WO2013127036A1

WO2013127036A1 - Needle retractable-type safe self-destructing syringe

Info

Publication number: WO2013127036A1
Application number: PCT/CN2012/000927
Authority: WO
Inventors: 王祖扬
Original assignee: Wang Zuyang
Priority date: 2012-02-29
Filing date: 2012-07-05
Publication date: 2013-09-06
Also published as: CN103285466B; CN103285466A

Abstract

A needle retractable-type safe self-destructing syringe comprising a barrel body (1). An inner needle base body (3) is arranged within a barrel neck (2) at an end part of the barrel body (1). The barrel neck (2) and the inner needle base body (3) form therebetween a flexible cushioning stopper mechanism (4). An asymmetric retracting-locking piece (10) having a flexibility feature is arranged at an end part of a syringe plunger (8). The asymmetric retracting-locking piece (10) is a plastic barb body and is formed with the plunger (8) in a single mold-forming. The flexibility feature implements engagement with and locking onto an outer sleeve-type retracting-locking component (5) connected to the lower part of the needle base body (3). In a stress environment of an asymmetric force, the needle base body (3) deflects to a side after being retracted into the barrel body, while an injection needle therefore swings in the direction of a nearly 45 degree angle towards a side of the inner wall of the barrel body (1) and is locked by the barrel neck (2). This prevents the injection needle and the needle base body (3) from being pushed out of the barrel neck (2) again, thus effectively preventing secondary injury and implementing safe self-destruction of the syringe.

Description

Needle back pull safe self-destructing syringe

Technical field

The invention relates to the technical field of medical instruments, in particular to a needle pull-back type self-destructing syringe, in particular to a mechanical connecting structure thereof.

Background technique

Comparative Document 1, Patent No.: ZL200710047077. 4, Application Date: 2007. 10. 16, Announcement No.: CN101411908, Patentee: Shanghai Top Tang Biochemical Technology Co., Ltd., this case discloses "a safe self-destructive vaccine syringe" The utility model comprises a cylinder body, a core rod is arranged in the cylinder body, a rubber plug is arranged near the end of the core rod, a needle is arranged in the cylinder neck of the cylinder body, and a needle tube is arranged at the needle head, wherein: the end of the core rod is The side wall of the rod body is provided with a lateral notch, the transverse notch is connected with the longitudinal notch at the end of the mandrel rod, the transverse notch is matched with the longitudinal notch, and the needle is sleeved by the upper needle seat and the lower needle seat, and the lower needle seat cavity is formed. Hollow, the lower needle seat is formed into a cylindrical structure, and the lower needle seat is provided with a lower needle seat rib relative to the inner wall of the other end of the mounting needle seat, and the end of the core rod is formed by the horizontal notch and the longitudinal notch communicating Elastomer, where the core rod body has a certain elasticity, wherein the longitudinal notch is narrow and wide, and the outer wall of the upper core rod of the lateral notch is protruded from the outer wall of the lower core rod, and the lateral gap can be The outer part is low in inner shape, the end of the core rod is formed in an arc shape, the upper needle seat is formed in a cylindrical shape, the upper part of the outer wall of the upper needle seat is provided with a reinforcing wing piece, and the lower part of the outer wall of the upper needle seat is provided with a fixed needle ring of the upper needle seat, the upper needle The outer diameter of the fixing collar is greater than the diameter of the outer wall of the upper needle seat 0. 05mm - 0. 3mm, the lower needle seat is cylindrical, the inner cavity is hollow, and the inner wall of the lower needle cavity is provided with a lower needle seat annular fixing Groove, lower needle seat annular fixing groove can cooperate with upper needle fixing convex ring, lower needle The inner diameter of the upper cavity of the annular fixing groove of the head seat is smaller than the outer diameter of the outer wall of the upper rod of the upper needle fixing collar 0. lram_ 0. 35mm, the inner diameter of the lower cavity of the lower needle seat annular fixing groove is lower than the fixed seat of the needle seat The outer diameter of the outer wall of the rod, the lower needle seat is provided with a lower needle ring annular rib at the end of the outer wall of the other end of the lower needle seat convex ring, and the inner wall of the cylinder neck is respectively provided with a cylinder neck upper limit ring and a cylinder The lower limit ring of the neck, the distance between the upper limit ring of the cylinder neck and the lower limit ring of the cylinder neck is 0. 3mm~ 1. 5mm, and the upper limit ring of the cylinder neck protrudes between the upper limit ring of the neck and the lower limit ring of the neck The inner wall is 0. lmm - 0. 6mm, the lower limit ring of the neck is protruded from the inner wall of the upper end ring of the cylinder neck and the lower limit ring of the cylinder neck 0. 02mm - 0. 25mm, the inner diameter of the inner cavity of the upper cylinder of the upper limit of the cylinder neck The inner diameter of the inner cavity of the cylinder between the upper limit ring of the cylinder neck and the lower limit ring of the cylinder neck, the inner diameter of the inner cylinder of the inner cylinder of the cylinder upper limit ring and the lower limit ring of the cylinder neck, the inner diameter of the inner cylinder of the lower cylinder of the cylinder The inner diameter of the inner cavity of the cylinder between the upper limit ring of the neck and the lower limit ring of the neck is smaller than the outer diameter of the annular rib of the lower needle seat. Lmm - 0. 5mm, the inner cavity of the cylinder is provided with a cylinder limiting rib at the inner wall of the other end of the cylinder neck, and the limiting rib of the cylinder body may be a linear annular rib, a circular rib composed of a plurality of vertical ribs, a vertical rib, An annular rib formed by a plurality of convex points, a cylindrical rib at the lower portion of the cylinder at the lower portion of the cylinder limiting rib, a distance between the limiting rib of the cylinder and the rib in the cylinder, and a thickness of the annular limiting piece, the cylinder The inner diameter of the limit rib is smaller than the diameter of the annular limit piece.

