WO2014048298A1

WO2014048298A1 - Sliding sleeve-type needle protection device and safety syringe

Info

Publication number: WO2014048298A1
Application number: PCT/CN2013/084084
Authority: WO
Inventors: Zuoqian Lin
Original assignee: SHANGHAI SOL-MILLENNIUM MEDICAL PRODUCTS Co Ltd
Current assignee: SHANGHAI SOL-MILLENNIUM MEDICAL PRODUCTS Co Ltd
Priority date: 2012-09-28
Filing date: 2013-09-24
Publication date: 2014-04-03
Anticipated expiration: 2015-03-28

Description

SLIDING SLEEVE -TYPE NEEDLE PROTECTION DEVICE

AND SAFETY SYRINGE

Field of Invention

[0001] The present invention relates to a needle protection device, and particularly to a needle protection device which can prevent a needle used in a medical instrument such as a syringe or a blood collector from causing accidental stick, as well as a safety needle assembly or safety syringe having such needle protection device.

Background of the Invention

[0002] In medical practices, a medical instrument with a pointed needle is used extensively, for example a syringe or a blood collector. These medical instruments are not only used and disposed by professionals in medical establishments, but also often used and disposed by non-professionals at home, for example, a diabetes patient injects insulin on his own.

[0003] Since the needle of the medical instrument such as the syringe is exposed outside after use, it is likely to injure related persons, and cause substantial difficulty to collection and disposal. Such sticks might lead to bacterial infection. Furthermore, when the used needle is used again, there is a risk of cross infection.

[0004] In order to prevent occurrence of accidental sticks and cross infection, there is proposed a disposable syringe of which the needle is retractable after use. However, such syringe is complicated in structure and high in cost. Furthermore, when the syringe of which the needle is retractable is moved from place to place after it has drawn a liquid medicament during use thereof, the needle is still exposed and still has a risk of accidental sticks.

Summary of the Invention

[0005] Accordingly, the present invention provides a needle protection device and a safety syringe using the same in order to prevent accidental sticks and reuse of the needle with a simple structure and low costs.

[0006] The needle protection device according to the present invention may be used in combination with a needle comprising a needle seat and a needle tube installed on the needle seat, and may comprise a collar and a sliding sleeve. The collar may be in a cylindrical shape having a longitudinal axis and configured to be positioned around the needle seat in a fixed manner. The sliding sleeve may be in a cylindrical shape, have an upper end portion and a lower end portion, and may be configured to be positioned around the collar and slide along the collar between a retracted position where the upper end portion of the sliding sleeve is positioned around the collar and an extended position where the lower end portion of the sliding sleeve is positioned around the collar. In which, an outer surface of the collar and an inner surface of the lower end portion of the sliding sleeve may be respectively formed with catching mechanisms cooperating with each other. When the sliding sleeve is at the extended position, it can be caught on the collar in an inseparable manner.

[0007] Preferably, the catching mechanisms comprise one or more bosses which are formed on the outer surface of the collar and extend in the longitudinal axial direction, and at least one snap groove formed on the inner surface of the lower end portion of the sliding sleeve. When the sliding sleeve is rotated relative to the collar at the extended position, at least one of said bosses may be snap-fitted in at least one of said snap grooves in an inseparable manner.

[0008] Still preferably, the catching mechanisms may comprise a circle of flange on one of the outer surface of the collar and the inner surface of the sliding sleeve, and at least one pair of protrusions on the other of the outer surface of the collar and the inner surface of the sliding sleeve. A distance of the pair of protrusions in the longitudinal axial direction is not smaller than a height of the flange.

[0009] Preferably, a longitudinal guide groove extending in the longitudinal axial direction may be formed on an outer surface of at least one of said boss. In snap groove-free regions on the inner surface of the sliding sleeve may be formed at least one guide rib which extends between the upper end portion and the lower end portion and is configured to slide in the longitudinal guide groove in the longitudinal axial direction. The guide rib and the longitudinal guide groove are configured such that when the sliding sleeve is rotated relative to the collar, the guide rib can disengage from the longitudinal guide groove.

[0010] Alternatively, in snap groove-free regions on the inner surface of the sliding sleeve is formed at least one longitudinal guide groove which extends between the upper end portion and the lower end portion. On the outer surface of at least one of said bosses is formed a guide rib which extends in the longitudinal axial direction and is configured to slide in the longitudinal guide groove in the longitudinal axial direction. The guide rib and the longitudinal guide groove are configured such that when the sliding sleeve is rotated relative to the collar, the guide rib can disengage from the longitudinal guide groove.

[0011] Preferably, a convex point is formed on one of the inner surface of the sliding sleeve and the outer surface of the collar, and a depression is formed on the other of the inner surface of the sliding sleeve and the outer surface of the collar. The convex point can be snap-fitted in the depression in a separable manner when the sliding sleeve slides to the extended position.

[0012] Certainly, a convex point may alternatively be formed on the guide rib protruding more than other portions of the guide rib, and a depression is formed in the longitudinal guide groove deeper than other portions of the longitudinal guide groove. When the sliding sleeve slides to the extended position, the convex point is snap-fitted in the depression in a separable manner. At the location of the depression is formed a circumferential guide groove which extends circumferentially and has a depth smaller than that of the depression. When the sliding sleeve is rotated relative to the collar at the extended position, the convex point can slide in the circumferential guide groove.

[0013] According to a preferred technical solution according to the present invention, a convex point is formed on one of the inner surface of the sliding sleeve and the outer surface of the boss, and a depression is formed on the other of the inner surface of the sliding sleeve and the outer surface of the boss. The convex point can be snap-fitted in the depression in a separable manner when the sliding sleeve slides to the extended position.

[0014] According to a preferred technical solution according to the present invention, a plurality of projections are formed on the inner surface of the upper end portion of the sliding sleeve, and a circumferential groove is formed on the outer surface of the boss. When the sliding sleeve is at the retracted position, the projections are snap-fitted into the circumferential groove in a separable manner.

[0015] According to a preferred technical solution according to the present invention, a circumferential groove is formed on the inner surface of the upper end portion of the sliding sleeve, and an outwardly protruding projection is formed on at least one of said bosses. When the sliding sleeve is at the retracted position, the projection is snap-fitted in the circumferential groove in a separable manner.

[0016] According to a preferred technical solution according to the present invention, an inwardly protruding upper flange is formed on the inner surface of the upper end portion of the sliding sleeve, and the upper end portion of the boss of the collar extends in a longitudinal direction out of the outer surface of the collar. When the sliding sleeve is at the retracted position, the upper flange abuts against an upper end face of the upper end portion of the boss to prevent the sliding sleeve from falling.

[0017] According to a preferred technical solution according to the present invention, an inwardly protruding lower flange is formed on the inner surface of the lower end portion of the sliding sleeve. When the sliding sleeve is at the extended position, the lower flange is engaged with the lower end portion of the collar to prevent the sliding sleeve from being pulled away from the collar from the extended position.

