Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/178—Syringes
  • A61M5/31—Details
  • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
  • A61M5/31511—Piston or piston-rod constructions, e.g. connection of piston with piston-rod
  • A61M5/31513—Piston constructions to improve sealing or sliding
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/178—Syringes
  • A61M5/31—Details
  • A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
  • A61M5/31511—Piston or piston-rod constructions, e.g. connection of piston with piston-rod
  • A61M2005/31521—Pistons with a forward extending skirt at their front end

Definitions

• the present invention relates to a Kol ⁇ ben / plug for a syringe and a syringe into which such a piston is inserted.
• a plunger for a syringe and a syringe into which such a piston is inserted are known, for example, from WO 98/17339 A1, which is incorporated herein by reference.
• PTFE polytetrafluoroethylene
• Teflon polytetrafluoroethylene
• German Patent DE 3346 351 published on April 9, 1992, describes a piston which is at least partially provided with a Teflon coating. Such a piston contacts the cylinder inner wall with Wüls ⁇ th exert a specific pressure on the cylinder inner wall, whereby the sealing effect should be ensured.
• the beads are formed so that the pointing away from the piston perpendicular to the bead surface points towards the wall of the Spriztenzy- Linders.
• the patent uses Teflon to provide a protective surface between the medium and the rubber part of the piston. In this case, therefore, it is exclusively an insulating function, the outstanding sliding properties of Teflon have not been taken into account.
• the term siliconizing was not mentioned.
• Patent AT-E 68 979 describes a filled, terminally sterilized syringe.
• the syringe is made of plastic.
• the syringe has a cylinder with a dista ⁇ len end with a Spritzenauslledge Swiss.
• the syringe outlet is sealed by a closure.
• the inner wall of the syringe is coated with silicone oil.
• the syringe is closed with a flexible rubber piston, which is also lubricious in the cylinder because of the silicone oil.
• the process for producing a filled, terminally sterilized syringe begins with the removal of waste particles or other impurities from the closure and the piston. Microbial contaminants on the cap and piston are destroyed.
• the cylinder comes with a variety washed by water jets to remove pyrogens and waste particles.
• silicone oil is applied to the inner wall of the syringe.
• the closure is then slipped onto the syringe outlet.
• the contrast agent is filled into the syringe through the proximal end of the syringe.
• the syringe is then closed with the piston.
• This assembled and filled syringe is sterilized in an autoclave. In addition to the usual autoclave pressure, an additional support pressure is generated in the autoclave.
• European Patent Application EP 0553 926 (filing date: Jan. 26, 1993) describes a method for the terminal sterilization of a prefilled plastic syringe or glass syringe, the syringe containing a contrast agent.
• the inner wall of the disposable syringes is coated with silicone oil.
• the syringe consists of a syringe barrel having a syringe outlet at the distal end.
• disposable syringe vials are given in the form previously described by Venten and Hoppert.
• the disposable syringes have an open proximal end, which extends through one in the disposable syringe slidable piston is closable.
• the piston is connected to a plunger.
• WO 95/12482 describes a process for the production of prefilled plastic syringes which are filled with a contrast agent.
• the inner wall of the syringe is coated with silicone oil.
• the syringes consist of a cylinder, a syringe outlet piece at the distal end, which is prepared for a Kanul lenansatz.
• the syringe comprises a piston which can slide in the cylinder. It seals off the proximal end of the syringe.
• the syringe has been produced by a process which leads to pyrogen-free objects. Likewise there are no particles left.
• the syringe is filled through the proximal end, while the syringe outlet is sealed with a closure.
• the filled syringe is closed with the piston.
• the syringe parts come out of the mold, they are blown off with gas to remove particles.
• the syringe is then washed and lubricated.
• the syringe is then sterilized so that the syringe can optionally be further processed, stored or transported.
• a solid Teflon piston has a considerable disadvantage in the case of syringes exposed to thermal stress.
• temperature fluctuations -10 0 C to + 40 0 C, to let the plastics of the syringe wall gegen ⁇ expand over the very solid Teflon material.
• autoclaving is a burden on the piston or syringe that one of both shows a cold flow behavior, which has after cooling the syringe leaks result.
• a high preload is necessary, which consequently results in a high degree of friction.
• the syringe according to the invention can be filled well with contrast agent and sterilized terminally.
