DE29800200U1 - Retractable and destructible safety syringe - Google Patents

Description

DEG-36 498

RETRACTABLE AND DESTRUCTIBLE SAFETY SYRINGE

Description

The present invention relates to a retractable and destructible safety syringe with a simple structure that can be easily and inexpensively manufactured and easily marketed.

Many different types of disposable syringes are used today. However, large quantities of these syringes pose a problem in terms of environmental pollution after they are thrown away. The used syringes pose a danger to medical staff; the staff can

&iacgr;&ogr; on the syringes with the patients’ viruses and bacteria. In particular, infection with the AIDS virus poses a potentially fatal risk for the staff.

To avoid such problems, various types of retractable syringes have been developed. For example, a spring has been inserted between the barrel of the syringe and the plunger, which retracts the needle into the barrel after injection. However, due to the properties of the liquid medicines in the syringe, there are significant limitations on the material of the spring. The structure of such a syringe is complicated, the manufacturing cost for it is large. Various types of safety syringes without springs have also been developed. In these syringes, there is a connecting element at the bottom of the barrel that connects the plunger to the needle when the plunger is pressed down to the bottom of the barrel. Then, when the plunger is retracted, the needle is drawn into the barrel by the plunger so that the medical staff are not at risk.

In order to prevent the liquid drug from leaking out and the needle from accidentally falling out of the barrel, the needle must be firmly connected to the barrel. However, if the needle is extremely firmly connected to the barrel, it will be difficult to retract the needle into the barrel. It is therefore difficult to meet these two requirements well at the same time.

In addition, it is relatively difficult to connect the piston securely to the needle. If the piston can easily

γ of the needle, which is desirable in itself, the connection may be unreliable and not sufficient to retract the needle into the cylinder. Here too, two contradictory requirements must be met simultaneously.

is In addition, it happens from time to time that the

The connection between the plunger and the needle is made before the injection is completed. This renders the syringe prematurely unusable.

The object of the present invention is to create a retractable and destructible safety syringe, in which no liquid medicine escapes between the cylinder and the needle and in which the needle cannot undesirably fall out of the cylinder. The needle should be easy to retract into the cylinder.

This object is achieved according to the invention with a retractable and destructible safety syringe, which comprises a syringe barrel with a first and a second end and an interior, wherein the first end is provided with a needle seat with a needle holding cavity and an annular shoulder section is formed between the interior and the cavity. The safety syringe according to the invention further comprises a piston with a first and a second end, wherein the first end is provided with a piston bottom and is inserted into the cylinder and the piston defines a first axis. In addition, a

Needle holder with a first and a second end is provided, wherein the outer periphery of the second end is inserted into the interior space at the first end of the cylinder and the needle holder defines a second axis. A needle is inserted into the first end of the needle holder. A needle retraction device comprises at least one pawl with a first and a second end, wherein the first end is pivotally and elastically attached to either the first end of the piston or the first end of the needle holder. The distance between the first end of the pawl and the first or the second axis is defined as a first distance. The second end of the pawl extends to the first end of the needle holder or to the first end of the piston, respectively, and in the free state the distance between the second end of the

is pawl and the first or second axis is defined as a second distance. The second distance is smaller than the first distance. A lock is provided with a first end and a second end, the first end being arranged at the first end of the needle holder or the first end of the piston. The first end of the lock extends along the axes to the first end of the piston or the first end of the needle holder. The second end of the lock is provided with a hook portion with a radially extending hook surface. When the first end of the piston is pressed towards the first end of the cylinder, the hook portion of the lock slides over the second end of the pawl, whereupon the pawl elastically engages the hook of the lock. When the piston is retracted from the first end of the cylinder to the second end thereof, the hook surface of the hook portion engages the second end of the pawl and forces the second end toward the center of the catch so that a firm engagement with the hook surface of the hook portion is achieved and the needle holder is retracted into the cylinder together with the needle. Preferably, two or more

Pawls are provided which are arranged radially around the axes.

The inner wall of the needle holding cavity or the outer wall of the needle holder can be provided with a sealing fastening ring. At least two sealing fastening rings can also be provided.

Both the inner wall of the needle holding cavity and the outer wall of the needle holder may further comprise mating sealing retaining rings.

&iacgr;&ogr; The safety syringe advantageously further comprises: A safety locking plate having a first and a second end, the first end being connected to the second end of the cylinder; a first locking portion at the second end of the safety locking plate; and a second locking portion at the second end of the piston. The second locking portion is locked to the first locking portion such that the locking device is located in proximity to the locking pawl, preventing the locking device from prematurely engaging the locking pawl in an undesirable manner.

In the safety syringe according to the invention, the piston can be easily and yet firmly connected to the needle so that the needle is reliably retracted into the cylinder.

