FR2628636A1 - Syringe grip for automatic discharger - has sprung double-jaw gripping mechanism on piston pushing member to secure end collar of syringe piston - Google Patents

Abstract

The device includes a gripping system (5) to hold the end collar of the syringe piston consisting of two branches movable in a guide to secure the collar between them. A pair of gripping members (13,15) are attached to the branches for ease of manipulation. An elastic recall device biasses the branches together to grip the collar securely between them. The gripping assembly is adjustably movable parallel to the longitudinal direction of the syringe for engagement with the syringe. USE - In constant-delivery automatic syringe discharge machine.

Description

SYRINGE PUMP APPARATUS WITH IMPROVED DEVICE
FOR MAINTAINING THE PISTON TERMINAL COLLAR OF A
SYRINGE ON THE PUSH SHOE OF THIS APPARATUS
The invention relates to a syringe-pushing device intended to allow a predetermined dose of a liquid enclosed in a syringe to be injected with a constant flow rate, comprising improved means for holding the end flange of the syringe plunger on the push-shoe of this device.

 Current syringe pump devices conventionally include means for holding the syringe barrel, a push-button shoe provided with means for holding the end flange of the syringe plunger and means for driving this shoe capable of moving it axially relative to to the syringe body.

 The main drawback of these devices, the reliability of which has also been tested for many years, lies in the design of the means for holding the collar of the piston on the push shoe.

This collar is, in fact, held pressed against the front end face of the shoe by means of a plate provided with a notch for the passage of the piston and actuated by a system of screws carried by the push shoe and making it possible to move it. at the front of this shoe.

The main drawbacks of such a device are threefold. On the one hand, it is impossible to clamp the syringe body before having blocked the collar, because the latter must be slid between the shoe and the retaining plate, an operation which requires lateral movement of this collar relative to its blocking position. As a result, the operator is forced to hold the syringe with one hand and the push-shoe with the other, and therefore no longer has a free hand to carry out the often necessary ancillary operations. since the flanges of the different syringes are variable, it is almost compulsory to move the support plate of the push-shoe as far as possible so as to ensure that the space between these elements will be sufficient for the housing of this flange. Locking the flange therefore requires making several turns of the screw and thus constitutes a relatively slow operation. The last inconvenience results, finally, from the fact that these devices are designed to carry syringes of different categories therefore of different diameters. Or the device for maintaining the. flange by mechanical clamping is incapable of providing a degree of freedom to the latter allowing its self-centering with respect to the axis of displacement of the piston so that the point of application of the pushing force exerted on the flange is often offset relative to the axis of displacement of the piston;
It follows the creation of parasitic friction forces between the latter and the inner wall of the syringe body which regularly cause the triggering of an alarm fitted to the syringe pump device and adapted to signal the appearance of possible overpressures during the 'injection.

 The present invention aims 8 'to overcome the aforementioned drawbacks and proposes to provide a syringe pump device, the means for holding the plunger flange can be actuated with one hand, after clamping the syringe body, and allow the instant immobilization of this collar.

 Another objective of the invention is to provide a syringe pump device, the means for holding the plunger flange are adapted to ensure automatic correction of misalignment of syringe body / syringe plunger.

 Another objective of the invention is to maintain the plunger flange preventing any axial movement of the syringe plunger during a possible depression in the syringe body.

 To this end, the invention relates to a syringe pump device intended to make it possible to inject with a constant flow rate, a predetermined dose of a liquid contained in a syringe comprising a body and a plunger provided with a terminal flange of diameter included between values d and D, said syringe pump device being of the type comprising means for holding the syringe body, a push-button shoe provided with means for holding the collar of the piston and means for driving said shoe suitable for move axially relative to the syringe body.

According to the present invention, this syringe pump device is characterized in that the means for holding the collar of the piston comprise a system of pliers carried by the push shoe and comprising
- two branches shaped towards one of their ends so as to cooperate in order to keep the flange of the piston pinched,
- means for guiding the two branches adapted to allow relative movement of said branches in a direction orthogonal to the axis of displacement of the piston, between two positions
a spread position in which the shaped ends of the branches are spaced apart by a distance greater than D,
a close position in which the shaped ends of the branches are spaced apart by a distance less than d,
a support member linked to a branch and a counter-support member carried by the push shoe adapted to allow the branches to move from their close position to their separated position,
- Elastic means connecting the branches and adapted to bring said branches from their separated position to their close position, under the effect of their restoring force, so as to keep the collar of the piston pinched between the shaped ends.

