Syringe

Abstract

The present invention relates to the field of medical devices, specifically a syringe, which includes a barrel, a piston, and a push rod mechanism; the frictional force between the piston and the barrel is defined as the first frictional force; the push rod mechanism is configured as a telescopic sleeve structure, and the push rod mechanism is configured to be integrally inserted into the barrel. The push rod mechanism and the barrel are restricted to a movable and inseparable connection structure. A helical spring is arranged inside the push rod mechanism. The push rod mechanism with the helical spring serves as a power source, and the difference between the driving force applied by the push rod mechanism to the piston and the first frictional force between the piston and the barrel is configured as a net power threshold, so that during the process of the push rod mechanism pushing the piston relative to the barrel, an effect of approximate uniform linear motion of the piston relative to the barrel can be achieved, which can reduce the working intensity of medical staff; the injection efficiency is improved compared with the prior art; it is lighter in weight and more convenient to carry, can be disinfected, and reduces the economic cost of the syringe.

Description

Technical Field

[0001] The present invention relates to the field of medical devices, specifically syringes. Background Art

[0002] In the prior art, there is also a patent document with the name of an intravenous syringe and the application number 201420404003.7; in this patent document, a valve ball is provided in the needle seat of the injection needle connected to the syringe, and the injection speed of the syringe is controlled by the gap between the valve ball and the needle seat. Among them, when the injection speed is too fast, the valve ball blocks the needle seat, and when the injection speed is reasonable, a gap is formed between the valve ball and the needle seat for the liquid medicine to pass through.

[0003] As can be seen from the above prior art, during intravenous injection, the injection speed of the syringe needs to be controlled; in the above prior art, in essence, manual operation is used as the power source, and a valve structure with a valve ball is configured inside the injection needle to control the speed.

[0004] In the prior art, there is also a patent document with the name of an intravenous injector and the application number 201620184707.7; in this patent document, an injector using an electric motor as the power source is specifically used to replace the syringe using manual operation as the power source; however, in actual application, this injector with an electric motor is not convenient to use. On the one hand, in addition to the electric motor, it also includes various structures such as a battery and a controller, resulting in a relatively heavy weight and being inconvenient to carry, which limits the application scenarios of the injector with an electric motor. On the other hand, since medical devices need to be disinfected, and it is difficult to adopt an appropriate disinfection method for the injector with an electric motor, resulting in inconvenient disinfection. If the injector with an electric motor is directly discarded, it will increase the economic cost of the injector.

[0005] Therefore, how to provide a non-electrically controlled intravenous syringe for controlling the injection speed during intravenous injection has become a technical problem to be solved. Summary of the Invention

[0006] To solve the technical problem of how to provide a non-electrically controlled intravenous syringe for controlling the injection speed during intravenous injection, the present invention provides a syringe.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] According to one aspect of the present invention, there is provided a syringe, including a barrel, a piston, and a push rod mechanism;

[0009] The piston is arranged inside the barrel, and the frictional force between the piston and the barrel is defined as the first frictional force;

[0010] The push rod mechanism is configured as a telescopic sleeve structure, and the push rod mechanism is configured to be integrally inserted into the empty cylinder. The push rod mechanism and the empty cylinder are restricted to a movable and inseparable connection structure. The piston is fixedly arranged at the end of the push rod mechanism located inside the empty cylinder. Wherein, a spiral spring is arranged inside the push rod mechanism. The push rod mechanism has a contracted state and a relaxed state. When the spiral spring drives the push rod mechanism to change from the contracted state to the relaxed state, the acting force of the push rod mechanism for driving the piston is defined as the driving force. The driving force is configured to be greater than the first frictional force, and the difference between the driving force and the first frictional force satisfies the net power threshold;

[0011] The push rod mechanism is further configured with a locking structure, and the locking structure is used to control the push rod mechanism to change from the contracted state to the relaxed state. Wherein, the locking mechanism is restricted inside the contour of the push rod mechanism.

[0012] Further, the empty cylinder is provided with a handle part and a nipple. The empty cylinder between the handle part and the nipple is defined as the first cylinder section, and the empty cylinder outside the handle part and the nipple is defined as the second cylinder section. External threads are provided on the second cylinder section;

[0013] It further includes a locking nut. The locking nut is provided with a positioning ring and a connecting sleeve with internal threads. The positioning ring and the connecting sleeve are integrally formed coaxially. The inner diameter of the positioning ring is smaller than the inner diameter of the connecting sleeve;

[0014] A positioning convex ring is arranged on the push rod mechanism, and the positioning convex ring forms a clearance fit with the inner wall of the empty cylinder;

[0015] The external threads on the second cylinder section, the positioning convex ring on the push rod mechanism, and the locking nut jointly restrict the push rod structure and the empty cylinder to a movable and inseparable connection structure. Wherein, the internal threads of the locking nut are connected to the external threads of the second cylinder section, and the movement path of the positioning convex ring is restricted between the positioning ring and the inner wall of the empty cylinder.

[0016] Further, the push rod mechanism is further provided with a detachable push handle;

[0017] The locking nut is sleeved on the push rod mechanism between the push handle and the positioning convex ring. The locking nut forms a clearance fit with the push rod mechanism between the push handle and the positioning convex ring. Wherein, the maximum radial length of the push handle is greater than the inner diameter of the positioning ring.

[0018] Further, the push rod mechanism is further provided with a first sleeve and a second sleeve;

[0019] The first sleeve and the second sleeve form the telescopic sleeve structure, wherein the second sleeve is inserted into the first sleeve;

[0020] Axial two ends of the first sleeve are respectively a head end and a tail end, the positioning convex ring is located on an outer circumferential surface of the first sleeve at the head end, the push handle is located at the tail end, and the push handle is detachably connected to the first sleeve.

[0021] Furthermore, the push rod mechanism is further provided with a friction assembly;

[0022] The spiral spring and the friction assembly are respectively arranged inside a contour of the telescopic sleeve structure, wherein the spiral spring and the friction assembly are in a separated state from each other;

[0023] Friction force between the friction assembly and the second sleeve is defined as a second friction force, along a telescopic direction of the first sleeve and the second sleeve, elastic force of the spiral spring acts on the second sleeve and the first sleeve respectively;

[0024] A difference between the elastic force of the spiral spring and the second friction force is the driving force, and the elastic force of the spiral spring is greater than the second friction force.

[0025] Furthermore, the friction assembly includes a positioning block, a positioning pin and a plurality of friction blocks;

[0026] The positioning block is located at one end of the positioning pin, and the positioning block and the positioning pin are fixedly connected or detachably connected;

[0027] A plurality of the friction blocks are located at the other end of the positioning pin, and the plurality of friction blocks and the positioning pin are detachably connected, wherein any one of the friction blocks is respectively configured as a deformable structure, along a direction from the positioning pin to the positioning block, a diameter of a prior friction block is smaller than a diameter of a subsequent friction block;

[0028] The second sleeve is provided with a friction cavity in a shape of a tapered cavity, an opening of the friction cavity faces the push handle, a distance from a cavity bottom of the friction cavity to the push handle is greater than a distance from the opening of the friction cavity to the push handle, an inner diameter of the friction cavity at the opening is greater than an inner diameter of the friction cavity at the cavity bottom;

[0029] A plurality of the friction blocks are inserted into the friction cavity, the positioning block is located outside the friction cavity, wherein the positioning block is restricted between the spiral spring and the push handle, and the elastic force of the spiral spring is applied to the first sleeve through the positioning block and the push handle.