[0018] According to a preferred technical solution according to the present invention, a radially raised portion is formed on the inner surface of the lower end portion of the sliding sleeve. When the sliding sleeve is at the extended position, the sliding sleeve is fixed at the extended position in a separable manner via an interference fit between the radially raised portion and the outer surface of the collar.

[0019] According to a preferred technical solution according to the present invention, the snap groove is formed on the radially raised portion.

[0020] According to a preferred technical solution according to the present invention, cross-sectional shapes of the boss and the snap groove are one of a swallow tail shape, a T shape, a rectangle, a square, and a toothed shape.

[0021] According to a preferred technical solution according to the present invention, a circumferential outer edge of the snap groove is a ramp to help the boss to enter the snap groove.

[0022] According to a preferred technical solution according to the present invention, a guide rib is formed on the inner surface of the sliding sleeve in the axial direction of the sliding sleeve, and a radially raised portion is formed at the lower portion of the guide rib.

[0023] According to a preferred technical solution according to the present invention, the guide rib and the boss of the collar are configured to guide the sliding sleeve to slide along the collar and prevent the sliding sleeve from rotating relative to the collar.

[0024] According to a preferred technical solution according to the present invention, the needle protection device may further comprise a snap cap configure to be positioned around the upper end portion of the sliding sleeve. The snap cap may comprise: an upper end face formed with a central hole through which a needle tube is allowed to extend and which allows the upper end face to abut against a top end of the sliding sleeve; and a flange formed by extending outwardly at the lower end of the snap cap. In which, a hook- like member is formed on the outer surface of the upper end portion of the sliding sleeve, and configured to snap-fit with the flange of the snap cap to connect the snap cap to the upper end portion of the sliding sleeve.

[0025] According to a preferred technical solution according to the present invention, one or more cavities are formed on an end wall of the collar. The positions of the one or more cavities correspond to one or more bosses of the collar.

[0026] According to a preferred technical solution according to the present invention, a slide-stopping protuberance is formed on the inner surface of the sliding sleeve and/or the outer surface of the collar, to prevent the sliding sleeve from moving relative to the collar in a separable manner. [0027] According to a preferred technical solution according to the present invention, the catching mechanisms may comprise a circle of flange on one of the outer surface of the collar and the inner surface of the sliding sleeve, and at least one pair of protrusions on the other of the outer surface of the collar and the inner surface of the sliding sleeve. A distance of one pair of protrusions in the longitudinal axial direction is not smaller than a height of the flange. When the sliding sleeve slides from the retracted position to the extended position, the flange passes across one of the pair of protrusions and is snap-fitted between the pair of protrusions.

[0028] According to a preferred technical solution according to the present invention, the pair of protrusions are staggered 90 degrees as viewed along the longitudinal axial direction.

[0029] According to a preferred technical solution according to the present invention, the protrusion to be passed across by the flange is in a wedge shape.

[0030] According to a preferred technical solution according to the present invention, an inwardly protruding upper flange is formed on the inner surface of the upper end portion of the sliding sleeve. When the sliding sleeve is at the retracted position, the upper flange can abut against the upper end portion of the collar to prevent the sliding sleeve from falling.

[0031] According to a preferred technical solution according to the present invention, a circle of flange may be formed on the outer surface of the collar, and one or more protrusions are also formed on the inner surface of the sliding sleeve below the upper flange. When the sliding sleeve is at the retracted position, the protrusion formed below the upper flange can abut against a lower portion of the flange on the outer surface of the collar.

[0032] According to a preferred technical solution according to the present invention, the collar may be fixed with the needle seat by an interference fit.

[0033] According to a preferred technical solution according to the present invention, a circle of raised portions formed on the inner surface of the collar may cooperate with a circle of recessed portions formed on the outer surface of the needle seat to achieve fixing. [0034] A safety syringe or a safety needle assembly provided by the present invention may comprise a needle seat and a needle tube mounted on the needle seat. The safety needle assembly may comprise the needle protection device according to the present invention.

[0035] According to a preferred technical solution according to the present invention, the safety needle assembly may further comprise a protective cap for enclosing the needle tube therein. An upper end portion of the protective cap is closed and a lower end portion thereof is open and configured to be positioned around an outer surface of an upper end portion of the sliding sleeve.

[0036] According to a preferred technical solution according to the present invention, an outwardly protruding external flange is formed on the outer surface of the upper end portion of the sliding sleeve. The lower end portion of the protective cap is configured to abut against the external flange.

[0037] The needle protection device and safety needle assembly according to the present invention are simple in structure and low in costs, and can prevent a medical instrument having a needle such as a syringe or a blood collector from accidental sticks in use and after use, and can prevent these medical instruments from reuse after use.

Brief Description of Drawings

[0038] Fig.l is a sectional view of a safety needle assembly in a before-use state according to one embodiment of the present invention.

[0039] Fig.2 is a sectional view of the safety needle assembly shown in Fig.l when a protective cap is taken off and a sliding sleeve is at a retracted position.

[0040] Fig.3 is a sectional view of the safety needle assembly shown in Fig.l when the sliding sleeve is at an extended position.

[0041] Fig.4 is a perspective view of a cross section taken along line A-A in Fig.3.

[0042] Fig.5 is a sectional view of the safety needle assembly shown in Fig.1 in an injection state.

[0043] Fig.6 is a sectional view of the safety needle assembly shown in Fig.l when the sliding sleeve is rotated upon completion of the injection.

[0044] Fig.7 is a perspective view of a cross section taken along line B-B in Fig.6.

[0045] Fig.8 is a perspective view of a collar of the safety needle assembly shown in

Fig. l .

[0046] Fig.9 is a front view of the collar shown in Fig.8.

[0047] Fig.10 is a top view of the collar shown in Fig.9.

[0048] Fig.11 is a sectional view taken along line C-C in Fig.10.

[0049] Fig.12 is a sectional view taken along line D-D in Fig.11.

[0050] Fig.13 is a perspective view of the sliding sleeve of the safety needle assembly of Fig. l .

[0051] Fig.14 is a front view of the sliding sleeve of Fig.13.

[0052] Fig.15 is a sectional view taken along line E-E of Fig.14 after an external flange is omitted.

[0053] Fig.16 is a sectional view taken along line F-F of Fig.15 after an external flange is omitted.

[0054] Fig 17 is a sectional view taken along line G-G in Fig.15.

[0055] Fig 18 is a sectional view taken along line H-H in Fig.15.

[0056] Fig 19 is a perspective view of a barrel of the safety needle assembly of Fig.l .

[0057] Fig 20 is a front view of the barrel of Fig.19.

[0058] Fig 21 is a top view of the barrel of Fig.19.

[0059] Fig 22 is a sectional view taken along line I-I in Fig.21.

[0060] Fig 23 is a perspective view of a protective cap of the safety needle assembly of Fig. l .

[0061] Fig 24 is a front view of the protective cap of Fig.23.

[0062] Fig 25 is a top view of the protective cap of Fig.23.

[0063] Fig 26 is a sectional view taken along line J- J in Fig.25.