Comparative Document 2, Patent No.: ZL200720067715. 4, Application Date: 2007. 03. 08, Announcement No.: CN201076648, Patentee: Shanghai Dingjiantang Biochemical Technology Co., Ltd., this case discloses "a metal hook structure The core rod includes a core rod body, the upper end portion of the core rod body is provided with a columnar fastener, and the columnar fastener is sleeved with a rubber plug, wherein the rubber plug is provided with a mounting hole, and the mounting hole is provided with a barb body. In the existing safety syringe structure, the function of retracting the needle by using the barb body is realized, and the safety injection is realized, and the general barb body is a metal piece or a plastic part. Metal parts need to be processed and matched or assembled with the core rod. The manufacturing process is complicated, difficult and not stable, which not only increases the processing procedure and manufacturing cost, but also increases the safety and product quality of the metal parts themselves and their assembly process. Uncertainty in terms of hidden dangers. Existing plastic barbs still have defects or imperfections in structure and thus cause safety hazards or safety holes in the use of the product. The existing plastic inverted fastener design can realize the needle pullback function, but in use, the needle is still in a normal trajectory after being pulled back, and the needle may be pushed out again, causing the user to be damaged twice.

In addition, the existing single-needle seat back-pull safety self-destructing syringe or safety syringe has the same problem, that is, how to solve the stability of the inner needle seat and the cylinder and achieve a certain strength to meet the stability requirements; At the same time, the required pulling force when retracting the needle holder should not be too large for convenient use. Although the rigid mating structure can achieve a stable locking effect of the inner needle seat and the inner wall of the cylinder, it is difficult or even impossible to achieve the convenience of use at the same time. The inherent instability of the plastic material and its susceptibility to changes in ambient temperature can result in poor product stability of the hard-fit structure, and the quality and precision of the production process are difficult to control, making it almost impossible to achieve mass production.

In summary, there is still a need to further improve the core structure of the existing pullback syringe and the locking structure between the inner needle seat and the cylinder to further improve the safety and stability of the product during use. The purpose of simplifying the processing process and reducing the manufacturing cost is achieved. Summary of the invention

The object of the present invention is to provide a needle pullback type needle changeable safety self-destructive injection Device. The needle holder and the syringe barrel are locked to each other by the elastic buffer mechanism, and the expansion force is generated by the deformation of the buffer gap, thereby achieving the locking and disengaging effects of the two. The elastic buffering mechanism can be disposed at the inner needle seat or at the inner wall of the cylinder. At the same time, the inner needle seat and the cylinder body form an elastic buffering engagement mechanism that can cooperate with each other. The end of the core rod is provided with an elastic locking function, and the locking member can be locked with the inner cavity of the syringe needle seat by means of engagement. When the needle holder is pulled back into the syringe barrel, under the force of the asymmetric elastic structure, the needle seat will be deflected to one side by force; the injection needle will therefore fall toward the inner wall side of the cylinder in the direction of nearly forty-five degrees. And locked by the neck of the cylinder, thereby causing the injection needle and the needle seat to be unable to be pushed out again to the neck of the cylinder, effectively preventing the secondary damage caused by the needle being pushed out again, realizing the safe self-destruct operation of the syringe, overcoming the existing The shortcomings and deficiencies in the technology.