In the safety syringe according to the invention, the needle cannot be prematurely connected to the plunger before the injection is completed.

Embodiments of the safety syringe according to the invention are explained in more detail below using the drawing &khgr;. Shown are: , f\

Fig. 1 is a perspective, exploded view of a first embodiment of the safety syringe;

Fig. 2 is a perspective view of the first embodiment of Fig. 1 in the assembled state;

Fig. 3 is a perspective view of the needle and needle holder of the first embodiment from below;

Fig. 4 is a sectional view through the first embodiment when a liquid drug is sucked into the cylinder of the syringe;

Fig. 5 is a sectional view through the first embodiment when the liquid drug is completely injected and the locking device attached to the piston base is engaged with the pawl on the needle holder;

&iacgr;&ogr; Fig. 6 is a partial side view when the liquid

drug is almost completely injected and the lock passes the pawl;

Fig. 7 is a partial side view when the locking device has passed the pawl and is engaged thereby;
Fig. 8 is a sectional view after the end of the injection, when the needle has been retracted into the barrel and automatically tilted to the side;

Fig. 9 is an enlarged view of the area 9 shown in dashed lines in Fig. 7 when the piston is pulled downwards and two locking pawls clamp the piston simultaneously;

Fig. 10 is a sectional view after the needle has been retracted into the cylinder and the piston has been pushed forward again to bend and destroy the needle;
Fig. 11 is a sectional view of a second embodiment of the safety syringe during aspiration of a liquid drug into the barrel of the syringe;

Fig. 12 is a side view of the needle and needle holder of the second embodiment;

Fig. 13 is an enlarged bottom view of the needle and needle holder of the second embodiment;

Fig. 14 is a sectional view according to Fig. 12 when the liquid drug is completely injected and the locking pawl attached to the plunger is engaged with the lock on the needle holder;

Fig. 15 is a side view of the needle and needle holder of a third embodiment of the safety syringe;

Fig. 16 is an enlarged bottom view of the needle and needle holder of the third embodiment; and
Fig. 17 is a sectional view according to Fig. 15 when the liquid drug is completely injected and the locking pawl attached to the piston is engaged with the lock on the needle holder.

&iacgr;&ogr; The first embodiment of a safety syringe 20 shown in Figs. 1 to 4 comprises a cylinder 21, a piston 22, a needle holder 23 and a needle 24. The cylinder 21 has a first end 28 and a second end 29 and surrounds an interior space 27. The first end 28 is provided with a needle seat 30 with a needle holding cavity 31. An annular shoulder section 33 is formed between the interior space 27 and the cavity 31. The piston 22 has a first end 34 and a second end 35. The first end 34 is provided with a piston bottom 36 and is inserted into the cylinder 21. The piston 22 defines a first axis 47. The needle holder 23 has a first end 37 and a second end 38. The outer periphery of the second end 38 is inserted into the interior 27 of the first end 28 of the cylinder 21. The needle holder 23 defines a second axis 48.

The needle 24 is inserted into the first end 37 of the needle holder 23, with the second axis 48 running in the extension of the first axis 47 of the piston 22.

As shown in Figs. 3 to 9, a needle retraction device comprises two pawls 25 and 25' and a lock 26. The pawls 25 and 25' each have a first end 49 and a second end 50. The first end 49 is pivotally and elastically attached to the first end 34 of the piston 22 or the first end 37 of the needle holder 23. The distance between the first end 49 of the pawl 25, 25* and the first or second axis 47, 48 is first

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Distance 51 is defined. The second end 50 of the pawl 25, 25' extends to the first end 37 of the needle holder 23 or the first end 34 of the piston 22. In the free state, the distance between the second end 50 of the pawl 25 and the first or second axis 47, 48 is defined as the second distance 52. The second distance 52 is smaller than the first distance 51.

According to Figs. 3 to 14, the locking device 26 has a first end 53 and a second end 54. The first end 53

γ is attached to the first end 37 of the needle holder 23 or the first end 34 of the piston 22. The first end 53 extends along the axes 47, 48 to the first end 34 of the piston 22 or to the first end 37 of the needle holder 23. The second end 54 of the lock 26 is provided with a hook portion 55 with a radially extending hook surface 56. A shaft 58 extends between the hook portion 55 and the first end 53 of the lock 26.

When the first end 34 of the piston 22 is advanced to the first end 28 of the cylinder 21, the hook portion 55 of the lock 26 slides over the second end 50 of the pawls 25 and 25', and the pawls 25 and 25' resiliently clamp the shaft 58. When the piston 22 is retracted from the first end 28 of the cylinder 21 to its second end 29, the hook surface 56 of the hook section 55 abuts the second end of the pawl 25 or 25' and forces the second end 50 in the direction shown by the arrows 57 or 57' (Fig. 9) towards the center of the lock 26, so that a firm engagement with the hook surface 56 of the hook section 55 is created, whereby the needle holder 23 can be drawn together with the needle 24 into the cylinder 21.