[0064] Fig 27 is a sectional view of a safety needle assembly according to another embodiment of the present invention upon completion of injection.

[0065] Fig.28 is a sectional view of the safety needle assembly of Fig.27 when the sliding sleeve is pulled up upon completion of injection.

[0066] Fig.29 is a sectional view of the safety needle assembly of Fig.27 after the sliding sleeve is pulled up and rotated upon completion of injection.

[0067] Fig.30 is a sectional view taken along line K-K in Fig.28.

[0068] Fig.31 is a sectional view taken along line L-L in Fig.29.

[0069] Fig.32 is a perspective view of a collar of the safety needle assembly shown in Fig.27.

[0070] Fig.33 is a top view of the collar shown in Fig.32.

[0071] Fig.34 is a perspective view of the sliding sleeve of the safety needle assembly of Fig.27.

[0072] Fig.35 is a top view of the sliding sleeve of Fig.34.

[0073] Fig.36 is a sectional view taken along line M-M in Fig.35.

[0074] Fig.37 is a perspective view of a snap cap of the safety needle assembly of Fig.27.

[0075] Fig.38 is a sectional view of the snap cap of Fig.37.

[0076] Fig.39 illustrates another embodiment of the present invention, wherein a protective cap is provided.

[0077] Fig.40 is a view showing the sliding sleeve in the embodiment of Fig.39 is at an extended position.

[0078] Fig.41 is a longitudinal sectional view of the sliding sleeve.

[0079] Fig.42 is a sectional view after the sliding sleeve position shown in Fig.41 is rotated 90° about a longitudinal axis.

[0080] Fig.43 is a sectional view when the present invention is applied to a syringe having a plastic outer sheath.

[0081] Fig.44 is a view illustrating another state of the present invention of Fig.43.

[0082] Fig.45 is a sectional view when the present invention is applied to another syringe having a plastic outer sheath.

[0083] Fig.46 is a view when the sliding sleeve of the present invention shown in Fig.45 is at an extended position. Detailed Description of Preferred Embodiments

[0084] Preferred embodiments of a needle protection device with a sliding sleeve and a safety syringe using such a needle protection device according to the present invention are described in detail with reference to the figures.

[0085] Fig. l is a view of a safety needle assembly before use according to one embodiment of the present invention. The safety needle assembly comprises a needle seat 8, a needle tube 6 mounted on the needle seat 8, a collar 1 fixed on the needle seat 8, and a sliding sleeve 2 slideably positioned around the collar 1. In which, the needle seat 8 and the needle tube 6 constitute a needle, and the collar 1 and the sliding sleeve 2 constitute the needle protection device according to the present invention. The safety needle assembly shown in Fig. l further comprises a barrel 4, a push rod 5 and a rubber piston 3 fixed at an upper end of the push rod 5. The barrel 4, the push rod 5 and the rubber piston 3 may be components of the known syringes in the art and will not be described in detail.

[0086] In the present application, the needle seat 8 may be a separate member mountable on the barrel 4, or may be integrally formed with the barrel 4 as part of the barrel 4 (as shown in Fig. l).

[0087] In the present application, a term indicating a direction, such as "up", "down", etc., is referred to with respect to the pages of the figures, not an absolute direction.

[0088] The safety needle assembly further comprises a protective cap 7 for enclosing the needle tube 6 therein. The protective cap 7 may of various suitable structures known in the art. For example, referring to Fig.23-Fig.26 at the same time, a top portion 71 of the protective cap 7 is closed, and a bottom portion 74 of the protective cap 7 is open. Between the top portion 71 and the bottom portion 74 are an upper end portion 72 and a lower end portion 73. The upper end portion 73 may have a certain taper. A plurality of reinforcing ribs extending in an up-down direction (namely, longitudinally) may be formed on an outer surface of the upper end portion 72. The lower end portion 73 is configured to be positioned around an outer surface of an upper end portion of the sliding sleeve 2. [0089] In order to reliably prevent the needle tube 6 from contacting the top portion 71 of the protective cap upon assembling, a step 76 may be formed between the upper end portion 72 and the lower portion 73 so that an inner surface of the step 76 abuts against an upper end face 18 of the sliding sleeve 2 (concurrently referring to Figs.8, 9 and 11) to form a predetermined space between the needle tube 6 and the top portion 71 of the protective cap. Alternatively, or on the basis of the above configuration, an outwardly protruding external flange 29 may be formed on the outer surface of the upper end portion of the sliding sleeve 2 (concurrently referring to Figs.13 and 14) so that an edge of the bottom portion 74 of the protective cap 7 abuts against the external flange 29. It may be appreciated that at this time, the inner surface of the step 76 may not be in contact with the upper end face of the sliding sleeve 2. Besides, as shown in Fig.13 and Fig.14, a plurality of ribs 30 in a direction of a longitudinal axis 21 are formed on the outer surface of the sliding sleeve 2 above the external flange 29, to increase a friction force between them and the inner surface of the lower end portion 73 of the protective cap 7, and prevent the protective cap 7 from rotating or disengaging accidentally in the direction of the longitudinal axis.

[0090] Then referring to Figs.8- 12, they illustrate an embodiment of a collar of the needle protection device of the present invention. In this exemplary embodiment, the collar 1 is a cylinder shape having a longitudinal axis 10. Although in the example shown in the figures, the collar 1 is approximately cylindrical, the present invention is not limited to this, so long as it is adapted for the needle tube 6 to pass therethrough and positioned around the needle seat 8, that is to say, so long as the shape of the collar 1 matches the shape of the needle seat 8.

[0091] The collar 1 may be fixedly mounted on the needle seat 8 via various known structures in the art. For example, concurrently referring to Fig.20-Fig.22, on the outer surface of the needle seat 8 may be formed a plurality of longitudinally extending ribs 81 , and outwardly protruding protrusions 82 are formed on the ribs 81, for example at upper ends of the ribs 81. Correspondingly, referring to Fig.8 and Fig.11 , grooves for rib 19 extending in the longitudinal axis 10 are formed on the inner surface of the collar 1, and a recess 20 is formed for example at an upper end of the groove for rib 19 (referring to Fig.12 at the same time). When the collar 1 is mounted on the needle seat 8, the ribs 81 slide along the grooves for rib 19 until the protrusions 82 snap-fit in the recesses 20 so that the collar 1 cannot rotate relative to the needle seat 8, nor can slide longitudinally relative to the needle seat 8 so that the collar 1 is fixedly positioned around the needle seat 8. The collar 1 may be positioned around the needle seat 8 by interference fit, or may be fixed via a circle of raised portions on the inner surface of the collar 1 being snap-fitted in a circle of recessed portions formed on the outer surface of the needle seat 8. The raised portion and the recessed portion may be in any suitable shape, preferably an inverted taper shape so that the collar can be easily mounted on the needle seat and cannot easily slide off the needle seat.