 The establishment of a syringe on such an apparatus requires two successive operations which can be carried out with a hand willow. Initially, the syringe body previously filled with the liquid to be injected is clamped conventionally on the device, the push-shoe being axially distant from the syringe. This push-shoe is then moved axially towards the syringe until it comes to abut against the collar, the branches being kept apart by means of the support and counter-support members. At this stage, the relaxation of these members makes it possible to instantly pinch the flange between the shaped ends of the branches, under the effect of the restoring force of the elastic means. Any axial movement of this flange relative to the push shoe, in particular under the the effect of a depression prevailing in the syringe body is then prohibited.

In common cases where the syringe pump device is provided with a longitudinal chute for positioning the syringe body, the means for guiding the branches of the clamp system are preferably adapted to allow relative movement of said branches in a direction (X, X ) substantially parallel to the longitudinal plane of symmetry of said chute
In addition, according to a preferred embodiment, the syringe pump device is provided with means for centering the clamp system with respect to the push shoe adapted to provide a degree of freedom in translation in the direction (X, X) at said audit. clamp system so as to allow self-centering of the latter relative to the axis of movement of the syringe plunger.

 The fact of providing a degree of freedom along the axis (X, X) has, in fact, the advantage of allowing automatic correction of misalignment of syringe body / syringe plunger, defects mainly due to differences in diameter syringes, geometrical defects of the latter and original alignment defects between the syringe barrel and plunger. It therefore follows that no parasitic friction force interferes with the movement of the piston.

Furthermore, according to another characteristic of the invention
- the clamp system comprises a fixed branch and a movable branch, said branches comprising a flat tme provided towards one of its ends with a hooking fin and being positioned in an inverted position with their #me plane arranged in a plane orthogonal to the axis of displacement of the piston and their fins aligned along the axis XX,
the centering means are adapted to provide a degree of freedom in translation along the axis XX to the fixed and mobile branches,
- The guide means are adapted to allow movement in translation of the movable branch along the axis XX.

Other characteristics, objects and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings which represent, by way of non-limiting example, a preferred embodiment. On these drawings which form an integral part of the present description
FIG. 1 is a perspective view of an improved syringe pump device according to the invention,
FIG. 2 is a perspective view from behind of the push shoe of this device,
FIG. 3 is a front perspective view of this push shoe,
FIG. 4 is a cross section thereof through a horizontal plane A,
FIG. 5 is a longitudinal section thereof through a vertical plane B,
- Figures 6a, 6b, 6c are perspective views of ;; 'syringe pump apparatus illustrating the successive stages of the establishment of a syringe.

 The syringe pump device represented in FIG. 1 is intended for the injection with a constant flow rate, of a predetermined dose of a liquid contained in a syringe comprising a syringe body and a plunger provided with a terminal collar. diameter between values d and D.

 Conventionally, this device comprises, a front face 1 comprising a longitudinal chute 2 for positioning the body 3a of the syringe 3, and a retaining flange 4 adapted to block said body 3a inside this chute 2.

 It further comprises a push shoe 5 provided with means for holding the collar 3b of the piston 3c and driven in translation, axially with respect to the axis of longitudinal symmetry of the chute 2 QU by means of a system of rack and pinion drive 6, the actuation of which is controlled by a centralized management unit. A control button 7 also makes it possible to disengage the rack drive 6 so as to allow the push-shoe 5 to be moved manually when the syringe 3 is put in place.

 The push shoe 5 comprises two flat front faces, front 5a and rear 5b, located in planes orthogonal to the axis of movement of this shoe. The front front face Sa comprises a longitudinal guide groove 8 formed along an axis (X, X) parallel to the longitudinal plane of symmetry of the chute 2.

Its rear front face 5b is, for its part, pierced with a longitudinal lumen 9, oriented relative to the guide groove 8 and opening into the latter. A distance from this guide light 9 and aligned with the guide groove 8 along the axis (X, X), the push shoe 5 also includes a second light 10, called a centering light.

 The actual holding means of the collar 3c of the piston 3b consist of a clamp system comprising two branches, a fixed branch 11 and a movable branch 12, having shaped ends llb ', 12b adapted to pinch the collar 3c .

