an inner piston passage, the inner piston passage is spaced from the piston rod in a radial direction with respect to the axis, and the liquid medicine from the medicine storage bottle must flow through the inner piston passage and enter the liquid medicine accommodating chamber.

In one embodiment, the rear end of the stem portion is a needle-like structure for piercing a sealing membrane of the vial.

In one embodiment, the injector head further comprises a cap removably located at the forward end of the cartridge for closing the injection wells.

In one embodiment, wherein the piston rod is configured to be fixed relative to the vial in use; or

The piston rod is configured to move rearwardly relative to the drug storage vial during rearward movement relative to the drug tube to compress a drug storage space within the drug storage vial.

According to another aspect of the present invention there is provided a needleless injector body for use with an injector head according to any of the above aspects and a vial, the needleless injector body comprising:

a base having a forward opening;

an outer housing having a rearward opening and mounted at a front end of the base to form an accommodating space between the base and the outer housing, the outer housing being provided with a front opening for fixedly mounting a cartridge;

an inner push rod located in the accommodating space and having a forward opening, the medicine storage bottle being fixedly accommodated in the inner push rod and a piston rod being fixed at the forward opening,

the outer shell can move back and forth relative to the inner push rod to drive the medicine tube to move back and forth relative to the medicine storage bottle and the piston rod so as to achieve medicine suction and injection.

In one embodiment, the needle-free injector body further comprises a locking mechanism coupled between the base and the inner ram, the locking mechanism configured to lock the inner ram relative to the base during aspiration and unlock the inner ram to move the inner ram forward relative to the outer housing after aspiration is complete.

In one embodiment, the rear end of the inner push rod is provided with a rear end flange protruding radially outward, and the locking mechanism comprises:

a stopper member configured to be capable of abutting against a front end surface of the rear end flange in a locked state to restrict forward movement of the inner push rod;

a button mounted on a rear end wall of the base and protruding rearward relative to the base,

wherein the button is configured to be pushed to move forward relative to the base and to directly or indirectly apply a pushing force to a rear end face of the inner push rod, the rear end flange of the inner push rod being capable of passing over the stopper member under the action of the pushing force, thereby releasing the locking of the inner push rod by the locking mechanism.

In one embodiment, the locking mechanism further comprises:

a spring receiving member provided between a rear end surface of the inner push rod and a rear end wall of the push button, the spring receiving member having a spring receiving chamber opened rearward;

a button spring located in the spring receiving chamber and capable of contacting the button at a rear end thereof,

wherein the button is pushable to indirectly apply a pushing force to the inner push rod through the button spring and the spring receiver.

In one embodiment, the button has a rear end wall and a side wall extending forwardly from the rear end wall and surrounding the axis, the front end of the side wall is provided with a boss projecting toward the axis of the needle-less injector body, and the stop member is configured to be movable relative to the button in a radial direction with respect to the axis,

wherein the boss abuts against a radially outer side of the stopper member in a locked state to restrict radially outward movement thereof, and moves forward relative to the stopper member when the push button is pushed to release the radially restricting thereof, at which time the stopper member can move radially outward to be out of contact with a front end surface of the rear end flange to release the locking of the inner push rod.

In one embodiment, the stop member is a ball, and the rear end face of the boss and the front end face of the rear end flange are both inclined surfaces, so that the stop member can be in rolling contact with the inclined surfaces during unlocking.

In one embodiment, the locking mechanism is an electromagnet.

In one embodiment, the needle-free injector body further comprises a resilient actuation mechanism located between the seat and the internal ram, the resilient actuation mechanism being configured to be operated to charge energy prior to injection and to be released after charging to actuate the internal ram forwardly by spring force to complete the injection. In one embodiment, the front end of the inner push rod is provided with a radially outwardly projecting front end flange, and the resilient actuating mechanism comprises an actuating spring arranged between the front end flange and the base.

In one embodiment, the actuation spring is sleeved outside the inner push rod.

In one embodiment, a spring shaft is fixedly connected to a front end flange of the inner push rod, the spring shaft is parallel to an axis of the inner push rod, and the actuating spring is sleeved on the spring shaft.

In one embodiment, the spring shaft is provided in plurality and each of the spring shafts is sleeved with one of the actuating springs, and each of the spring shafts is uniformly arranged around the inner push rod.

In one embodiment, the inner push rod is provided at its middle portion with a middle flange disposed along its circumference, and the resilient actuating mechanism comprises an actuating spring disposed between the middle flange and the base.

In one embodiment, the base includes a rear end portion and a base sidewall, an inner thread is provided on an inner surface of the base sidewall, an outer thread corresponding to the inner thread is provided on an outer surface of the rear portion of the outer housing, and the outer housing is movable rearward relative to the base by cooperation of the inner thread and the outer thread to stably compress the actuating spring.

In one embodiment, the outer housing and the inner plunger are at least partially transparent or hollow in the radial direction in relation to the drug reservoir, so that the volume of the drug solution in the drug reservoir is visible to the outside.

According to a further aspect of the invention there is provided a needleless injector comprising a needleless injector body according to any one of the above aspects and an injector head for use with the needleless injector body.

In one embodiment, the front opening of the outer shell of the needleless injector body is provided with an internal thread facing the axis of the needleless injector body, the medicine tube of the injector head is provided with an external thread, and the internal thread and the external thread are matched to detachably mount the medicine tube on the needleless injector body.

According to another aspect of the present invention, there is provided a needleless injector body for use with an injector head and a drug storage vial having a vial body with a drug storage vial receiving cavity and a vial stopper slidable back and forth within the drug storage vial receiving cavity relative to the vial body, the needleless injector body comprising:

a base having a forward opening;

an internal pusher system including an internal pusher located within the receiving space and having a forward opening, the drug vial being fixedly received within the internal pusher and a piston rod being fixed at the forward opening;

the medicine supplementing push rod is arranged at the rear end of the inner push rod, and the front end of the medicine supplementing push rod can be contacted with the bottle stopper of the medicine storage bottle; and

a conducting device, one part of the conducting device is connected with the medicine supplementing push rod, the other part of the conducting device can be directly or indirectly connected with the base or the outer shell,

wherein the outer shell can move back and forth relative to the inner push rod to drive the medicine tube to move back and forth relative to the medicine storage bottle and the piston rod so as to realize medicine suction and injection,

and in the process of medicine suction, the base or the external shell drives the medicine supplementing push rod to push the bottle stopper of the medicine storage bottle forwards relative to the bottle body through the conduction device so as to compress the space in the medicine storage bottle.

In one embodiment, the needleless injector body further comprises a locking mechanism coupled between the base and the internal ram system, the locking mechanism configured to lock the internal ram system relative to the base in a forward or rearward direction during inhalation and to unlock the internal ram system to move the internal ram system forward relative to the outer housing after inhalation is complete.

In one embodiment, the seat and the outer housing are rotatably engaged with respect to each other such that relative movement of the outer housing and the seat in the direction of the axis of the needleless injector body is achieved by relative rotation therebetween.

In one embodiment, the internal putter system further comprises a conductive rod, a front end of the conductive rod being connected to the conductive device, a rear end of the conductive rod being adapted to engage the locking mechanism and to be rotationally fixed relative to the base when the conductive rod is locked by the locking mechanism.

In one embodiment, the conduction device comprises a rotary motion conduction device, the rotary motion conduction device is configured to transmit specific rotary motion of the conduction rod to the medicine supplement push rod so as to drive the medicine supplement push rod to rotate,

and a motion conversion mechanism is arranged in the needleless injector body, one part of the motion conversion mechanism is jointed with the medicine supplementing push rod, and the other part of the motion conversion mechanism is jointed with the internal push rod, so that the medicine supplementing push rod is converted into linear motion relative to the internal push rod along the axial direction of the needleless injector body along with the rotation motion of the conduction rod.

In one embodiment, the outer housing rotates relative to the base to move forward relative to the base during inhalation,

and the rotational motion conduction means includes a unidirectional rotational motion conduction means configured to be able to transmit the rotational motion of the conduction rod to the drug supplement pusher during forward movement of the outer case relative to the base by rotating relative to the base, but not to transmit the rotational motion of the conduction rod to the drug supplement pusher during backward movement of the outer case relative to the base by rotating relative to the base.

In one embodiment, the unidirectional rotational motion transmission device comprises a unidirectional bearing, an outer ring of the unidirectional bearing is fixedly connected with the transmission rod, and an inner ring of the unidirectional bearing is fixedly connected with the drug infusion push rod in a rotational direction around the axis of the needleless injector body.

In one embodiment, the motion conversion mechanism includes a nut member disposed within the receiving space of the inner ram and fixedly coupled to the inner ram, and the supplemental medication ram is threadably engaged with the nut member.

In one embodiment, the nut member comprises at least two nut members spaced apart from one another, the at least two nut members being arranged around the supplemental medication ram and the nut members being movable radially of the needle-free injector body toward and away from the axis of the needle-free injector body to engage and disengage the supplemental medication ram.