As shown in Figs. 3 to 9, the safety syringe 20 can, if necessary, be provided with at least two locking pawls 25, 25' arranged radially around the axes 47, 48.

According to Figs. 1 to 9, the inner wall of the needle holding cavity 31 of the cylinder 21 or the outer wall of the needle holder 23 comprises, if necessary, one or more sealing fixing rings 32.

According to Figs. 15 to 17, both the inner wall of the needle holding cavity 31 of the cylinder 21 and the outer wall of the needle holder 23 can, if necessary, have one or more matching and cooperating sealing fastening rings 32, 39.

1 and 2, the safety syringe 20 further includes a safety latch plate 41, a first latch portion 42 and a second latch portion 43. The safety latch plate 41 has a first end 45 and a second end 46. The first end 45 is connected to the second end 29 of the cylinder 21. The first latch portion 42 is disposed at the second end 46 of the safety latch plate 41. The second latch portion 43 is disposed at the second end 35 of the piston 22. The second latch portion 43 can be latched to the first latch portion 42 such that the catch 26 is located near the pawl 25 without the catch 26 being able to inadvertently engage the pawl 25.

As shown in Figs. 1 to 4, before use, the needle 24 is inserted into the needle holding cavity 31 of the seat 30. The sealing fastening ring 39 of the needle holder 23 is closely and firmly engaged with the sealing fastening ring 32 on the inner wall of the cavity 31. The needle 24 is surrounded by a needle cover 44. The piston 22 with the piston bottom 36 is inserted into the interior 27 of the cylinder 21. The first locking portion 42 of the safety locking plate 41 is engaged in the second locking portion 43 on the second end 35 of the piston 22. The lock 26 is located near the pawls 25 and 25', but is separate from them.

Before an injection, the operator inserts the needle 24 into a bottle containing a liquid medicine. He then releases the safety catch plate 41, which makes it possible to pull out the piston 22 so that the liquid medicine is sucked into the cylinder 21 (Fig. 4). The needle 24 is then directed upwards and the piston 22 is pushed slightly upwards to expel the air in the upper section of the cylinder 21 at the tip 40 of the needle 24. After the injection, as shown in Figs. 5 and 9, the piston 22 is pushed back to the

Î bottom of the cylinder 21. The locking device 26 can simply push the pawls 25 and 25' to the side and automatically engage with the pawls 25 and 25' on the second end 38 of the needle holder 23. The pawls 25 and 25' clamp the shaft 58 of the locking device 26 elastically. Then, as shown in Fig. 8, when the piston 22 is retracted, the two opposing pawls 25 and 25' are pressed down by the hook surface 56 of the locking device 26 and are each pivoted about the bending sections 59 and 59' in the direction indicated by the arrows 58 and 58'. The opposing pawls 25 and 25' clamp the shaft 58 of the locking device 26 firmly. The greater the downward pulling force on the piston 22, the greater the clamping force. The pawls 25 and 25' can therefore clamp the hook surface 56 of the locking device 26 very tightly without becoming loose (see Fig. 9).

When, as shown in Fig. 8, the needle 24 is completely retracted into the cylinder 21, the pawls 25 and 25' are only loosely engaged with the locking device 26, so that the tip 40 of the needle 24 tilts to the side due to the unstable position. The tip 40 is thus located under the shoulder section 33 of the cylinder 21. The narrow rear end 60 of the needle cover 44, which was initially attached to the needle holder 23, is then inserted into the needle holding cavity 31 to close it. This prevents the tip 40 of the needle 24 from unexpectedly coming out of the

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needle holding cavity 31. Finally, as shown in Fig. 10, the piston 22 is pushed forward to press the tip 40 against the shoulder 33 of the cylinder 21 and bend and destroy the needle 24.
Fig. 11 to 14 show a second embodiment of the safety syringe. The syringe is handled in the same way as in the first embodiment. The only difference between the two embodiments is that the arrangement of the locking pawls 25 and 25' and the locking mechanism 26 are swapped.