[0030] Further, a telescopic cavity is also provided inside the second sleeve. The telescopic cavity and the friction cavity are configured to be coaxial and isolated from each other, wherein the friction cavity is located inside the telescopic cavity;

[0031] The positioning block is located outside the telescopic cavity;

[0032] The helical spring is restricted in the space between the positioning block and the telescopic cavity, and the helical spring surrounds the friction cavity.

[0033] Further, an end plate is also provided on the second sleeve;

[0034] Axial two ends of the second sleeve are respectively a head end and a tail end. Among them, the end plate is located at the head end, and the openings of the friction cavity and the telescopic cavity are respectively located at the tail end;

[0035] The piston is coaxially arranged on the end plate, wherein the end plate and the inner wall of the empty cylinder form a clearance fit.

[0036] Further, a locking pin is provided on the inner surface of the first sleeve, and the locking pin protrudes from the inner surface of the first sleeve;

[0037] A guiding groove and a locking groove are provided on the outer surface of the second sleeve, and the guiding groove and the locking groove are respectively recessed in the outer surface of the second sleeve;

[0038] The extending direction of the guiding groove is configured as the axial center line direction of the second sleeve, and the extending direction of the locking groove is configured as the circumferential direction of the second sleeve. The guiding groove and the locking groove communicate with each other;

[0039] The moving path of the locking pin is restricted in the guiding groove and the locking groove. Among them, when the locking pin is located in the locking groove, the push rod mechanism is in the contracted state. When the locking pin moves from the locking groove to the guiding groove, the push rod mechanism changes from the contracted state to the expanded state.

[0040] Further, the net power threshold specifically includes a net power upper limit value, a net power lower limit value, and net power values between the net power upper limit value and the net power lower limit value. The above technical solutions have the following advantages or beneficial effects:

[0041] The syringe provided by the present invention is provided with a spiral spring inside the push rod mechanism. The push rod mechanism with the spiral spring serves as a power source, and the difference between the driving force exerted by the push rod mechanism on the piston and the first frictional force between the piston and the barrel is configured as a net power threshold, so that during the process of the push rod mechanism pushing the piston relative to the barrel, the piston can form an effect of approximately uniform linear motion relative to the barrel, which can reduce the working intensity of medical staff; improve the injection efficiency compared with the prior art; be lighter in weight and more convenient to carry, and can be disinfected, reducing the economic cost of the syringe. Description of the Drawings

[0042] Figure 1 Schematic structural diagram of the syringe provided in Embodiment 1 of the present invention;

[0043] Figure 2 Cross-sectional view of the syringe provided in Embodiment 1 of the present invention;

[0044] Figure 3 Cross-sectional view of a part of the syringe provided in Embodiment 1 of the present invention;

[0045] Figure 4 Schematic structural diagram of the lock nut provided in Embodiment 1 of the present invention;

[0046] Figure 5 Schematic structural diagram of the barrel provided in Embodiment 1 of the present invention;

[0047] Figure 6 Cross-sectional view of the syringe provided in Embodiment 1 of the present invention;

[0048] Figure 7 Cross-sectional view of the syringe provided in Embodiment 1 of the present invention;

[0049] Figure 8 Cross-sectional view of the syringe provided in Embodiment 1 of the present invention;

[0050] Figure 9 Schematic structural diagram of the friction assembly provided in Embodiment 1 of the present invention;

[0051] Figure 10 Schematic structural diagram of the first sleeve and the push handle provided in Embodiment 1 of the present invention;

[0052] Figure 11 Schematic structural diagram of the second sleeve and the piston provided in Embodiment 1 of the present invention;

[0053] Figure 12 Schematic structural diagram of the first sleeve, the second sleeve and the piston provided in Embodiment 1 of the present invention;

[0054] Figure 13Cross-sectional view of the first sleeve, second sleeve and piston provided in Embodiment 1 of the present invention;

[0055] Figure 14 Schematic structural diagram of the second sleeve, piston and push handle provided in Embodiment 1 of the present invention. Detailed implementation manners

[0056] Embodiment 1:

[0057] In this embodiment, a syringe is provided to solve the technical problem of how to provide a non-electrically controlled intravenous syringe for controlling the injection speed during intravenous injection.

[0058] Specifically, referring to Figure 1 or Figure 2 , the syringe of this embodiment includes a barrel 1, a piston 2 and a push rod mechanism 3;

[0059] The piston 2 is arranged inside the barrel 1, and the frictional force between the piston 2 and the barrel 1 is defined as the first frictional force;

[0060] The push rod mechanism 3 is configured as a telescopic sleeve structure. The push rod mechanism 3 is configured to be integrally inserted into the barrel 1. The push rod mechanism 3 and the barrel 1 are restricted to a connection structure that can move but cannot be separated. The piston 2 is fixedly arranged at the end of the push rod mechanism 3 located inside the barrel 1. Among them, a spiral spring 301 is arranged inside the push rod mechanism 3. The push rod mechanism 3 has a contracted state and a relaxed state. When the spiral spring 301 drives the push rod mechanism 3 to change from the contracted state to the relaxed state, the acting force of the push rod mechanism 3 for driving the piston 2 is defined as the driving force. The driving force is configured to be greater than the first frictional force, and the difference between the driving force and the first frictional force satisfies the net power threshold;

[0061] The push rod mechanism 3 is further configured with a locking structure 390 for controlling the push rod mechanism 3 to change from the contracted state to the relaxed state. Among them, the locking mechanism is restricted inside the contour of the push rod mechanism 3.

[0062] In this embodiment, the barrel 1 is used to store the liquid medicine;

[0063] In this embodiment, a piston 2 is arranged inside the barrel 1; when an operator operates the syringe of this embodiment, the whole push rod mechanism 3 can be pushed or pulled manually in the operation mode of a common syringe in the prior art, so that the whole push rod mechanism 3 pushes or pulls the piston 2, and then the piston 2 makes a pushing action for injecting the liquid medicine or a retracting action for sucking the liquid medicine inside the barrel 1; in addition, in this embodiment, the push rod mechanism 3 also has another control method, which will be described in detail later.

[0064] In this embodiment, the push rod mechanism 3 is configured as a telescopic sleeve structure. Specifically, the lengths of both axial ends of the push rod mechanism 3 are variable. Refer to Figure 2 , Figure 7 or Figure 8 . Therefore, the push rod mechanism 3 has a contracted state and a relaxed state. Among them, the contracted state refers to the state when the lengths of both axial ends of the push rod mechanism 3 are restricted to the minimum length (refer to Figure 2 ), and the relaxed state refers to the state when the lengths of both axial ends of the push rod mechanism 3 change from the minimum length to the maximum length (refer to Figure 7 or Figure 8 ).