In one embodiment, the at least two nut members are configured to: when the force in the axial direction of the needle-free injector body is applied to the nut members by the medicine replenishing push rod and reaches a predetermined threshold value, the at least two nut members move in the radial direction away from the axis to disengage from the medicine replenishing push rod.

In one embodiment, a resilient member is mounted between the circumferential outer surface of the nut member and the circumferential inner surface of the inner ram, the resilient member being compressed when the two nuts are disengaged from the supplemental medication ram.

In one embodiment, the needleless injector body further comprises a nut stop member disposed at a front end of each of the nut members, wherein a surface of the nut member in contact with the nut stop member is a force ramp having a rear end radially farther from an axis of the needleless injector than a front end of the force ramp, the nut stop member being configured to press the force ramp rearwardly into engagement with the drug infusion push rod; and the nut members move away from each other in the radial direction to disengage from the supplemental medication push rod when the nut stop member ceases to apply force to the nut members.

In one embodiment, a front end of the nut stop member is directly contactable with a rear end of the body of the drug storage bottle to enable continued compression of the nut member under rearward force from the body when the drug storage bottle is mounted in the internal ram, and to cease applying force to the nut member after the drug storage bottle is removed from the internal ram.

In one embodiment, the nut limiting member is a wedge-shaped block, and the wedge-shaped block is provided with a force application inclined surface which is in contact with the force application inclined surface.

In one embodiment, the nut stopper member is a spherical structure, and a ball movement groove is provided at a front end position of a radially outer edge of the nut member, the nut stopper member being confined in the ball movement groove so as not to be disengaged therefrom.

In one embodiment, the nut stop member is an annular structure coaxial with the needleless injector body, and the section of the annular structure cut by a plane on which the axis of the annular structure is located is circular.

In one embodiment, the rear end of the internal push rod system is provided with a rear end flange projecting radially outwardly, and the locking mechanism comprises:

a stop member configured to be abuttable against a front face of the rear end flange in a locked state to limit forward movement of the internal pusher system;

wherein the button is configured to be pushed to move forward relative to the base and to apply a pushing force directly or indirectly to a rear end face of the internal ram system, the rear end flange of the internal ram system being able to pass over the stop member under the action of the pushing force, thereby releasing the locking of the internal ram system by the locking mechanism.

In one embodiment, the locking mechanism further comprises:

a spring receiver disposed between a rear end face of the internal pusher system and a rear end wall of the button, the spring receiver having a rearwardly open spring receiver cavity;

wherein the button is pushable to indirectly apply a pushing force to the internal pusher system through the button spring and the spring receiver.

wherein the boss abuts against a radially outer side of the stop member in the locked state to restrict radially outward movement thereof, and moves forward relative to the stop member when the button is pushed to release the radially stop thereof, at which time the stop member can move radially outward to be out of contact with a front end face of the rear end flange to release the locking of the internal push rod system.

In one embodiment, the locking mechanism is an electromagnet.

In one embodiment, the needle-free injector body further comprises a resilient actuation mechanism located between the seat and the internal ram system, the resilient actuation mechanism being configured to be operated to charge energy prior to injection and to be released after charging to actuate the internal ram system forwardly by spring force to complete the injection.

In one embodiment, the front end of the inner push rod is provided with a radially outwardly projecting front end flange, and the resilient actuating mechanism comprises an actuating spring arranged between the front end flange and the base.

In one embodiment, the actuation spring is sleeved outside the inner push rod.

In one embodiment, the number of the spring shafts is plural, and each of the spring shafts is sleeved with one of the actuating springs, and each of the spring shafts is arranged around the inner push rod.

In one embodiment, the outer periphery of the inner pushrod is provided with an inner pushrod flange protruding radially outward, a circumferential outer surface of the inner pushrod flange is in contact with a circumferential inner surface of the outer housing, and the circumferential outer surface of the inner pushrod flange and the circumferential inner surface of the outer housing are provided with a movement restricting structure configured to restrict the inner pushrod from rotating relative to the outer housing but to allow the inner pushrod to move in a forward and backward direction relative to the outer housing.

In one embodiment, the movement limiting structure comprises a keyway or guide rod formed on the circumferential outer surface of the inner ram flange and the circumferential inner surface of the inner housing extending in the axial direction of the needleless injector body.

According to another aspect of the invention, there is provided a needleless injector comprising a needleless injector body according to any one of the aspects and an injector head for use with the needleless injector body.

In one embodiment, the injector head is capable of being used with a drug storage vial, the injector head comprising:

a piston rod, the piston rod comprising:

a rod part fixedly connected to a rear end of the piston,

In one embodiment, the valve core is a ball-shaped structure; or

In one embodiment, the piston is provided with an inner piston passage extending in a direction parallel to the axis, the inner piston passage is spaced from the piston rod in a radial direction with respect to the axis, and the liquid medicine from the medicine bottle has to flow through the inner piston passage and enter the liquid medicine accommodating chamber.

In one embodiment, the front opening of the outer shell of the needleless injector body is provided with an internal thread facing the axis of the needleless injector, the medicine tube of the injector head is provided with an external thread, and the internal thread and the external thread are matched to detachably mount the medicine tube on the needleless injector body.

According to the invention, the medicine storage bottle such as a cassette bottle can be accommodated in the needleless injector main body for a long time, medicine suction and injection can be completed in each use, the operation process can be completed efficiently and in a labor-saving manner, and the whole process does not need to take out the medicine storage bottle or separate the medicine tube from the medicine storage bottle. And the medicine storage bottle is accommodated in the needleless injector, so that the problems of the medicine storage bottle, such as loss, pollution and the like, can be avoided.

Drawings

For a better understanding of the above and other objects, features, advantages and functions of the present invention, reference should be made to the preferred embodiments illustrated in the accompanying drawings. The same or similar reference numbers in the drawings refer to the same or similar parts. It will be appreciated by persons skilled in the art that the drawings are intended to illustrate preferred embodiments of the invention without any limiting effect on the scope of the invention, and that the various components in the drawings are not drawn to scale.

FIG. 1 shows a cross-sectional view of the injector head of a needle-free injector according to a preferred embodiment of the present invention in a disassembled state;

FIG. 2 is a cross-sectional view of the syringe tip and vial of FIG. 1 in an attached state;

FIG. 3 is a cross-sectional view of the injection head of FIG. 2 during a drug inhalation procedure;

FIG. 4 is a cross-sectional view of the injection head of FIG. 2 during an injection procedure;

figures 5 and 6 are cross-sectional views of the front end of the injection head of figure 2 in a ready state and a drug-aspirating state, respectively;

FIGS. 7-8 are cross-sectional views of an alternative to FIGS. 5-6;

FIGS. 9-10 are cross-sectional views of another alternative to FIGS. 5-6;

fig. 11 is a cross-sectional view of a needleless injector body in accordance with a preferred embodiment of the present invention;

FIG. 12 is a cross-sectional view of the rear portion of the needleless injector of FIG. 11, with the locking mechanism in a locked condition;

FIG. 13 is another cross-sectional view of the rear portion of the needle-free injector of FIG. 11 with the locking mechanism in an unlocked condition;

FIGS. 14-19 are cross-sectional views of the syringe head and drug vial mounted to a needle-free injector body and use of the needle-free injector for aspiration and needle-free injection;

fig. 20 is a cross-sectional view of an alternative version of the needle-free injector of fig. 14-19;

fig. 21 is a cross-sectional view of another alternative version of the needle-free injector of fig. 14-19;

FIGS. 22-28 are cross-sectional views of another preferred embodiment of an injector head and drug vial mounted to a needle-free injector body and used for aspiration and needle-free injection;

fig. 29 is a cross-sectional view of the needle-free injector body of fig. 22-28 after completion of a needle-free injection;

FIG. 30A is a cross-sectional view of the internal tappet system, the nut member, and the one-way bearing of FIGS. 22-28 in an assembled state;

FIG. 30B is a schematic view taken along line A-A of FIG. 30A;

FIG. 31 is a cross-sectional schematic view of the internal pusher system, nut member and one-way bearing in combination in an alternative embodiment of the structure of FIGS. 22-28;

FIG. 32A is a schematic view of the components of FIG. 31 with the nut member engaged with the supplemental medication push rod;

FIG. 32B is a schematic view of the components of FIG. 31 with the nut member disengaged from the supplemental medication push rod;

FIGS. 33A-33B are schematic views of an alternative to FIGS. 32A-32B;

fig. 34A-34B are schematic views of another alternative to fig. 32A-32B.

Detailed Description

Hereinafter, a needle-free injector body and an injector head of the needle-free injector according to the present invention will be described in detail with reference to the accompanying drawings. The following is given only by way of preferred embodiments according to the invention, on the basis of which other ways of implementing the invention may be conceived by those skilled in the art, which also fall within the scope of the invention.

The invention provides an injection head of a needleless injector, a needleless injector body and the needleless injector. Fig. 1-34B illustrate some preferred embodiments according to the present invention.

