EP0345132B1 - Precompression dosing pump with improved priming action - Google Patents

Description

The present invention relates to a precompression metering pump with improved priming.

Among the dispensing valves which are commonly placed on tanks containing liquids or pastes, the precompression dosing pumps have many advantages. First of all, the emission of the fluid product essentially results from manual actuation. This eliminates the need for a propellant, such as freon, which is accused of being an atmospheric pollutant, or even nitrogen, which occupies a dead volume in the container. The latter also does not need to be particularly reinforced to contain a product under high pressure. The metering function is also very useful in the cosmetic or pharmaceutical industry where the quantity of product delivered each time the pump is actuated must be sufficiently precise. The precompression of the volume of product to be expelled also makes the use of this type of valve particularly clean, avoiding any untimely leakage or simply not fusing with the desired vigor. This arrangement finally leads to good isolation of the contents of the tank from the ambient air, which prevents clogging of the dispensing valve with dried or oxidized product.

A particularly advantageous precompression dosing pump has been designed, at least in principle it seems, by the company Rudolph Albert (cf. French patent 1,486,392 filed in 1966). More reliable and more precise, it is indeed satisfied with a single return spring so that it has not stopped since being improved. To illustrate, three figures are attached to this description which show the vertical section of an embodiment of this pump of the prior art. This is actually a much more recent configuration. The latter, disclosed more or less in French patent 2,305,241 from the company S.T.E.P. in 1975, ensures the operation of the pump regardless of the orientation of the valve relative to the vertical.

From Figures 1 to 3 which show the pump at different times of its use, it appears that it consists of five cylindrical parts assembled so that their respective axes of revolution are combined. In the figures, the resulting common axis is arranged vertically. This is how the upper part of the cups is situated on the side of the product emission while their lower parts are inserted in a reservoir (not shown) of product to be emitted.

• une tourette 1 présentant une embase 11 pour s'adapter au goulot du réservoir, ou récipient, de produit et y être assujettie de façon étanche par des moyens complémentaires (également non représentés),
• un corps de pompe 2 dont le dessus 21 s'encliquette dans la tourette 1 précédente et dont le fond 22 communique avec l'intérieur du réservoir soit directement (comme représenté), soit par l'intermédiaire d'un tube plongeur emmanché sur une douille solidaire du corps 2 (non représentés). En outre, un manchon 24 prolonge intérieurement le fond 22 du corps de pompe. L'espace annulaire entre ce manchon 24 et le corps de pompe 2 correspond alors à l'essentiel de la chambre de pompe 23 de la pompe-doseuse,
• un premier piston 3 pouvant coulisser de façon étanche au sein du corps de pompe 2 depuis une position haute montrée sur la figure 1 (le piston 3 étant en contact avec la couronne intérieure 12 de la tourette 1) jusqu'à une position basse montrée sur la figure 2 et définie comme nous le verrons plus loin. Le piston 3 se prolonge par ailleurs vers le haut en une tige 31 d'actionnement. Celle-ci est percée d'un canal 33 central pour l'émission du produit. La section de ce dernier n'est pas constante. En particulier elle présente, à peu près à mi-hauteur du canal 33, un brusque étranglement 32,
• un piston différentiel 4. Celui-ci se prolonge vers le haut par un pointeau 41 s'engageant dans la tige 31 du premier piston 3 de sorte que son sommet conique est adapté à reposer contre l'étranglement 32. Vers le bas, le piston différentiel 4 se prolonge par une jupe 42 adaptée à s'emmancher autour du manchon 24 solidaire du corps de pompe 2. Alors que là surface extérieure de la jupe 42 sert au guidage à l'intérieur du corps de pompe 2, sa surface intérieure présente inférieurement une lèvre d'étanchéité 43. Celle-ci permet d'interrompre la communication entre le réservoir et la chambre de pompe 23 dès qu'il y a emmanchement des pièces. La surface intérieure de la jupe 42 est de plus munie d'un décrochement 45 servant de butée contre le manchon 24 et déterminant ainsi la position basse du piston différentiel 4 (cf. figure 2). Entre son pointeau 41 et sa jupe 42, le piston différentiel 4 présente enfin un gradin 44 dirigé vers le haut qui conditionne son mode de fonctionnement hyraulique,
• un ressort 5 de rappel disposé entre le piston différentiel 4 et le fond 22 du corps de pompe 2.