The safety syringe 20 described thus essentially consists of the cylinder 21, the piston 22, the needle holder 23, the needle 24, preferably two or more locking pawls 25, 25' on the needle holder 23 or piston 22 and the

is the movable one-way lock 26 on the piston 22 or needle holder 23. When the piston bottom 36 of the piston 22 is pushed forward to the bottom of the cylinder 21, the lock 26 firmly engages the pawls 25, 25' so that the needle holder 23 can be retracted into the cylinder 21 together with the needle 24. The tip 4 0 of the needle 24 is then pressed against the shoulder section 33 of the cylinder 21 and bent over, thereby destroying it. For the sealing and easily releasable engagement of the needle holder 23 with the needle holding cavity 31 on the cylinder 21, the sealing fastening rings 32, 3 9 are provided on the outer wall of the needle holder 23 and the inner wall of the needle holding cavity 31. The safety locking plate 41 is arranged between the cylinder 21 and the piston 22, which prevents the piston 22 from being pushed forwards inadvertently and the pawls 25, 25' from undesirably prematurely engaging the locking device 26.

The present invention therefore has the following advantages:

1. No liquid comes out of the safety syringe due to the relatively firm connection between the needle holder and the cylinder.

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liquid medicine and the needle cannot fall out of the cylinder. The needle can still be easily retracted into the cylinder.

2. The piston can be easily and securely connected to the needle so that the needle is reliably retracted into the cylinder.

3. It safely prevents the needle from being accidentally connected to the plunger before the injection.

Claims (7)

- 12 - Protection claims 1. Retractable and destructible safety syringe, with a cylinder (21) having a first end (28) and a second end (29) and an interior space (27), the first end (28) being provided with a needle seat (30) with a needle holding cavity (31) and an annular shoulder portion (33) being formed between the interior space (27) and the needle holding cavity (31); a piston (22) having a first end (34) and a second end (35), the first end (34) being provided with a piston bottom (36) and inserted into the cylinder (21) and the piston (22) defining a first axis (47); a needle holder (23) having a first end (37) and a second end (38), the outer periphery of the second end (38) being inserted into the interior (27) at the first end (28) of the cylinder (21) and the needle holder (23) defining a second axis (48); and with a needle (24) inserted into the first end (3 7) of the needle holder (23); characterized by a needle retraction device with at least one locking pawl (25) with a first end (49) and a second end (50), wherein the first end (49) is pivotably and elastically attached to the first end (34) of the piston (22) or the first end (37) of the needle holder (23) and the distance between the first end (49) of the locking pawl (25) and the first or second axis (47, 48) is defined as the first distance (51), and wherein the second end (50) of the locking pawl (25) extends to the first end (37) of the needle holder (23) or the first end (34) of the piston (22) and in the free state the distance between the second end (50) of the locking pawl (25) and the first or M it i ·« ·* - 13 - the second axis (47, 48) is defined as a second distance (52) which is smaller than the first distance (51); and with a locking device (26) with a first end (53) and a second end (54), the first end (53) being attached to the first end (3 7) of the needle holder (2 3) or the first end (34) of the piston (22) and the first end (53) extending along the axes (47, 48) to the first end (34) of the piston (22) or the first end (37) of the needle holder (23) and the second end (54) of the locking device (26) with &iacgr;&ogr; a hook portion (55) with a radially extending hook surface (56) such that when the first end (34) of the piston (22) is advanced to the first end (28) of the cylinder (21), the hook portion (55) of the locking device (26) over the second end (50) of the pawl (25) slides and the pawl (25) elastically engages the hook (55) of the lock (26), and that when the piston (22) is retracted from the first end (28) of the cylinder (21) to its second end (29), the hook surface (56) of the hook section (55) rests against the second end of the pawl (25) and forces the second end (50) towards the centre of the lock (26) so that a firm engagement with the hook surface (56) of the hook section (55) is created for retracting the needle holder (23) and the needle (24) into the cylinder (21). 2. Safety syringe according to claim 1, characterized in that at least two locking pawls (25, 25') are provided radially around the axes. 3. Safety syringe according to claim 1, characterized in that a sealing fastening ring (32) is provided on the inner wall of the needle holding cavity (31) or the outer wall of the needle holder (23). - 14 - 4. Safety syringe according to claim 3, characterized in that at least two sealing fastening rings (32) are provided. 5. Safety syringe according to claim 1, characterized in that both the inner wall of the needle holding cavity (31) of the cylinder (21) and the outer wall of the needle holder (23) have matching sealing fastening rings (32, 39). 6. Safety syringe according to claim 5, characterized in that at least two sealing fastening rings (32, 39) are provided. 7. Safety syringe according to one of the preceding claims, characterized by a locking plate (41) having a first end (45) and a second end (46), the first end (45) being connected to the second end (29) of the cylinder (21); by a first locking portion (42) at the second end (46) of the locking plate (41); and by a second locking portion (43) at the second end (35) of the piston (22), the second locking portion (43) being locked onto the first locking portion (42) such that the locking device (26) is located near the pawl (25), but cannot inadvertently engage therewith.