It should be noted that, in the first place, the "axial direction" mentioned herein is understood to be the direction of the axis X of the needleless injector, and in this axial direction, the direction toward the patient when the needleless injector is used is referred to as "front side", and the direction opposite thereto is referred to as "rear side". The "radial direction" referred to herein is a radial direction with respect to the axial direction, which is shown by X' in fig. 15.

Fig. 1 is an exploded view of a preferred embodiment of a needleless injector head 2, the injector head 2 being used in conjunction with a drug storage vial 1, which drug storage vial 1 may be, for example, a cartridge vial according to national standards. Figures 2-4 show a schematic view of the connection of the injector head 2 to the drug vial 1 which can be mounted together on the needleless injector body 3 (see figure 11) when the injector head 2 is correctly connected to the drug vial 1.

As can be seen from fig. 1-4, the injector head 2 is of a substantially rotationally symmetrical construction about an axis X and comprises in particular a cartridge 21 and a piston rod 22. The medicine tube 21 has a cavity with an opening at the rear end, and the front end of the medicine tube 21 is provided with injection micropores 211 communicating the cavity with the outside. The piston rod 22 includes a piston 221 and a rod portion 222, wherein the piston 221 is located in the chamber and can move back and forth in the chamber, and the piston 221 can define a liquid medicine accommodating chamber 215 together with the side wall and the front wall of the cartridge 21; the stem portion 222 is fixedly attached to the rear end of the piston 221 and extends into the vial 1. Further, a medical fluid passage 222c is provided in the piston rod 22 to communicate the medical fluid storage chamber 215 with the vial 1, and the medical fluid passage 222c preferably extends along the axis X.

Preferably, the rear end of the stem portion 222 is a needle-like structure 222b for puncturing a sealing membrane at the front end of the medicine storage bottle 1. Also preferably, the injector head 2 further comprises a cap 23 removably located at the front end of the cartridge 21 for closing the injection wells 211. The cap 23 may be provided with cap protrusions 231 and the cartridge may be provided with cartridge recesses 214, the cap protrusions 231 and the cartridge recesses 214 being engageable with each other to facilitate mounting of the cap 23 on the cartridge 21. In other embodiments, not shown, the cap 23 may not be additionally provided, and the cartridge 21 may be configured to enable the injection micro-hole 211 to be self-closed and self-opened.

Referring to fig. 3, when the cap 23 is mounted on the front end of the cartridge 21, the piston rod 22 moves backward relative to the cartridge 21, and a negative pressure is generated in the medical fluid storage chamber 215 so that the medical fluid in the drug storage bottle 1 can be sucked into the medical fluid storage chamber 215 through the medical fluid passage 222 c. Preferably, the rear end of the medicine storage space of the medicine storage bottle 1 may be closed by a movable stopper 12, and the stopper 12 is configured to be freely movable relative to the body 11 by the gas pressure. That is to say, in the medicine suction process, the bottle plug 12 can move forward relative to the bottle body 11 to ensure that the pressure in the medicine storage space is not reduced, so that the medicine suction speed is stable in the whole medicine suction process. Referring to fig. 4, after the inhalation is completed, the cap 23 may be removed and the piston rod 22 is controlled to move forward relative to the cartridge 21 to eject the medical fluid in the medical fluid accommodating chamber 215 through the injection micro holes 211.

In order to prevent contamination due to backflow of the medical fluid from the medical fluid accommodating chamber 215 to the drug storage bottle 1 during inhalation and injection, a check valve configured to allow only the medical fluid from the drug storage bottle 1 to enter the medical fluid accommodating chamber 215 may be further provided at the front end of the piston rod 22. Fig. 5 to 10 show three specific embodiments of the one-way valve.

The two kinds of check valves shown in fig. 5 to 8 include a valve core which is embedded in the piston 221 and moves back and forth with a small amplitude with respect to the piston 221, the valve core is formed in a rotationally symmetrical structure with respect to an axis, and the liquid medicine from the medicine bottle 1 must flow through a gap between the valve core and the piston 221 to enter the liquid medicine accommodating chamber 215. Of course, in other embodiments not shown, the valve core may not be of a symmetrical configuration. Specifically, in this embodiment, the piston 221 is deformed due to the negative pressure during the drug inhalation process, and the valve element is slightly moved forward relative to the piston 221 by the suction force, so that a passage is formed between the valve element and the piston 221. After the medicine is sucked, the piston rod 22 stops moving, and the medicine liquid is supplied into the medicine liquid accommodating cavity through the passage, so that the negative pressure disappears. Particularly, when the cap 23 is removed from the cartridge 21, the pressure inside the chemical liquid accommodating chamber is the same as the external pressure because the medicine tube 21 has the minute hole 211 at the front end. At this time, the valve core can be pressed back to the original position, and the backflow of the liquid medicine is avoided.

Specifically, the check valve of one embodiment shown in fig. 5 and 6 is a ball valve, the valve core 223 is a sphere, and the piston 221 is provided with a receiving structure adapted to the outer contour of the sphere. Fig. 5 is a schematic view when no liquid chemical flows through the valve body 223, and fig. 6 is a schematic view when the liquid chemical flows through the valve body 223. As can be seen from fig. 6, the liquid medicine reaches the valve spool 223 via the liquid medicine passage 222c and flows through a gap between the valve spool 223 and the piston 221 (i.e., bypasses the valve spool 223) to enter the liquid medicine accommodating chamber 215.

The spool 224 of the alternate embodiment check valve shown in fig. 7 and 8 includes two portions: the front portion is a conical structure 224a and the rear portion is a cylindrical structure 224b, the cylindrical structure 224b is connected to the bottom surface of the conical structure 224a, and the diameter of the bottom surface of the conical structure 224a is larger than that of the cylindrical structure 224 b. Preferably, the front end surface 221b of the piston 221 ' is matched with the rear end surface of the conical structure 224a, and when the valve core 224 is installed on the piston 221 ', the front end part of the integral structure of the valve core 224 and the piston 221 ' forms a conical structure. And the spool 224 is made of an elastic material. During the drug suction process, the front end of the conical structure 224a is sucked forward due to the negative pressure in the drug solution containing cavity (and the impact force of the drug solution). On the other hand, the rear end of the cylindrical structure 224b has a small protrusion 224c engaged with the piston 221 ', and since the front end of the valve element 224 is applied with a forward suction force and the rear end is fixed with respect to the piston 221', the valve element 224 is slightly elastically deformed, and the conical structure 224a of the valve element 224 is slightly moved forward with respect to the piston 221 ', so that a gap is formed between the conical structure 224a of the valve element 224 and the piston 221', through which the liquid medicine has to flow into the liquid medicine accommodating chamber 215.

Fig. 9 and 10 show a structure of a check valve according to still another embodiment. The check valve in fig. 9 and 10 does not have a spool, but a piston inner passage 221c is provided in the piston 221', and the piston inner passage 221c may be parallel to the axial direction or may be at an angle to the axial direction. And there is a space between the piston inner passage 221c and the piston rod 22 in the radial direction with respect to the axis. The liquid medicine from the medicine bottle 1 flows through the liquid medicine passage 222c in the rod portion 222 and the piston inner passage 221c in the piston 221' in sequence to enter the liquid medicine accommodating chamber 215.

In the embodiment shown in the drawings, the piston rod 22 is fixed relative to the drug storage vial 1 during both the drug inhalation and injection operations, and the introduction of the drug solution from the drug storage vial 1 into the drug solution containing chamber 215 is achieved only by the pressure difference between the drug solution containing chamber 215 and the drug storage vial 1 during the drug inhalation process. However, in other embodiments, not shown, the rear end of the piston rod 22 may be provided with a piston capable of moving within the vial, and the piston rod 22 may move not only backwards relative to the vial 21 but also simultaneously backwards relative to the vial 1 during inhalation to compress the space within the vial by the piston within the vial, which operation can further increase the inhalation rate.

Fig. 11 shows a preferred embodiment of a needleless injector body 3 for use with an injector head 2 and a vial 1 as described above. As can be seen in fig. 11, the needleless injector body 3 comprises a seat 31, an outer housing 32 and an inner ram 33. Wherein the base 31 has a forward opening, the outer housing 32 has a rearward opening and is mounted at the front end of the base 31 to form a receiving space between the base 31 and the outer housing 32, and the outer housing 32 is provided with a front opening for fixedly mounting the cartridge 21. The inner push rod 33 is located in the accommodating space and has a forward opening, the medicine storage bottle 1 can be accommodated in the inner push rod 33 and moves together with the inner push rod 33, and the piston rod 22 is fixedly mounted at the forward opening.

The connection relationship of the above-mentioned components can have various options. For example, the outer shell 32 and the cartridge 21 may be connected by a screw, and referring to fig. 14, the cartridge 21 is provided with a cartridge external screw 213 on the rear outer surface thereof, and the front opening of the outer shell 32 is provided with a housing internal screw 322a, and the cartridge external screw 213 can be engaged with the housing internal screw 322a to fix the cartridge 21 and the outer shell 32 relative to each other. The cartridge 21 may be provided with a retaining flange 212 to snap fit over the front face of the outer housing 32.

