Needle force buffering mechanism and syringe equipped with needle force buffering mechanism

Abstract

A syringe equipped with a needle force buffering mechanism (B) and a needle force buffering mechanism (B). This syringe is equipped with a needle force buffering mechanism (B) and an injection propulsion mechanism (C) and can be equipped with a barrel set (A). The needle force buffering mechanism (B) is connected to the barrel (10) of the barrel set (A) by a buffering member (20) equipped with an elastic arm (202). The needle force buffering mechanism (B) can be connected to the barrel set (A) ejected by the injection propulsion mechanism (C). The elastic arm (202) of the buffering member (20) generates an elastic collision within the syringe to absorb the impact force, thereby providing a buffering protection performance for the ejected barrel set (A) and ensuring that the barrel set (A) is not damaged by the extremely large impact force during ejection.

Description

[Technical Field]

[0001] The present invention relates to syringes, and more particularly to needle force damping mechanisms and syringes equipped with needle force damping mechanisms. [Background technology]

[0002] In currently known syringes, in addition to a hollow outer casing for mounting a barrel set, in order to facilitate a user's subcutaneous injection of a medicinal liquid, an injection propelling device is mounted within the outer casing and located behind the barrel set so that the user can use the injection propelling device to push the barrel set for injection.

[0003] The overall structural design of the syringe described above uses an injection propulsion device to drive the barrel set in the front section of the syringe to eject a needle, allowing the needle in the barrel to puncture the subcutaneous muscle of the human body and inject a medicinal solution. However, because the injection propulsion device must provide sufficient ejection force to drive the barrel set to eject the needle to puncture the subcutaneous muscle of the human body, the barrel may be damaged by a strong impact force between the barrel set that ejects the needle forward and components within the syringe during injection. In particular, when the barrel of the barrel set is made of glass, the glass barrel is connected to the injection propulsion device through a rear end portion having wings. When the barrel set is ejected, the syringe lacks an impact protection mechanism, so the wings and other parts of the glass barrel are easily damaged by a strong impact force, and the connection structure between the injection propulsion device and the barrel is also damaged, making it difficult for the injection propulsion device to perform an injection operation normally. Therefore, further improvements to the conventional syringe structure are needed. Summary of the Invention [Problem to be solved by the invention]

[0004] The technical problem to be solved by the present invention is to provide a needle force damping mechanism and a syringe equipped with the needle force damping mechanism, thereby solving the problem that when the injection propulsion mechanism of a conventional syringe ejects a barrel set and ejects a needle, the barrel in the barrel set is easily damaged by a strong impact force. [Means for solving the problem]

[0005] The technical solution proposed in the present invention is to provide a needle force buffering mechanism mounted in a syringe. The needle force buffering mechanism is connected to a barrel set. When the barrel set is ejected by an injection propelling mechanism in the syringe to eject a needle, the needle force buffering mechanism and the barrel set can move together. The needle force buffering mechanism has the following features: The syringe includes a buffer member connected to the barrel set, the buffer member including at least one elastic arm, and the buffer member imparts buffer elasticity to the barrel set ejected to output a needle by elastic contact of the elastic arm in the syringe.

[0006] The beneficial effect provided by the needle force buffering mechanism of the present invention is that the elastic arm of the buffering member is connected to the barrel of the barrel set, and when the needle force buffering mechanism and the barrel set that is ejected to eject a needle by the injection propulsion mechanism are movable together, the elastic arm of the buffering member elastically collides within the syringe to absorb the impact force, thereby providing a complete buffering protection mechanism for the barrel set that is ejected to eject a needle, and ensuring that the barrel will not be damaged by a strong impact when ejecting a needle.

[0007] In the needle force buffering mechanism, the buffering member includes a member base and two elastic arms symmetrically mounted on the front end of the member base, the front end of the member base having two symmetrically arranged hook portions, the two elastic arms symmetrically arranged and positioned on two sides of the two hook portions, the two hook portions hook onto two barrel wing portions at the rear end of the barrel of the barrel set, and the two elastic arms are positioned outside the two barrel wing portions and protrude from the front sides of the barrel wing portions. Therefore, the elastic arms of the buffering member can provide balanced shock absorption performance during the firing of the barrel set.

[0008] In the needle force buffering mechanism, each of the elastic arms includes a curved concave portion that bends backward and two curved convex portions that are arranged symmetrically on two sides of the curved concave portion and bend forward, and the elastic arm is connected to the member base via the two curved convex portions so as to form a space between the elastic arm and the member base to buffer deformation.

[0009] In the needle force buffering mechanism, a spring plate may be further attached to the rear end of the buffering member, the spring plate having a central hole and a plurality of elastic abutment portions arranged around the central hole, each of which may be contacted by the injection propulsion mechanism at various injection positions to generate a sound as an audio prompt, and / or each of which may provide resistance to the injection propulsion mechanism being driven to move forward, thereby achieving the effect of slowing down the injection speed.

[0010] Another technical solution proposed in the present invention is to provide a syringe having a barrel set mounted therein for containing a liquid medicine. an outer casing having a front accommodating chamber and a rear accommodating chamber disposed in front of and in communication with each other, the barrel set being mounted in the outer casing and movable within the front accommodating chamber and the rear accommodating chamber; an injection propelling mechanism mounted in the rear housing of the outer casing and protruding from the rear end of the outer casing, the injection propelling mechanism being disposed behind the barrel set and operable to eject the barrel set forward from the front housing of the outer casing to output the needle and inject the medicinal solution; a needle force buffering mechanism mounted in a rear accommodating chamber of the outer casing, the needle force buffering mechanism being connected to a rear end of the barrel of the barrel set and movable together with the barrel set, the needle force buffering mechanism including a buffering member, the buffering member including at least one elastic arm, the buffering member providing buffering elasticity to the barrel set ejected to eject the needle by elastic contact of the elastic arm with the syringe; and a needle retraction mechanism mounted in a rear accommodating chamber of the outer casing and positioned in front of the needle force buffering mechanism, wherein after the barrel set passes through the needle retraction mechanism and the injection propulsion mechanism is actuated to eject the barrel set and the needle force buffering mechanism connected thereto, completing the needle ejection operation and the injection operation of the medicinal solution, the needle retraction mechanism is triggered to drive the barrel set and the needle force buffering mechanism connected to the barrel set, and the injection propulsion mechanism moves backward until the needle of the barrel set returns to the outer casing.