[0065] In this embodiment, the entire push rod mechanism 3 and the hollow cylinder 1 form a sliding pair. The push rod mechanism 3 can be inserted into the hole (refer to Figure 6 ), and the entire push rod mechanism 3 can push or pull the piston 2; at the same time, the entire push rod mechanism 3 and the hollow cylinder 1 form a movable and inseparable connection structure, so that the entire push rod mechanism 3 cannot be separated from the hollow cylinder 1; on this basis, based on the fact that the push rod mechanism 3 is configured as a telescopic sleeve structure, its power source is the elastic force of the spiral spring 301 located inside the push rod mechanism 3. Therefore, during the process of the push rod mechanism 3 changing from the contracted state to the relaxed state, since the push rod mechanism 3 is inseparable from the hollow cylinder 1, when the lengths of both axial ends of the push rod mechanism 3 continuously increase, the push rod mechanism 3 can apply a driving force to the piston 2 inside the hollow cylinder 1;

[0066] Moreover, in this embodiment, since the driving force of the push rod mechanism 3 driving the piston 2 is greater than the first frictional force formed between the piston 2 and the hollow cylinder 1, it is ensured that the piston 2 can make a pushing action for injecting the liquid medicine. Among them, the direction of the driving force received by the piston 2 is the first direction A, and the direction of the first frictional force between the piston 2 and the hollow cylinder 1 is the second direction B. The first direction A and the second direction B are opposite to each other. In other words, the first frictional force is one of the resistances during the movement of the piston 2 (here referring to the process of the pushing action for injecting the liquid medicine);

[0067] It should be understood that during the movement of the piston 2 (here referring to the process of the pushing action for injecting the liquid medicine), in addition to being resisted by the first frictional force, the piston 2 is also resisted by the resistance of the liquid medicine inside the hollow cylinder 1.

[0068] It should be understood that the driving force of the push rod mechanism 3 driving the piston 2 is not equal to the elastic force of the spiral spring 301 located inside the push rod mechanism 3; in the following content, the definition of the driving force is specifically proposed, which will not be mentioned for the time being.

[0069] In the syringe of this embodiment, in order to prevent the push rod mechanism 3 from automatically driving the piston 2 to push the injection liquid, a locking structure 390 is further provided on the push rod mechanism 3; specifically, when the push rod mechanism 3 is locked by the locking structure 390, the entire push rod mechanism 3 is in a contracted state. At this time, the push rod mechanism 3 cannot apply a driving force to the piston 2 because the locking structure 390 restricts the telescopic movement of the push rod mechanism 3. When the push rod mechanism 3 is unlocked, the push rod mechanism 3 changes from the contracted state to the expanded state. At this time, the push rod mechanism 3 applies a driving force to the piston 2, and at this time, the locking mechanism can no longer restrict the telescopic movement of the push rod mechanism 3.

[0070] During the actual operation of using the syringe of this embodiment by medical staff, the following two operation methods can be adopted:

[0071] The first operation method is manual operation; specifically, refer to Figure 2 or Figure 6 , medical staff cannot unlock the locking structure 390. Thus, medical staff use the syringe of this embodiment as an ordinary syringe in the prior art, including pulling the entire push rod mechanism 3 when drawing the injection liquid, so that a negative pressure is generated in the inner cavity between the piston 2 and the barrel 1 to draw the injection liquid, and also including pushing the entire push rod mechanism 3 after drawing the injection liquid, so that a positive pressure is generated in the inner cavity between the piston 2 and the barrel 1 to discharge the injection liquid.

[0072] The second operation method is intravenous injection operation; specifically, refer to Figure 2 or Figure 7 or Figure 8 , during the process of drawing the injection liquid, medical staff cannot unlock the locking structure 390. After drawing the injection liquid, the staff unlocks the locking structure 390. The elastic force of the spiral spring 301 overcomes at least the first frictional force and the resistance of the injection liquid, so that the piston 2 is driven by the driving force of the push rod mechanism 3 to achieve the intravenous injection operation of automatically injecting the injection liquid.

[0073] In the syringe of this embodiment, in order to keep the injection speed of the injection liquid uniform, the driving force applied by the push rod mechanism 3 to the piston 2 and the first frictional force of the piston 2 are configured as follows: on the one hand, the driving force is greater than the first frictional force; on the other hand, the difference between the driving force and the first frictional force is limited within the net driving force threshold; among them, the idea of controlling the injection speed (flow rate of the injection liquid) in the prior art is changed to controlling the speed of the piston 2 (the moving speed of the piston 2 relative to the barrel 1) in this embodiment, and then the idea of controlling the speed of the piston 2 is realized according to the technical solution of controlling the force on the piston 2. This force is the difference between the driving force and the first frictional force, and moreover, the range of the difference between the driving force and the first frictional force should be limited;

[0074] Since the first frictional force between the piston 2 and the empty cylinder 1 remains unchanged, and the resistance formed by the liquid medicine and the empty cylinder 1 cannot be controlled (the viscosities of the liquid medicines are different), therefore, to limit the range of the difference between the driving force and the first frictional force, what actually needs to be limited is the magnitude of the change in the driving force.

[0075] If the driving force applied to the piston 2 at a previous moment is greater than the driving force applied to the piston 2 at a subsequent moment, the moving speed of the piston 2 is in an accelerating state;

[0076] If the driving force applied to the piston 2 at a previous moment is less than the driving force applied to the piston 2 at a subsequent moment, the moving speed of the piston 2 is in a decelerating state;

[0077] According to the above time-varying relationship between the driving force and the moving speed of the piston 2, the following two test models can be configured;

[0078] For the first test model, set the resistance formed by the liquid medicine and the empty cylinder 1 to an ideal value, use the first frictional force as the resistance parameter, and only measure the change in the driving force;

[0079] For the second test model, use the resistance formed by the liquid medicine and the empty cylinder 1 and the first frictional force together as the resistance parameter, and measure the change in the driving force.

[0080] The technical means for measuring the driving force can adopt the measuring means of the existing technology. For example: use a cylinder to cooperate with a measuring tooling (positioning device), set a force measuring instrument and a push rod between the piston 2 of the cylinder and the piston 2 in the empty cylinder 1, and respectively position the force measuring instrument and the push rod movably with the measuring tooling, fix and position the empty cylinder 1 and the cylinder relative to the measuring tooling, and control the linear moving speed of the force measuring instrument and the push rod to be a linear uniform motion through the cylinder, so that the piston 2 can form a linear uniform motion relative to the empty cylinder 1. At this time, by reading the data of the force measuring instrument, the value of the driving force applied to the piston 2 in the empty cylinder 1 can be obtained. More specifically, it is the values of multiple driving forces, and the values of the multiple driving forces are different.

[0081] The above measuring method can be applied to the above two test models.