The piston rod 22 may be snap-fitted with the inner push rod 33, in particular, with continued reference to fig. 14, a snap projection 222d is provided on an outer surface of the piston rod 22, a snap groove 33a is provided at a corresponding position of the inner push rod 33, and the snap projection 222d is snapped into the snap groove 33a to fix the piston rod 22 relative to the inner push rod 33. The rear portion 222a of the piston rod 22 may have a larger radial dimension to match the inner pushrod 33. Further, the space inside the inner ram 33 may be provided with a space having a size corresponding to the drug storage bottle 1, in which the drug storage bottle 1 is fittingly placed after the piston rod 22 and the inner ram 33 are snapped into each other and in which there is no room for allowing the drug storage bottle 1 to move relative to the inner ram 33.

Thus, the outer housing 32 is fixed relative to the cartridge 21, the inner ram 33 is fixed relative to the vial 1 and the piston rod 22, and the outer housing 32, the inner ram 33, and the base 31 are all movable relative to one another throughout the aspiration and injection process. Therefore, the outer housing 32 can move the cartridge 21 and the inner ram 33 can move the vial 1 and the piston 221.

Specifically, the outer housing 32 can move back and forth relative to the inner ram 33 to move the cartridge 21 back and forth relative to the vial 1 and the piston rod 22 for inhalation and injection. More specifically, during inhalation (see fig. 17), the inner push rod 33 is fixed relative to the base 31, and the outer housing 32 moves forward relative to the inner push rod 33; during an injection (see fig. 19), the outer housing 32 is fixed relative to the base 31 and the inner ram 33 moves forward relative to the outer housing 32. The specific inhalation and injection procedures will be described in detail later.

Preferably, the needle-free injector body 3 further comprises a locking mechanism 34, the locking mechanism 34 being connected between the chassis 31 and the inner plunger 33 for locking the inner plunger 33 relative to the chassis 31 during inhalation and unlocking to enable forward movement of the inner plunger 33 relative to the outer housing 32 after inhalation is complete.

Fig. 12 and 13 show a preferred embodiment of the locking mechanism 34, but without the internal push rod 33. The state shown in fig. 12 is a state in which the lock mechanism 34 is in a locked state, and the state shown in fig. 13 is a state in which the lock has been released. Fig. 16 to 19 show a state in which the inner push rod 33 is engaged with the lock mechanism 34.

The rear end of the inner push rod 33 is provided with a rear end flange 333 (see fig. 16) projecting radially outward, the rear end flange 333 being for engagement with the lock mechanism 34. Referring to fig. 12, 13 and 16, the locking mechanism 34 includes a stop member 344, a button 341, a spring receiver 342 and a button spring 343. The stop member 344 can abut against the front end surface 333a of the rear end flange 333 in the locked state to restrict the forward movement of the inner push rod 33; the button 341 is mounted on the rear end wall of the base 31 and projects rearward with respect to the base 31; a spring receiver 342 is provided between the rear end face of the inner push rod 33 and the rear end wall of the button 341, the spring receiver 342 having a spring receiving chamber opened rearward; the button spring 343 is located in the spring receiving chamber and can contact the button 341 at its rear end.

In this way, the button 341 can be pushed to push the button spring 343 and the spring receiver 342 to indirectly push the inner push rod 33, and the rear end flange 333 of the inner push rod 33 can thereby pass over the stopper member 344, so that the lock mechanism 34 releases the lock of the inner push rod 33. In other embodiments, which are not shown, the button spring 343, the spring receiver 342, and the like may not be provided, and the button 341 may directly push the inner plunger 33, thereby unlocking the inner plunger 33 from the lock mechanism 34.

Preferably, with continued reference to fig. 12-19, the button 341 has a rear end wall and a side wall 341b extending forward from the rear end wall and about the axis X, the front end of the side wall 341b is provided with a boss 341c projecting toward the axis of the needle-free injector body 3, and the stopper member 344 is movable relative to the button 341 in a radial direction about the axis. Wherein, in the locking state as shown in fig. 12, 16-18, the protruding portion 341c abuts against the radial outside of the stop member 344 to limit the stop member 344 from moving radially outward, and the stop member 344 can stably abut against the front end surface 333a of the rear end flange 333 of the inner push rod 33 to lock the inner push rod 33 because the stop member 344 cannot move radially outward; the projection 341c moves forward relative to the stopper member 344 when the button 341 is pushed to release the radial stopper thereof, and the stopper member 344 can move radially outward to come out of contact with the front end surface of the rear end flange 333 of the inner push rod 33 to release the locking of the inner push rod 33, and fig. 13 and 19 show a state after the lock mechanism 34 is released from the locking.

More preferably, the stop member 344 may be two spheres symmetrically disposed with respect to the axis, and the rear end surface 341d (see fig. 12) of the protruding portion 341c and the front end surface 333a (see fig. 11) of the rear end flange 333 of the inner push rod 33 are both inclined surfaces, so that the stop member 344 can be in rolling contact with the inclined surfaces during unlocking, thereby enabling the user to unlock the button 341 with a small pushing force.

In other embodiments not shown, other locking mechanisms 34 may also be provided. For example, the locking mechanism 34 may be an electromagnet. After the injection head 2 and the medicine storage bottle 1 are installed in the needleless injector body 3, the electromagnet can be electrified and locks the internal push rod 33, and then medicine suction is performed. After aspiration is complete, the electromagnet may be de-energized and the electromagnet magnetically deactivated, at which time the inner plunger 33 can be moved forward relative to the outer housing 32 to complete the injection.

Preferably, referring to fig. 11, 14-19, the needle-less injector body 3 further comprises an elastic actuating mechanism located between the base 31 and the inner plunger 33, the elastic actuating mechanism is configured to be operated to be charged before injection and to be released to actuate the inner plunger 33 forward by elastic force after charging, and the inner plunger 33 drives the piston rod 22 to push the liquid medicine in the liquid medicine containing cavity 215 of the medicine tube 21 to complete injection. In other embodiments, not shown, the resilient actuating mechanism may also be a gas spring or an air bag or the like.

Specifically, the front end of the inner push rod 33 is provided with a front end flange 331a protruding radially outward, and the elastic actuating mechanism includes an actuating spring 36 provided between the front end flange 331a and the base 31. The actuating spring 36 is fitted over the outer side of the inner push rod 33.

Preferably, a screw thread is provided between the outer housing 32 and the base 31, and the rearward movement of the outer housing 32 relative to the base 31 is achieved by the screw thread contact. Specifically, referring to fig. 11, the base 31 includes a rear end portion and a base sidewall 312 extending forward from the rear end portion, and an internal thread 312a is provided on an inner surface of the base sidewall 312. The outer surface of the rear portion of the outer housing 32 is provided with an external thread, and the actuation spring 36 can be stably compressed during the backward movement of the outer housing 32 relative to the base 31 by the engagement of the internal thread and the external thread.

It is also preferred that the outer housing 32 and the part of the inner plunger 33 which corresponds to the drug reservoir 1 in the radial direction be configured to be at least partially transparent or hollow out, so that the volume of the drug solution in the drug reservoir 1 can be clearly seen to the outside.

Fig. 14-20 show the needleless injector 4, the drug reservoir 1, from the mounted position to the completion of the injection, in a sequence comprising the following main steps: the method comprises the steps of installation, pressurization and energy storage, medicine suction and injection. The respective steps will be described in turn with reference to the accompanying drawings.

Fig. 14 shows a schematic view of the process of mounting the injector head 2 and drug vial 1 to the needleless injector body 3. It will be seen that the plunger rod 22 of the injector head 2 is first inserted into the drug storage vial 1 and then the injector head 2 and drug storage vial 1 are mounted as a unit to the needleless injector body 3. When the vial 1 enters the inner plunger 33 and moves back to the point where it cannot be moved any further, the piston rod 22 and the inner plunger 33 are just snapped together and the cartridge 21 and the outer housing 32 are also just screwed together.

The condition of the components after installation is shown in fig. 15, with the needleless injector 4 in a ready-to-use condition. In this state, the cartridge 21 has been fixed relative to the outer housing 32, the piston rod 22 and the vial 1 have been fixed relative to the inner ram 33, and the locking mechanism 34 is in its natural state, not yet locking the inner ram 33 relative to the base 31.

The process shown in fig. 15 to 16 is a process of pressurizing the actuation spring 36. Specifically, by rotating the outer housing 32 to move backward relative to the base 31 (by a screw thread fit therebetween), the front end portion 322 of the outer housing 32 can apply a force to the front end flange 331a of the inner push rod 33 to simultaneously move the inner push rod 33 backward. As the outer housing 32 is threaded relative to the base 31, the rear end flange 333 of the inner ram 33 just snaps over the rear of the stop member 344, the stop member 344 now abutting against the front surface of the rear end flange 333 to lock the inner ram 33. During this process, the actuation spring 36 is compressed and charged in preparation for the final injection step.