• the contrast agent are amidotrizoic acid, gadopene acid, gadobunol, gadolinium, iopamidol, iopromide, iotro-1an, iotroxinic acid.
• the piston according to the invention has a core element.
• a ring element surrounds the core element at a distance.
• the two elements are connected by webs.
• the ring element according to the invention is coated on its äuße ⁇ ren circumferential surface with a sliding material.
• This sliding material allows the piston to be easily moved into the cylinder of a syringe, which would not be possible if the circumferential surface of the piston were made of thermoplastic, since the thermoplastic had a high coefficient of friction with materials for syringe barrels such as glass or plastic ⁇ points. Since the peripheral surface of the ring element is coated with the expensive sliding material, the costs can be kept low.
• the core element and the ring element are separated from each other and there is a distance between the two, there is less solid material for the core element and the ring element.
• the radial extent of the material is less than the radius. With the same expansion coefficient, therefore, the thermal expansion is reduced because of Length smaller. Thus, even when the syringe is heated with the piston according to the invention, the piston is not destroyed by the thermal expansion.
• the rigid core in which a piston rod can be screwed, ensures that the piston rod does not deform the piston during an injection and increases the friction between the piston and a cylinder wall.
• the webs When the webs extend radially from the core element to the ring element, the webs can absorb the thermal expansion by upsetting.
• the lands When the lands are tangentially attached to the core member, they do not extend radially from inside to outside. Upon thermal expansion of the core element and the ring element, the webs are bent at their attachment points. Therefore, not even a compression of the webs is necessary.
• the injection mold can be easily manufactured.
• the ring element is subdivided into a plurality of ring segments spaced apart in the circumferential direction, the ring segments can deform tangentially in the case of a thermal expansion instead of a radial deformation, which could lead to destruction, so that no destruction occurs.
• the sliding material adheres better to the outer peripheral surface of the ring material. If the sliding material has a sealing lip, it is possible to achieve a particularly good sealing. In particular, it is possible to achieve a dynamic seal which occurs when the piston is moved to the distal end of the syringe. This is particularly advantageous in the case of a sliding material with a low coefficient of friction between the sliding material and the syringe barrel wall.
• the core element, the webs and the ring element are to be formed in one piece from the same material, a particularly cost-effective injection molding process for this one-piece component is possible.
• Preferred materials for the core element, the webs and the ring element are thermoplastics, polypropylene or polycarbonate.
• Preferred materials for the sliding element are thermoplastic elastomers. Preferred examples are: Evoprene 968, Cabriton PR 6173 B, Cawitone PR 6173 D, Cawitone PR 6173 E, Caviton PR 6173 F, Thermoflex 55 1A5 + 900, Uniprene 7010 RS 70 + 801 (SEBS), Santoprene 181-57 WI80 (TPV).
• the syringes are usually rotationally symmetrical, only the finger holders and device holders and sometimes also the syringe outlet piece deviate from the symmetry.
• the syringe outlet piece can be arranged eccentrically.
• Particularly preferred is the Luer-Lock, since it comes into play exclusively in the application of contrast agents when mechanical pump devices are used.
• the luer lock and the hose connected therewith prevent unintended movements of the physician from being transmitted directly to the cannula.
• the simple luer approach and the record approach are known. It is also possible to weld and thereby seal the syringe outlet. It is advantageous then that a Sprit ⁇ zenauslledge tenu has a predetermined breaking point, which allows easy opening of the Spritzenauslrud tenues before use.
• the proximal and distal ends of the syringe must be closable.
• the distal end is sealed off by a closure which can be placed on the syringe outlet piece.
• the syringe outlet piece in this patent covers the ceiling of the syringe barrel.
• the syringe outlet includes a tube leading to the needle or tube, an end piece contacting the needle or tube, and a threaded cylinder on the inside, the cylinder surrounding the tip and a thread for for example, wearing a luer-lock.
• the syringe outlet piece may be integral or multi-piece.
• the ceiling can be curved, flat or pyramidal. Mixed forms are also conceivable.
• the piston closes the proximal end of the syringe. It must be slidable in the cylinder and must safely retain the medium from the environment. It should be as little as possible permeable to gases and liquids. Even temperature fluctuations must be absorbed without a malfunction.