[0082] After obtaining the value of the driving force through the above measuring means, the difference between the value of any driving force and the first frictional force is obtained respectively, and then the aforementioned net driving force threshold can be obtained. Among them, the net driving force threshold has a net driving force upper limit value, a net driving force lower limit value, and a net driving force value between the net driving force upper limit value and the net driving force lower limit value;

[0083] In terms of the first test model, the upper limit value of the net driving force is actually the difference between the maximum value of the driving force obtained by using the above measurement means and the first frictional force, and the lower limit value of the net driving force is actually the difference between the minimum value of the driving force obtained by using the above measurement means and the first frictional force; the remaining net driving force values are the differences between the values of the driving force obtained by using the above measurement means and the first frictional force.

[0084] In terms of the second test model, the upper limit value of the net driving force is actually the difference between the maximum value of the driving force obtained by using the above measurement means and the sum of the first frictional force and the resistance of the liquid medicine in the empty cylinder 1, and the lower limit value of the net driving force is actually the difference between the minimum value of the driving force obtained by using the above measurement means and the sum of the first frictional force and the resistance of the liquid medicine in the empty cylinder 1; the remaining net driving force values are the differences between the values of the driving force obtained by using the above measurement means and the sum of the first frictional force and the resistance of the liquid medicine in the empty cylinder 1.

[0085] In the process of actually setting the driving force of this embodiment, as long as the magnitude of the driving force is limited within the above net driving force threshold, the speed change of the piston 2 in the empty cylinder 1 can be regarded as a uniform motion; in other words, when the magnitude of the driving force is limited within the net driving force threshold, the resulting change in the speed of injecting the liquid medicine is small and can be tolerated by the patient.

[0086] In the prior art (a venous syringe, application number 201420404003.7), when the force applied by the medical staff's hand to the venous syringe is too large, the valve cavity will block the injection needle, so that the speed of injecting the liquid medicine of the syringe becomes zero, making it difficult to maintain a uniform injection speed and reducing the injection efficiency.

[0087] Compared with the above prior art, the syringe of this embodiment first adopts a push rod mechanism 3 configured as a telescopic sleeve structure, and a spiral spring 301 is arranged in the push rod mechanism 3. Thus, the push rod mechanism 3 with the spiral spring 301 serves as the power source for injecting the liquid medicine, replacing the manual power source in the above prior art, which can reduce the work intensity of medical staff; then, the difference between the driving force exerted by the push rod mechanism 3 on the piston 2 and the first frictional force of the piston 2 relative to the empty cylinder 1 satisfies the net driving force threshold, so that during the process of the push rod mechanism 3 pushing the piston 2 relative to the empty cylinder 1, an effect of approximately uniform linear motion of the piston 2 relative to the empty cylinder 1 can be formed, improving the injection efficiency compared with the above prior art; then, the push rod mechanism 3 of this embodiment is also provided with a locking structure 390, so that medical staff can control the syringe of this embodiment to inject the liquid medicine in a manual manner or in an automatic venous injection manner, making the use of the syringe of this embodiment more convenient and flexible.

[0088] In the prior art (a venous syringe with an application number of 201620184707.7), a motor is used as the power source to replace the manual power source and control the syringe, achieving the effect of injecting the liquid medicine at a uniform speed.

[0089] In this embodiment, compared with the above prior art, a mechanical structure of a push rod mechanism 3 configured to be retractable is adopted. A spiral spring 301 is arranged inside the push rod mechanism 3. The push rod mechanism 3 with the spiral spring 301 serves as the power source, and the difference between the driving force exerted by the push rod mechanism 3 on the piston 2 and the first frictional force between the piston 2 and the barrel 1 is configured as the net power threshold, so that during the process of the push rod mechanism 3 pushing the piston 2 to move relative to the barrel 1, the piston 2 can form an approximately uniform linear motion effect relative to the barrel 1. Compared with the above prior art, it is lighter in weight, more convenient to carry, can be disinfected, and even the used syringe can be directly discarded, reducing the economic cost of the syringe.

[0090] Therefore, the syringe provided in this embodiment solves the technical problem of how to provide a non-electrically controlled venous syringe for controlling the injection speed during the intravenous injection process.

[0091] Further, on the basis of the foregoing solution, how to limit the push rod mechanism 3 and the barrel 1 to a connection structure that is movable and inseparable is preferably achieved by the following solution;

[0092] See Figures 2 to 5 、 Figure 10 For the syringe of this embodiment, the barrel 1 is provided with a handle portion 102 and a nipple 103. The barrel 1 between the handle portion 102 and the nipple 103 is defined as the first barrel section 104, and the barrel 1 outside the handle portion 102 and the nipple 103 is defined as the second barrel section 105. The second barrel section 105 is provided with an external thread;

[0093] It further includes a locking nut 4. The locking nut 4 is provided with a positioning ring 401 and a connecting sleeve 402 with an internal thread. The positioning ring 401 and the connecting sleeve 402 are integrally formed coaxially. The inner diameter of the positioning ring 401 is smaller than the inner diameter of the connecting sleeve 402;

[0094] The push rod mechanism 3 is provided with a positioning convex ring 302, and the positioning convex ring 302 forms a clearance fit with the inner wall of the barrel 1;

[0095] The external thread of the second barrel section 105, the positioning convex ring 302 of the push rod mechanism 3 and the locking nut 4 jointly limit the push rod structure and the barrel 1 to a connection structure that is movable and inseparable. Among them, the internal thread of the locking nut 4 is connected to the external thread of the second barrel section 105, and the movement path of the positioning convex ring 302 is limited between the positioning ring 401 and the inner wall of the barrel 1.

[0096] During the actual assembly of the syringe of this embodiment, the staff first sleeved the locking nut 4 on the push rod mechanism 3. Then, the end of the push rod mechanism 3 with the positioning convex ring 302 was inserted into the barrel 1. Next, the internal thread of the locking nut 4 was connected to the external thread of the second barrel section 105 of the barrel 1, and thus the connection structure in which the push rod mechanism 3 and the barrel 1 are restricted to be movable and inseparable can be achieved.

[0097] After the locking nut 4 is connected to the barrel 1, the positioning convex ring 302 of the push rod mechanism 3 is restricted between the locking nut 4 and the inner wall of the barrel 1, so that the whole push rod mechanism 3 can move along the direction from the second barrel section 105 to the first barrel section 104, and the movement length is the sum of the lengths of the second barrel section 105 and the first barrel section 104. Also, the whole push rod mechanism 3 can move along the direction from the first barrel section 104 to the second barrel section 105. However, after the positioning convex ring 302 contacts the positioning ring 401 of the locking nut 4, the movement of the push rod mechanism 3 along the direction from the first barrel section 104 to the second barrel section 105 is terminated.

[0098] In order to achieve that the positioning convex ring 302 is restricted between the locking nut 4 and the inner wall of the barrel 1, it is only necessary to configure the outer diameter of the positioning convex ring 302 to be larger than the inner diameter of the positioning ring 401.