[0092] As shown in Figs.8, 9, 10 and 12, a plurality of bosses 12 extending in the direction of the longitudinal axis 10 are formed on an outer surface 11 of the collar 1. The figures show four bosses 12 arranged symmetrically. However, it should be appreciated that the present invention is not limited to this. Preferably, the bosses 12 are integrally molded with the outer surface 11 of the collar.

[0093] The bosses 12 may extend along an entire longitudinal length of the collar 1 , an upper end thereof may extend beyond the collar 1 and forms an upper end face 18. A lower end of the boss 12 may flush with a lower end of the collar 1 and forms a lower end face 17 (referring to Fig.11 at the same time). When the sliding sleeve 2 is located at a retracted position, referring to Figs. l , 2 and 5, an upper flange 24 in the sliding sleeve 2 (see Fig.14-Fig.16) abuts against the upper end face 18 to prevent the fall of the sliding sleeve 2. When the sliding sleeve 2 is located at an extended position, referring to Fig.3 and Fig.6, the lower end face 17 of the collar may abut against or engage the lower flange 25 of the sliding sleeve 2 (see Fig.14-Fig.16) to reliably prevent the sliding sleeve 2 from being pulled away from the collar 1 at the extended position.

[0094] Fig.13-Fig.18 illustrate an embodiment of the sliding sleeve 2 in the needle protection device of the present invention, of which in the sectional views shown in Figs.15-18, the external flange 29 of Fig.13 and Fig.14 is not shown. [0095] The sliding sleeve 2 may be cylindrical, but not limited to a circular cross section so long as the sliding sleeve 2 can be positioned around the collar 1. The sliding sleeve 2 has a longitudinal axis 21. When the sliding sleeve 2 is positioned around the collar 1 , preferably the longitudinal axis 21 of the sliding sleeve 2 coincides with the longitudinal axis 10 of the collar.

[0096] The sliding sleeve 2 is positioned around the collar 1 , more specifically, around on the bosses 12 on the outer surface of the collar 1 , and is slideable along the outer surface of the bosses 12 between the retracted position and the extended position. Referring to Figs. l , 2 and 5, when the sliding sleeve 2 is at the retracted position, an upper end portion 22 of the sliding sleeve 2 is positioned around the collar 1 , whereupon the needle tube 6 is exposed outside the sliding sleeve 2. Referring to Figs.3 and 6, when the sliding sleeve 2 is at the extended position, a lower end portion 23 of the sliding sleeve 2 is positioned around the collar 1 , whereupon the needle tube 6 is enclosed by the sliding sleeve 2.

[0097] It should be appreciated that the sliding sleeve 2 is divided into the upper end portion 22 and the lower end portion 23 only for ease of understanding. The upper end portion 22 generally corresponds to the portion of the sliding sleeve 2 positioned around the collar 1 when at the retracted position, and the lower end portion 23 generally corresponds to the portion of the sliding sleeve 2 positioned around the collar 1 when at the extended position.

[0098] As a preferred embodiment, a longitudinal slide guide mechanism may be formed between the inner surface of the sliding sleeve 2 and the outer surface of the boss 12. Referring to Figs.15-17, a guide rib 26 extending in the direction of the longitudinal axis 21 is formed on the inner surface of the sliding sleeve 2 between an upper flange 24 and a lower flange 25. The figures show two guide ribs 26 arranged symmetrically. But the present invention is not limited to this. Referring to Figs.8, 9, 10 and 12, a longitudinal guide groove 16 is formed on the outer surface of the boss 12 in the direction of the longitudinal axis 10. The guide rib 26 can slide in the longitudinal guide groove 16 in the direction of the longitudinal axis 10 or 21 , constituting the longitudinal slide guide mechanism to guide the sliding sleeve 2 to slide longitudinally relative to the boss 12.

[0099] Cross sections of the guide rib 26 and the longitudinal guide groove 16 engaging with each other are shaped and sized such that when the sliding sleeve 2 is rotated relative to the collar 1 , the guide rib 26 can disengage from the longitudinal guide groove 16. In other words, the guide rib 26 is engaged with the longitudinal guide groove 16 circumferentially in a separable manner.

[0100] Although all of the four bosses 12 shown in the figures are formed with the longitudinal guide grooves 16, the longitudinal guide grooves 16 may be formed on only two bosses 12, corresponding to the guide ribs 26.

[0101] As stated above, in order to temporarily retain the sliding sleeve 2 at the retracted position shown in Figs. l, 2 and 5, one or more projections 31 are formed on the inner surface of the upper end portion 22 of the sliding sleeve 2. In the embodiment as shown in Figs.15, 16 and 18, there are four symmetrically arranged projections 31, of which two projections 31 are respectively formed at the upper ends of the two guide ribs 26. However, the present invention is not limited to this. Corresponding to the projections 31, a circumferential groove 15 is formed at the upper end portion of each boss 12 of the collar 1 (see Figs.8 and 9). When the sliding sleeve 2 is located at the retracted position, the projections 31 are snap-fitted in the circumferential grooves 15 in a separable manner so that the sliding sleeve 2 is temporarily held at the retracted position.

[0102] The so-called "separable manner" means that members snap-fitted together or engaged together can separate from each other under a suitable external force.

[0103] In order to temporarily retain the sliding sleeve 2 at the extended position shown in Figs.3 and 6, referring to Figs.15 and 16, a convex point 27 which is more convex than the remaining portions of the guide rib 26 and in the shape of, for example, a hemisphere or a water droplet may be formed on the guide rib 26, preferably at the lower end of the guide rib 26. Correspondingly, in the longitudinal guide groove 16 of the boss 12 is formed a depression 13 with a depth greater than the remaining portions of the longitudinal guide groove 16 (see Figs.8 and 9). When the sliding sleeve 2 is located at the extended position, the convex point 27 is snap-fitted in the depression 13 in a separable manner so as to temporarily hold the sliding sleeve 2 at the extended position and meanwhile prevent dead lock of the sliding sleeve caused by accidental rotation of the sliding sleeve.

[0104] Although in the embodiment shown in the figure, the longitudinal guide groove 16 of each boss 12 has one depression 13, and each guide rib 26 has one convex point 27, the object of the present invention can be achieved so long as there are at least a pair of corresponding convex point 27 and the depression 13, though preferably two or more pairs of convex points 27 and depressions 13 are symmetrically arranged circumferentially.

[0105] It should be appreciated that the longitudinal guide groove 16 and the guide rib 26 are not requisite, so, as far as retention of the extended position, the convex points 27/depressions 13 may be provided being unrelated to the longitudinal guide grooves 16 and guide ribs 26.

[0106] At least one snap groove 28 is formed on the inner surface of the lower end portion 23 of the sliding sleeve 2. The figure shows two symmetrically arranged snap grooves 28. As best shown in Fig.17 and Fig.18, the snap grooves 28 may be defined by a circle of ridges 32 formed on the inner surface of the sliding sleeve 2 and each having a generally barb-shaped cross section. In the embodiment shown in the figures, the snap grooves 28 are delimited by three ridges 32 and the lower flange 25. The snap groove 28 is configured such that when the sliding sleeve 2 slides between the retracted position and the extended position, the snap groove 28 does not interfere with the boss 12 of the collar 1; when the sliding sleeve 2 is rotated relative to the collar 1 at the extended position, the boss

12 is snap-fitted in the snap groove 28 in an inseparable manner.

