DESCRIPTION OF SYMBOLS

[0048] 10 . . . automatic injection device

[0049] 11 . . . cylinder holder

[0050] 12 . . . piston holder

[0051] 13 . . . adaptor

[0052] 14 . . . flange insert groove

[0053] 21 . . . syringe barrel

[0054] 22 . . . flange

[0055] 23 . . . piston

[0056] 24 . . . piston flange

[0057] 25 . . . flange cut part

[0058] 31 . . . syringe barrel

[0059] 32 . . . flange

[0060] 33, 33a, 33b . . . guide projection

[0061] 34, 34a, to 34d . . . guide projection

[0062] 40 . . . adaptor

[0063] 41 . . . guide groove

[0064] 42 . . . guide groove

[0065] 51 . . . press projection

[0066] 52 . . . reinforcing rib

[0067] 52a . . . radial part of reinforcing rib

[0068] 52b . . . concentric part of reinforcing rib

DETAILED DESCRIPTION OF THE INVENTION

[0069] FIG. 1 shows the state in which a flange 32 of a syringe barrel 31 is fitted in a flange insert groove 14 of an adaptor 40 (cylinder holder). FIG. 2 shows the adaptor 40 in which FIG. 2(a) is a plan view seen from an attaching direction of the syringe barrel and FIG. 2(b) is an A-A cross section in FIG. 2(a) viewed from rear side. FIG. 3 is an enlarged cross sectional view of a portion of the flange insert groove 14. A guide groove 41 is formed in an arcuate shape on a front sidewall surface of the flange insert groove 14 provided in the adaptor.

[0070] In the meantime, FIG. 4 shows the flange of the syringe barrel, which is used together with the adaptor, viewed from the tip side of the syringe ((a) is a whole view of the front surface and (b) is an enlarged view of the part B of (a)). As shown in this drawing, the front surface of the flange 32 is provided with arcuate guide projections 33 (33a, 33b). An F-F cross section of FIG. 4 is shown in FIG. 5(a), and a C-C cross section in FIG. 5(b). As shown in the cross sectional view of FIG. 5(a), the guide projection 33 of this embodiment has a cross section shape in accordance with the guide groove 41 of the adaptor and an arcuate shape in the lengthwise direction, and is adapted to be able to rotate along the guide groove 41 of the adaptor. It is preferable to form the end portion of the guide projection in a longitudinal direction in a tapered shape as shown in FIG. 5(b) so as to be smoothly guided into the guide groove.

[0071] FIG. 6 is a cross sectional view of the flange insert groove seen from rear side showing the mounting of the syringe barrel onto the adaptor. First, as shown in FIG. 6(a), the flange 32 is inserted into the flange insert groove 14 while keeping the flange cut part 25 substantially vertical. Thereafter, as shown in FIG. 6(b), the guide projection 33 is rotated while being fitted in the guide groove 41 until it reaches the use position.

[0072] Referring to FIG. 7, the opening length of the flange groove will be described. FIG. 7(b) is a conventional adaptor; since it has no guide groove, the arc part of the groove needs to be made large to prevent the flange from slipping out upwardly. For this reason, the opening L′ can only be slightly larger than the length of the flange in the flange cut part direction W (see FIG. 17). On the other hand, since the adaptor of the present invention shown in

[0073] FIG. 7(a) can prevent the upward slip off with the guide groove 41, the arc part of the groove can be made short. As a result, the opening length L can be made large and thereby facilitating the mounting operation of the syringe. As a matter of course, the adaptor of the present invention may be arranged such that the length of the arc part of the flange insert groove is as long as those of conventional types to prevent the slipping off of the syringe more securely. But, for general uses, it is preferable to make the opening length large placing higher priority on the operational convenience and workability.

[0074] There are no particular restrictions on the cross section shapes of the guide projection and the guide groove of the adaptor as long as they fit with each other easily and the syringe will not slip off upwardly. In the case of the trapezoidal cross section shape shown in FIG. 5(a), for example, arrangement may be such that the height h is 1 to 3 mm, the bottom surface width t1 is 1 to 3 mm, and the upper surface width t2 is 0.5 to 2.5 mm. The guide groove may be formed in accordance with this shape. Also the size of guide projection in a longitudinal direction (circumferential direction) may be conveniently made shorter than the opening length of the flange insertion groove while keeping it within a range in which an upward floating up is effectively prevented when the syringe is mounted. For example, for a syringe barrel with an outer diameter of 30 to 40 mm, the size of guide projection in a longitudinal direction may be 20 to 120 degrees, and preferably 30 to 90 degrees in terms of angles taking the center of barrel as the center of angle.