[0099] It should be understood that, in addition to the foregoing preferred solution, in other embodiments, internal threads may also be provided on the inner wall of the barrel 1, and correspondingly, positioning convex edges may be provided on the outer circumferential surface of the push rod mechanism 3. The structure of the positioning convex edges is similar to the structure of the foregoing positioning convex ring 302. The positioning convex edges can be restricted between the locking nut 4 and the inner wall of the barrel 1 by using the locking nut 4 with external threads, and the external thread of the locking nut 4 is connected to the internal thread of the barrel 1.

[0100] It should be understood that in this embodiment, it is not recommended to directly connect the push rod mechanism 3 and the barrel 1 to form a connection structure that is movable and inseparable. This is because, in the subsequent content of this embodiment, this setting method will conflict with the locking structure 390 of the push rod mechanism 3. If some embodiments are configured in this setting method, it is necessary to change the specific structure of the locking structure 390 of the push rod mechanism 3.

[0101] Further, in the prior art, a push handle is usually provided at the root of the push rod of the syringe (the end far from the barrel), and this push handle is used to increase the contact area with a person's finger and reduce the pressure applied to the person's finger; since the push handle of the syringe in the prior art is fixedly provided with the push rod, and the diameter or the maximum radial length of the push handle is greater than the diameter of the push rod, thus, in this embodiment, the locking nut 4 in this embodiment can only be sleeved on the push rod along the direction from the head of the push rod (the end inserted into the barrel 1) to the root. However, since the push rod mechanism 3 in this embodiment is provided with a positioning convex ring 302, and the diameter of the positioning convex ring 302 is greater than the inner diameter of the positioning ring 401 of the locking nut 4 in this embodiment, it is impossible to sleeve the locking nut 4 on the push rod with a positioning convex ring 302 in the prior art.

[0102] Therefore, on the basis of all the foregoing solutions, how to sleeve the foregoing locking nut 4 on the push rod mechanism 3 is preferably achieved by the following solution:

[0103] See Figure 2 or Figure 10 , in the syringe of this embodiment, the push rod mechanism 3 is further provided with a detachable push handle 303;

[0104] The locking nut 4 is sleeved on the push rod mechanism 3 located between the push handle 303 and the positioning convex ring 302, and the locking nut 4 forms a clearance fit with the push rod mechanism 3 located between the push handle 303 and the positioning convex ring 302, wherein the maximum radial length of the push handle 303 is greater than the inner diameter of the positioning ring 401.

[0105] When the push rod mechanism 3 is provided with a detachable push handle 303, when the push handle 303 and the push rod mechanism 3 are in a separated state as a whole, the locking nut 4 can be directly sleeved on the push rod mechanism 3, and the positioning ring 401 of the locking nut 4 forms a clearance fit with the push rod mechanism 3 as a whole; after the locking nut 4 is sleeved on the push rod mechanism 3, the push handle 303 can be connected to the push rod mechanism 3.

[0106] The principle of sleeving the locking nut 4 and the push rod is as follows: the inner diameter of the positioning ring 401 of the locking nut 4 matches the outer diameter of the push rod mechanism 3 located between the positioning convex ring 302 and the push handle 303, so that the inner diameter of the positioning ring 401 and the outer diameter of the push rod mechanism 3 can form a clearance fit. At the same time, the inner diameter of the positioning ring 401 of the locking nut is less than the maximum radial length of the push handle 303 and less than the diameter of the positioning convex ring 302, so that when the push handle 303 is connected to the push rod mechanism 3, the locking nut 4 cannot be directly sleeved on the push rod mechanism 3.

[0107] The connection manner between the push handle 303 and the push rod mechanism 3 can adopt various connection manners in the prior art, including but not limited to threaded connection, snap connection, positioning pin connection or bonding, etc.

[0108] Further, based on all the foregoing solutions, refer to Figure 2 , Figures 6 to 8 , Figures 10 to 14 , in the syringe of this embodiment, the push rod mechanism 3 is further provided with a first sleeve 304 and a second sleeve 305;

[0109] The first sleeve 304 and the second sleeve 305 form a telescopic sleeve structure, wherein the second sleeve 305 is inserted into the first sleeve 304;

[0110] The two axial ends of the first sleeve 304 are respectively a head end and a tail end. The positioning convex ring 302 is located on the outer circumferential surface of the first sleeve 304 at the head end, and the push handle 303 is located at the tail end, and the push handle 303 is detachably connected to the first sleeve 304.

[0111] Wherein, the inner circumferential surface of the first sleeve 304 and the outer circumferential surface of the second sleeve 305 form a clearance fit, so that the first sleeve 304 and the second sleeve 305 can form a telescopic pair;

[0112] The positioning convex ring 302 and the push handle 303 are respectively arranged at the two axial ends of the first sleeve 304. When the positioning convex ring 302 is restricted between the locking nut 4 and the inner wall of the empty cylinder 1, the second sleeve 305 can move within the space formed by the first sleeve 304 and the empty cylinder 1, while the first sleeve 304 is restricted by the positioning convex ring 302 being locked by the nut 4 and the empty cylinder 1, and the first sleeve 304 can only move within the empty cylinder 1. Thus, the first sleeve 304 and the second sleeve 305 respectively form a movable and inseparable connection structure relative to the empty cylinder 1.

[0113] Further, based on all the foregoing solutions, in the syringe of this embodiment, refer to Figure 2 , Figures 6 to 9 , the push rod mechanism 3 is further provided with a friction assembly 310;

[0114] The spiral spring 301 and the friction assembly 310 are respectively arranged inside the contour of the telescopic sleeve structure, wherein the spiral spring 301 and the friction assembly 310 are in a separated state;

[0115] The frictional force between the friction assembly 310 and the second sleeve 305 is defined as the second frictional force. Along the telescopic direction of the first sleeve 304 and the second sleeve 305, the elastic force of the spiral spring 301 acts on the second sleeve 305 and the first sleeve 304 respectively;

[0116] The difference between the elastic force of the spiral spring 301 and the second frictional force is the driving force, and the elastic force of the spiral spring 301 is greater than the second frictional force.

[0117] In the foregoing content, it has been mentioned that the elastic force of the helical spring 301 is not the driving force exerted by the push rod mechanism 3 on the piston 2. This is because when the push rod mechanism 3 is in the contracted state, the elastic force of the helical spring 301 is the largest and the axial length of the helical spring 301 is the smallest. When the push rod mechanism 3 changes from the contracted state to the expanded state, the elastic force of the helical spring 301 gradually decreases and the axial length of the helical spring 301 gradually becomes longer. Thus, if only the elastic force of the helical spring 301 is used as the 'driving force exerted by the push rod mechanism 3 on the piston 2', then as the length of the helical spring 301 gradually becomes longer, the elastic force of the helical spring 301 at a certain moment will change to be less than the 'first frictional force between the piston 2 and the empty cylinder 1', resulting in the piston 2 stopping at a certain position in the empty cylinder 1 and being unable to complete the injection work. If the elastic force of the helical spring 301 is increased, it is possible that the difference between the elastic force of the helical spring 301 and the 'first frictional force between the piston 2 and the empty cylinder 1' exceeds the net driving force threshold, causing the actual 'driving force' exerted by the push rod mechanism 3 on the piston 2 to be too large, resulting in too fast an injection speed of the liquid medicine and making it unbearable for the patient.