The process shown in fig. 16 to 17 is a drug inhalation step. Specifically, the outer housing 32 is rotated to move forward relative to the base 31 (by a threaded engagement therebetween), while the inner ram 33 remains fixed relative to the base 31 as a result of being locked by the locking mechanism 34, that is, the outer housing 32 moves forward relative to the inner ram 33 during this process. Since the cartridge 21 is fixed relative to the outer housing 32 and the reservoir 1 and piston rod 22 are fixed relative to the inner ram 33, the cartridge 21 moves forward relative to the reservoir 1 and piston rod 22. Further, since the injection micro-holes 211 of the cartridge 21 are closed by the cap 23, the liquid medicine accommodating chamber 215 is present in the cartridge 21 when the cartridge 21 moves forward relative to the piston rod 22, and the pressure in the liquid medicine accommodating chamber 215 is small so that the liquid in the medicine storage bottle 1 can be sucked into the liquid medicine accommodating chamber 215 through the liquid medicine passage 222c in the piston rod 22, thereby completing the medicine suction.

The step shown in fig. 18 is an injection preparation step before the inhalation step and the injection step, and the purpose of this step is to discharge gas possibly mixed in the drug tube 21 before injection. In this step, the cap 23 is first removed, exposing the injection micro-holes 211. The outer housing 32 is then rotated to move slightly rearwardly relative to the base 31, while the inner ram 33 and piston rod 22 remain stationary relative to the base 31. Thus, the cartridge 21 is actually moved slightly backward relative to the piston rod 22, the piston rod 22 slightly compresses the medical fluid accommodating chamber 215 in the cartridge 21, and the gas in the medical fluid accommodating chamber 215 can be discharged from the injection micro-holes 211 under pressure.

The process shown in fig. 19 is an injection step. In this step, the outer housing 32 and the cartridge 21 are fixed with respect to the base 31, and the inner push rod 33, the drug storage vial 1 and the piston rod 22 are moved forward with respect to the base 31, thereby completing the injection by the piston rod 22 pressing the drug solution in the drug solution containing chamber 215. In particular, the injection step still further comprises a unlocking step and a resilient actuation step.

When injection is required, the button 341 at the rear end of the base 31 is pressed, the button 341 moves forward, the convex portion 341c at the front end of the button 341 moves forward to release the radial restriction on the stop member 344, the stop member 344 can move radially outward to release the lock on the rear end flange 333 of the inner push rod 33, and the forward movement of the button 341 also pushes the inner push rod 33 forward through the button spring 343 and the spring accommodating portion, the inner push rod 33 passes over the stop member 344, so that the lock on the inner push rod 33 by the lock mechanism 34 is released.

The inner push rod 33 can move forward relative to the base 31 after unlocking. At this time, the pressurized and stored actuating spring 36 applies a large pushing force to the front end flange 331a of the inner plunger 33, so that the inner plunger 33 drives the piston rod 22 to move forward and press the medical fluid in the medical fluid accommodating chamber 215, so that the medical fluid is ejected through the injection micro-holes 211.

As can be seen from the above steps, the front end flange 331a of the inner push rod 33 has at least two setting purposes: in the step of pressurizing and accumulating energy, when the outer shell 32 moves backward relative to the base 31, the front end flange 331a of the inner push rod 33 is forced to drive the inner push rod 33 to move backward relative to the base 31 together, and finally the inner push rod 33 reaches the locking position and is locked by the locking mechanism 34; secondly, in the injection step, the actuating spring 36 abuts between the base 31 and the front end flange 331a of the inner push rod 33, so that the spring pushes the inner push rod 33 forward by applying a pushing force to the front end flange 331a to complete the injection.

Fig. 20 shows a modification of the above embodiment. In the needleless injector shown in fig. 20, the inner push rod 33 is provided with a middle flange 331b, and the actuation spring 36 abuts between the seat 31 and the middle flange 331 b. And the inner push rod 33 is also lengthened appropriately in order for the actuation spring 36 to be long enough to provide a sufficiently large actuation force. This arrangement avoids the actuation spring 36 obscuring the vial 1 so that the contents of the vial 1 are clearly visible to the outside.

Fig. 21 shows another variation of the above embodiment. In the needleless injector shown in fig. 21, a spring shaft 37 is fixedly connected to a front end flange 331a of the inner rod 33 of the needleless injector body 3, the spring shaft 37 extends rearward from the front end flange 331a in a direction parallel to the axis X, and an actuating spring 36' is fitted over the spring shaft 37. Preferably, in order to apply a uniform pushing force to the inner pushing rod 33, the spring shaft 37 may be provided in plurality and each spring shaft 37 is sleeved with an actuating spring 36', and each spring shaft 37 is arranged around the inner pushing rod 33 in a uniform or non-uniform manner. In fig. 21, two spring shafts 37 are provided in the needle-less injector body 3, the two spring shafts 37 extending in directions Y and Z, respectively, which are symmetrical with respect to the axis X.

The other arrangements of the needleless injector shown in fig. 20 and 21 are similar to those shown in fig. 14 to 19 and will not be described again.

Fig. 22-28 are schematic views of another embodiment of injector head 2 in use with a needleless injector body. As can be seen in FIG. 22, the needleless injector body 3 comprises a base 31, an outer housing 32 and an internal ram system 334. Wherein the base 31 has a forward opening, the outer housing 32 has a rearward opening and is mounted at the front end of the base 31 to form a receiving space between the base 31 and the outer housing 32, and the outer housing 32 is provided with a front opening for fixedly mounting the cartridge 21. The internal ram system 334 includes an internal ram 33, the internal ram 33 is located in the receiving space and has a forward opening, the drug vial 1 is capable of being received in the internal ram 33 and moving with the internal ram 33, and the piston rod 22 is fixedly mounted at the forward opening.

Preferably, the outer housing 32 and the part of the inner plunger 33 corresponding to the drug storage vial 1 in the radial direction may be configured to be at least partially transparent or hollow out, so that the volume of the drug solution in the drug storage vial 1 can be clearly seen to the outside.

The connection relationship of the above-mentioned components can have various options. For example, the outer shell 32 and the cartridge 21 may be threadedly coupled, and referring to fig. 22, the cartridge 21 is provided with a cartridge external thread 213 on the rear outer surface thereof, and the front opening of the outer shell 32 is provided with a housing internal thread 322a, the cartridge external thread 213 being capable of cooperating with the housing internal thread 322a to fix the cartridge 21 and the outer shell 32 relative to each other. The cartridge 21 may be provided with a retaining flange 212 to snap fit over the front face of the outer housing 32.

The piston rod 22 may be snap-fitted with the inner push rod 33, in particular, with continued reference to fig. 22, a snap projection 222d is provided on an outer surface of the piston rod 22, a snap groove 33a is provided at a corresponding position of the inner push rod 33, and the snap projection 222d is snapped into the snap groove 33a to fix the piston rod 22 relative to the inner push rod 33. The rear portion 222a of the piston rod 22 may have a larger radial dimension to match the inner pushrod 33. Further, the space inside the inner push rod 33 may be provided with a space having a size corresponding to the medicine cartridge 1, in which the medicine cartridge 1 is fittingly placed after the piston rod 22 and the inner push rod 33 are snapped to each other and in which there is no room for allowing the medicine cartridge 1 to move relative to the inner push rod 33.

Thus, throughout the aspiration and injection process, the outer housing 32 is fixed relative to the cartridge 21, the inner ram 33 is fixed relative to the vial 1 and the plunger rod 22, and the outer housing 32, the inner ram system 334 and the base 31 are axially movable relative to each other. Therefore, the outer housing 32 can move the cartridge 21 and the inner ram 33 can move the vial 1 and the piston 221.

Specifically, the outer housing 32 is movable back and forth relative to the inner ram system to move the cartridge 21 back and forth relative to the vial 1 and the piston rod 22 for aspiration and injection. More specifically, during inhalation (see fig. 25), the inner ram system 334 is fixed relative to the base 31 and the outer housing 32 moves forward relative to the inner ram 33; during an injection (see fig. 27), the outer housing 32 is fixed relative to the base 31 and the internal ram system 334 moves forward relative to the outer housing 32. The specific inhalation and injection procedures will be described in detail later.

Preferably, the needleless injector body 3 further comprises a locking mechanism 34, the locking mechanism 34 being connected between the chassis 31 and the internal ram system 334 for locking the internal ram system 334 in the axial direction relative to the chassis 31 during inhalation and unlocking to enable forward movement of the internal ram system 334 relative to the outer housing 32 after inhalation is complete.

Preferably, the outer housing 32 and the base 31 are connected in a screw-fit manner to achieve the transformation of the relative rotational movement of the two into a relative linear movement. Specifically, referring to fig. 29, the base 31 includes a rear end portion and a base sidewall 312 extending forward from the rear end portion, and an internal thread 312a is provided on an inner surface of the base sidewall 312. The outer rear surface of the outer housing 32 is provided with an external thread, the cooperation of which enables a back and forth movement of the outer housing 32 relative to the base 31 by rotation of the two relative to each other.