In order to achieve the above object, the technical solution of the present invention is: A needle pullback type self-destructing syringe. The utility model comprises a cylinder body; a needle seat body is arranged in the cylinder neck of the end of the cylinder body; a core rod is arranged in the cylinder body; and a rubber plug is arranged near the end of the core rod. The utility model is characterized in that: the upper part of the needle seat body is placed in the neck of the cylinder, and the middle part of the needle seat body forms an elastic sealing limit portion, and the lower part of the needle seat body is connected with the outer casing type pull-back locking component, and the surface of the elastic sealing limit portion is opened with a ring shape The buffer gap, the outer wall of the elastic sealing limit portion outside the annular buffer gap forms an annular seal limit engagement portion, and the end of the core rod is provided with an asymmetric elastic locking pullback member.

The invention discloses a needle pullback type safe self-destructing syringe. The end of the syringe core rod is provided with an asymmetric pull-back locking member with elastic function; the asymmetric structure and the elastic function design ensure that the locking member can be smoothly inserted into the inner cavity of the needle seat, and realize the two functions by utilizing the elastic expansion function. Jack-back pullback of the side asymmetric engaging portion and the inner cavity of the needle seat Lock the component snap-in card and lock it. Since the annular groove of the inner cavity of the outer-type pull-back locking component card also has elastic buffering characteristics, when the asymmetric pull-back locking member touches in the advancing state, the two will relatively generate buffer deformation, which facilitates the locking member to be snapped into the outer casing. The inner cavity of the locking assembly is pulled and interlocked with the outer casing pull-back locking assembly when the locking member is retracted. When the needle holder is pulled back into the syringe barrel, under the force of the asymmetric force, the needle seat will deflect toward one side, and the needle will therefore fall to the side of the inner wall of the cylinder in the direction of nearly forty-five degrees. The cylinder is locked by the neck of the cylinder, thereby preventing the injection needle and the needle seat from being pushed out of the neck of the cylinder again, effectively preventing the needle from being pushed out again to cause secondary damage, and realizing the safe self-destruct operation of the syringe. In an embodiment of the invention, the asymmetric elastic pull-back locking member is a plastic barb. The plastic barb body is designed with the asymmetry and the elastic structure ingeniously matched with a specific angle and size design, so that the barb body has an elastic buffer locking function. The above asymmetric elastic pull-back locking member is integrated with the core rod, and the integral part is formed by one-time open molding, which does not require separate processing or subsequent assembly, which effectively reduces the manufacturing cost, simplifies the assembly process, and reduces the assembly process. The product is easy to use and stable in working condition. The asymmetric elastic pull-back piece at the end of the core rod has excellent engagement and locking effect on the inner cavity of the needle seat, the overall structure of the product is reasonable, the concept is clever, and it is easy to popularize and apply. Compared with the existing product design and technology, the design has Significant technical breakthroughs with outstanding safety and practical features.

DRAWINGS

Figure 1 is a schematic view of the structure of the present invention.

2 is an assembled view of the hub body and the jacket type pull-back locking assembly of the present invention. Figure 3 is a schematic view showing the structure of the barb body of the present invention.

Figure 4 is a first use state diagram of the present invention.

Figure 5 is a second state of use of the present invention.

Figure 6 is a diagram showing a third state of use of the present invention.

detailed description

The invention will now be further described with reference to the accompanying drawings.