[0118] Therefore, in this embodiment, within the push rod mechanism 3, in addition to providing the helical spring 301 as a power source, a friction assembly 310 is also provided for cooperating with the helical spring 301 to control the driving force exerted by the push rod mechanism 3 on the piston 2.

[0119] Specifically, in this embodiment, the elastic force of the helical spring 301 is configured to be relatively large, thereby avoiding the occurrence of the phenomenon as described above that 'the elastic force of the helical spring 301 at a certain moment will change to be less than the 'first frictional force between the piston 2 and the empty cylinder 1', resulting in the piston 2 stopping at a certain position in the empty cylinder 1 and being unable to complete the injection work'. And, the friction assembly 310 is used as a resistance to limit the elastic force of the helical spring 301, avoiding the occurrence of the phenomenon as described above that 'the difference between the elastic force of the helical spring 301 and the 'first frictional force between the piston 2 and the empty cylinder 1' exceeds the net driving force threshold, causing the actual 'driving force' exerted by the push rod mechanism 3 on the piston 2 to be too large, resulting in too fast an injection speed of the liquid medicine and making it unbearable for the patient'.

[0120] Further, referring to Figure 2 、 Figures 6 to 9 、 Figure 11 In the syringe of this embodiment, the friction assembly 310 includes a positioning block 311, a positioning pin 312, and a plurality of friction blocks 313.

[0121] The positioning block 311 is located at one end of the positioning pin 312, and the positioning block 311 and the positioning pin 312 are fixedly connected or detachably connected.

[0122] A plurality of friction blocks 313 are located at the other end of the positioning pin 312, and the plurality of friction blocks 313 and the positioning pin 312 are detachably connected. Among them, any one of the friction blocks 313 is respectively configured as a deformable structure. Along the direction from the positioning pin 312 to the positioning block 311, the diameter of the prior friction block 313 is smaller than that of the subsequent friction block 313;

[0123] The second sleeve 305 is provided with a friction cavity 306 in a conical cavity shape. The opening of the friction cavity 306 faces the push handle 303. The distance from the bottom of the friction cavity 306 to the push handle 303 is greater than the distance from the opening of the friction cavity 306 to the push handle 303. The inner diameter of the friction cavity 306 at the opening is greater than the inner diameter of the friction cavity 306 at the bottom of the cavity;

[0124] A plurality of friction blocks 313 are inserted into the friction cavity 306, and the positioning block 311 is located outside the friction cavity 306. Among them, the positioning block 311 is restricted between the helical spring 301 and the push handle 303. The elastic force of the helical spring 301 is applied to the first sleeve 304 through the positioning block 311 and the push handle 303.

[0125] The friction block 313 is preferably made of rubber or silica gel material; the friction block 313 is preferably set in a spherical or cylindrical shape. Among them, any one of the friction blocks 313 is respectively provided with a through hole for being penetrated; the friction block 313 is sleeved on the positioning pin in an elastic deformation manner;

[0126] One end of the positioning pin 312 is connected to the positioning block 311, and the other end is used for installing a plurality of friction blocks 313. Among them, one end of the positioning pin 311 for installing a plurality of friction blocks 313 is provided with a blocking block, and the blocking block is configured as a cone. Its pointed cone part is used to first insert into the friction block 313, and its cone bottom diameter is relatively large, which can block the friction block 313 after the friction block 313 is set on the positioning pin 312; the through hole of the aforementioned friction block 313 is penetrated by the blocking block, and the through hole of the friction block 313 generates elastic deformation during the penetration process, and, after the blocking block penetrates the friction block 313, the cone bottom of the blocking block prevents the friction block 313 from detaching from the positioning pin 312.

[0127] Among them, when the push rod mechanism 3 is in a contracted state (see Figure 2 or Figure 6 ), the distance between the first sleeve 304 and the second sleeve 305 is the minimum distance. At this time, the axial length of the helical spring 301 is the minimum length, the elastic force of the helical spring 301 is the maximum elastic force, and at the same time, a plurality of friction blocks 313 are located in the friction cavity 306 near the bottom of the cavity, and the second frictional force between the plurality of friction blocks 313 and the friction cavity 306 is the maximum frictional force;

[0128] Also, when the push rod mechanism 3 is in the relaxed state and the distance between the first sleeve 304 and the second sleeve 305 is at its maximum distance (see Figure 8 ), the axial length of the helical spring 301 is at its maximum length, the elastic force of the helical spring 301 is at its minimum elastic force. At the same time, a plurality of friction blocks 313 are located in the friction cavity 306 near the opening, and the second frictional force between the plurality of friction blocks 313 and the friction cavity 306 is at its minimum frictional force;

[0129] Therefore, from the perspective of the transition of the push rod mechanism 3 from the contracted state to the relaxed state, when the helical spring 301 is at its maximum elastic force, the second frictional force is also at its maximum frictional force. Thus, the difference between the elastic force of the helical spring 301 and the second frictional force can be configured to be not higher than the upper limit value of the net driving force in the net driving force threshold. Also, when the helical spring 301 is at its minimum elastic force, the second frictional force is also at its minimum frictional force. Thus, the difference between the elastic force of the helical spring 301 and the second frictional force can be configured to be not lower than the lower limit value of the net driving force in the net driving force threshold.

[0130] The diameters of the plurality of friction blocks 313 are different and are configured such that along the direction from the positioning pin 312 to the positioning block 311, the diameter of the earlier friction block 313 is smaller than the diameter of the later friction block 313;

[0131] When the plurality of friction blocks 313 are located in the friction cavity 306 near the bottom of the cavity, any one of the friction blocks 313 comes into contact with the inner wall of the friction cavity 306 and deforms. At this time, the second frictional force is the sum of the frictional forces between all the friction blocks 313 and the friction cavity 306;

[0132] When the plurality of friction blocks 313 move a first distance along the direction from the bottom of the cavity to the opening, the friction block 313 with the smallest diameter near the bottom of the cavity separates from the friction cavity 306. At this time, the second frictional force is the sum of the frictional forces between the remaining plurality of friction blocks 313 and the friction cavity 306;

[0133] And so on. When the plurality of friction blocks 313 move a second distance along the above direction, the two friction blocks 313 with the smallest diameter near the bottom of the cavity separate from the friction cavity 306,...

[0134] And so on. When the plurality of friction blocks 313 move to a third distance along the above direction, the three friction blocks 313 with the smallest diameter near the bottom of the cavity separate from the friction cavity 306,...

[0135] Until, when the plurality of friction blocks 313 move to the friction cavity 306 at the opening and the friction block 313 with the largest diameter away from the bottom of the cavity separates from the friction cavity 306, the second frictional force at this time is zero.

