Patent GB-1452790-A (GB)
Title: Automatic injection device
IPC: A61M5/20
Filed: 1973-10-16
Abstract: 1452790 Automatic injection device A J A GOURLANDT G C L GOURLANDT Y B T CAUQUELIN and J F R LAFON 16 Oct 1973 48200/73 Heading A5R [Also in Division H2] An automatic injection device comprises a syringe 3, means for retaining and placing an animal in a transverse position and at a given angle with respect to the syringe, means for advancing and withdrawing the syringe and means for displacing a piston 20. The syringe 3 (Fig. 1) is removably mounted on a semitubular extension 6a of a housing 6, the latter housing an electric motor comprising an electromagnet 33 Fig. 3a with a magnetic core 34 forming a piston, between two half-bearings so that the syringe can slide through the bearings. A plate 14 having a right angled abutment member 16 which carries a stud 17 in alignment with an aperture 18 in the plate 14 and at a certain distance from the latter, is adjustably mounted on a casing 1. Plates of different orientation with respect to the syringe axis may be used. The housing 6 is secured to a wall 7 of the casing 1 by a rod 6b (Fig. 3a) projecting through a slit in the wall 7, the latter being aligned in the direction of the common axis of the electromagnet and the syringe. A syringe rod 21 is connected through a syringe head 22 to a movable assembly 23 comprising a rod 23a, a rod head 24, a stud 25 whose ends are supported by the semi-tubular extension 6a, and a rear extension 26 of the rod 23a. A ring 27 screwed on the rear end of the syringe body 8 bears upon a removable tubular element 29 which is provided with a flange 29a abutting against the rear end of the body 8, and has a front face 29b which stops the piston during its rearward stroke. Tubular elements of various lengths may be used to vary the amplitude of the rearward stroke of the piston. The electric winding of the electro-magnet 33 is connected via an electronic assembly to a push-switch 19. A return spring 35 bears, on one hand, upon an end plate 36a, and on the other, upon a piston ring 37 secured to the magnetic core 34 by a hollow screw 38, the latter forming an adjustable stop for the rear extension 26 of the rod 23a. On energizing the electromagnet, the magnetic core 34 along with the moving assembly 23 and the syringe 3 moves in the direction of the arrow F. A needle 13 projects outwardly from the casing 1 and penetrates into the body of the animal. Before a ring 44 abuts against a rod bearing 43, the front face 3a of the ring 27 abuts against the rear face of the semi-bearing 9a thereby stopping the forward displacement of the syringe body 8. The magnetic core 34, however, continues to move forward and a spring 46 is compressed as an increasing resistance to the forward displacement of the piston and the assembly 23 is offered by the injection liquid in the syringe. When the forward stroke of the core is completed, the syringe is gradually decompressed thereby moving the piston forward and injecting the liquid into the animal. During the rearward stroke of the piston when the electromagnet is deenergized, the injection liquid is sucked in the syringe body 8. In another embodiment, the electromagnet is energized by the actuation of one or two contacts caused by putting in place of the foot of the animal.