Patent GB-1132065-A (GB)
Title: Hypodermic injector
Inventor: LOVE DOUGLAS STANLEY
IPC: A61M5/30
Filed: 1964-11-13
Abstract: 1,132,065. Needleless hypoderim injector. EXPRESS INJECTOR CO. Ltd. 12 Nov., 1965 [13 Nov., 1964], No. 46367/64. Heading A5R. A needleless hypodermic injector comprises a housing for an introvertable ampoule, means in the housing for rigidly supporting the ampoule against expansion when the liquid content thereof is exposed to pressure, and in impact-producing piston which abuts or is arranged to contact (and is arranged subsequently to follow) a plunger which is slidably mounted to act directly on the ampoule, the piston being actuated by a single spring which is so mounted that friction between the spring and adjacent portions of the injector may help to diminish the natural vibrations of the spring which is selected according to the size of the ampoule, ampoule discharge orifice, piston and plunger so as to reduce to less than 0.0013 second the effective time gap between the skinpiercing discharge and the tissue-penetrating discharge of the liquid content of the ampoule thereby to provide virtual continuity in the stream of liquid during the skin-piercing discharge and the tissue-penetrating discharge. The injector further includes an indirect triggering mechanism which comprises a main locking means for the piston, which main locking means is releasable by movement of an actuating member mounted in the housing, means providing a regular and unvarying force acting upon the actuating member in the direction of the movement thereof, and secondary locking means for the actuating member, which secondary locking means is manually operable. In an illustrated embodiment, the injector comprises a tubular housing 10 (see Figure 1) at one end of which is a socket 10a for receiving and rigidly supporting an ampoule 11 which comprises an elongated shell 11a closed by a flanged plug 12 from which extends a tubular projection 13 provided with an orifice. Slidably mounted in the housing by a ball bearing sleeve 26 is a plunger 25 which is provided with a stepped end 25a having a diameter slightly less than the diameter of the bore of the shell of the ampoule, the sleeve and plunger normally being retained in the position illustrated by compression springs 27 and 28, respectively. The ampoule is retained in the housing by a nozzle cap 14 (see Figure 2) having a bayonet lock 15 adapted to mate with helical lugs 16 formed on the housing. The nozzle cap is provided with a flanged tubular member 17 in which is embedded a support 18 adapted to receive the tubular projection of the ampoule. Formed in the end of the support is an orifice 23 which terminates a tapered rheologically advantageous discharge channel 24. The tubular member, the end of which has annular serrations 19, and the nozzle cap are surrounded by a protective outer casing 20 which is provided along its circumferential external wall surface with longitudinal splines (not shown) and at its end with circular and radial grooves 22, see Figure 3 (not shown) and which is made for example of a sterilisable plastics material. Threadably attached to the other end of the housing is a cylindrical main housing 29 (see Figure 5) which encloses a spring- operated mechanism and a main locking mechanism. The spring-operated mechanism comprises a first tubular guide member 30 slidably mounted in the main housing by a pin 31 and cooperating longitudinal groove 32. Surrounding the first tubular guide member for movement relative both thereto and to the main housing is a second tubular guide member 33 terminating in a piston 34 which abuts the plunger. The guide members are longitudinally relatively displaceable under the force of a main spring 35 and are retained together in opposition to this force by a "balls and cone" main locking mechanism comprising an actuating member in the form of a spindle 36 which is slidably located within the first tubular guide member. Formed in the first tubular guide member is a plurality of holes 38 in each of which is located a ball 39 which is seated in a circumferential recess 40, formed in the second tubular guide member, to be retained therein by a conical extension 41 to the spindle which normally is biased, by means providing a regular and unvarying force in the form of a spring 37, in the position illustrated. Located within a tubular extension 43 of the first tubular guide member is a safety device in the form of a transversely slidable first latch 42 having a central hole through which passes the spindle, the latch engaging a reduced diameter portion 36a of the spindle and being retained in this position by a block 44 and cooperating spring 45; the first latch has a nose 42b engaged in a recess 46a of a control ring 46 which is rotated to slide the latch thereby to release the safety device and to allow the spindle subsequently to be moved by the indirect triggering mechanism which is housed in a cap 55 threadably secured to the end of the tubular extension of the first tubular guide member. The triggering mechanism comprises a cylindrical guide member 47 which has a flanged end retained in position by ring 58 and in which is slidably mounted the spindle. Formed in the cylindrical guide member is a plurality of holes 50 in each of which is located a ball 49 which is seated in a circumferential recess 48 formed adjacent the end of the spindle, the balls being retained in the holes and recess by a sleeve 51, which is slidably mounted around the cylindrical guide member, thereby to constitute the secondary locking means. The interior of the sleeve, which is biased by spring 53 against the flanged end of an actuating button 54, has a circumferential recess 52 which is able, on depression of the button, to accommodate the balls thereby to release the spindle which moves under the force exerted on the conical extension thereof by the balls of the main locking means; such movement of the spindle releases the main locking means and allows movement of the piston, and hence of the plunger, under the force exerted by the main spring. The movement of the spindle is arrested by a transversely slidable second latch 56 (identical with the first latch) having a nose 56b and being associated with a spring 57, the latches being so arranged that only one latch at a time can engage the spindle; accurate rotative positioning of the control ring is facilitated by engagement of a spring loaded ball (not shown), carried by the tubular extension of the first tubular guide member, with one of two relatively radially displaced notches 63 formed in the control ring. Also formed on the control ring are two lugs 61 which cooperate with two slots 62 formed in the cylindrical main housing to allow the control ring and cap to enter therein thereby to allow the main locking means to be reset and the main spring to be reloaded. The ampoule may be an ampoule disclosed in either of Specifications 964584 or 1047562.