The invention is a needle pull-back type safe self-destructing syringe, which comprises a cylinder body 1. a needle seat body 3 is arranged in the cylinder neck 2 at the end of the cylinder body 1, and a core rod 8 is arranged in the cylinder body 1, the core The rubber rod 9 is disposed near the end of the rod 8 , which is different from the prior art in that: the upper part of the needle seat body 3 is placed in the cylinder neck 2 , and the middle part of the needle seat body 3 forms an elastic sealing limit portion 4 , the needle seat body The lower portion is connected with the outer casing type pull-back locking assembly 5, and the annular sealing gap 6 is formed on the surface of the elastic sealing limiting portion 4, and the outer sealing portion of the elastic sealing limiting portion 4 outside the annular buffering gap 6 forms an annular sealing limit engagement. In the portion 7, the end of the core rod 8 is provided with an asymmetric elastic locking pullback member 10. The elastic sealing limit portion can achieve the requirement of stable engagement between the inner needle seat body and the cylinder body, and can realize the effect of lightly withdrawing.

An elastic mechanism is formed on one side or both sides of the asymmetric elastic locking pullback member, and a side outer end of the elastic mechanism of the asymmetric elastic locking pullback member protrudes from the asymmetric elastic locking pullback member and the rod body connecting portion The outer wall is so as to ensure its latching and deflection function with the needle head.

In a specific implementation, the asymmetric elastic locking pullback member 10 is a barb body, the barb body is made of plastic material, and is integrated with the core rod 8 body, once opened, or the barb body and The core rod 8 is a component assembly structure. In a specific implementation, the above-mentioned barbs can also be assembled to the end of the core rod through other assembly structures.

In a specific implementation, the lower end of the barb body forms a base portion 11, and the upper portion of the base portion 11 forms a first folding arm 12 that is deflected toward one side, and the outer side wall of the connection portion between the first folding arm 12 and the base portion 11 is formed. a concave arc 13 angle or a chamfer angle of 45 degrees to 179 degrees, the lower end of the first folding arm 12 is connected to the upper end of the base portion 11, and the upper end of the first folding arm 12 and the second folding arm 14 One end is connected, the other end of the second folding arm 14 is suspended, and the outer side of the junction of the first folding arm 12 and the second folding arm 14 forms a circular arc surface 15, and the inner side of the junction of the first folding arm 12 and the second folding arm 14 forms 2 An internal angle 17 of 90 degrees, a width of the opening between the hanging end of the second folding arm 17 and the first folding arm 15 is 0.5 mm - 40 mm, and the length of the first folding arm 12 is 0.5 mm - 50 mm The length of the second folding arm 14 is 0.5 mm - 60 mm. The structure is designed in such a way as to ensure the locking effect and deflection function of the needle head.

In a specific implementation, four core-shaped reinforcing ribs 18 having a cross-shaped angular distribution are formed at the core rod 8. The outer edge of the reinforcing rib 18 is provided with a limiting flap 19, and the limiting flap 19 and the reinforcing rib 18 are After being connected by at least two contacts 20, after the syringe is assembled, the top end of the limiting flap just abuts against the lower end of the cylinder, preventing the external force from being applied before the syringe is used, causing the core rod to move forward, causing the syringe to be accidentally scrapped. When in use, simply bend the limit flap along the contact to fold it away from the rib.

In a specific implementation, the annular buffer gap 6 is an annular groove structure, the height of the slot to the bottom of the groove is 0.05 mm - 4 mm, the width of the annular buffer gap 6 is 0.05 mm - 4 mm, and the outer side of the annular buffer gap 6 The distance between the groove wall and the arc-shaped top of the surface of the annular seal limiting engaging portion 7 is 0.1 mm-6 mm, and the annular groove gap 6 is located at the outer groove wall slot and the annular sealing limit The distance between the outer wall of the engaging portion is 0.1 mm to 6 mm, and the distance between the bottom of the outer groove wall of the annular buffering gap 6 and the outer wall of the annular sealing limit engaging portion 7 is 0.1 mm to 6 mm, and the annular seal The surface of the limiting engaging portion 7 is curved, and the distance from the surface of the annular sealing limit engaging portion 7 to the edge of the curved surface is smaller than the distance from the top of the arc to the lower edge of the curved surface. An annular recess 22 is formed in the outer wall of the elastic sealing stopper portion 4 at the lower portion of the engaging portion 7.

In a specific implementation, the annular recess 22 is located at the same level as the groove bottom of the annular buffer gap 6 or above the groove bottom of the annular buffer gap 6.