[0011] In addition to the advantages of the needle force damping mechanism described above, the syringe of the present invention offers the following beneficial effects: an outer casing can be used to mount the needle force damping mechanism, the injection propulsion mechanism, and the needle retraction mechanism. The injection propulsion mechanism then ejects the barrel set connected to the needle force damping mechanism to eject the needle and perform the injection of the medicinal liquid. Meanwhile, the needle force damping mechanism provides buffering protection for the barrel of the ejected barrel set. After the injection of the medicinal liquid is completed, the needle retraction mechanism automatically retracts the barrel set into the outer casing, thereby retracting and protecting the needle tip.

[0012] In the syringe of the present invention, a safety lock mechanism connected to the injection propulsion mechanism may be further mounted in the outer casing, which limits the movement of the injection propulsion mechanism, thereby preventing the injection propulsion mechanism from being accidentally triggered when the safety lock mechanism is in the locked position, and can be operated to perform the needle ejection operation and the injection operation when the safety lock mechanism is switched to the unlocked position. [Brief explanation of the drawings]

[0013] The following drawings are intended only to illustrate and explain the present invention and not to limit the scope of the invention. [Figure 1] FIG. 1 is a perspective view of one embodiment of the needle force damping mechanism of the present invention in combination with a barrel set and several mechanisms within a syringe. [Figure 2] FIG. 2 is a perspective view of FIG. 1 as seen from another angle. [Figure 3] FIG. 3 is a perspective view of an embodiment of the needle force damping mechanism of FIGS. 1 and 2. [Figure 4] FIG. 3 is a perspective view of the embodiment of the needle force damping mechanism of FIGS. 1 and 2, seen from another angle. [Figure 5] FIG. 10 is a perspective view of another embodiment of the needle force damping mechanism of the present invention. [Figure 6] FIG. 6 is a perspective view of the needle force buffering mechanism of FIG. 5 as seen from another angle. [Figure 7] FIG. 7 is a perspective view of the combination of the alternative embodiment of the needle force damping mechanism of FIGS. 5 and 6 with a barrel set and several mechanisms within a syringe. [Figure 8] 1 is a perspective external view of an embodiment of a syringe of the present invention. FIG. [Figure 9] FIG. 1 is an exploded perspective view of an embodiment of a syringe of the present invention. [Figure 10] 10 is an exploded perspective view of the syringe embodiment of FIG. 9 from another angle. FIG. [Figure 11] FIG. 11 is a cross-sectional side view of the syringe embodiment of FIGS. 9 and 10. [Figure 12]FIG. 11 is a cross-sectional top view of the syringe embodiment of FIGS. 9 and 10. [Figure 13] FIG. 11 is a perspective view of the syringe embodiment of FIGS. 9 and 10 with the outer casing and safety locking mechanism removed. [Figure 14] FIG. 11 is a partial perspective view of the syringe embodiment of FIGS. 9 and 10 with the safety lock mechanism and injection button in a locked position. [Figure 15] FIG. 15 is a partial perspective view of the safety locking mechanism of FIG. 14 with the locking ring rotated to an unlocked position. [Figure 16] FIG. 13 is an exploded perspective view of the needle force buffering mechanism, needle retraction mechanism, injection push rod, and barrel set of the syringe of FIGS. 9 to 12. [Figure 17] FIG. 17 is a perspective view of FIG. 16 as seen from another angle. [Figure 18] FIG. 13 is an exploded perspective view of the needle force buffering mechanism with an additional spring plate, the needle retraction mechanism, the injection push rod, and the barrel set of the syringe of FIGS. 9-12. [Figure 19] FIG. 19 is a perspective view of FIG. 18 as seen from another angle. [Figure 20] FIG. 14 is a reference view (1) of the embodiment of the syringe of FIGS. 10 to 13 in use. [Figure 21] FIG. 14 is a reference view (2) of the embodiment of the syringe of FIGS. 10 to 13 in a use state. [Figure 22] FIG. 14 is a reference view (3) of the embodiment of the syringe of FIGS. 10 to 13 in use. [Figure 23] FIG. 14 is a reference view (4) of the embodiment of the syringe of FIGS. 10 to 13 in use. [Figure 24] FIG. 14 is a reference view (5) of the embodiment of the syringe of FIGS. 10 to 13 in use. [Figure 25] FIG. 14 is a reference view (6) of the embodiment of the syringe of FIGS. 10 to 13 in use. [Figure 26] 22 is a cross-sectional side view of the syringe embodiment of FIG. 21 with the needle protector sleeve being removed from the outer casing by using a needle protector sleeve extraction device. [Figure 27]FIG. 23 is a cross-sectional side view of the syringe embodiment of FIG. 22 with the locking ring of the safety locking mechanism rotated to an unlocked position. [Figure 28] FIG. 24 is a cross-sectional view (1) of the syringe embodiment of FIG. 23 with the injection button pressed to eject the needle. [Figure 29] FIG. 24 is a cross-sectional view (2) of the syringe embodiment of FIG. 23 with the injection button pressed to eject the needle. [Figure 30] 25 is a cross-sectional view of the syringe embodiment of FIG. 24, in which a syringe propulsion mechanism drives the piston of the barrel set for injection and infusion. [Figure 31] FIG. 25 is a cross-sectional view of the syringe embodiment of FIG. 24, in which the needle retraction mechanism drives the barrel set to perform the needle retraction action. [Explanation of symbols]

[0014] A: Barrel set (needle sleeve assembly); 10: Barrel; 101: Barrel wing part; 11: Needle; 12: Piston; 13: Needle protection sleeve; B: Needle force buffering mechanism; 20: Buffering member; 201: Component base; 202: Elastic arm; 203: Hooking part; 204: Alignment guide slot; 21: Spring plate; 211: Elastic abutment part; 212: Notch; 30: Outer casing; 301: Front accommodating chamber; 302: Rear accommodating chamber; 303: Annular retaining wall; 304: Thread groove; 305: Positioning buckle part; 31: Outer protective layer; 311: Injection direction indication mark; 312: Lock position mark; 313: Unlock position mark; 32: Needle protection sleeve removal device; 321: Sleeve part; 322: Hooking part; 323: Operation end part; C: Injection propulsion mechanism; 40: Inner sleeve; 40 1: inner sleeve base; 402: axial support part; 403: stop arm; 41: injection button; 411: pressing end; 412: extension arm; 413: guide protrusion; 42: injection push rod; 421: rod part; 422: baffle part; 423: rear rod end; 424: pressing plate; 43: rear elastic element; D: needle retraction mechanism; 50: front fastener; 501: fastener base; 50 2: Ratchet arm; 503: Threaded end; 5031: Threaded rib; 504: Receiving chamber; 505: End wall; 506: Fastener hole; 51: Forward resilient element; E: Safety locking mechanism; 60: Inner liner tube; 601: Rotation guide groove; 602: Locking area; 603: Unlocking area; 61: Locking ring; 612: Connection end; 613: Rotation guide protrusion; 614: Support part; 615: Guide groove. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention relates to a syringe equipped with a needle force buffering mechanism and a needle force mechanism. In connection with the accompanying drawings and preferred embodiments of the present invention, the present invention will be further detailed with respect to the technical means adopted to achieve the intended object of the present invention.