[0136] Therefore, from the perspective of the positions of the plurality of friction blocks 313 relative to the friction cavity 306, when the plurality of friction blocks 313 move along the direction from the cavity bottom to the opening, and the number of the plurality of friction blocks 313 in contact with the friction cavity 306 remains unchanged, as the positions of the plurality of friction blocks 313 are different within the same movement distance, the change amount of the frictional force of the friction blocks 313 within the same movement distance remains a linear change amount, and the second frictional force between the friction assembly 310 and the second sleeve 305 can be appropriately reduced. However, when the number of the plurality of friction blocks 313 in contact with the friction cavity 306 is changed, when the plurality of friction blocks 313 move from the previous movement distance to the subsequent movement distance, at least one friction block 313 is separated from the friction cavity 306, and the change amount of the second frictional force in the previous movement distance and the change amount of the second frictional force in the subsequent movement distance can be regarded as a stepwise change amount, and the second frictional force between the friction assembly 310 and the second sleeve 305 can be significantly reduced;

[0137] Conversely, from the perspective of the positions of the plurality of friction blocks 313 relative to the friction cavity 306, when the plurality of friction blocks 313 move along the direction from the opening to the cavity bottom, and the movement positions are different within the same movement distance, the change amount of the frictional force of the friction blocks 313 within the same movement distance remains a linear change amount, and the second frictional force between the friction assembly 310 and the second sleeve 305 can be appropriately increased. Moreover, when the number of the plurality of friction blocks 313 in contact with the friction cavity 306 is changed, the change amount of the second frictional force in the previous movement distance and the change amount of the second frictional force in the subsequent movement distance can be regarded as a stepwise change amount, and the second frictional force between the friction assembly 310 and the second sleeve 305 can be significantly increased.

[0138] Furthermore, for the syringe of the present embodiment, referring to Figure 2 、 Figures 7 to 8 、 Figure 11 In addition, a telescopic cavity 307 is further provided in the second sleeve 305. The telescopic cavity 307 and the friction cavity 306 are configured to be coaxial and in a mutually isolated state, wherein the friction cavity 306 is located inside the telescopic cavity 307;

[0139] The positioning block 311 is located outside the telescopic cavity 307;

[0140] The helical spring 301 is restricted in the space between the positioning block 311 and the telescopic cavity 307, and the helical spring 301 surrounds the friction cavity 306.

[0141] The telescopic cavity 307 and the friction cavity 306 are configured to be coaxial and in a mutually isolated state, and in essence, there is a part of the second sleeve 305 between the telescopic cavity 307 and the friction cavity 306;

[0142] The helical spring 301 is inserted into the telescopic cavity 307. When the push rod mechanism 3 is in the retracted state, the helical spring 301 is restricted within the telescopic cavity 307. When the push rod mechanism 3 is in the expanded state, a part of the helical spring 301 is restricted within the telescopic cavity 307.

[0143] The aforementioned friction assembly 310 is disposed within the friction cavity 306 such that the helical spring 301 and the friction assembly 310 are separated by a part of the second sleeve 305 located between the telescopic cavity 307 and the friction cavity 306. Thus, the helical spring 301 and the friction assembly 310 are configured to be coaxial and isolated from each other.

[0144] From another perspective, a part of the second sleeve 305 located between the telescopic cavity 307 and the friction cavity 306 can be regarded as a 'guide post structure' sleeving the helical spring 301.

[0145] Furthermore, for the syringe of this embodiment, refer to Figure 2 、 Figure 7 、 Figure 8 、 Figure 13 , the second sleeve 305 is further provided with an end plate 308;

[0146] The two axial ends of the second sleeve 305 are respectively the head end and the tail end. Among them, the end plate 308 is located at the head end, and the openings of the friction cavity 306 and the telescopic cavity 307 are respectively located at the tail end;

[0147] The piston 2 is coaxially arranged on the end plate 308. Among them, the end plate 308 forms a clearance fit with the inner wall of the barrel 1.

[0148] The elastic force of the helical spring 301 acts on the end plate 308 and the positioning block 311 respectively. When the push rod mechanism 3 changes from the retracted state to the expanded state, the elastic force of the helical spring 301 forces the end plate 308 and the positioning block 311 to separate from each other. Among them, the end plate 308 drives the entire second sleeve 305 to form a separation movement relative to the first sleeve 304, and the positioning block 311 drives the entire friction assembly 310 to form a separation movement relative to the second sleeve 305. Moreover, the elastic force of the helical spring 301 is applied to the push handle 303 through the positioning block 311, and the push handle 303 drives the first sleeve 304 to form a separation movement relative to the second sleeve 305.

[0149] Furthermore, for the syringe of this embodiment, refer to Figures 10 to 14 , the inner surface of the first sleeve 304 is provided with a locking pin 391, and the locking pin 391 protrudes from the inner surface of the first sleeve 304;

[0150] The outer surface of the second sleeve 305 is provided with a guide groove 392 and a locking groove 393, and the guide groove 392 and the locking groove 393 are respectively recessed from the outer surface of the second sleeve 305;

[0151] The extending direction of the guiding groove 392 is configured to be the axial line direction of the second sleeve 305, and the extending direction of the locking groove 393 is configured to be the circumferential direction of the second sleeve 305. The guiding groove 392 and the locking groove 393 are communicated with each other;

[0152] The moving path of the locking pin 391 is restricted within the guiding groove 392 and the locking groove 393. Wherein, when the locking pin 391 is located within the locking groove 393, the push rod mechanism 3 is in a contracted state. When the locking pin 391 moves from the locking groove 393 to the guiding groove 392, the push rod mechanism 3 changes from the contracted state to the expanded state.

[0153] Wherein, the locking pin 391 and the locking groove 393 together form the aforementioned locking structure 390;

[0154] During the actual assembly process of the syringe of this embodiment, the staff aligns the first sleeve 304 and the second sleeve 305, so that the locking pin 391 on the first sleeve 304 is inserted into the guiding groove 392 of the second sleeve 305. The staff pushes the first sleeve 304 and the second sleeve 305 to shorten the distance therebetween, so that the locking pin 391 slides within the guiding groove 392 until the locking pin 391 reaches the communication part of the guiding groove 392 and the locking groove 393. The locking pin 391 is blocked and cannot continue to move along the guiding groove 392. At this time, the staff twists the first sleeve 304 and / or the second sleeve 305, so that the locking pin 391 moves along the locking groove 393 and finally is inserted into the deep part of the locking groove 393 and stops moving, realizing the locking function of the locking structure 390 for the first sleeve 304 and the second sleeve 305;

[0155] In the process of actually using the syringe of this embodiment, after the staff picks up the syringe of this embodiment, the locking state of the current first sleeve 304 and the second sleeve 305 is maintained. At this time, the staff can push or pull the entire push rod mechanism 3, so that the entire push rod mechanism 3 drives the piston 2 to make a forward or backward movement in the barrel 1; when the staff pulls the push rod mechanism 3 to make the piston 2 make a backward movement and causes the barrel 1 to generate negative pressure, the staff can use the negative pressure to draw the liquid medicine; after the staff draws the liquid medicine with the syringe of this embodiment, the staff installs the needle or the indwelling needle on the nipple 103 of the barrel 1. Then, the staff can rotate the first sleeve 304 so that the first sleeve 304 rotates relative to the barrel 1, forcing the aforementioned locking pin 391 to move from the locking groove 393 to the communication point between the locking groove 393 and the guiding groove 392; when the locking pin 391 moves to the communication point between the locking groove 393 and the guiding groove 392, the first sleeve 304 and the second sleeve 305 are unlocked. At this time, the helical spring 301 drives the first sleeve 304 and the second sleeve 305 to separate from each other, realizing the automatic intravenous injection action process; in the automatic intravenous injection action process, under the elastic force of the helical spring 301, the distance between the first sleeve 304 and the second sleeve 305 gradually increases, forcing the locking pin 391 to move in the guiding groove 392 until the piston 2 contacts the inner wall of the barrel 1 at the nipple 103, and the distance between the first sleeve 304 and the second sleeve 305 reaches the maximum distance and terminates the movement. At the same time, the locking pin 391 stops moving relative to the guiding groove 392.