[0075] Although the cross section is a trapezoid in this embodiment, it may be a square, a triangular, or etc.

[0076] Preferably, in the present invention, the rear surface of the flange is provided with a press projection. Also in the present invention, by providing a reinforcing rib on the rear surface of the flange, the breakage of the flange may further prevented.

[0077] FIG. 8 shows an example of the flange 32 having press projections 51 and reinforcing ribs 52. When the flange is fitted in the use position by inserting it into the flange insert groove, the tip of the press projection is compressed generating elastic force to press the flange forwardly, and thus the flange is firmly secured. As shown in FIG. 9(a), the press projection 51 preferably has a narrower width toward the tip to make it more easily deformed by being pressed. The outer cylinder of the syringe is generally formed of a resin such as polypropylene, and the adaptor is formed of ABS, polycarbonate, or the like. Depending on the selection of the material, the cylinder holder side may be arranged to be compressible. When the above described materials are used, the projection of the syringe barrel is compressed. At this moment, even if the tip of the projection undergoes plastic deformation by compression, a certain level of the compressive force is preserved and therefore the flange is firmly secured by the resiliency.

[0078] The shape and the height of the projection may be determined taking these materials into account. Generally, it is preferable to arrange such that the distance from the front surface of the flange to the tip of the press projection is larger than the width of the flange insert groove by about 0.1 to about 2.5 mm, more preferably about 0.2 to about 1.0 mm. The press projection may have a conical shape as shown in FIG. 9(b).

[0079] FIG. 10 shows the state in which the flange 32 is fitted in the flange groove. The press projection 51 has undergone deformation, thereby pressing the flange 32 against the front surface of the flange groove 14. The position of disposing the press projections 51 is, as shown in FIG. 8, preferably a position close to the back side of the guide projection 33 formed on the front surface of the flange.

[0080] There are no particular restrictions on the shape of the reinforcing ribs, and an example may include a combined shape of a concentric part 52b and a radial part 52a as shown in FIG. 8. In this example, since the press projections 51 are formed on the extension of the radial part, the radial part is deformed accordingly. The press projection may be arranged in other places.

[0081] Next, other embodiments of the guide projection will be shown.

[0082] In the example shown in FIG. 11, a guide projection 34, which is shorter than the guide projection shown in FIG. 4, is formed in four places. As shown in the enlarged view of FIG. 11(b), the end-to-end distance including adjacent two guide projections 34a and 34b is preferably arranged in the same manner as the length of the guide projection 33 in the lengthwise direction shown in FIG. 4. The E-E cross sectional view is the same as the one in FIG. 5, and arrangement may be made in the same manner as the example of the guide projection of FIG. 4. In FIG. 11, an example is shown in which a press projection and reinforcing ribs are formed on the rear surface.

[0083] The guide projection may be of a plurality of truncated cones placed in a line in the circumferential direction; in which case, a plurality of truncated cones may be disposed at the positions where the guide projections of FIG. 4 are provided.

[0084] As described, in a preferable embodiment of the present invention, the number of the arcuate guide projections may be even number and each half number is symmetrically positioned on the flange where the two flange cut portions are not provided.

[0085] Although, in the above described examples, the guide projection is formed on each side of the flange cut part (top and bottom in FIGS. 4 and 11), it may be formed on only one side. The guide groove of the adaptor to be used in combination with the guide projection may be open in the top part as with the guide groove 41 shown in FIG. 2 or closed as with the guide groove 42 shown in FIG. 12. When the top part is closed, the flange can be inserted into the adaptor keeping its guide projection down, and then be rotated until the use position is reached.

[0086] The above-described embodiment is one example of the present invention, and it should be noted that various changes can be made without departing from the scope of the present invention.

[0087] As described above, according to the present invention, there can be provided provide a syringe barrel a cylinder holder, where the syringe is not easily broken in injecting liquid of high viscosity at high pressure and can be easily mounted.