• the piston is not provided with the mechanical emptying of the syringes with its own stamp. Rather, a stem pel, which is part of the pumping device, engages in a closure in the interior of the piston, so that a movement of the piston is easily possible. (see EP 0 584 531)
• proximal and distal are defined by the treating physician.
• the fuel outlet piece on which, for example, the cannula or a Hose leading to a cannula is connected.
• the piston At the proximal end is the piston which pushes the medium through the distal end during application. The movement of the piston can be done manually or mechanically.
• the Aus ⁇ pressure piston also includes piston .. For the manual operation of the syringe, it is helpful for the operator when the syringe at the proximal end carries finger mounts.
• the finger holders usually have at least one surface as an abutment for the index finger and middle finger, wherein the surface of the finger holder is substantially perpendicular to the axis of the syringe barrel.
• a syringe then preferably carries one or more device holders at the preferably proximal end.
• Such a mechanical pump is described particularly well in EP 0 584 531 (Reilly et al., Filing date 21. 07. 1993). Mixed forms of finger holder and device holder are possible.
• the medium in the filled syringe is a mixture of a fluid medium and at least one gas.
• the gas volume should be as small as possible, a gas volume which assumes the value zero is desirable.
• the medium may be a liquid, a solution, a suspension or an emulsion.
• a fluid medium which is a contrast agent.
• contrast agent are the following generic contrast agents: amidotrizoic acid, gadopentetic acid, gadobutrol, gadolinium EOB-DTPA, iopamidol, iopromide, iotrolan and iotroxin.
• the piston is designed to be complementary to the shape of the distal end of the syringe in order to minimize a residual volume which can not be removed from the syringe in spite of complete depression of the piston.
• a medical syringe according to the invention is preferred in which the piston has a convex, planar or concave configuration or else has pyramidal, conical, pyramidal truncated conical, frustoconical or hemispherical configurations, whereby depending on the design of the end of the syringe the protuberance points distally or proximally ,
• a syringe according to the invention in which the syringe is autoclavable at a support pressure.
• At least the syringe body is poured or sprayed in a sterile room at least 250 0 C.
• a syringe according to the invention in which the sterile syringe can be packed in a sterile container which has at least one gas-permeable but not germ-permeable wall.
• a syringe must be cleaned of foreign objects.
• Foreign bodies are all the particles which are not from the material of the syringe and the medium and the detached fragments of the syringe.
• Pyrogens are substances that, as fragments of bacteria, provoke an immune response in humans. In particular, they are lipopolysaccharides, ie cell wall components of gram-negative bacteria.
• Sterilization methods which are particularly suitable are radiation sterilization or chemical sterilization processes.
• Chemical sterilization processes include treatment with ethylene oxide, propane-3-olide and diethyl carbonate, furthermore hydrogen peroxide and an ozone / vapor mixture.
• the parts of the syringe are sterilized in bacteria-sealed but gas-permeable foil or aluminum.
• the sterilization takes place with the aid of thermal and / or chemical sterilization, with gamma rays or X-rays, neutron beams or beta rays or a mixture of the previously mentioned beams.
• the treatment with hydrogen peroxide or ozone / vapor mixture is preferred.
• the syringe body is filled through the distal or proximal end, either the piston or the Seal the opposite end seal. Subsequently, the filling opening is closed by the closure or the piston.
• the distal end is closed with a closure or by welding the distal end.
• the distal end has a predetermined breaking point proximal to the weld. This allows the distal end to be easily opened after welding.
• the syringe or cartridge is thermally sterilized in the autoclave or sterilizer with hot air or by means of microwaves.
• a support pressure in the sterilization space of the autoclave or the sterile chamber by a gas in the sterilization room, wherein the pressure on the outer surface of the syringe is greater than, equal to or less than the pressure on the inner surface of the syringe.
• the support pressure shall be defined as the pressure corresponding to the sum of the partial pressures in the sterilization room minus the partial pressure of the vapor.
• the piston is reju ⁇ stiert after sterilization. This ensures that the piston is in an optimal position. Sometimes the friction between the piston and the cylinder is so great that a setting of the piston in the stable position, in which no pressure difference between the inside and the outside of the syringe does not occur independently.
• the packaging of the sterilized syringe in a container and the sterilization of the filled container can take place in a sterile room.
• This step is particularly advantageous because it alone gives a certainty of offering the treating doctor a syringe which is also externally sterile. This can reduce the risk of contamination.