The five parts forming the pump of the prior art are:

• a turret 1 having a base 11 to adapt to the neck of the reservoir, or container, of product and to be subjected thereto in a leaktight manner by complementary means (also not shown),
• a pump body 2, the top 21 of which snaps into the preceding tower 1 and the bottom 22 of which communicates with the interior of the tank either directly (as shown), or by means of a dip tube fitted on a socket secured to the body 2 (not shown). In addition, a sleeve 24 internally extends the bottom 22 of the pump body. The annular space between this sleeve 24 and the pump body 2 then corresponds to most of the pump chamber 23 of the dosing pump,
• a first piston 3 which can slide in leaktight manner within the pump body 2 from a high position shown in FIG. 1 (the piston 3 being in contact with the inner ring 12 of the spinner 1) to a low position shown on Figure 2 and defined as we will see later. The piston 3 also extends upwards into an actuating rod 31. This is pierced with a central channel 33 for the emission of the product. The section of the latter is not constant. In particular, it presents, roughly halfway up the channel 33, a sudden constriction 32,
• a differential piston 4. This is extended upwards by a needle 41 engaging in the rod 31 of the first piston 3 so that its conical top is adapted to rest against the throttle 32. Downwards, the piston differential 4 is extended by a skirt 42 adapted to be fitted around the sleeve 24 secured to the pump body 2. While the outer surface of the skirt 42 is used for guiding inside the pump body 2, its inner surface has below a sealing lip 43. This makes it possible to interrupt the communication between the reservoir and the pump chamber 23 as soon as there is fitting of the parts. The inner surface of the skirt 42 is further provided with a recess 45 serving as a stop against the sleeve 24 and thus determining the low position of the differential piston 4 (cf. FIG. 2). Between its needle 41 and its skirt 42, the differential piston 4 finally has a step 44 directed upwards which conditions its hydraulic operating mode,
• a return spring 5 disposed between the differential piston 4 and the bottom 22 of the pump body 2.

In order to cause the emission of a dose of product, it is necessary to manually push the rod 31 of the first piston 3 inside the pump body 2. This ensures the application of the needle 41 against the constriction 32, spring 5 tending to oppose the descent of the differential piston 4. The elasticity of the parts promotes the establishment of a tight contact which guarantees the closing of the emission channel 33. At the same time, the differential piston 4 is driven green the bottom 22 of the pump body 2. The skirt 42 presented by this piston 4 then engages on the sleeve 24 secured to the pump body 2 so that the pump chamber 23 is isolated both from the outside and from the tank. Assuming that it is initially filled with product, it soon sees a pressure increase considerably as a result of the forced decrease in the volume of the chamber 23. However, this pressure also applies to the step 44 of the differential piston 4, the surface of which is purposely greater than that of the lower edge of the skirt 42. Also, when it has become sufficiently high, it manages to exert on the differential piston 4 a strong vertical capable of opposing that of the spring 5. The needle 41 then withdraws from the constriction 32 and provides a green passage outside to the product under pressure. The various parts are then in the configuration of FIG. 3.

As soon as the pressure of the product in the pump chamber 23 has dropped, the spring 5 ensures the closing of the emission channel 33 by again pressing the needle 41 of the differential piston 4 against the throttle 32 of the rod 31. By releasing moreover the manual effort, the spring 5 causes the pistons 3 and 4 to rise. The pump chamber 23 sees its volume increase again. There is therefore a depression. As soon as the skirt 42 of the differential piston 4 releases the sleeve 24, this causes the product to be sucked in from the reservoir into the chamber 23. The product which it now contains is none other than the next dose which will be emitted during a subsequent actuation of the pump.

However, this operating mode remains dependent on a satisfactory initial filling of the pump chamber 23. And, frankly, priming is the weak end of this type of precompression dosing pumps. Because, if the pump chamber 23 contains air, reducing its size is not enough to properly pressurize this much more compressible gas than the liquid or pasty products usually distributed. The volume of air is therefore not expelled from the pump chamber 23, the needle 41 remaining pressed against the throttle 32. When the pistons are raised, there is therefore no depression there and no significant suction does not carry the product into the room.

This problem of priming was recognized very early. And, already in 1971, the STEP company proposed in the French patent 2,133,259 a remedy. In principle, it was a question of allowing the evacuation of the compressed air out of the pump chamber in order to favor the establishment of negative pressures during its subsequent volume increase. However, this idea has so far been implemented only in the context of a discharge of compressed air inside the container.

For the pump shown in FIGS. 1 to 3, this is advantageously achieved by means of a godron 25 placed at the base of the sleeve 24 on the side of the chamber 23. When the latter is filled with air, it is indeed possible to fully depress the differential piston 4 (that is to say until it comes into abutment on the sleeve 24 at its recess 45). As shown in Figure 2, the gadroon 25 then causes the local lifting of the skirt 42 so that air can escape into the interior of the pump body 2 which communicates with the tank. It should be noted that this lifting no longer occurs after priming, the height of the gadroon being chosen so that the emission of the product takes place before the piston 4 is pushed down to its level.