 The fixed branch 11 is in the form of an L, the core lla of which is disposed in abutment against the rear face 5b and the planar fin llb protrudes with respect to the front front face Sa of the push shoe 5 through centering light 10. This fin llb also has a chamfered end so as to facilitate the positioning of the flange. The centering light 10 is pa # r elsewhere of section adapted to allow a displacement of small amplitude of this fin llb and therefore of the fixed branch 11 along the axis (X, X).

 The core of this fixed branch is pierced with a longitudinal lumen llc of conjugate form of the lumen 9 of the shoe and arranged opposite said lumen. In addition, the end of this core 11a opposite the fin 11b is provided with a member, called a counter-support 13, extending orthogonally to the rear of the push shoe 5.

 The movable branch 12 has a flat core 12a of cross-section conjugate with that of the guide groove 8 so as to be housed in the latter without projecting with respect to the front face Sa of the push shoe 5, and a picking return 12b forming a V with said soul.

This core 12a with a chamfered bore is held in the groove 8 by means of a connecting pin 14, in the example a chamfered head screw, passing through the slots 9, llc of the shoe 5 and of the fixed branch 11 and connecting said core to a support member 15.

 This support member 15 disposed against the rear face Sa of the push shoe 5 has the form of a jumper adapted to overlap the core lla of the fixed branch 11 so as to maintain the latter in abutment against the rear face 5b of the shoe 5 while authorizing a movement of this branch along the axis- (X, X). During this movement, this fixed branch 11 is guided, on the one hand, at the level of its fin llb, inside the centering light 10 and, on the other hand, by means of two studs 16 projecting from the rear face 5b of the push shoe 5 and arranged on either side of the island core of this fixed branch 11.

 The support member 15 also includes a thrust zone 15a projecting relative to the rider and adapted to allow, in cooperation with the counter-support member 13, to move this member 15 along the core lla of the fixed branch 11 and therefore to move the mobile branch 12 along the axis (X, X) and thus to separate the shaped end 12b of this mobile branch 12 from that of the fixed branch 11.

 The reverse movement is obtained instantaneously by means of a spring 17 disposed on the rear face side 5b of the shoe and fixed, on the one hand, on a lug 18disposed in the extension of the fin llb of the fixed branch 11 and, on the other hand, on screw 14.

 The advantages of the invention emerge from FIGS. 6a to 6c which illustrate the successive stages of the placement of a syringe 3 on a syringe pump device according to the invention.

 Unlike the existing devices, the syringe body 3a 3 is initially clamped by means of the retaining flange 4 (FIG. 6e).

 Once the syringe 3 is positioned in the chute 2, the operator can take hold of the push-shoe 5 and move the latter, the rack system being in the disengaged position, keeping the arms 11, 12 in their separated position by means of the support 15 and counter support 13 (FIG. 6b).

 Once the collar 3c is positioned between the shaped ends llb, 12b of the branches 11, 12, it suffices to release the support members 15 and of the counter-support 13 so as to instantly pinch this collar and keep it pressed against the front face. Sa of the push shoe 5 with a degree of freedom in translation allowing self-centering of the piston 3b relative to the syringe body 3c (FIG. 6c).

 It can therefore be seen that, during all of these operations, the operator has one hand free, which constitutes a primary advantage in the medical field.

 It should be noted, moreover, that the flange 3c, whatever its thickness, is pressed against the flat front face Se of the push shoe 5 which therefore constitutes a reference bearing face allowing the management unit of the thrust system parameters to perform its calculations from a rigorous position.

Claims (10)