• This advantage also stands out in the case of the syringes to be emptied mechanically, since the doctor also touches the syringe here.
• the syringes to be emptied mechanically are used in sterile treatment rooms. Only sterile or disinfected materials may be placed in these rooms. Thus, even a syringe to be emptied mechanically must be externally sterile.
• a further advantage is that the filled and terminal filled syringe is packed in sterile plastic film and / or aluminum foil under optionally aseptic conditions. It is advantageous that the syringe is packed in possibly sterile blisters, wherein asepti ⁇ cal conditions prevail if necessary.
• the syringe which lies in the container is externally sterilized again by treating the syringe with ethylene oxide, propan-3-olide and / or diethyldicarbonate. Furthermore, hydrogen peroxide and an ozone / vapor mixture are known.
• the packaging of the sterilized syringe in a container and the sterilization of the filled container can take place in a sterile space.
• This step is particularly advantageous because it alone provides a security to offer the treating doctor a syringe which is also externally sterile. This can reduce the risk of contamination.
• Even with the mechanically emptied syringes advantage comes to advantage, since the doctor touches the syringe here.
• the syringes to be emptied mechanically are used in sterile operating rooms. Only sterile or disinfected materials may be introduced into these rooms. Thus, even a syringe to be emptied mechanically must be absolutely sterile on the outside.
• Chemical sterilization processes include treatment with ethylene oxide, propane-3-olide and diethyl carbonate, furthermore hydrogen peroxide and an ozone / vapor mixture. Such methods are described in:
• the invention also encompasses a process for the preparation of a prefilled sterile syringe which comprises the following features:
• the invention further comprises a combination of a pre-filled, terminally sterilized syringe according to the invention, and an application device comprising automatic injectors and connections, wherein the injectomat is a pumping system and the ports connect the outlet of the syringe to the patient.
• an application device comprising automatic injectors and connections, wherein the injectomat is a pumping system and the ports connect the outlet of the syringe to the patient.
• Fig. 1 is a syringe as used for the invention
• Fig. 2 is a cross-sectional view of a piston as used for the invention
• Fig. 3 is an enlargement of the portion X in Fig. 2;
• Fig. 4 is an enlargement of the portion Y in Fig. 2;
• FIG. 5 shows a view of a piston of a first embodiment seen from the distal side of the syringe
• Fig. 6 is a view of the piston of the first embodiment seen from the proximal side;
• FIG. 7 shows a view of a piston of a second embodiment from the proximal side
• FIG. 8 is a view of a piston of a third embodiment seen from the proximal side
• FIG. 9 is a view of a piston of a fourth embodiment seen from the proximal side
• FIG. 10 shows a view of a piston of a fifth embodiment, seen from the proximal side
• FIG. 11 shows a view of a piston of a sixth embodiment from the proximal side
• FIG. 12 shows a view of a piston of a seventh embodiment from the distal side
• Fig. 13 is a view of the piston of the seventh embodiment seen from the proximal side.
• Fig. 1 shows a syringe as used for the present invention.
• a syringe 1 has a cylinder 2 and a piston 3.
• the cylinder 1 has at a dista ⁇ len end a cap 4 with a central opening and a lug 5 for receiving a needle or a hose.
• a flange 6 for holding or for insertion into a motor-driven Betchanists ⁇ element (not shown) is provided.
• a piston rod 7 is screwed into the piston 3.
• top refers to the position of the syringe 1 as shown in FIG. That is, “top” refers to the direction to the distal end, “bottom” refers to the direction to the proximal end.
• the piston 3 has a generally cup-shaped core element 8 which is open at the bottom. On an inner circumferential surface of the core element 8, an internal thread 9 is provided into which the piston rod 7 can be screwed.
• the core element 8 has a lateral peripheral surface 10.
• the peripheral side surface 10 of the core member 8 is surrounded at a distance from an annular ring member 11.
• the ring element 11 extends in height, ie from a proximal end
• the ring element 11 has at its upper, distal portion a circumferential, radially extending projection or flange 16.
• the ring element 11 has at its lower, proximal portion a circumferential projection 17 with an undercut 18.
• the core element 8 and the ring element 11 are connected by a plurality of webs 19.
• the webs extend substantially over the height of the ring element 11 or of the core element 8. According to a modification, however, the webs 19 extend only over a smaller height than the core element 8 and the ring element 11.