In a specific implementation, the barrel neck 2 of the barrel 1 is externally sleeved with a barrel sheath 23. In a specific implementation, the inner wall of the cylinder neck 2 of the cylinder 1 is provided with an annular seal limiting recess 24 matched with the annular seal limiting engagement portion 7, and the depth of the annular seal limiting recess 24 is 0.01. Mm-4mm, the height of the annular seal limiting recess 24 is 0.01mm-6mm, and the bottom of the recess of the annular seal limiting recess 24 is curved.

In a specific implementation, at least one limiting collar 25 is formed on the outer wall of the hub body 3, and an annular limiting slot 26 is formed on the inner wall of the inner cavity of the outer casing pull-back locking component 5 to cooperate with the limiting collar 25. .

In a specific implementation, the inner casing of the outer casing pull-back locking assembly 5 is hollow, and the inner wall of the inner cavity forms an annular engagement locking portion 27 near the lower end opening.

In an embodiment, the upper portion of the annular locking locking portion 27 forms an annular groove 28, and the inner side wall 29 of the annular groove 28 has a thickness of 0.01 mm to 3 mm, and the inner side wall of the annular groove 28 and the outer side wall of the annular groove 28 30 forms an angle of 2 to 90 degrees, and an inner diameter formed at an upper end of the inner side wall of the annular groove 28 is 1 mm to 80 mm, and a notch width of the annular groove 28 is larger than a groove width. In actual operation, as shown in FIG. 3 to FIG. 4, after the liquid absorption is started, the core rod is slowly advanced, because the total width of the asymmetric elastic locking pullback member is larger than the annular groove at the outer casing type pull back locking assembly. The inner diameter, when the two are touched, the side of the asymmetric elastic locking pullback member is deformed, so that the width is narrowed and then enters the inner cavity of the outer casing pull-back locking assembly. When entering the inner cavity, the force effect is lost, and the asymmetric elastic lock is obtained. The pullback member returns to its original shape. At this time, the injection is completed, and the core rod is pulled backward. The side end of the asymmetric elastic locking pullback member (the hanging end of the second folding arm of the barb body) is just stuck in the outer casing type pull back locking assembly. In the annular groove, under the action of the tension of the core rod, the pulling force is transmitted to the body of the needle seat through the outer casing type pull-back locking component, and the annular buffer gap of the elastic sealing limit portion of the needle seat body is deformed by force, with the ring The buffering gap is narrowed, and the annular sealing limit engaging portion slides out from the annular sealing limit recess at the cylinder body, and finally the entire needle head is pulled into the cylinder inner cavity to act as an asymmetric elastic locking pullback member. Down, needle Deflection to the side portion, departing from the normal trajectory displacement, it can not be re-fitted to the inner tube neck, to achieve self-destruct syringes security operation.

The above is a further detailed description of the present invention in conjunction with the specific preferred embodiments. It will be apparent to those skilled in the art that the present invention may be practiced without departing from the spirit and scope of the invention.

Claims

Claim

A needle pullback type safe self-destructing syringe, comprising a cylinder body (1), a needle seat body (3), a cylinder body (1) in a cylinder neck (2) at an end portion of the cylinder body (1) There is a core rod (8), and a rubber plug (9) is arranged near the end of the core rod (8), characterized in that: the upper part of the needle seat body (3) is placed in the neck (2), the needle The middle portion of the seat body (3) forms an elastic sealing limit portion (4), and the lower portion of the needle seat body (3) is connected with the outer casing type pull-back locking assembly (5), and the surface of the elastic sealing limit portion (4) is provided with an annular buffer gap. (6), an annular sealing limit engagement portion (7) is formed at the outer wall of the elastic sealing limit portion (4) outside the annular buffer gap (6), and the end of the core rod (8) is provided with an asymmetric elastic locking back Pull the piece (10).

2 . The needle pullback safety self-destructing syringe according to claim 1 , wherein: the asymmetric elastic locking pullback member (10) is a barb body, and the barb body is made of plastic material. And integrated with the core rod (8), one-time open molding, or the barb body and the core rod (8) component assembly structure.