In order to promote the medicine suction rate in the medicine suction process, the needleless injector main body 3 further comprises a medicine supplementing push rod 8, the medicine supplementing push rod 8 is installed at the rear end of the inner push rod 33, and the front end of the medicine supplementing push rod 8 can be in contact with a bottle stopper of the medicine storage bottle. In order to transmit the relative movement of the outer housing 32 and the base 31 to the drug delivery plunger 8, the needleless injector body 3 further comprises a transmission means. One part of the conduction device is connected with the medicine supplementing push rod 8, and the other part can be directly or indirectly connected with the base 31 or the outer shell 32 so as to conduct the specific relative movement of the base 31 and the outer shell 32 to the medicine supplementing push rod 8. During the drug suction process, the base 31 or the outer shell 32 drives the drug replenishing push rod 8 to push the bottle stopper 12 forward relative to the body of the drug storage bottle 1 through the conduction device so as to compress the space in the drug storage bottle 1.

Preferably, the internal pusher system 334 further comprises a conductive rod 335 for mating with a conductive device, the conductive rod 335 having a front end connected to the conductive device, a rear end 3351 of the conductive rod 335 for engaging the locking mechanism 34, and the conductive rod 335 also being rotationally fixed relative to the base 31 when the conductive rod 335 is locked by the locking mechanism 34. A thrust bearing 7 is also mounted between the transfer rod 335 and the inner push rod 33.

It can be seen that in this embodiment the conducting means is indirectly connected to the base 31 by a conducting rod 335, thereby enabling a specific movement of the base 31 to be induced to the conducting means. In other embodiments, not shown, however, the base 31 may be connected directly to the conducting means without the conducting rod 335.

Preferably, the axes of the conductive rod 335 and the supplemental medication push rod 8 are also both the axis X of the needleless injector body. The interior of the conductive rod 335 may be provided with a supplemental medication pushrod receiving cavity 332 (see fig. 29) extending along the axis X, with the supplemental medication pushrod 8 fittingly mounted within the supplemental medication pushrod receiving cavity 332. Moreover, the outer surface of the medicine supplementing push rod 8 is a threaded surface, and the surface of the medicine supplementing push rod accommodating cavity 332 is a smooth surface, so that the medicine supplementing push rod 8 can move in the medicine supplementing push rod accommodating cavity 332 along the axial direction.

In the present embodiment, during inhalation, the base 31 rotates relative to the outer housing 32 to move forward relative to the outer housing 32, and correspondingly, the conduction means includes a rotational movement conduction means. The base 31 transmits the rotation motion to the medicine supplementing pushing rod 8 through the rotation motion transmission device to drive the medicine supplementing pushing rod 8 to rotate together, in order to convert the rotation motion of the medicine supplementing pushing rod 8 into the linear motion to push the bottle stopper 12 forwards, a motion conversion mechanism is fixedly arranged in the accommodating space of the inner pushing rod 33, one part of the motion conversion mechanism is engaged with the medicine supplementing pushing rod 8, and the other part of the motion conversion mechanism is engaged with the inner pushing rod 33 to convert the medicine supplementing pushing rod 8 into the linear motion relative to the inner pushing rod 33 along the axial direction along with the rotation motion of the base 31 relative to the outer shell 32 (namely relative to the inner pushing rod 33).

The motion conversion mechanism may, for example, include a nut member 9, the nut member 9 engaging the patch push rod 8 in a threaded fit. In other embodiments, not shown, the motion conversion mechanism may also include other components capable of converting relative rotational motion into relative linear motion.

More preferably, the rotational motion conduction means comprises unidirectional rotational motion conduction means. The unidirectional rotation motion conduction device can only transmit the unidirectional rotation of the conduction rod 335 to the drug supplement push rod 8. Specifically, the unidirectional rotation motion transmission means can transmit the rotation motion of the conductive rod 335 to the drug replenishing push rod 8 during the rotation of the outer housing 32 relative to the base 31 in the first rotation direction and the forward motion relative to the base 31; however, during the backward movement of the outer housing 32 relative to the base 31 in the direction opposite to the first rotational direction relative to the base 31, the unidirectional rotational movement transmission means cannot transmit the rotational movement of the conductive rod 335 to the drug replenishing push rod 8.

The unidirectional rotational motion conduction means includes, for example, a unidirectional bearing as shown in fig. 22-34B. As shown in fig. 30A to 30B, the outer race 61 of the one-way bearing 6 is fixedly connected to the conductive rod 335, and the inner race 62 of the one-way bearing 6 is fixedly connected to the drug replenishing push rod 8 in the rotational direction. The contact surfaces of the inner ring 62 and the drug supplement pusher 8 may be provided with, for example, a guide or a key groove extending in the direction of the axis X to restrict the relative rotation of the inner ring 62 and the drug supplement pusher 8, but not to restrict the relative linear movement in the axial direction.

During inhalation, the base 31 rotates relative to the outer housing 32 to move the outer housing 32 forward relative to the base 31, and in the rotating motion with such a relative rotating direction, the outer ring 61 of the one-way bearing 6 can transmit the rotating motion to the inner ring 62 to rotate the patch push rod 8. The drug refill pushrod 8 rotates relative to the nut member 9 and moves forward relative to the nut member 9 and further relative to the inner pushrod 33 (where the entire inner pushrod system 334 is locked by the locking mechanism 34 in the axial direction), thereby pushing the stopper 12 of the drug storage bottle 1 and facilitating the entry of the drug solution in the drug storage bottle 1 into the drug tube 21 under pressure.

The rear end of the conductive rod 335 is provided with a rear end 3351 (see fig. 27) of the conductive rod 335 that protrudes radially outward, the rear end 3351 of the conductive rod 335 being formed as a flanged structure, the rear end 3351 being for engaging the locking mechanism 34. The locking mechanism 34 includes a stop member 344, a button 341, a spring receiver 342, and a button spring 343. The stop member 344 is capable of abutting against a front end face of a rear end 3351 (formed as a flanged structure) of the conductive rod 335 in a locked state to limit forward movement of the conductive rod 335; the button 341 is mounted on the rear end wall of the base 31 and projects rearward with respect to the base 31; a spring receiver 342 is provided between the rear end surface of the conductive rod 335 and the rear end wall of the button 341, the spring receiver 342 having a spring receiving chamber opened rearward; the button spring 343 is located in the spring receiving chamber and can contact the button 341 at its rear end.

In this way, the button 341 can be pushed to push the button spring 343 and the spring receiver 342 to indirectly push the conductive rod 335, and the rear end 3351 of the conductive rod 335 (which is formed as a flange structure) can pass over the stopper member 344 so that the locking mechanism 34 unlocks the conductive rod 335. In other embodiments, which are not shown, the button spring 343, the spring receiver 342, and the like may not be provided, and the button 341 may directly push the conductive rod 335, thereby unlocking the lock mechanism 34 from locking the conductive rod 335.

In the present embodiment, a movement restricting structure (not shown) is provided between the circumferential outer surface of the front end flange 331a of the inner push rod 33 and the circumferential inner surface of the outer housing 32, and the movement restricting structure is configured to be able to restrict the inner push rod 33 from rotating relative to the outer housing 32, but to allow the inner push rod 33 to move back and forth in the axial direction relative to the outer housing 32. The movement restricting structure may be, for example, a key groove or a guide bar extending in the axial direction provided on the circumferential outer surface of the front end flange 331a and the circumferential inner surface of the outer case 32.

Due to the movement limiting structure, the inner push rod 33 can rotate with the outer housing 32 during pressurizing and drug inhalation. While the inner ram 33 is only able to rotate with the outer housing 32 and cannot move linearly when the inner ram system 334 is entirely locked by the locking mechanism 34.

There is a particular connection relationship between the internal pushrod 33 and the conductive rod 335. Specifically, the outer circumferential surface of the conductive rod fitting portion 3352 of the front end of the conductive rod 335 and the inner circumferential surface of the inner push rod 33 are in contact and fitted with a large sliding friction therebetween (e.g., a contact surface where both are rough), and can rotate with one following the other when one is not subjected to an external force, but both can rotate relative to each other if both are subjected to an external force.

Specifically, when the conductive rod 335 is not locked by the locking mechanism 34, for example, during the pressurization process, the conductive rod 335 can rotate together with the inner push rod 33, and the rotation direction is not the transmission direction of the one-way bearing 6, so that the outer ring 61 of the one-way bearing 6 does not transmit the rotation motion to the inner ring 62, the medicine supplement push rod 8 is driven by the nut member 9 (i.e., indirectly driven by the inner push rod 33) to move linearly, and no relative displacement is generated between the medicine supplement push rod 8 and the inner push rod 33. While the conductive rod 335 is locked by the locking mechanism 34, the conductive rod 335 can only rotate with the locking mechanism 34, for example, during inhalation, the conductive rod 335 is in accordance with the rotation direction of the base 31, while the inner push rod 33 is in accordance with the rotation direction of the outer housing 32, there is relative rotation between the inner push rod 33 and the conductive rod 335, but since the inner push rod system 334 is entirely locked by the locking mechanism 34, the inner push rod 33 only rotates relative to the conductive rod 335 and does not translate relative thereto.