[0016] FIGS. 1-2 and 7 show perspective schematic views of two embodiments of the needle force buffering mechanism B of the present invention connected to a syringe barrel set A and an injection propulsion mechanism C. Referring to FIGS. 9, 10, 12, and 16-18, the needle force buffering mechanism B has an injection propulsion mechanism C and can be installed in a syringe connected to a barrel set A. The barrel set A includes a barrel 10 containing a drug solution therein. A needle 11 is attached to the front end of the barrel 10, and a piston is attached inside the barrel 10. In the embodiment shown in the drawings, two barrel wing portions protrude radially from the rear end of the barrel 10. The syringe injection propulsion mechanism C includes an injection push rod 42. The injection push rod 42 is attached via the needle force buffering mechanism B and is inserted into the barrel 10 from the rear end. When the injection propulsion mechanism C of the syringe performs a needle ejection operation on the barrel set A, the needle output buffering mechanism B is movable together with the barrel set A and provides a buffering effect for the barrel set A in the syringe by using the buffering member 20. Then, the injection push rod 42 of the injection propulsion mechanism C drives the piston 12 in the barrel 10, which ejects the medicinal liquid in the barrel 10 through the needle 11 to perform the injection operation.

[0017] In addition, the syringe further includes a needle retraction mechanism D. The needle retraction mechanism D is positioned in front of the needle force buffering mechanism B, and is configured to perform a needle retraction operation by driving the barrel set A and the needle force buffering mechanism B by the needle retraction mechanism D after the barrel set A completes an injection operation. Meanwhile, the needle retraction mechanism D positioned in front is used as a contact point for the needle force buffering mechanism B.

[0018] As shown in FIGS. 1 to 4 and 5 to 7, the needle force buffering mechanism B includes a buffering member 20. The buffering member 20 is connected to the barrel set A and includes at least one elastic arm 202. The buffering member 20 is movable together with the barrel set A, and generates a buffering elastic force by elastic contact deformation of the elastic arm 202 inside the syringe, so that the needle force buffering mechanism B can impart buffering elasticity to the barrel set A for ejecting the needle.

[0019] In the embodiment shown in FIGS. 3-4 and 5-6, the buffer member 20 includes a member base 201 and two elastic arms 202 attached to the front end of the member base 201. The front end of the member base 201 has two symmetrically arranged hook portions 203. The two elastic arms 202 are symmetrically arranged and disposed on two sides of the two hook portions 203. Each of the hook portions 203 may further have an alignment guide slot 204 formed therein. The alignment guide slot 204 allows a portion of the injection propulsion mechanism C to move therethrough, thereby triggering the needle retraction mechanism D positioned forward to perform a needle retraction operation.

[0020] 3 to 4 and 5 to 6, the buffer member 20 abuts against the rear end of the barrel 10 by means of a member base 201, and can be hooked onto two barrel wing portions 101 at the rear end of the barrel 10 by means of two hooking portions 203. The two elastic arms 202 are positioned outside the two barrel wing portions 101 so as to enable the buffer member 20 to be connected to the rear end of the barrel 10, and the two elastic arms 202 protrude from the front sides of the barrel wing portions 101. In this embodiment, each of the elastic arms 202 includes a curved concave portion that bends backward and two curved convex portions that are symmetrically disposed on two sides of the curved concave portion and bend forward, and the other ends of the two curved convex portions that face the curved concave portions are connected to the member base 201. A buffer deformation space exists between the elastic arm 202 and the member base 201, so that the two curved convex portions of the elastic arm 202 of the buffer member 20 that are bent forward and protrude can be used as hitting portions. The shape and structure of the elastic arm 202 are not limited to those described above.

[0021] In the embodiment shown in FIGS. 5 to 7, the needle force buffering mechanism B includes one buffering member 20 and a spring plate 21. The shape and structure of the buffering member 20 are essentially the same as those of the buffering member 20 in the previous embodiment. The spring plate 21 is securely attached to the rear end of the member base 201 of the buffering member 20. The spring plate 21 has a central hole and a plurality of elastic abutment portions 211 arranged around the central hole. Each of the elastic abutment portions 211 extends toward the central hole. That is, the end of each of the elastic abutment portions 211 facing toward the central hole is a free end. Each of the elastic abutment portions 211 can generate a sound when touched at various injection positions by the injection propulsion mechanism C, thereby using the sounds generated by touching the elastic abutment portions 211 at various positions on the spring plate 21 as audio prompts. Otherwise, each of the above elastic abutment portions 211 is used to provide resistance force to the injection propulsion mechanism C at various injection positions, slowing down the movement speed of the injection propulsion mechanism C and thereby achieving the effect of slowing down the injection speed.

[0022] 7, the injection propulsion mechanism C includes an injection push rod 42. The injection push rod 42 is mounted through the central hole of the spring plate 21 of the needle force buffering mechanism B and the member base 201 of the buffering member 20, and can be driven to push the piston 12 in the barrel 10. A plurality of protrusions 425 are formed on the outer surface of the injection push rod 42. The plurality of protrusions 425 are arranged on the injection push rod 42 with different lengths along the axial direction, and the protrusions 425 can contact the elastic abutment portions 211 at corresponding positions to vibrate and generate sounds.

[0023] Regarding the use of the needle force buffering mechanism B of the present invention in a syringe, as shown in FIGS. 1, 2 and 7, the needle force buffering mechanism B can be mounted inside the syringe and connected to the rear end of the barrel 10 of the barrel set A inside the syringe. When the barrel set A ejects the needle by the injection propelling mechanism C inside the syringe, the needle force buffering mechanism B can be pushed together with the barrel set A. Furthermore, when performing the needle ejection operation, the needle force buffering mechanism B provides a buffering effect for the barrel set A to prevent the barrel set A from being damaged due to collision with the internal structure of the syringe. In addition, as shown in FIG. 7 , the needle force buffering mechanism B may further utilize a spring plate 21 disposed at the rear end of the buffer member 20, so that when the injection push rod 42 pushes the barrel 10 forward to perform an injection, the protrusions 425 at various positions on the injection push rod 42 may come into contact with the elastic abutment portions 211 at corresponding positions on the spring plate 21 as the injection push rod 42 moves, vibrating and generating sounds; and / or the elastic resistance generated when the elastic abutment portions 211 of the spring plate 21 come into contact with the protrusions 425 may be utilized to slow down the movement speed of the injection push rod 42 and thereby slow down the injection speed.