[0107] The so-called "inseparable manner" means that if members snap-fitted together or engaged together are to be separated, a very large force is needed to achieve the separation, even permanent damages are caused to the members snap-fitted together or engaged together during the separation.

[0108] In order to guide the sliding sleeve 2 to rotate relative to the boss 12, a circumferential slide guide mechanism may be formed between the inner surface of the sliding sleeve 2 and the outer surface of the boss 12. As shown in Fig.8 and Fig.9, a circumferential guide groove 14 is formed on the boss 12 at the location of the depression 13. The depth of the depression 13 is also greater than that of the circumferential guide groove 14. The convex point 27 on the inner surface of the sliding sleeve 2 can slide along the circumferential guide groove 14, guiding the sliding sleeve 2 to rotate relative to the boss 12 and constituting the circumferential slide guide mechanism.

[0109] Then referring to Fig.1 -Fig.7, what is to be described is a method of using the safety needle assembly having the needle protection device of the present invention.

[0110] Fig. l illustrates a before-use state of the safety needle assembly according to the present invention. The push rod 5 is completely received in the barrel 4, the collar 1 is fixed on the needle seat 8, the sliding sleeve 2 is retained at the retracted position, the protective cap 7 is positioned around the sliding sleeve 2 to enclose the needle tube 6.

[0111] In use, the protective cap 7 is removed. The sliding sleeve 2 is temporarily retained at the retracted position by the projections 31 on the inner surface of the sliding sleeve 2 being snap-fitted in the circumferential grooves 15 on the bosses of the collar, to prevent the sliding sleeve 2 from sliding and interfering in the operation. At this time, the push rod 5 is pulled downward to draw the liquid medicament, as shown in Fig.2.

[0112] In medical practice, usually the safety needle assembly which has already drawn the liquid medicament needs to be transferred from place to place, or might not be immediately used for injection after drawing of the liquid medicament. In order to protect the needle tube 6 and prevent occurrence of accidental sticks after this procedure, the sliding sleeve 2 may be pushed upward and temporarily retained at the extended position by the convex points 27 on the inner surface of the sliding sleeve 2 being snap-fitted in the depressions 13 on the collar bosses 12 in a separable manner, so that the needle tube 6 is covered in the sliding sleeve 2, as shown in Fig.3. When the sliding sleeve 2 is temporarily retained at the extended position, the bosses 12 on the collar 1 are located outside the snap grooves 28 of the sliding sleeve 2, as shown in Fig.4.

[0113] Fig.5 shows an injection state. Upon injection, an appropriate force is applied to push the sliding sleeve 2 back to the retracted position, and the sliding sleeve 2 is temporarily retained at the retracted position by the projections 31 on the inner surface of the sliding sleeve 2 being snap-fitted in the circumferential grooves 15 on the bosses of the collar, to prevent possible sliding of the sliding sleeve 2 from interfering in the injection process.

[0114] Fig.6 illustrates a state upon completion of injection. The sliding sleeve 2 is slid to the extended position again, then the sliding sleeve 2 is rotated related to the collar 1 so that the bosses 12 on the collar 1 are snap-fitted in the snap grooves 28 of the sliding sleeve 2 in an inseparable manner, so as to prevent accidental sticks of the needle tube 6 and meanwhile prevent reuse of the safety needle assembly, as shown in Fig.7.

[0115] Those skilled in the art should understand that the above description is only exemplary. Having the benefit of the present invention, those skilled in the art may make various variations, modifications or substitutions to the above-described embodiments according to specific situations.

[0116] For example, the guide ribs 26 on the inner surface of the sliding sleeve 2 are interchangeable with the longitudinal guide grooves 16 on the bosses 12 of the collar, that is, the guide ribs may be formed on the outer surface of the bosses 12 while the longitudinal guide grooves may be formed on the inner surface of the sliding sleeve 2. Similarly, the convex points 27 on the inner surface of the sliding sleeve 2 are interchangeable with the depressions 13 on the bosses 12, and the projections 31 on the inner surface of the sliding sleeve 2 are interchangeable with the circumferential grooves 14 on the bosses.

[0117] Again for instance, the convex points 27/depressions 13 and projections 31 /circumferential grooves 14 are used to temporarily retain the sliding sleeve 2 at the extended position and the retracted position, but this structure is not requisite. For example, since the depth of the longitudinal guide grooves 16 is smaller than that of the depressions 13, the frictional force between the convex points 27 and the longitudinal guide grooves 16 is, in some applications, sufficient to temporarily retain the sliding sleeve 2 at the extended position and the retracted position. Even without the convex points, the frictional force between the sliding sleeve 2 and the bosses 12 may be designed to achieve the temporary retention at the extended position and the retracted position.

[0118] Figs.28-38 illustrate a safety needle assembly according to another embodiment of the present invention. Although these figures do not show the protective cap, the safety needle assembly of the instant embodiment may have the same protective cap as the protective cap shown in Figs.23-25, or any protective cap adapted to be positioned around the upper portion of the sliding sleeve. Besides the needle protection device, the safety needle assembly of the instant embodiment may have the same structure as shown in Figs.1-27, or any suitable structure already known in the art. Only the needle protection device in the instant embodiment is described as follows.

[0119] Figs.27, 28 and 29 are sectional views illustrating that the sliding sleeve is pulled up and rotated upon completion of the injection of the safety needle assembly. In the needle protection device according to the instant embodiment, a collar 100 is fixed on the needle seat, a sliding sleeve 200 is configured to slide up and down along the collar 100 to take an extended position or a retracted position.

[0120] Figs.32 and 33 illustrate the collar 100 in the safety needle assembly of the instant embodiment. The collar 100 is generally a hollow cylinder such as a circular cylinder and comprises ribs 130 formed on an inner surface thereof and bosses 110 formed on an outer surface 140 thereof. The ribs 130 are located between the ribs 81 on the outer surface of the needle seat (referring to Figs.20 and 22), and may, upon installation, guide the collar to be positioned around the needle seat and prevent the collar from rotating relative to the needle seat 8. The bosses 110 can be snap-fitted into snap grooves 223 on an inner surface of the sliding sleeve 200 so that the sliding sleeve 200 is fixed at the position shown in Fig.29, as shown in Figs.30 and 31 (which will be described in detail hereunder). The bosses 110 can further be used to guide guide ribs 220 (to be described in detail hereunder) on the inner surface of the sliding sleeve 200 to slide between the bosses 110 and prevent the sliding sleeve 200 from rotating relative to the collar 100.

[0121] In a preferred embodiment, cavities 120 may be formed on an end wall 150 of the collar 100. The positions of the cavities 120 correspond to those of the bosses 110 on an outer surface 140. The presence of the cavities 120 allows the bosses 110 to generate elastic displacement of certain degree in a radial direction, to help the boss 110 be snap-fitted into the snap grooves 223 in the sliding sleeve 200 (referring to Figs.30 and 31).