Fig. 22-28 show the needleless injector 4, the drug reservoir 1, from being mounted to the process of completing an injection, which comprises the following main steps in sequence: the method comprises the steps of installation, pressurization and energy storage, medicine suction and injection. The respective steps will be described in turn with reference to the accompanying drawings.

Fig. 22 shows a schematic view of the process of mounting the injector head 2 and drug vial 1 to the needleless injector body 3. It will be seen that the plunger rod 22 of the injector head 2 is first inserted into the drug storage vial 1 and then the injector head 2 and drug storage vial 1 are mounted as a unit to the needleless injector body 3. When the vial 1 enters the inner plunger 33 and moves back to the point where it cannot be moved any further, the piston rod 22 and the inner plunger 33 are just snapped together and the cartridge 21 and the outer housing 32 are also just screwed together.

The condition of the components after installation is shown in fig. 23 with the needleless injector 4 in a ready-to-use condition. In this state, the cartridge 21 has been fixed relative to the outer housing 32, the piston rod 22 and the vial 1 have been fixed relative to the inner ram 33, and the locking mechanism 34 is in its natural state, not yet locking the inner ram system 334 relative to the base 31.

The process shown in fig. 23 to 24 is a process of pressurizing the actuation spring 36. Specifically, when the outer housing 32 is rotated to move backward relative to the base 31 (by the thread fit therebetween), the front end 322 of the outer housing 32 can drive the inner push rod 33 to rotate together, so as to drive the inner push rod 33 to move backward. As the outer housing 32 is threaded relative to the base 31, the rear end 3351 of the conductive rod 335 (which is formed as a flanged structure) just engages the rear of the stop member 344, which stop member 344 now abuts against the front surface of the rear end 3351 of the conductive rod 335 (which is formed as a flanged structure) to lock the internal ram system 334. During this process, the actuation spring 36 is compressed and charged in preparation for the final injection step.

The process shown in fig. 24 to 25 is a drug inhalation step. Specifically, the outer housing 32 is rotated to move forward relative to the base 31 (by a threaded engagement therebetween), while the inner ram 33 remains fixed in the axial direction relative to the base 31 as a result of being locked by the locking mechanism 34, that is, the outer housing 32 moves forward (but rotates together) relative to the inner ram 33 during this process. Since the cartridge 21 is fixed relative to the outer housing 32 and the reservoir 1 and piston rod 22 are fixed relative to the inner ram 33, the cartridge 21 moves forward relative to the reservoir 1 and piston rod 22. Further, since the injection micro-holes 211 of the cartridge 21 are closed by the cap 23, the liquid medicine accommodating chamber 215 is present in the cartridge 21 when the cartridge 21 moves forward relative to the piston rod 22, and the pressure in the liquid medicine accommodating chamber 215 is small so that the liquid in the medicine storage bottle 1 can be sucked into the liquid medicine accommodating chamber 215 through the liquid medicine passage 222c in the piston rod 22, thereby completing the medicine suction.

During the drug inhalation process, the conductive rod 335 rotates together with the base 31 relative to the outer shell 32, and the conductive rod 335 transmits the rotation motion to the drug supplementing push rod 8 through the one-way bearing 6. The refill rod 8 is rotated relative to the nut member 9, thereby effecting forward movement of the refill rod 8 relative to the nut member, i.e., relative to the inner rod 33. The front end 81 (see fig. 22) of the drug replenishing push rod 8 pushes the stopper 12 to further press the space inside the drug storage bottle 1, thereby facilitating the discharge of the drug solution into the drug solution containing chamber 215.

The step shown in fig. 26 is an injection preparation step before the inhalation step and the injection step, and the purpose of this step is to discharge gas possibly mixed in the drug tube 21 before injection. In this step, the cap 23 is first removed, exposing the injection micro-holes 211. The outer housing 32 is then rotated to move slightly rearwardly relative to the base 31, while the inner ram 33 and piston rod 22 remain axially fixed relative to the base 31. Thus, the cartridge 21 is actually moved slightly backward relative to the piston rod 22, the piston rod 22 slightly compresses the medical fluid accommodating chamber 215 in the cartridge 21, and the gas in the medical fluid accommodating chamber 215 can be discharged from the injection micro-holes 211 under pressure.

The process shown in fig. 27 is an injection step. In this step, the outer housing 32 and the cartridge 21 are fixed with respect to the base 31, and the inner push rod 33, the drug storage vial 1 and the piston rod 22 are moved forward with respect to the base 31, thereby completing the injection by the piston rod 22 pressing the drug solution in the drug solution containing chamber 215. In particular, the injection step still further comprises a unlocking step and a resilient actuation step.

When injection is required, the button 341 at the rear end of the base 31 is pressed, the button 341 moves forward, the convex portion 341c at the front end of the button 341 moves forward to release the radial restriction of the stopper member 344, the stopper member 344 can move radially outward to release the lock on the rear end 3351 (which is formed as a flange structure) of the conductive rod 335, and the forward movement of the button 341 also pushes the inner ram system 334 forward through the button spring 343 and the spring receiving portion, the conductive rod 335 goes over the stopper member 344, so that the lock on the inner ram system 334 by the lock mechanism 34 is released.

The internal pusher system 334 is able to move forward relative to the base 31 after being unlocked. At this time, the pressurized and stored actuating spring 36 applies a large pushing force to the front end flange 331a of the inner plunger 33, so that the inner plunger 33 drives the piston rod 22 to move forward and press the medical fluid in the medical fluid accommodating chamber 215, so that the medical fluid is ejected through the injection micro-holes 211.

After completion of one injection, the next injection can be performed without removing the vial 1. That is, the medical fluid in the drug storage bottle 1 can be supplied for a plurality of injections. It will be appreciated, then, that after multiple injections, the stopper 12 of the drug vial 1 will be advanced by the supplemental medication push rod 8 continuously (which refers to a duration in space rather than time). Fig. 28 and 29 illustrate the configuration of the needle-free injector body after completion of multiple injections.

Then, at this time, if the patch push rod 8 is to be pushed back to the initial position, it is optionally rotated with respect to the nut member 9. To accelerate this operation, it is also preferable to arrange the nut member 9 such that it allows the patch push rod 8 to move directly rearward relative to the nut member 9 without rotating relative to the nut member 9.

To achieve this, the nut member 9 may be provided as at least two nut members separated from each other, the at least two nut members being movable radially outward to disengage from the patch push rod 8 under certain conditions. Fig. 31 to 34B show three examples thereof.

In the example shown in fig. 31-34B, at least two nut members are arrayed around the patch push rod 8 and each nut member is movable radially toward or away from the axis to engage or disengage the patch push rod 8.

In the example shown in fig. 31 to 32B, there are two nut members 9a, each nut member 9a is provided at its front end with a nut stopper member 91a, and the surface of the nut member 9a in contact with the nut stopper member 91a is a force receiving slope. Wherein the rear end of the force-bearing ramp is radially further from the axis X of the needleless injector than the front end thereof. The nut stop member 91a is a wedge having a force application slope in contact with the force application slope.

As shown in FIG. 32A, when the drug storage bottle 1 is mounted in the needleless injector, the drug storage bottle 1 can press the nut stopper member 91a backward, the nut stopper member 91a applies a force to the force-receiving slant surface of the nut member 9a, and since the force received by the force-receiving slant surface is perpendicular to the slant surface, the force received by the nut member 9a has a force component inward in the radial direction of the needleless injector body, which presses the nut member 9a into engagement with the drug supplement push rod 8.

As shown in fig. 32B, when the vial 1 is removed, the nut stop member 91a slides forward, the pressure applied to the nut member 9a is reduced, and the nut member 9a moves radially outward out of engagement with the supplemental medication push rod 8. The supplemental medication push rod 8 can now be pushed back directly to the initial position.

Preferably, a second stopper member 92a is further provided at the rear end of the nut stopper member 91a to prevent the nut stopper member 91a from moving backward by too much to exert an excessive force on the nut member 9 a.

The example in fig. 33A and 33B is similar to the example in fig. 32A and 32B, but a nut stopper member 91B formed in a ring structure is used instead of the wedge block. The ring-like structure is coaxial with the needleless injector body 3 and has a circular cross-section (as shown in fig. 33A and 33B) taken on a plane in which the axis X lies. In such an embodiment, the contact between the nut stopper member 91b and the nut member 9b is point contact.

In the state shown in fig. 33A, the nut stopper member 91b presses the nut member 9b into engagement with the drug replenishing push rod 8 by the backward pressing action of the drug storage bottle 1; in the condition shown in figure 33B, the vial 1 has been removed, the nut stop member moved forwardly and the nut member 9B moved radially outwardly to disengage the patch ram 8.