 1 / - Syringe pump device intended to enable a predetermined dose of a liquid contained in a syringe (3) comprising a body (3a) and a pis-ton (3c) to be injected with a constant flow rate. '' a terminal flange (3b) of diameter between values d and D, said syringe pump device being of the type comprising means (2, 4) for holding the syringe body (3a) (3), a push shoe (5) provided with means for retaining the collar (3b) of the piston (3c) and means (6) for driving said shoe capable of moving it axially relative to the body (3a) of the syringe (3), and being characterized in that the means for holding the collar (3b) of the piston (3c) comprise a system of pliers carried by the push shoe (5) and comprising  - two branches (11, 12) shaped towards one of their ends (lob, 12b) so as to cooperate in order to keep the flange (3b) of the piston (3c) pinched,  - guide means (8) of the two branches (11, 12) adapted to allow relative movement of said branches in a direction orthogonal to the axis of movement of the piston (3c), between two positions  a spread position in which the shaped ends (lob, 12b) of the branches (11, 12) are spaced apart by a distance greater than D,  a close position in which the shaped ends (lob, 12b) of the branches (11, 12) are spaced apart by a distance less than d,  - A support member (15) linked to a branch (11) and a counter-support member (13) carried by the push shoe (5), adapted to allow movement of the branches (11, 12) from their close position towards their separated position,  - elastic means (17) connecting the branches (11, 12) and adapted to bring said branches from their separated position to their close position, under the effect of their restoring force, so as to maintain the flange (3b) of the piston (3c) pinched between the shaped ends illb, 12b).  2 / - Apparatus according to claim 1 comprising a longitudinal chute (2) for positioning the body (3a) of the syringe (3), characterized in that the guide means (8) of the branches (11, 12) of the clamp system are adapted to allow relative movement of said branches in a direction (X, X) substantially parallel to the longitudinal plane of symmetry of said chute.  3 / - Apparatus according to claim 2, characterized in that it comprises centering means (10) of the clamp system relative to the push shoe (5) adapted to provide a degree of freedom in translation in the direction (X , X) #audit clamp system so as to allow self-centering of the latter relative to the axis of movement of the syringe plunger (3c) (3).  4 / - Apparatus according to one of claims 2 or 3, characterized in that  the clamp system comprises a fixed branch (11) and a movable branch (12), said branches comprising a flat core (island, 12a) provided towards one of its ends with a hooking fin (llb, 12b), and being positioned in the inverted position with their àmeplana (pila, 12a) disposed in a plane orthogonal to the axis of displacement of the piston (3c) and their fins (lob, 12b) aligned along axis XX,  the centering means (10) are adapted to provide a degree of freedom in translation along the axis XX to the fixed (11) and mobile (12) branches,  - The guide means (8) are adapted to allow movement in translation of the movable branch (12) along the axis XX.  5 / - Apparatus according to claim 4, characterized in that  the shoe (5) has two flat front faces, called front (5a) and rear (5b), located in planes orthogonal to the axis of displacement of the piston (3c),  the guide means consist of a longitudinal groove (8), called the guide groove, formed in the front end face (5a) of the push shoe (5) along the axis (X, X), into which a longitudinal light opens (9),  the centering means consist of a hole (10), called a centering, aligned with the guide groove (8) along the axis (X, X) and formed at a distance from the latter,  - The fixed branch (11) has a flat core (island) provided with a light (lake) of cross-section combined with that of the light (9) of the shoe (5) and is disposed against the rear face (5b) of said shoe , with its guide light (lake) facing the guide groove (8) of said shoe, the hooking fin (island) projecting relative to the front face (5) of the shoe through the centering light (10),  - The movable branch (12) is disposed inside the guide groove (8) and secured to the support member (15) by means of a connecting pin (14) connecting said support member to the 'flat soul (12a) of said branch, and passing through the slots (9, llc) of the shoe (5) and the fixed branch (11).  6 / - Apparatus according to claim 5, characterized in that the support member (15) has the shape of a jumper adapted to keep the fixed branch (11) in abutment against the rear face (5b) of the shoe ( 5).  7 / - Apparatus according to one of claims 5 or 6, characterized in that the guide groove (8) is of section adapted so that the core (12a) of the movable branch (12) is profiled with the front face (5a) of the shoe (5) so that said shoe has a front face (5a) planar, reference support of the flange (3b) of the piston (3c).  8 / - Apparatus according to one of claims 5 to 7, characterized in that the fixed branch (11) has a plane fin (lob) forming a square with the core (lia) of said branch.  9 / - Apparatus according to one of claims 5 to 8, characterized in that the elastic means consist of a spring (17) disposed on the rear face side (5b) of the shoe (5) and secured respectively to the axis of connection (14) and to the fixed branch (11), towards the end of the latter provided with the hooking fin (lib).  10 / - Apparatus according to one of claims 5 to 9, characterized in that the counter-support member (13) is carried by the fixed branch (11) towards the end of the latter opposite to the fin hooking (11b).