• the core element 8, the ring element 11 and the webs 19 are manufactured in one piece by injection molding from a thermoplastic.
• a thermoplastic are particularly suitable polypropylene.
• the layer 22 of sliding material has at the upper portion a circumferential sealing lip 23.
• a circle is designated by X, which surrounds the sealing lip 23.
• the circle X is shown enlarged in Fig. 3.
• the sealing lip 23 has a substantially obliquely upwardly and outwardly extending cross section, wherein the upper The top of the rectangle is bevelled.
• the sealing lip 23 together with the upper side of the layer 22 of sliding material form a V-shaped circumferential recess 24.
• the sealing lip 23 is relatively long and has a relatively flat angle relative to the axis of the piston 3. This fulfills two functions.
• the dynamic behavior is such that upon actuation of the syringe 1, ie pushing the piston 3 to the distal end, the sealing lip is pressed against the Zylinderinnen ⁇ wall. In the static ratio, ie without movement, the sealing lip 23 is pressed by its elasticity against the ZyIInderinnenwandung and ensures a seal.
• an outwardly projecting circumferential additional sealing lip 25 is provided.
• a circle is designated by Y, which surrounds the sealing lip 25.
• the circle Y is shown enlarged in Fig. 4.
• the sealing lip 25 provides additional security in the sealing of the piston 3 relative to the cylinder 2 of the syringe.
• the layer 22 of sliding material extends into the undercut 18.
• the layer 22 of sliding material is sprayed onto the still warm formation of the core element 8 and the ring element 11 after injection molding of the core element 8, the webs 19 and the ring element 11.
• an additional particularly intimate connection of the layer 22 of sliding material and the core element 8 and the ring element 11 is produced.
• the layer 22 is formed from a thermoplastic elastomer ge. This has the consequence that a small friction value of ⁇ between the layer 22 of sliding material and the inner wall of the cylinder 2 of the syringe 1 can be achieved.
• FIG. 5 shows the piston of a first embodiment from below before the layer 22 of sliding material has been applied
• FIG. 6 shows the piston of the first embodiment from above until the layer 22 of sliding material has been applied.
• the piston 26 has a core member 27 and a ring member 28 which are connected by four webs 29a, 29b, 29c and 29d.
• the core element 27 is relatively small in relation to the entire piston 26, its diameter is approximately ⁇ of the diameter of the piston.
• On the upper side see FIG. 6) a groove 30 is shown, into which the layer 22 of sliding material enters during the spraying, so that the layer 22 of sliding material is reliably held on the upper side of the piston 26.
• the webs 29a to 29d extend radially from the core element 27 to the ring element 28.
• the webs 29a to 29d compress in their longitudinal direction and thus absorb the thermal expansion.
• four webs 29a to 29d are provided. According to a modification, however, three or five or more webs may be provided.
• the layer 22 is held on the sliding material by the flange 16 and the projection 17.
• Fig. 7 shows a piston 31 of a second embodiment from above.
• the piston 31 of the second embodiment is essentially similar to the piston 26 of the first embodiment. det. Therefore, a description of the same features will not be repeated.
• the piston 31 of the second embodiment differs from the piston 16 of the first embodiment in that ridges 32a, 32b, 32c and 32d do not extend radially from the core member 27 to the ring member 28, but rather that the ridges 32a to 32d are tangentially attached to the core member 27.
• This procedure has the advantage that upon expansion of the core element 27 and the ring element 28 when heated, the webs 32a to 32d are not compressed, but instead exert a rotational movement on the core 27. Therefore, the thermal expansion of the piston 31 can be better absorbed when heated.
• Fig. 8 shows a piston 33 of a third embodiment from above.
• the piston 33 of the third embodiment substantially corresponds to the piston 26 of the first embodiment. Therefore, the description of the same features will not be repeated.
• the piston 33 of the third embodiment differs from the piston 26 of the first embodiment in that a ring member 34 is not continuous, but is divided into ring segments 35a, 35b, 35c, 35d, 35e and 35f which are circumferentially spaced from each other , Ste ⁇ ge 36a, 36b, 36c, 36d, 36e and 36f extend radially from the core member 27 to the ring segments 35a to 35f.
• the third embodiment has the advantage that, given thermal expansion of the ring element 34, the gaps between the ring segments 35a to 35f can accommodate the expansion.
