Injection devices

Details Injection devices Injection devices

1995-09-25

1997-02-04

Rimell, Sam

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

604134, 604117, A61M 520

Patent

active

055993095

DESCRIPTION:

BRIEF SUMMARY
This invention relates to injection devices.
In GB-B-2239180 an injection device has an elongate body of several parts which can be dismantled to insert and remove a syringe before and after use. The piston of the syringe is operated by a spring-loaded rod or plunger whose rear end is trapped by a catch, releasable by a press button. But initially this is impotent, held out of reach of the catch by an outer sleeve whose rear end it closes, the sleeve and button being lightly urged to the rear by a spring. For an injection, the device can be held by this sleeve and when the forward end is pressed against the skin, the sleeve moves forwards, bringing the button in range of the catch. Pressing the button then releases the plunger and the injection is carried out, the first part of the plunger stroke projecting the needle by shifting the syringe and the second part ejecting the fluid charge of the syringe through the needle. The arrangement gives a certain security against inadvertent actuation, and makes self-administration of an injection more reliable.
However, there are some drawbacks with this device. In particular, the plunger has to be specially formed first to have an effective engagement by the catch and secondly to provide an abutment for the coil compression spring which drives it. The part of the plunger which engages the catch of course has to be at the rear end, which means that the coil spring has to begin forward of the catch, so as not to interfere. Since the coil spring has to be quite long even when compressed (to be able to extend over both parts of the plunger stroke while maintaining its pressure on the syringe piston) the abutment on the plunger must be a good distance from the rear end. It also has to be a good distance from the syringe, to allow sufficient travel for the plunger. The arrangement leads to a device which is about three times as long as the syringe body.
Another snag is that a syringe with its own plunger already fitted and not removable is not usable in the device.
It is the aim of this invention to provide an injection device which, while having most of the benefits of GB-B-2239180, can be considerably more compact and be usable with syringes having their own plungers.
According to the present invention there is provided an injection device in which a charged capsule with a needle at its forward end and a plunger projecting from its rear end is housed in an elongate body with coil spring means which, when released from compression, act on the plunger to push that forwards and thereby carry out the injection, and a release mechanism for the spring means including a sleeve over a substantial part of the body initially retained in or urged into a rearward position but which has to be shifted forwards in relation to the body to allow the spring means to be released, characterised in that the spring means act between the rear end of the body and a drive member that receives the rear end of the plunger, and in that the release mechanism includes a detent, provided by the body, that engages the drive member adjacent its forward end.
In one form, the release mechanism includes an outwardly projecting formation on the drive member that initially engages the detent, the sleeve being arranged when shifted forwards, to engage said formation and press it inwards releasing it from the detent.
Conveniently, the drive member will be generally cylindrical and surrounded by the coil spring means which act against an abutment adjacent the forward end of said drive member. The rear end of the drive member will be at least partially closed to engage the rear end of the plunger.
The forward end of the device may have a removable cap which, when properly fitted on the body, is abutted by the sleeve, the sleeve thereby being prevented by moving forwards to allow release of the spring means.
In another form, the release mechanism includes a trigger, carried by said body, which initially engages the drive member, the trigger being accessible through an aperture in said sleeve, being held inopera

REFERENCES:
patent: Re32922 (1989-05-01), Levin et al.
patent: 3712301 (1973-01-01), Sarnoff
patent: 5042977 (1991-08-01), Bechtold et al.
patent: 5071353 (1991-12-01), Van Der Wal
patent: 5273544 (1993-12-01), Van Der Wal
patent: 5295965 (1994-03-01), Wilmot
patent: 5300030 (1994-04-01), Crossman et al.
patent: 5358489 (1994-10-01), Wyrick
patent: 5478316 (1995-12-01), Bitdinger et al.

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