[0156] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A syringe, characterized in that It includes a barrel, a piston and a push rod mechanism; The piston is arranged in the hollow cylinder, and the friction force between the piston and the hollow cylinder is defined as a first friction force; The push rod mechanism is configured as a retractable sleeve structure, the push rod mechanism is configured to be inserted into the empty cylinder as a whole, the push rod mechanism and the empty cylinder are restricted to a movable and inseparable connection structure, the piston is fixedly arranged at the end of the push rod mechanism located in the empty cylinder, wherein a coil spring is arranged in the push rod mechanism, the push rod mechanism has a contracted state and a relaxed state, when the coil spring drives the push rod mechanism to change from the contracted state to the relaxed state, the force of the push rod mechanism for driving the piston is defined as a driving force, the driving force is configured to be greater than the first friction force, and the difference between the driving force and the first friction force meets the net power threshold; The push rod mechanism is further provided with a locking structure, the locking structure being used to control the push rod mechanism to change from the contracted state to the expanded state, wherein the locking structure is confined within the contour of the push rod mechanism; The push rod mechanism is also provided with a detachable push handle; The push rod mechanism is also provided with a first sleeve and a second sleeve; The first sleeve and the second sleeve constitute the telescopic sleeve structure, wherein the second sleeve is inserted into the first sleeve; The push rod mechanism is also provided with a friction component; The coil spring and the friction assembly are respectively arranged inside the contour of the telescopic sleeve structure, wherein the coil spring and the friction assembly are in a mutually separated state; The friction force between the friction assembly and the second sleeve is defined as a second friction force, and along the extension and contraction directions of the first sleeve and the second sleeve, the elastic force of the coil spring acts on the second sleeve and the first sleeve respectively; The difference between the elastic force of the coil spring and the second friction force is the driving force, and the elastic force of the coil spring is greater than the second friction force; The friction assembly includes a positioning block, a positioning pin and a plurality of friction blocks; The positioning block is located at one end of the positioning pin, and the positioning block and the positioning pin are fixedly connected or detachably connected; A plurality of friction blocks are located at the other end of the positioning pin, and the plurality of friction blocks are detachably connected to the positioning pin, wherein any one of the friction blocks is respectively configured as a deformable structure, and along the direction from the positioning pin to the positioning block, the diameter of the preceding friction block is smaller than the diameter of the succeeding friction block; The second sleeve is provided with a friction cavity in the shape of a cone cavity, the opening of the friction cavity faces the push handle, the distance from the cavity bottom of the friction cavity to the push handle is greater than the distance from the cavity opening to the push handle, and the inner diameter of the friction cavity at the opening is greater than the inner diameter of the friction cavity at the cavity bottom; A plurality of friction blocks are inserted into the friction cavity, and the positioning block is located outside the friction cavity, wherein the positioning block is confined between the coil spring and the push handle, and the elastic force of the coil spring is applied to the first sleeve through the positioning block and the push handle.

2. The syringe according to claim 1, characterized in that The hollow cylinder is provided with a handle portion and a nipple, the hollow cylinder between the handle portion and the nipple is defined as a first cylinder section, the hollow cylinder outside the handle portion and the nipple is defined as a second cylinder section, and the second cylinder section is provided with an external thread; It also includes a locking nut, wherein the locking nut is provided with a positioning ring and a connecting sleeve having an internal thread, the positioning ring and the connecting sleeve are coaxially integrally formed, and the inner diameter of the positioning ring is smaller than the inner diameter of the connecting sleeve; The push rod mechanism is provided with a positioning convex ring, and the positioning convex ring forms a clearance fit with the inner wall of the hollow cylinder; The external thread of the second barrel section, the positioning protrusion ring of the push rod mechanism and the locking nut jointly limit the push rod mechanism and the empty barrel to a movable and inseparable connection structure, wherein the internal thread of the locking nut is connected to the external thread of the second barrel section, and the movable path of the positioning protrusion ring is limited between the positioning ring and the inner wall of the empty barrel.

3. The syringe according to claim 2, characterized in that The locking nut is sleeved on the push rod mechanism located between the push handle and the positioning convex ring, and the locking nut forms a clearance fit with the push rod mechanism located between the push handle and the positioning convex ring, wherein the maximum radial length of the push handle is greater than the inner diameter of the positioning ring.

4. The syringe according to claim 3, characterized in that The axial ends of the first sleeve are a head end and a tail end respectively, the positioning protruding ring is located on the outer circumferential surface of the first sleeve at the head end, the push handle is located at the tail end, and the push handle is detachably connected to the first sleeve.

5. The syringe according to claim 1, characterized in that A telescopic cavity is also provided in the second sleeve, and the telescopic cavity and the friction cavity are configured to be coaxial and isolated from each other, wherein the friction cavity is located inside the telescopic cavity; The positioning block is located outside the telescopic cavity; The coil spring is confined in the space between the positioning block and the telescopic cavity, and the coil spring surrounds the friction cavity.

6. The syringe according to claim 5, characterized in that The second sleeve is also provided with an end plate; The axial ends of the second sleeve are respectively a head end and a tail end, wherein the end plate is located at the head end, and the opening of the friction chamber and the opening of the telescopic chamber are respectively located at the tail end; The piston is coaxially arranged on the end plate, wherein the end plate forms a clearance fit with the inner wall of the hollow cylinder.

7. The syringe according to claim 4, characterized in that A locking pin is provided on the inner surface of the first sleeve, and the locking pin protrudes from the inner surface of the first sleeve; The outer surface of the second sleeve is provided with a guide groove and a locking groove, and the guide groove and the locking groove are respectively recessed in the outer surface of the second sleeve; The extending direction of the guide groove is configured as the axial direction of the second sleeve, the extending direction of the locking groove is configured as the circumferential direction of the second sleeve, and the guide groove and the locking groove are connected; The movable path of the locking pin is limited within the guide groove and the locking groove, wherein when the locking pin is located in the locking groove, the push rod mechanism is in the contracted state, and when the locking pin moves from the locking groove to the guide groove, the push rod mechanism changes from the contracted state to the expanded state.

8. The syringe according to claim 1, characterized in that The net power threshold value specifically includes a net power upper limit value, a net power lower limit value, and a net power value between the net power upper limit value and the net power lower limit value.

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