The needle pullback safety self-destructing syringe according to claim 2, wherein: the lower end of the barb body forms a base portion (11), and the upper portion of the base portion (11) is deflected toward one side. The first folding arm (12), the outer side wall of the connection between the first folding arm (12) and the base portion (11) forms a concave arc (13) angle or a chamfer angle of 45 degrees to 179 Degree, the lower end of the first folding arm (12) is connected to the upper end of the base portion (11), the upper end of the first folding arm (12) is connected to one end of the second folding arm (14), and the second folding arm (14) is another One end is suspended, and the outer side of the junction of the first folding arm (12) and the second folding arm (14) forms an arc surface (15), and the inner side of the junction of the first folding arm (12) and the second folding arm (14) is formed. An inner angle of 2 degrees to 90 degrees (17), formed between the free end of the second folding arm (17) and the first folding arm (15) The width of the opening is 0.5 mm - 40 mm, the length of the first folding arm (12) is 0.5 mm - 50 mm, and the length of the second folding arm (14) is 0.5 mm - 60 mm.

The needle pull-back safety self-destructing syringe according to claim 1, wherein the core rod (8) forms four ribs (18) with a cross-shaped angular distribution, and the rib (18) A limit flap (19) is provided at the outer edge.

5. A needle pullback safety self-destructing syringe according to claim 4, wherein: said limit flap (19) and said rib (18) pass at least two contacts

(20) Connection.

6. A needle pullback safety self-destructing syringe according to claim 3, wherein: said floating end of said second folding arm (14) forms a tip (21), and the second folding arm

The suspended end of (14) protrudes from the outer edge of the base portion (11).

The needle pullback safety self-destructing syringe according to claim 1, wherein: the annular buffer gap (6) is an annular groove structure, and the height from the notch to the bottom of the groove is 0.05 mm- 4mm, the width of the annular buffer gap (6) is 0.05 for -4匪, the distance between the outer groove wall of the annular buffer gap (6) and the arc-shaped top of the annular seal limit engagement portion (7) is 0.1mm. -6mm, annular buffer gap (6) The distance between the outer groove wall groove and the outer wall of the annular seal limit engagement part (7) is 0.1mm-6mm, annular buffer gap (6) outer groove wall groove The distance between the bottom and the outer wall of the annular seal limit engagement portion (7) is 0.1mm-6mm, and the surface of the annular seal limit engagement portion (7) is curved, and the annular seal is engaged. The distance from the surface arc top to the curved edge of the portion (7) is smaller than the distance from the top of the arc to the lower edge of the curved surface, and the outer edge of the elastic sealing limit portion (4) of the lower portion of the annular sealing limit engaging portion (7) An annular recess (22) is formed.

The needle pullback safety self-destructing syringe according to claim 1, wherein: the annular recess (22) is located at the same level or higher than the groove bottom of the annular buffer gap (6). The bottom of the groove of the buffer (6).

A needle pull-back safety self-destructing syringe according to claim 1, wherein: the barrel neck (2) of the barrel (1) is externally sleeved with a barrel sheath (23).

10 . The needle pull-back safety self-destructing syringe according to claim 1 , wherein: the inner wall of the cylinder neck ( 2 ) of the cylinder body ( 1 ) is provided with an annular seal limit engagement portion. (7) The matching annular seal limit recess (24), the depth of the annular seal limit recess (24) is 0.01mm-4mm, and the height of the annular seal limit recess (24) is 0.01mm-6mm The bottom of the recess of the annular seal limiting recess (24) is curved.

The needle pullback safety self-destructing syringe according to claim 1, wherein: at least one limiting convex ring (25) is formed at an outer wall of the needle seat body (3), and the outer casing is pulled back. The inner wall of the locking component (5) is provided with an annular limiting groove (26) which cooperates with the limiting convex ring (25).

12 . The needle pull-back safety self-destructing syringe according to claim 1 , wherein: the inner casing pull-back locking assembly ( 5 ) has a hollow inner cavity, and an inner wall of the inner cavity is formed in a ring shape near the lower end opening. The locking portion (27) is engaged.

The needle pullback safety self-destructing syringe according to claim 1, wherein: an upper portion of the annular engagement locking portion (27) forms an annular groove (28), and an annular groove (28) The inner side wall (29) has a thickness of 0.01 mm to 3 mm, and the inner side wall of the annular groove (28) forms an angle of 2 to 90 degrees with the outer side wall (30) of the annular groove (28), and the inner side of the annular groove (28) The inner diameter formed at the upper end of the wall is from 1 mm to 80 mm.

14. A needle pullback safe self-destructing syringe according to claim 1, wherein: said annular groove (28) has a notch width greater than a groove width.