[0122] Hereunder, reference is made to Figs.34-36 to describe the sliding sleeve 200 of the instant embodiment. The sliding sleeve 200 is generally a barrel, e.g., a circular barrel. Guide ribs 220 are formed on the inner surface of the sliding sleeve 200 in an axial direction of the sliding sleeve. The guide ribs 200 may be in variously forms so long as they are slideable between the bosses 110 of the outer surface 140 of the collar 100.

[0123] Those skilled in the art should appreciate that with regard to guiding the sliding sleeve 200 to slide along the collar 100 and preventing the sliding sleeve 200 from rotating relative to the collar 100, it is either possible that at least one boss 110 is provided between two or more guide ribs 220, or that at least one guide rib 220 is provided between two or more bosses 110.

[0124] A lower portion of each of the guide ribs 220 is formed with a radially raised portion 221. A radially inwardly projecting distance of the radially raised portion 221 is designed such that when the sliding sleeve 200 is pulled up (referring to Fig.28), the sliding sleeve 200 is fixed at the extended position in a separable manner by means of interference fit between the radially raised portion 221 and the outer surface 140 of the collar 100. A magnitude of the interference can be selected according to factors such as material, weight and the like of the parts, or selected by means of experiments such that when the radially raised portion 221 contacts the outer surface 140 of the collar 100, the sliding sleeve 200 is fixed at the extended position shown in Fig.28; when the sliding sleeve 200 is pushed or pulled downwardly, the sliding sleeve 200 may be pulled or pushed back to the retracted position shown in Fig.27, i.e., the sliding sleeve 200 is fixed at the pulled-up position shown in Fig.28 in a separable manner. In use of the safety needle assembly, if the safety needle assembly which has already drawn the liquid medicament needs to be transferred (referring to Fig.3), the needle tube is protected out of contact during transfer by the sliding sleeve 200 being fixed at the extended position in a separable manner. [0125] A lower flange 211 protruding towards the center may be formed at a lower end of the sliding sleeve 200 to prevent the sliding sleeve 200 from disengaging from the collar 100 due to excessive force when the sliding sleeve 200 is pulled up, as shown in Figs.28, 29, 35 and 36. An inner diameter of the lower flange 211 is smaller than an outer diameter of the outer surface 140 of the collar 100 so that the lower flange 211 can abut against the end wall 150 of the collar 100 to prevent the sliding sleeve 200 from being further pulled up.

[0126] Referring to Figs.30, 31 and 36, a snap groove 223 is formed on a lower portion of the radially raised portion 221. The boss 110 of the collar 100 is snap-fitted in the snap groove 223 in an inseparable manner. Cross-sectional shapes of the boss 110 and the snap groove 223 may be one of rectangle, square, toothed shape, swallow tail shape and T shape, or any known structure in the art that can prevent the boss 110 from disengaging from the snap groove 223.

[0127] In order to facilitate rotation of the sliding sleeve 200 relative to the collar 100 so as to catch the boss 110 in the snap groove 223, as shown in Figs.30, 31, 35 and 36, a circumferential outer edge 222 of the snap groove 223 may be formed as a ramp.

[0128] Referring to Fig.36, a slide-stopping protuberance 240 may be formed on an upper portion of the inner surface of the sliding sleeve 200. The slide-stopping protuberance 240 may be in any shape, including but not limited to a sphere, a cube, a cuboid, a cone and etc.. The slide-stopping protuberance 240 may be provided on the guide rib 220, or on the inner surface of the sliding sleeve other than the guide ribs. There can be any number of slide-stopping protuberances arranged at any desired positions of the upper portion of the inner surface of the sliding sleeve 200. The slide-stopping protuberances at different positions can have different shapes. The slide-stopping protuberances 240 are designed such that when the sliding sleeve 200 is located at the position shown in Fig.27, the slide-stopping protuberances engage the outer surface 140 and/or bosses 110 of the collar 100 in a separable manner by means of interference fit with the outer surface 140 and/or bosses 110 of the collar 100, thereby preventing the sliding sleeve 200 from moving relative to the collar 100, and particularly when a tip of the needle tube faces downwardly during the injection, preventing the sliding sleeve 200 from accidentally sliding towards the tip of the needle tube and interfering in normal performance of the injection.

[0129] Those skilled in the art should understand that the slide-stopping protuberances can be provided on the collar, or simultaneously provided on the collar and the sliding sleeve.

[0130] Referring to Fig.27, as a preferred embodiment, an upper end portion of the sliding sleeve 200 may be connected to a snap cap 300. At a lower end of the snap cap 300 is formed an outwardly extending flange 340. Referring to Figs.27, 34 and 36 at the same time, a hook- like member 230 is formed at the upper end of the outer surface 210 of the sliding sleeve 200. The hook- like member 230 may be an annular hook- like member as shown in the figure, or discrete hook- like members formed at several positions. The flange 340 of the snap cap 300 may be snap-fitted in the hook-like member 230 so as to connect the snap cap 300 with the sliding sleeve 200.

[0131] As shown in Figs.37 and 38, the snap cap 300 is in a shape of a barrel of which the inner shape may match the outer surface of the upper end of the sliding sleeve 200 so that the snap cap 300 can be positioned around the outer surface of the upper end of the sliding sleeve 200. An upper end face 330 of the snap cap 300 extends from an upper end of the snap cap 300 towards the center, and is formed with a central hole 310. The central hole 310 can permit the needle tube or an upper portion of the needle seat to pass therethrough. Meanwhile, a diameter of the central hole 310 is smaller than an outer diameter of the sliding sleeve 200, and preferably smaller than an inner diameter of the sliding sleeve 200. Therefore, the upper end face 330 may abut against the top end of the sliding sleeve 200.

[0132] Since the snap cap 300 is connected together with the sliding sleeve 200 and the upper end face 330 may abut against the top end of the sliding sleeve 200, in the state as shown in Fig.27, even without the above slide-stopping protuberances, the sliding sleeve 200 will not slide downwardly and disengage from the collar 100.

[0133] The safety needle assembly shown in Figs.28-38 and the safety needle assembly shown in Figs.1-27 have substantively the same operation mode, which will not be described in detail here.

[0134] Figs.39-46 illustrate another embodiment of the present invention, wherein the like reference numbers denote the like parts. As shown in Fig.39, the collar 1 is positioned around on the needle seat 8. The collar 1 may be fixed to the needle seat 8 in a manner as stated above. Here, the fixation is achieved by a circle of raised portions 101 on the inner surface of the collar 1 being snap-fitted into a circle of recessed portions formed on the outer surface of the needle seat 8. The raised portions and the recessed portions are preferably in shape of inverted cone such that the collar can be easily mounted on the needle seat and cannot easily disengage. The sliding sleeve 2 is positioned around the collar 1 and can slide up and down.