[0024] The syringe of the present invention can be fitted with a barrel set A for performing needle ejection, injection, and needle retraction operations. As shown in FIGS. 8 to 12, the barrel set A includes a barrel 10 containing a medicinal solution. A needle 11 is attached to the front end of the barrel 10. A needle protection sleeve 13 may be attached around the needle 11. A piston 12 for injecting the medicinal solution from the needle 11 is attached inside the barrel 10. Two barrel wing portions 101 protrude radially from the rear end of the barrel 10. In this embodiment, the barrel 10 is a component made of a transparent material, but is not limited to a transparent material.

[0025] 8 to 12, the syringe mainly includes an outer casing 30, an injection propelling mechanism 30, a needle force buffering mechanism B, and a needle retracting mechanism D. In addition, the syringe may further include a safety locking mechanism E.

[0026] As shown in FIGS. 9 to 12, the outer casing 30 is a hollow component that penetrates axially from front to rear. The outer casing 30 includes a front housing chamber 301 positioned at the front and a rear housing chamber 302 positioned at the rear. The front housing chamber 301 and the rear housing chamber 302 are connected to each other. An annular retaining wall 303 is formed between the front housing chamber 301 and the rear housing chamber 302. The outer casing 30 has at least one screw groove 304 disposed on the side wall of the rear housing chamber 302 and adjacent to the annular retaining wall 303, and at least one positioning buckle portion 305 disposed on the rear side of the screw groove 304. The barrel set A is mounted inside the outer casing 30 and is movable forward and rearward. When unused, the needles 11 of the barrel set A are positioned within the front housing chamber 301 without protruding from the front end of the outer casing 30. The barrel 10 extends from a front storage chamber 301 to a rear storage chamber 302. The rear end of the barrel 10, which has the barrel wing portion 101, is positioned within the rear storage chamber 302. In this embodiment, the front section of the outer casing 30, which has the front storage chamber 301, is transparent so that the user can easily observe the state of the barrel 10 within the outer casing 30. However, without being limited to this, the front section of the outer casing 30, which has the front storage chamber 301, may also be an opaque section.

[0027] 9 and 10 , an injection direction indication mark 311 may be disposed on the outer surface of the outer casing 30 to help the user identify the position of the needle 11 in the syringe. Alternatively, the outer protective layer 31 may also be disposed on the outer surface of the outer casing 30, and the injection direction indication mark 311 may be disposed on the outer protective layer 31.

[0028] As shown in FIGS. 8 to 12 , once the needle protection sleeve 13 has been attached to the needle 11 of barrel set A, a needle protection sleeve removal device 32 may be further attached to the front end of the outer casing 30 to facilitate the user's removal of the needle protection sleeve 13. The needle protection sleeve removal device 32 is connected to the needle protection sleeve 13 and is configured to assist the user in removing the needle protection sleeve 13 disposed within the outer casing 30. In this embodiment, the needle protection sleeve removal device 32 includes a sleeve portion 321, a hook portion 322 attached to the rear end of the sleeve portion 321, and an operating end portion 323 disposed at the front end of the sleeve portion 321. The sleeve portion 321 of the needle protection sleeve removal device 32 is inserted into the outer casing 30 from the front end and fitted around the needle protection sleeve 13. The operating end portion 323 is positioned outside the front end of the outer casing 30. The hook portion 322 has two hooks so that the hook portion 322 can hook onto the rear end of the needle protection sleeve 13 .

[0029] As shown in Figures 9 to 13, the injection propelling mechanism C is mounted in the outer casing 30 and protrudes outward from the rear end of the outer casing 30. The injection propelling mechanism C includes an inner sleeve 40, an injection push rod 42, a rear elastic element 43, and an injection button 41. The injection propelling mechanism C is operable to eject the barrel set A to perform a needle ejection operation and an injection operation.

[0030] As shown in Figures 9 to 13, the inner sleeve 40 is mounted in the rear accommodation chamber 302 of the outer casing 30. The inner sleeve 40 includes an inner sleeve base 401. At least one stop arm 403 is disposed at the rear end of the inner sleeve base 401, and an axial support portion 402 is disposed at the rear end of the inner sleeve base 401. In this embodiment, the inner sleeve 40 has two of the stop arms 403 disposed diametrically opposite each other. The two stop arms 403 are disposed on two radially opposing sides of the axial support portion 402.

[0031] As shown in FIGS. 9 to 13 , the injection push rod 42 is mounted in the inner sleeve 40 and can be engaged in a predetermined position. The injection push rod 42 can be inserted into the barrel 10 to push the piston 12. In this embodiment, the injection push rod 42 includes a rod portion 421, a baffle portion 422, a rod rear end 423, and at least one pressing plate 424. The rod rear end 423 is disposed at the rear end of the rod portion 421. The baffle portion 422 is disposed between the rod portion 421 and the rod rear end 423. The pressing plate 424 protrudes forward from the front side of the baffle portion 422 and is disposed on one side of the rod portion 421. In this embodiment, the injection push rod 42 has two pressing plates 424. The two pressing plates 424 are disposed diametrically opposite each other and on the other side of the rod portion 421. The rod portion 421 of the injection push rod 42 can be inserted into the barrel 10, and the front end of the rod portion 421 presses against the piston 12. The baffle portion 422 of the injection push rod 42 can be engaged by the stop arm 403 of the inner sleeve 40.

[0032] As shown in FIGS. 9 to 13 , the rear resilient element 43 is mounted within the inner sleeve 40. The rear resilient element 43 is capable of storing elastic potential energy. When the injection push rod 42 is actuated to be released from its engagement state within the inner sleeve 40, the elastic potential energy of the rear resilient element 43 is released, providing the injection force to the injection push rod 42. In this embodiment, the rear resilient element 43 is a compression spring. The rear resilient element 43 is mounted around the outside of the rear rod end 423 of the injection push rod 42, and the two ends of the rear resilient element 43 abut against the baffle portion 422 of the injection push rod 42 and the axial support portion 402 of the inner sleeve 40, respectively.