• Fig. 9 shows a piston 37 of a fourth embodiment.
• the piston 37 of the fourth embodiment substantially corresponds to the piston 33 of the third embodiment. Therefore, the description of the same features will not be repeated.
• the piston 37 of the fourth embodiment differs from the piston 33 of the third embodiment in that lands 38a, 38b, 38c, 38d, 38e and 38f do not radially engage the core member 37, but that the lands 38a to 38f are tangent to the core member 27 attack as in the piston 31 of the second embodiment.
• the piston 37 of the fourth embodiment combines the advantages provided by the second embodiment and the third embodiment. A thermal expansion of the core element 27 and of the annular element 34 can be absorbed excellently.
• Fig. 10 shows a piston 39 of a fifth embodiment from above.
• the piston 39 substantially corresponds to the piston 26 of the first embodiment. Therefore, a description of the same features will not be repeated.
• the piston 39 of the fifth embodiment differs from the piston 26 of the first embodiment in that a core member 40 is made larger in comparison with the entire piston 39.
• the diameter of the core element 40 of the fifth embodiment corresponds approximately to 2/3 of the diameter of the piston 39 of the fifth embodiment. This allows a great stability for the core element 40.
• Webs 41a, 41b, 41c and 41d can be made very short. This embodiment is particularly advantageous if no large Temperaturerhöhun ⁇ conditions are to be expected, so that the thermal expansion remains limited.
• the webs 41a to 41d are not radially attached to the core element 40, but they are provided tangentially as in the second embodiment. Thus, the same advantage can be achieved in the modification as in the second embodiment.
• Fig. 11 shows a piston 42 of a sixth embodiment.
• the piston 42 of the sixth embodiment corresponds to the piston 39 of the fifth embodiment. Therefore, the description of the same features will not be repeated.
• the piston 42 of the sixth embodiment has the ring member 34 divided into ring segments 35a to 35f as in the piston 37 of the fourth embodiment.
• lands 43a, 43b, 43c, 43d, 43e, and 43f are tangentially attached to the ring member 40.
• the lands 43a to 43f are not mounted in the middle of the ring segments 35a to 35f, but the lands 43a to 43f are respectively attached to one end of the ring segments 35a to 35f as shown in FIG 11 is shown.
• the procedure in the piston 42 of the sech ⁇ th embodiment therefore additionally has the advantage that the ring segments 35a to 35f can fold inwards at their free ends. In this way, the ring segments 35a to 35f can absorb the thermal expansion even better in the case of thermal expansion.
• the ring segments 35a to 35f are not uniformly thick, as shown in Fig. 11, but the ring segments 35a to 35f are chamfered at their free ends on the inner side. As a result, the ring segments 35a to 35f can turn even better inward, the webs 43a to 43f serving as fulcrums. Thus, the ring segments 35a to 35f can even better escape the thermal expansion.
• FIGS. 12 and 13 show a piston 44 of a seventh embodiment.
• the piston 44 of the seventh embodiment corresponds to the piston 42 of the sixth embodiment. Therefore, the description of the same features will not be repeated.
• the piston 44 of the seventh embodiment differs from the piston 42 of the sixth embodiment in that lands 45a, 45b, 45c, 45d, 45e and 45f connect the core member 40 to the ring segments 35a to 35e which are not radially aligned. but which are slightly inclined relative to the radial direction.
• the webs 45a to 45f are respectively mounted in the middle of the ring segments 35a to 35f.
• the lands 45a to 45f are not inclined so much as to be tangentially attached to the core member 40, but are located slightly closer to the radial direction.
• the thermal expansion can be absorbed when the piston and the syringe are heated, the thermal expansion.

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• Health & Medical Sciences (AREA)
• Vascular Medicine (AREA)
• Engineering & Computer Science (AREA)
• Anesthesiology (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Hematology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Infusion, Injection, And Reservoir Apparatuses (AREA)

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• 2004
  • 2004-08-24 DE DE200410040969 patent/DE102004040969A1/de not_active Ceased
• 2005
  • 2005-08-19 WO PCT/EP2005/008994 patent/WO2006021380A1/de active Application Filing
  • 2005-08-19 JP JP2007528705A patent/JP2008510539A/ja active Pending
  • 2005-08-19 EP EP05783046A patent/EP1793882A1/de not_active Withdrawn

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