[0135] A circle of flange 102 is formed on the outer surface of the collar 1. At least one pair of protrusions 201 and 20 are formed on the inner surface of the lower end portion of the sliding sleeve 2, wherein a distance of one pair of protrusions along a longitudinal axial direction of the sliding sleeve is not smaller than a height of the flange 102 so that when the sliding sleeve is located at the extended position shown in Fig.40, the flange 102 passes across one of the pair of protrusions and is snap-fitted between the pair of protrusions so that the sliding sleeve can be locked at the extended position. Preferably, two pairs of protrusions are employed. As shown in Figs.41 and 42, the protrusions 201 and 20 form one pair and are staggered 90 degrees as viewed along the longitudinal axial direction of the sliding sleeve. Another pair of protrusions are provided oppositely in a diametrical direction respectively. In order to help the sliding sleeve to slide from the retracted position to the extended position, the protrusions to be passed across by the flange may be produced in a wedge shape. Certainly, vice versa, i.e., at least one pair of protrusions may be formed on the outer surface of the collar 1 , and a circle of flange may be formed on the inner surface of the sliding sleeve. The relative positions of the protrusions may be selected arbitrarily so long as the sliding sleeve is locked at the extended position.

[0136] As shown in Figs.39 and 40, an inwardly protruding upper flange 202 is formed on the inner surface of the upper end portion of the sliding sleeve. When the sliding sleeve is located at the retracted position, the upper flange can abut against the upper end portion of the collar to prevent the sliding sleeve from falling. The upper flange may be integrally formed with the sliding sleeve, or positioned around the upper end portion of the sliding sleeve as a separate member.

[0137] As shown in Fig.39, a circle of flange 102 is formed on the outer surface of the collar 1, one or more protrusions 203 are formed on the inner surface of the sliding sleeve below the upper flange 202. Here, one protrusion may mean one local protrusion or one circle of protrusions. When the sliding sleeve is located at the retracted position, the protrusion can abut against a lower portion of the flange 102 on the outer surface of the collar so that the sliding sleeve can be axially fixed when being located at the retracted position. Certainly, this is not requisite. A height of the protrusion here is small so that the sliding sleeve may separate from the collar and thereby leave the retracted position.

[0138] Other details are same as those of the previous embodiments and will not be described in detail any more here.

[0139] In addition, the needle protection device of the present invention may also be applied to a conventional glass syringe. As shown in Figs.43-46, a plastic outer jacket 400 is positioned around the conventional glass syringe 600. The plastic outer jacket 400 extends along an entire barrel length, having a lower portion caught on the lower portion of the barrel by means of a lower stop 401 of certain elasticity between the lower portion of the plastic outer jacket and the push rod, or having a lower portion fixed at the lower end of the barrel by press fit, as shown in Fig.45. The upper portion of the plastic outer jacket 400 may encompass the needle tube and thereby functions as the needle seat, as shown in Figs.43 and 44; the upper portion of the plastic outer jacket 400 may not encompass the needle tube and only extends to the position of the needle seat, as shown in Figs.45 and 46. The collar is positioned around the upper portion of the plastic outer jacket in a fixed manner. The sliding sleeve is positioned around on the collar and slides between the retracted position and the extended position along the collar.

[0140] Therefore, the needle seat mentioned upon describing the present invention may also refer to the upper portion of the plastic outer jacket which is positioned around the barrel and functions as the barrel. The above depictions regarding the needle seat also apply to the plastic outer jacket herein. This structure is particularly adapted for prefilled products, such as prefilled insulin syringes.

[0141] In the embodiment, the protective cap may not only be positioned around the outer surface of the sliding sleeve, but also installed within the plastic outer jacket, as shown in Fig.45.

[0142] Although the present invention has been particularly described with reference to the accompany drawings in the above, it should be understood by those skilled in the art that the above detailed descriptions are only exemplary and for illustrative purpose, but not to limit the protection scope of the present invention. Taught by the present invention, those skilled in the art may make various variations, modifications or substitutions to the above-described embodiments according to specific situations without departing from the protection scope of the present invention. These variations, modifications or substitutions fall within the protection scope of the present invention.

Claims

WHAT IS CLAIMED IS:

1. A sliding sleeve-type needle protection device, used in combination with a needle comprising a needle seat and a needle tube installed on the needle seat, characterized in that the needle protection device comprises:

a collar (1) which is in a cylindrical shape having a longitudinal axis (10) and is configured to be positioned around the needle seat (8) in a fixed manner,

a sliding sleeve (2) which is in a cylindrical shape, has an upper end portion (22) and a lower end portion (23), and is configured to be positioned around the collar (1) and slide along the collar (1) between a retracted position where the upper end portion (22) of the sliding sleeve is positioned around the collar (1) and an extended position where the lower end portion (23) of the sliding sleeve is positioned around the collar (1),

wherein an outer surface of the collar (1) and an inner surface of the lower end portion (23) of the sliding sleeve (2) are respectively formed with catching mechanisms cooperating with each other such that when the sliding sleeve (2) is at the extended position, the sliding sleeve (2) is caught on the collar (1) in an inseparable manner.

2. The needle protection device according to claim 1, characterized in that the catching mechanisms comprise one or more bosses (12) which are formed on the outer surface of the collar (1) and extend in the longitudinal axial direction, and at least one snap groove (28) formed on the inner surface of the lower end portion (23) of the sliding sleeve (2), at least one of said bosses (12) being configured to be snap-fitted in at least one of said snap grooves (28) in an inseparable manner when the sliding sleeve (2) is rotated relative to the collar (1) at the extended position.

3. The needle protection device according to claim 2, characterized in that, at least one of said bosses is formed in outer surface thereof with a longitudinal guide groove (16) extending in the longitudinal axial direction,

the inner surface of the sliding sleeve (2) is formed in snap groove-free regions thereof with at least one guide rib (26) which extends between the upper end portion (22) and the lower end portion (23) and is configured to slide in the longitudinal guide groove (16) in the longitudinal axial direction, the guide rib (26) and the longitudinal guide groove (16) are configured such that when the sliding sleeve (2) is rotated relative to the collar (1), the guide rib (26) is allowed to disengage from the longitudinal guide groove (16).

4. The needle protection device according to claim 2, characterized in that, the inner surface of the sliding sleeve is formed in snap groove-free regions thereof with at least one longitudinal guide groove which extends between the upper end portion and the lower end portion,

at least one of said bosses is formed on the outer surface thereof with a guide rib which extends in the longitudinal axial direction and is configured to slide in the longitudinal guide groove in the longitudinal axial direction,

the guide rib and the longitudinal guide groove are configured such that when the sliding sleeve is rotated relative to the collar, the guide rib is allowed to disengage from the longitudinal guide groove.

5. The needle protection device according to claim 3 or 4, characterized in that, the guide rib (26) is formed with a convex point (27) which protrudes more than other portions of the guide rib, the longitudinal guide groove (16) is formed with a depression (13) which is deeper than other portions of the longitudinal guide groove, the convex point (27) is configured to be snap-fitted in the depression (13) in a separable manner when the sliding sleeve (2) slides to the extended position.