[0033] As shown in FIGS. 9 to 13 , the injection button 41 is connected to the rear end of the inner sleeve 40, is movable forward and backward, and protrudes outward from the rear end of the outer casing 30. The injection button 41 has a pressing end 411 and at least one extension arm 412 disposed at the front end of the pressing end 411. In this embodiment, the injection button 41 has two extension arms 412 disposed diametrically opposite each other. Each extension arm 412 corresponds to a stop arm 403 of the inner sleeve 40. The injection button 41 is operable to press the stop arm 403 corresponding to its position in the inner sleeve 40 and extend via the extension arm 412, thereby disengaging the baffle portion 422 of the injection push rod 42 from the stop arm 403 of the inner sleeve 40 and releasing the injection push rod 42 from the engaged state. In this embodiment, at least one guide protrusion 413 may further be disposed on the outer surface of the pressing end 411. The guide projection 413 is used in conjunction with a safety lock mechanism E.

[0034] As shown in Figures 9 to 12 and 14 to 15, in order to ensure the safety of using the injection propulsion mechanism C, an outer casing 30 is attached to a safety lock mechanism E connected to the injection propulsion mechanism C. By limiting the movement of the injection propulsion mechanism C by the safety lock mechanism E, the injection propulsion mechanism C is prevented from being accidentally triggered when the safety lock mechanism E is in the locked position, and when the safety lock mechanism E is switched to the unlocked position, the injection propulsion mechanism C can be operated to perform the needle ejection operation and the injection operation.

[0035] In the embodiment shown in Figures 9 to 12 and 14 to 15, the safety locking mechanism E includes an inner liner tube 60 and a locking ring 61. The inner liner tube 60 is mounted in the rear housing chamber 302 of the outer casing 30. At least one rotation guide groove 601 is defined in the rear section of the inner liner tube 60. The rotation guide groove 601 has a locking region 602 and an unlocking region 603. The locking ring 61 is a hollow component. A connecting end 612 is defined in the front end of the locking ring 61. At least one rotation guide protrusion 613 is disposed on the outer surface of the connecting end 612. The locking ring 61 has a central hole and at least one guide groove 615 disposed in the rear section of the hole wall of the central hole. The guide groove 615 includes a rotating section and an axially movable section. The locking ring 61 is disposed behind the outer casing 30. The connecting end 612 protrudes into the rear section of the inner liner tube 60 and is rotatable. The rotation guide protrusion 613 is disposed in a rotation guide groove 601 of the inner liner tube 60 corresponding to the position of the rotation guide protrusion 613. The lock ring 61 is rotatable relative to the inner liner tube 60, and switches the position of the rotation guide protrusion 613 between a lock region 602 and an unlock region 603 of the rotation guide groove 601. An indicator portion 614 may be further disposed on the outer surface of the lock ring 60. The indicator portion 614 is used to indicate the use state of the lock ring 61.

[0036] When the rotation guide protrusion 613 is located in the locking region 602, the guide protrusion 413 of the injection button 41 is restricted in the rotation section of the guide groove 615 of the locking ring 61, so that the locking ring 61 can prevent the injection button 41 from moving forward when pressed. The injection button 41 is in a locked state to prevent the injection button 41 from being accidentally touched and triggering the injection propulsion mechanism C. When the rotation guide protrusion 613 of the locking ring 61 is rotated to the unlocking region 603, the guide protrusion 413 of the injection button 41 is switched to the axially movable section of the guide groove 615 of the locking ring 61, releasing the injection button 41 from being restricted in the locked state. The axially movable section of the guide groove 615 provides a space for the guide protrusion 413 of the injection button 41 to move forward, so that the injection button 41 can be moved forward when pressed.

[0037] As shown in Figures 8 to 10, when the syringe has a safety lock mechanism E, a lock position mark 312 and an unlock position mark 313 are arranged on the outer surface of the rear end of the outer casing 30 to make it easier for the user to identify the state of the syringe, or the lock position mark 312 and the unlock position mark 313 are arranged on the outer protective layer 31 on the outer surface of the outer casing 30. As shown in Figures 14 to 15 and 21 to 22, an indicator portion 614 arranged on the outer surface of the lock ring 61 provides an indication. When used together with the lock position mark 312 and the unlock position mark 313, when the rotation guide protrusion 613 of the lock ring 61 is positioned within the lock region 602, the indicator portion 614 points to the lock position mark 312, and when the rotation guide protrusion 613 of the lock ring 61 is rotated to the unlock region 603, the indicator portion 614 points to the unlock position mark 313, making it easier for the user to recognize the state of the syringe.

[0038] As shown in FIGS. 8 to 10 , the needle force buffering mechanism B is mounted within the outer casing 30. The needle force buffering mechanism B and the barrel set A can move together. The specific configuration of the needle force buffering mechanism B has been disclosed above in the description of the needle force buffering mechanism B, and the same content will not be repeated here. In this embodiment, as shown in FIGS. 16 and 17 , the needle force buffering mechanism B is mounted within the inner sleeve 40 of the injection propulsion mechanism C and connected to the rear end of the barrel 10 of the barrel set A. The rod portion 421 of the injection push rod 42 of the injection propulsion mechanism C is mounted via the needle force buffering mechanism B, which is mounted at the rear end of the barrel 10. The rod portion 421 is inserted into the barrel 10 and abuts against the piston 12. The baffle portion 422 of the injection push rod 42, which has a pressing plate 424, is disposed behind the needle force buffering mechanism B. The pressing plate 424 faces the alignment guide slot 204 of the buffer member 20 of the needle force buffering mechanism B.

[0039] 18 and 19, when the spring plate 21 having a plurality of elastic abutment portions 211 is attached to the rear side of the buffer member 20 of the needle force buffering mechanism B, a plurality of protrusions 425 are additionally disposed on the outer surface of the rod portion 421 of the injection push rod 42. The plurality of protrusions 425 are disposed on the injection push rod 42 at different length positions along the axial direction or at the same length positions along the axial direction so that they come into contact with the elastic abutment portions 211 at corresponding positions, vibrate, and generate sound at each of the protrusions 425. In addition, the contact resistance between the protrusions 425 and the elastic abutment portions 211 can provide the effect of slowing down the moving speed of the injection push rod 42.