In addition, in an embodiment not shown in the drawings, it is also possible to provide the nut stopper member as a spherical structure, and a ball movement groove in which the nut stopper member is confined so as not to be disengaged therefrom should be correspondingly provided at a front end position of a radially outer edge of the nut member.

The structure in fig. 34A and 34B is a more preferable structure. In this example, when the supplemental medication push rod 8 applies an axial force to the nut member 9c (i.e., the supplemental medication push rod 8 has a tendency to move axially relative to the nut member 9c without relative rotation) and the force reaches a predetermined threshold, the nut member 9c will move radially outward out of engagement with the non-push rod.

That is, when it is desired to push the supplemental medication push rod 8 back into place, simply pushing the supplemental medication push rod 8 rearward, the nut member 9c will naturally move radially outward allowing the supplemental medication push rod 8 to translate along the axis.

Meanwhile, not only when the patch push rod 8 is subjected to a rearward force, but also when the patch push rod 8 is subjected to a forward thrust force and the thrust force reaches a predetermined threshold value, the nut member 9c is moved radially outward to be disengaged from the patch push rod 8. Specifically, during use, when the medicine replenishing push rod 8 is pushed excessively, the nut member 9c is disengaged from the medicine replenishing push rod, so that the medicine storage bottle is protected.

The injection head, the needle-free injector body and the needle-free injector body assembly of the needle-free injector can accommodate the medicine storage bottle in the needle-free injector body for a long time, and can finish medicine suction and injection in each use. The medicine supplementing push rod can push the bottle plug forwards in the medicine suction process so as to further improve the medicine suction efficiency. And the medicine storage bottle is accommodated in the needleless injector main body, so that the problems of the medicine storage bottle, such as loss, pollution and the like, can be avoided.

From the foregoing, those skilled in the art will readily recognize alternative structures to those disclosed as possible and that combinations of the disclosed embodiments can be made to produce new embodiments, which also fall within the scope of the appended claims.

Claims

1. An injector head of a needleless injector, capable of being used with a drug storage bottle (1), characterized in that said injector head (2) comprises:

the injection device comprises a medicine tube (21), a cavity with an opening at the rear end is arranged in the medicine tube, and an injection micropore (211) which is communicated with the cavity and the outside is formed at the front end of the medicine tube;

a piston rod (22) comprising:

a piston (221) located in the chamber and capable of moving back and forth in the chamber, the piston capable of defining a liquid medicine accommodating chamber (25) together with the side wall and the front wall of the cartridge;

a rod portion (222) fixedly connected to a rear end of the piston,

wherein, when in use, the rear end of the rod part of the injection head can be inserted into a medicine storage bottle and extends into the medicine storage bottle, and a medicine liquid channel (222c) communicating the medicine liquid accommodating cavity and the medicine storage bottle is arranged in the piston rod,

the injection head and the medicine storage bottle can be mounted on a needleless injector main body together, the piston rod is configured to be capable of moving backwards relative to the medicine tube so that medicine liquid in the medicine storage bottle can enter the medicine liquid accommodating cavity through the medicine liquid channel, and can move forwards relative to the medicine tube so as to push the medicine liquid in the medicine liquid accommodating cavity to be ejected outwards through the injection micropores, and the piston rod is fixed relative to the medicine storage bottle in the process of ejecting the medicine liquid outwards through the injection micropores.

2. The syringe head according to claim 1, wherein the liquid medicine passage extends in an axial direction of the piston rod, and a check valve allowing only liquid medicine to enter the liquid medicine-accommodating chamber from the medicine storage bottle is provided at a front end of the piston rod.

3. The injector head according to claim 2, wherein the one-way valve comprises a valve core (223, 224) which can be embedded in the piston and can move back and forth with a small amplitude relative to the piston, and the liquid medicine from the medicine storage bottle has to flow through a gap between the valve core and the piston and enter the liquid medicine accommodating cavity.

4. The injector head according to claim 3,

the valve core (223) is of a spherical structure; or

The front part of the valve core (224) is a conical structure (224a) and the rear part is a cylindrical structure (224b), the cylindrical structure is connected to the bottom surface of the conical structure, and the diameter of the bottom surface of the conical structure is larger than that of the cylindrical structure.

5. The injector head according to claim 2, wherein the piston is provided with an inner piston channel (221c) extending in a direction parallel to the axis, the inner piston channel being spaced from the piston rod in a radial direction with respect to the axis, and the medical fluid from the drug vial is required to flow through the inner piston channel into the medical fluid accommodating chamber.

6. The injector head according to claim 1, wherein the rear end of the stem is a spike-like structure (222b) for piercing a sealing membrane of the vial.

7. The injector head according to claim 1, further comprising a cap (23) removably located at the front end of the cartridge for closing the injection wells.

8. The injector head according to claim 1,

the piston rod is configured to be fixed relative to the vial in use; or

9. A needleless injector body for use with an injector head according to any of claims 1 to 8 and a drug vial, wherein the needleless injector body (3) comprises:

a base (31) having a forward opening;

an outer housing (32) having a rearward opening and mounted at the base front end to form a receiving space between the base and the outer housing, the outer housing being provided with a front opening for fixedly mounting a cartridge;

an inner ram (33) located within the receiving space and having a forward opening, the vial being fixedly received within the inner ram and the piston rod being fixed at the forward opening,

10. The needle free injector body according to claim 9, further comprising a locking mechanism (34) connected between the seat and the inner ram, the locking mechanism being configured to lock the inner ram (33) relative to the seat (31) during aspiration and to unlock the inner ram (33) for forward movement relative to the outer housing (32) after aspiration.

11. The needle free injector body according to claim 10, wherein the rear end of the inner ram is provided with a rear end flange (333) protruding radially outward, and wherein the locking mechanism comprises:

a stop member (334) configured to abut against a front face of the rear end flange in a locked condition to limit forward movement of the inner ram;

a button (341) mounted on a rear end wall of the base and projecting rearwardly relative to the base,

12. The needle free injector body of claim 11, wherein the locking mechanism further comprises:

a spring receiver (342) disposed between a rear end face of the inner push rod and a rear end wall of the push button, the spring receiver having a spring receiving cavity that opens rearward;

a button spring (343) located in the spring receiving chamber and capable of contacting the button at a rear end thereof,

13. The needle free injector body according to claim 11, wherein the button has a rear end wall and a side wall extending forward from the rear end wall and surrounding an axis of the needle free injector body, a front end of the side wall is provided with a boss (341c) protruding toward the axis, and the stopper member is configured to be movable relative to the button in a radial direction with respect to the axis,

14. A needleless syringe body according to claim 13, wherein the stop member is a ball and the rear end face (341d) of the boss and the front end face (333a) of the rear end flange are both inclined surfaces, such that the stop member is able to make rolling contact with the inclined surfaces during unlocking.

15. The needle free injector body of claim 10, wherein the locking mechanism is an electromagnet.

16. The needle free injector body of claim 9, further comprising a resilient actuation mechanism located between the seat and the internal ram, the resilient actuation mechanism configured to be operated to charge prior to injection and releasable after charging to actuate the internal ram forward by spring force to complete injection.

17. The needle free injector body according to claim 16, wherein the front end of the inner ram is provided with a radially outwardly projecting front end flange (331a), the resilient actuation mechanism comprising an actuation spring disposed between the front end flange and the seat.

18. The needle free injector body of claim 17, wherein the actuation spring is sleeved outside the inner pushrod.

19. The needle-free injector body according to claim 17, wherein a spring shaft (37) is fixedly attached to a front end flange of the inner push rod, the spring shaft being parallel to an axis of the inner push rod, the actuation spring being sleeved on the spring shaft.

20. The needle free injector body of claim 19, wherein the plurality of spring shafts are provided and each of the plurality of spring shafts is provided with one of the actuation springs, each of the plurality of spring shafts being arranged around the inner plunger.

21. The needle free injector body according to claim 16, wherein the middle of the inner ram is provided with a middle flange (331b) disposed circumferentially therealong, and the resilient actuation mechanism comprises an actuation spring disposed between the middle flange and the seat.

22. The needle free injector body according to claim 17, wherein the seat comprises a rear end and a seat side wall (312), an inner thread (312a) being provided on an inner surface of the seat side wall, and an outer thread corresponding to the inner thread being provided on an outer surface of the rear portion of the outer housing, the outer housing being movable rearwardly relative to the seat by cooperation of the inner thread and the outer thread to stably compress the actuation spring.

23. The needle free injector body according to claim 9, wherein the outer housing and the portion of the inner ram corresponding in the radial direction to the drug storage vial are configured to be at least partially transparent or hollowed out to enable the volume of drug solution within the drug storage vial to be visible to the outside.

24. A needle-free injector (4) comprising a needle-free injector body according to any of claims 9 to 23 and an injector head for use with the needle-free injector body.

25. The needle free injector of claim 24, wherein the front opening of the outer housing of the needle free injector body is provided with an internal thread (322a) facing the axis of the needle free injector, and the cartridge of the injector head is provided with an external thread (213), the internal thread and the external thread cooperating to detachably mount the cartridge on the needle free injector body.