6. The needle protection device according to claim 5, characterized in that, at the location of the depression (13) is formed a circumferential guide groove (14) which extends circumferentially and has a depth smaller than that of the depression, and the convex point is configured to slide in the circumferential guide groove (14) when the sliding sleeve (2) is rotated relative to the collar at the extended position.

7. The needle protection device according to claim 2, characterized in that, a convex point (27) is formed on one of the inner surface of the sliding sleeve (2) and the outer surface of the boss (12), a depression (13) is formed on the other of the inner surface of the sliding sleeve and the outer surface of the boss, and the convex point (27) is configured to be snap-fitted in the depression (13) in a separable manner when the sliding sleeve slides to the extended position.

8. The needle protection device according to claim 2, characterized in that, a plurality of projections (31) are formed on the inner surface of the upper end portion of the sliding sleeve (2), a circumferential groove (15) is formed on the outer surface of the boss (12), and the projections (31) are configured to be snap-fitted into the circumferential grooves (15) in a separable manner when the sliding sleeve (2) is at the retracted position.

9. The needle protection device according to claim 2, characterized in that, the upper end portion of the sliding sleeve is formed on the inner surface thereof with a circumferential groove, at least one of said bosses is formed with an outwardly protruding projection, and the projection is configured to be snap-fitted in the circumferential groove in a separable manner when the sliding sleeve is at the retracted position.

10. The needle protection device according to claim 9, characterized in that, an inwardly protruding upper flange (24) is formed on the inner surface of the upper end portion of the sliding sleeve (2),

the upper end portion of the boss (12) of the collar extends in a longitudinal direction out of the outer surface (11) of the collar (1),

the upper flange (24) is configured to abut against an upper end face (18) of the upper end portion of the boss to prevent the sliding sleeve (2) from falling when the sliding sleeve (2) is located at the retracted position.

11. The needle protection device according to claim 1 or 2, characterized in that, an inwardly protruding lower flange (25) is formed on the inner surface of the lower end portion of the sliding sleeve (2), and the lower flange (25) is configured to engaged on the lower end portion of the collar (1) to prevent the sliding sleeve (2) from being pulled away from the collar (1) from the extended position when the sliding sleeve is located at the extended position.

12. The needle protection device according to claim 2, characterized in that, a radially raised portion (221) is formed on the inner surface of the lower end portion of the sliding sleeve, and the sliding sleeve (200) is configured to be fixed at the extended position in a separable manner by an interference fit between the radially raised portion and the outer surface (140) of the collar (100) when the sliding sleeve is located at the extended position.

13. The needle protection device according to claim 12, characterized in that, the snap groove (223) is formed on the radially raised portion (221).

14. The needle protection device according to claim 13, characterized in that, cross-sectional shapes of the boss (110) and the snap groove (223) are one of a swallow tail shape, a T shape, a rectangle, a square, and a toothed shape.

15. The needle protection device according to claim 13, characterized in that, a circumferential outer edge (222) of the snap groove (223) is a ramp to help the boss (110) enter the snap groove (223).

16. The needle protection device according to claim 12, characterized in that, a guide rib (220) is formed on the inner surface of the sliding sleeve in the axial direction of the sliding sleeve, and the radially raised portion (221) is formed at the lower portion of the guide rib.

17. The needle protection device according to claim 16, characterized in that, the guide rib (220) and the boss (110) of the collar (100) are configured to guide the sliding sleeve (200) to slide along the collar (100) and prevent the sliding sleeve (200) from rotating relative to the collar (100).

18. The needle protection device according to claim 12, characterized in that, the needle protection device further comprises a snap cap (300) configured to be positioned around the upper end portion of the sliding sleeve (200), the snap cap (300) comprising: an upper end face (330) formed with a central hole (310) through which a needle tube is allowed to extend so that the upper end face abuts against a top end of the sliding sleeve (200); and

a flange (340) formed by the lower end of the snap cap (300) extending outwardly, wherein a hook-like member (230) is formed on outer surface (210) of the upper end portion of the sliding sleeve (200), the hook- like member (230) is configured to snap-fit with the flange (340) of the snap cap (300), thereby connecting the snap cap to the upper end portion of the sliding sleeve.

19. The needle protection device according to claim 2, characterized in that, one or more cavities (120) are formed on an end wall (150) of the collar (100), and the positions of the one or more cavities (120) correspond to the one or more bosses (110) of the collar.

20. The needle protection device according to claim 2, characterized in that, a slide-stopping protuberance (240) is formed on the inner surface of the sliding sleeve (200) and/or the outer surface of the collar (100), to prevent the sliding sleeve (200) from moving relative to the collar (100) in a separable manner.

21. The needle protection device according to claim 1, characterized in that, the catching mechanisms comprise a circle of flange on one of the outer surface of the collar and the inner surface of the sliding sleeve, and at least one pair of protrusions on the other of the outer surface of the collar and the inner surface of the sliding sleeve, a distance of the one pair of protrusions in the longitudinal axial direction is not smaller than a height of the flange, and the flange is configured to pass across one of the pair of protrusions and be snap-fitted between the pair of protrusions when the sliding sleeve slides from the retracted position to the extended position.

22. The needle protection device according to claim 21, characterized in that, the pair of protrusions are staggered 90 degrees as viewed along the longitudinal axial direction.

23. The needle protection device according to claim 21, characterized in that, the protrusion to be passed across by the flange is in a wedge shape.

24. The needle protection device according to claim 21, characterized in that, an inwardly protruding upper flange is formed on the inner surface of the upper end portion of the sliding sleeve, and the upper flange is configured to abut against the upper end portion of the collar to prevent the sliding sleeve from falling when the sliding sleeve is located at the retracted position.

25. The needle protection device according to claim 24, characterized in that, a circle of flange is formed on the outer surface of the collar, one or more protrusions are formed on the inner surface of the sliding sleeve below the upper flange, and the protrusion formed below the upper flange is configured to abut against a lower portion of the flange on the outer surface of the collar when the sliding sleeve is located at the retracted position.

26. The needle protection device according to claim 1, characterized in that, the collar is fixed with the needle seat by an interference fit.

27. The needle protection device according to claim 1, characterized in that, a circle of raised portions formed on the inner surface of the collar are configured to cooperate with a circle of recessed portions formed on the outer surface of the needle seat to form fixation.

28. A safety syringe, comprising a needle seat and a needle tube mounted on the needle seat, characterized in that, the safety syringe further comprises the needle protection device according to any one of claims 1-27.

29. The safety syringe according to claim 28, characterized in that the safety syringe further comprises a protective cap (7) for enclosing the needle tube, an upper end portion of the protective cap is closed, a lower end portion thereof is open and is configured to be positioned around an outer surface of an upper end portion of the sliding sleeve (2).

30. The safety syringe according to claim 29, characterized in that, an outwardly protruding external flange (29) is formed on the outer surface of the upper end portion of the sliding sleeve (2), and the lower end portion of the protective cap (7) is configured to abut against the external flange (29).