[0040] Furthermore, some medications may require a slower injection rate during injection, for example, to improve patient comfort, or may be designed to require a slower injection rate. In this situation, the number of protrusions 425 disposed on the outer surface of the rod portion 421 of the injection push rod 42 can be increased, thereby enhancing the deceleration effect. Increasing the number of protrusions 425 also increases the contact friction between the protrusions 425 and the elastic abutment portion 211 of the spring plate 21. This increases the deceleration effect on the injection push rod 42, thereby reducing the speed at which the injection push rod 42 pushes the piston 12 within the barrel 10 and reducing the injection rate. Therefore, designers can adjust the number and location of the protrusions 425 according to the product design requirements of the syringe. For example, to enhance the deceleration effect, multiple protrusions 421 are attached around the rod portion 421 at specific axial length positions on the injection push rod 42. The multiple protrusions 425 are located at the same axial length position. The multiple protrusions 425 simultaneously contact the multiple elastic abutment portions 211 of the spring plate 21 to generate sounds together. The rhythm of the prompt sounds is not mixed.

[0041] As described above, the elastic abutment portion 211 of the spring plate 21 and the protrusion 425 of the injection push rod 42 cooperate to simultaneously provide the effect of generating a prompt sound and the effect of adjusting the injection speed. It is worth mentioning that in another embodiment of the present invention, by changing the material and / or shape and structure, the elastic abutment portion 211 of the spring plate 21 and the protrusion 425 of the injection push rod 42 can only cooperate to provide the effect of slowing down the injection speed, but basically do not generate any prompt sound that the user can hear.

[0042] 18-19 , a notch 212 may be formed on the spring plate 21 and correspond to the position of the alignment guide slot 204 of the buffer member 20. Therefore, the pressing plate 424 of the injection push rod 42 can enter the alignment guide slot 204 on the buffer member 20 after passing through the notch 212 of the spring plate 21, so as to prevent the spring plate 21 on the rear side of the buffer member 20 from interfering with the movement of the injection push rod 42.

[0043] As shown in Figures 9 to 12, the needle retraction mechanism D is mounted inside the outer casing 30 and disposed in front of the needle output buffering mechanism B. The needle retraction mechanism D is connected to the barrel set A. The needle retraction mechanism D is operable to drive the barrel set A positioned at the needle output position to move the needle 11 backward until it completely returns to the needle retracted position inside the outer casing 30, thereby achieving the effect of retracting and protecting the needle tip.

[0044] In the embodiment shown in FIGS. 9 to 12, the needle retraction mechanism D includes a front fastener 50 and a front resilient element 51. The front fastener 50 is mounted in the rear housing chamber 302 of the outer casing 30 and can be engaged in a predetermined position. The front end of the inner sleeve 40 of the injection propulsion mechanism C is connected to the front fastener 50. The barrel 10 of the barrel set A is mounted via the front fastener 50. The front resilient element 51 is mounted to the front fastener 50 to store resilient potential energy. When the needle retraction mechanism D is actuated, the front fastener 50 is released from its engaged positioning state, allowing the front resilient element 51 to release its resilient potential energy and directly or indirectly drive the barrel set A to move rearward from the needle-output position to the needle-retracted position via the front fastener 50.

[0045] In the embodiment shown in FIGS. 9 to 12 , the front fastener 50 includes a fastener base 501 and a threaded end 503 disposed at the front end of the fastener base 501. A plurality of threaded ribs 5031 are disposed on the outer surface of the threaded end 503. A plurality of retractable ratchet arms 502 are disposed on the fastener base 501. Each of the ratchet arms 502 has a ratchet tooth. The front fastener 50 is aligned with the threaded ribs 5031 of the threaded end 503 and a threaded groove 304 disposed adjacent to the annular retaining wall 303 of the outer casing 30, thereby being mounted within the outer casing 30 with a short radial rotation and connected to the front end of the inner sleeve 40 of the injection propulsion mechanism C via the fastener base 501. Therefore, the inner sleeve 40 is movable together with the front fastener 50. The front fastener 50 is engaged in a predetermined position within a corresponding positioning buckle portion 305 of the outer casing 30 via ratchet teeth on the ratchet arm 502 and is operable to be released from the engaged state to rotate and move axially within the outer casing 30.

[0046] In the embodiment shown in FIGS. 9 to 12 , the front fastener 50 has a housing chamber 504, an end wall 505 disposed at the rear end of the housing chamber 504, and a fastener hole 506 disposed in the end wall 505 and communicating with the housing chamber 504. The barrel 10 is installed through the fastener hole 506 and the housing chamber 504. The front resilient element 51 is installed within the housing chamber 501. The two ends of the front resilient element 51 abut against the annular retaining wall 303 and the end wall 505 of the outer casing 30 to store elastic potential energy. The front fastener 50 is operable to remove the restriction on radial rotation, thereby pushing the front fastener 50 and the connected inner sleeve 40 to rotate a certain angle in the opposite direction via the elastic potential energy initially released by the front resilient element 50, thereby allowing the thread rib 5031 to continue axially moving rearward after disengaging from the thread groove 304 of the outer casing 30. In this embodiment, in the above-mentioned needle retraction mechanism D, the pressure plate 424 of the injection push rod 42 moving straight forward passes through the alignment guide slot 204 of the buffer member 20 of the needle output buffering mechanism B, whereby the pressure plate 424 pushes and retracts the ratchet arm 502 of the front fastener 50, thereby disengaging the front fastener 50 from the positioning buckle portion 305 of the outer casing 30.

[0047] As shown in FIGS. 20 to 25, with the overall structural design described above, the syringe of the present invention can assemble a barrel set A within an outer casing 30. The needle force buffering mechanism B, injection propulsion mechanism C, and needle retraction mechanism D are connected to each other within the outer casing 30. The injection propulsion mechanism C ejects the barrel set A connected to the needle force buffering mechanism B, ejecting the needle and injecting the medicinal liquid. Meanwhile, the needle force buffering mechanism B provides buffering protection for the barrels 10 of the ejected barrel set A, and the needle retraction mechanism D automatically retracts the barrel set A into the outer casing 30 after the injection of the medicinal liquid is completed, thereby providing the effects of needle retraction and needle tip protection. The syringe may further include an injection propulsion mechanism C and a safety lock mechanism E connected to each other within the outer casing 30. By limiting the movement of the injection propulsion mechanism C by the safety lock mechanism E, the injection propulsion mechanism C is prevented from being accidentally triggered when the safety lock mechanism E is in the locked position, and when the safety lock mechanism E is switched to the unlocked position, the injection propulsion mechanism C can be operated to perform the needle ejection operation and the injection operation.

[0048] The syringe embodiment shown in Figures 9 to 12 is used as an example to further explain the usage scenario of the syringe of the present invention. Referring to Figures 20 to 25, the initial state of the syringe is shown. As shown in Figures 20, 11, and 12, a barrel set A is disposed inside an outer casing 30. A needle protection sleeve puller 32 disposed at the front end of the outer casing 30 protrudes into the outer casing 30 and connects to the needle protection sleeve 13 of the barrel set A. A safety lock mechanism E disposed between the outer casing 30 and the needle propelling mechanism C protrudes from the injection button 40 at the rear end of the outer casing 30 to prevent the injection propelling mechanism C from being accidentally triggered.

[0049] As shown in FIGS. 21 and 26, before using the syringe, the needle protection sleeve 13 is removed from the outer casing 30 using the needle protection sleeve removal device 32. At this time, the needle 11 of barrel set A is still inside the outer casing 30. Then, as shown in FIGS. 22 and 27, the front end of the outer casing 30 abuts against a part of the human body that will receive the injection, and the lock ring 61 of the safety lock mechanism E is rotated forward, switching the rotation guide protrusion 613 on the lock ring 61 from the locked region 602 to the unlocked region 603 of the rotation guide groove 601 of the inner liner tube 60. Meanwhile, the guide protrusion 413 of the injection button 41 is switched to the axially movable section of the guide groove 615 of the lock ring 61, releasing the injection button 41 from the locked state and providing space for the injection button 41 to move forward.

[0050] Next, as shown in FIGS. 23, 24, 28, 29, 30, when the injection button 41 is pressed forward, it pushes the stop arm 403 of the inner sleeve 40 forward and extends the extension arm 412, thereby disengaging the baffle portion 422 of the injection push rod 42 from the stop arm 430 of the inner sleeve 40. Therefore, the rear elastic element 43 releases its elastic potential energy to eject the injection push rod 42. The needle 11 of the barrel set A is then pushed out from the front end of the outer casing 30 via the injection push rod 42 so that the needle 11 can pierce the skin of the human body. During the needle ejection process of the barrel set A, the elastic arm 22 of the needle force buffering mechanism B at the rear end of the barrel 10 elastically collides with the needle retraction mechanism D to absorb the impact force, thereby ensuring that the barrel 10 is not damaged by the impact. After the needle 11 punctures the skin of the human body, the elastic potential energy released by the rear elastic element 43 continues to push the piston 12 inside the barrel 10 forward via the injection push rod 42, and the medicinal liquid inside the barrel 10 is injected into the human body through the needle 11.

[0051] 25 and 31 , after the injection is completed, the injection push rod 42 moves forward into the needle force buffering mechanism B due to the elastic potential energy released by the rear elastic element 43. The pressure plate 424 of the injection push rod 42 passes through the alignment guide slot 204 of the buffer member 20 of the needle force buffering mechanism B and pushes the ratchet arm 502 of the front fastener 50 of the needle retraction mechanism D forward, causing the ratchet arm 502 to retract and disengage from the positioning buckle portion 305 of the outer casing 30. This releases the elastic potential energy of the front elastic element 51 disposed between the outer casing 30 and the front fastener 50, pushing the front fastener 50 and the inner sleeve 40 connected thereto to rotate by a certain angle in the opposite direction. The screw rib 5031 disengages from the screw groove 304 of the outer casing 30, and the elastic potential energy released by the forward elastic element 51 pushes the needle retraction mechanism D, the barrel set A connected thereto, and the injection propulsion mechanism C to move axially backward, after which the needle 11 of the barrel set A moves back into the outer casing 30, completing the needle retraction operation.

[0052] Although many features and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, this disclosure is merely illustrative, and changes may be made in the details, particularly in matters of shape, size, and arrangement of parts, within the principles of the invention to the maximum extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. A needle force buffering mechanism is mounted in a syringe, the needle force buffering mechanism is connected to a barrel set, and when the barrel set is ejected by an injection propulsion mechanism in the syringe to eject a needle, the needle force buffering mechanism and the barrel set can move together, and the needle force buffering mechanism comprises: a buffering member connected to the barrel set, the buffering member including at least one elastic arm, the buffering member providing buffering elasticity to the barrel set ejected to output the needle by elastic contact of the elastic arm with the syringe; A needle output buffer mechanism.

2. 2. The needle force buffering mechanism according to claim 1, wherein the buffering member includes a member base and two elastic arms symmetrically attached to a front end of the member base, the front end of the member base having two symmetrically arranged hook portions, the two elastic arms being symmetrically arranged and disposed by two sides of the two hook portions, the two hook portions hooking onto two barrel wing portions at rear ends of barrels of the barrel set, and the two elastic arms being positioned outside the two barrel wing portions and protruding from front sides of the barrel wing portions.

3. 3. The needle force buffering mechanism according to claim 2, wherein each of the elastic arms includes a curved concave portion that bends backward and two curved convex portions that are arranged symmetrically on two sides of the curved concave portion and bend forward, and the elastic arms are connected to the member base via the two curved convex portions.

4. 4. The needle force damping mechanism of claim 3, wherein each of the latch portions has an alignment guide slot formed therein, and a portion of the injection propulsion mechanism passes through the alignment guide slot.

5. 5. The needle force damping mechanism according to claim 2, further comprising a spring plate, the spring plate being securely attached to the rear end of the member base, the spring plate having a central hole and a plurality of resilient abutment portions disposed around the central hole and extending toward the central hole, each of the resilient abutment portions being positionally contactable by a respective one of the protrusions on the outer surface of the injection push rod of the injection propulsion mechanism.

6. A syringe having a barrel set mounted therein for containing a medical solution, the syringe comprising: an outer casing having an interior including a front accommodating chamber and a rear accommodating chamber disposed in front and behind and communicating with each other, the barrel set being mounted in the outer casing and movable within the front accommodating chamber and the rear accommodating chamber; an injection propelling mechanism mounted in the rear chamber of the outer casing and protruding from the rear end of the outer casing, the injection propelling mechanism being disposed behind the barrel set and operable to eject the barrel set forward from the front chamber of the outer casing to eject a needle and inject the medicinal solution; a needle force buffering mechanism mounted in a rear accommodating chamber of the outer casing, the needle force buffering mechanism being connected to a rear end of a barrel of the barrel set and movable together with the barrel set, the needle force buffering mechanism including a buffering member having at least one elastic arm, the buffering member providing buffering elasticity to the barrel set ejected to eject the needle by elastic contact of the elastic arm with the syringe; a needle retraction mechanism mounted in a rear accommodating chamber of the outer casing and positioned in front of the needle force buffering mechanism, wherein the barrel set passes through the needle retraction mechanism, the injection propulsion mechanism is actuated to eject the barrel set and the needle force buffering mechanism connected thereto, and after completing the needle ejection operation and the injection operation of the medicinal solution, the needle retraction mechanism is triggered to drive the barrel set and the needle force buffering mechanism connected thereto, and the injection propulsion mechanism moves backward until the needle of the barrel set returns to the outer casing; and A syringe comprising:

7. 7. The syringe according to claim 6, wherein the buffer member includes a member base and two elastic arms symmetrically attached to a front end of the member base, the elastic arms including a curved concave portion bending backward and two curved convex portions bending forward and symmetrically disposed on two sides of the curved concave portion, the elastic arms being connected to the member base via the two curved convex portions, the front end of the member base having two symmetrically disposed hook portions, the two elastic arms being symmetrically disposed and disposed by the two sides of the two hook portions, the two hook portions being hooked onto two barrel wing portions at the rear end of the barrel, and the two elastic arms being positioned outside the two barrel wing portions and protruding from the front sides of the barrel wing portions.

8. 8. The syringe according to claim 6 or 7, further comprising a safety lock mechanism mounted within the outer casing and connected to the injection propulsion mechanism, the safety lock mechanism being switchable between a locked state and an unlocked state of the injection propulsion mechanism.

9. the injection propulsion mechanism includes an inner sleeve, an injection push rod, a rear resilient element, and an injection button; the inner sleeve is mounted in the rear accommodating chamber of the outer casing, the inner sleeve includes an inner sleeve base, at least one stop arm is disposed at a rear end of the inner sleeve base, and an axial support portion is disposed at the rear end of the inner sleeve base; the injection push rod is mounted in the inner sleeve and can be inserted into the barrel to push the piston, the injection push rod including: a rod portion, a rear rod end disposed behind the rod portion, a baffle portion disposed between the rod portion and the rear rod end, and at least one pressure plate disposed in front of the baffle portion and to a side of the rod portion, the baffle portion can be engaged by the stop arm, and the pressure plate can trigger the needle retraction mechanism to perform a needle retraction operation via the needle force buffering mechanism; the rear resilient element is mounted within the inner sleeve and disposed between the baffle portion and the axial support portion, and when the injection push rod is engaged with the inner sleeve, the rear resilient element stores elastic potential energy; 8. The syringe according to claim 6 or 7, wherein the injection button is connected to the rear end of the inner sleeve, is movable forward and rearward, and protrudes outside the rear end of the outer casing, the injection button has a pressing end and at least one extension arm arranged at the front end of the pressing end, the injection button is operable to press the stop arm and extend via the extension arm to release the injection push rod from the engaged state, and the rear resilient element releases the elastic potential energy to eject the injection push rod.

10. The syringe further comprises a safety lock mechanism, the safety lock mechanism is mounted within the outer casing and connected to the injection propulsion mechanism, and the safety lock mechanism is switchable between a locked state and an unlocked state of the injection propulsion mechanism; At least one guide protrusion is disposed on the pressing end of the injection button of the injection propelling mechanism; the safety locking mechanism includes an inner liner tube and a lock ring, the inner liner tube is mounted within the outer casing, at least one rotation guide groove is defined in a rear section of the inner liner tube, the rotation guide groove has a lock region and an unlock region, a connecting end is defined in a front end of the lock ring, at least one rotation guide protrusion is disposed on an outer surface of the connecting end, and the lock ring has at least one guide groove; 10. The syringe according to claim 9, wherein the guide groove includes a rotating section and an axially movable section, the locking ring is disposed behind the outer casing, a connecting end of the locking ring protrudes into the rear section of the inner liner tube and is rotatable, the rotation guide protrusion is disposed in the rotation guide groove corresponding to its position on the inner liner tube, and when the position of the rotation guide protrusion is switched between the lock region and the unlock region, the injection propulsion mechanism is switched between the locked state and the unlocked state by cooperation between the rotation guide groove of the locking ring and the rotation guide protrusion of the injection button.

11. 10. The syringe according to claim 9, wherein the needle retraction mechanism includes a front fastener and a front resilient element, the front fastener is mounted in a rear accommodating chamber of the outer casing and can be engaged in a predetermined position, a front end of the inner sleeve of the injection propulsion mechanism is connected to the front fastener, a barrel of the barrel set is mounted through the front fastener, the front resilient element is mounted in the front fastener to store resilient potential energy, and when the needle retraction mechanism is triggered by a pressure plate of the injection push rod, the front fastener is released from its engaged positioning state, allowing the front resilient element to release the resilient potential energy and drive the front fastener, the barrel set, the needle output buffering mechanism, and the injection propulsion mechanism to move rearward to a needle retracted position.

12. an annular retaining wall is formed between the front accommodating chamber and the rear accommodating chamber of the outer casing, the outer casing is disposed on a side wall of the rear accommodating chamber, the outer casing has at least one screw groove disposed adjacent to the annular retaining wall, and at least one positioning buckle portion disposed on a rear side of the screw groove; the front fastener of the needle retraction mechanism includes a fastener base and a threaded end disposed at a front end of the fastener base, a plurality of threaded ribs disposed on an outer surface of the threaded end, a plurality of retractable ratchet arms disposed on the fastener base, each of the ratchet arms having a ratchet tooth, the front fastener is mounted within the outer casing by cooperation of the threaded ribs and the thread grooves, the fastener base of the front fastener is connected to a front end of an inner sleeve of the injection propulsion mechanism, and the inner sleeve is movable together with the front fastener; 12. The syringe of claim 11, wherein the front fastener is engaged in a predetermined position within a corresponding positioning buckle portion of the outer casing via ratchet teeth of the ratchet arm, and the ratchet arm can be triggered by a pressure plate of the injection push rod to remove restriction on radial rotation of the front fastener, and the front fastener and the inner sleeve are pushed to rotate with the elastic potential energy released from the front resilient element, allowing the thread rib to disengage from the thread groove of the outer casing.

13. 8. The syringe of claim 7, wherein the needle force buffering mechanism further includes a spring plate, the spring plate being securely attached to the rear end of the member base, the spring plate having a central hole and a plurality of resilient abutment portions disposed around the central hole and extending toward the central hole, each of the resilient abutment portions being positionally contactable by a respective one of the protrusions on the outer surface of the injection push rod of the injection propulsion mechanism.

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