This priming method is particularly suitable for liquid products which do not fear contact with air. But for pasty products, the discharge of air into the tank only results in the formation of a bubble which generally adheres to the pump body 2. Thus, when the pistons go up, the air in the bubble is preferably at again sucked into the pump chamber 23 which therefore hardly ever starts. As for products which must not remain in the presence of air, it is clear that a backflow inside the container is contraindicated. This is how the present invention aims to arrange the precompression dosing pump of the prior art described above in order to improve priming without introducing the air initially contained in the pump chamber. inside the reservoir of product to be emitted.

• un corps de pompe ayant un fondcommuniquant avec un réservoir dudit produit et un dessus ouvert à l'atmosphère,
• un piston creux pour isoler et mettre en pression une chambre de pompe au sein dudit corps de pompe, ledit piston creux se prolongeant par ledit dessus ouvert dudit corps de pompe en une tige d'actionnement percée de part en part d'un canal de sortie débouchant à une extrémité libre de ladite tige,
• un piston différentiel logé dans ladite chambre de pompe pour interrompre la communication avec ledit réservoir et/ou ledit canal de sortie,
• un ressort de rappel pour rappeler lesdits pistons creux et différentiel,

   caractérisé en ce qu'est en outre prévu un ensemble d'amorçage comprenant des moyens élastiques et au moins une pièce cylindrique qui collabore d'une part avec ledit piston différentiel afin de constituer un premier clapet de sortie réservé à l'émission dudit produit et d'autre part avec ladite tige d'actionnement afin de constituer un second clapet de sortie permettant l'évacuation au sein dudit canal de sortie de l'air initialement contenu dans ladite chambre de pompe, ledit premier clapet étant fermé lorsque ledit second clapet est ouvert et inversement.More specifically, it relates to a precompression dosing pump used for the emission of a liquid or pasty product, said pump comprising

• a pump body having a bottom communicating with a reservoir of said product and a top open to the atmosphere,
• a hollow piston for isolating and pressurizing a pump chamber within said pump body, said hollow piston extending through said open top of said pump body into an actuating rod pierced right through an outlet channel opening at a free end of said rod,
• a differential piston housed in said pump chamber for interrupting communication with said reservoir and / or said outlet channel,
• a return spring for recalling said hollow and differential pistons,

characterized in that a priming assembly is further provided comprising elastic means and at least one cylindrical part which collaborates on the one hand with said differential piston in order to constitute a first outlet valve reserved for the emission of said product and on the other hand with said actuating rod in order to constitute a second outlet valve allowing evacuation within said outlet channel of the air initially contained in said pump chamber, said first valve being closed when said second valve is open and vice versa.

Claims 2 and following appended to this memo will make it possible to grasp the structure of the present priming assembly, the function of which has just been described in summary.

• les figures 1 à 3 montrent en coupe longitudinale une pompe-doseuse à précompression de l'art antérieur à laquelle la présente invention s'applique. Sur la figure 1, la pompe est au repos; sur la figure 2, elle est en phase d'amorçage et, sur la figure 3, elle est en phase d'émission du produit liquide ou pâteux à distribuer;
• les figures 4 à 6 montrent en coupe longitudinale une pompe-doseuse à précompression comportant une première variante du présent perfectionnement. Si l'ensemble de la pompe est dessiné en position de repos sur la figure 4 et en phase d'amorçage sur la figure 5, la figure 6 ne présente qu'un détail du canal intérieur de la tige d'actionnement correspondante;
• les figures 7 et 8 montrent en coupe longitudinale une pompe-doseuse à précompression comportant une deuxième variante du présent perfectionnement. Les positions de repos et d'amorçage sont respectivement représentées sur les figures 7 et 8;
• la figure 9 montre la coupe d'un moule adapté à la tige d'actionnement de la pompe-doseuse à précompression des figures 7 et 8;
• les figures 10 et 11 montrent en coupe longitudinale une pompe-doseuse à précompression comportant une troisième variante du présent perfectionnement. Les figures 10 et 11, qui représentent toutes deux la pompe en position de repos, se distinguent par un aménagement particulier de la pompe de la figure 11 qui lui octroie de façon connue des propriétés d'admission progressive;
• la figure 12 montre la coupe d'un moule adapté à la tige d'actionnement de la pompe-doseuse à précompression des figures 10 et 11;
• les figures 13 et 14 montrent en coupe longitudinale une pompe-doseuse à précompression comportant une quatrième variante du présent perfectionnement. Au repos sur la figure 13, l'amorçage s'effectue sur la figure 14;
• Les figures 15 et 16 montrent en coupe longitudinale une pompe-doseuse à précompression comportant une cinquième variante du présent perfectionnement. La figure 15 présente la position de repos tandis que la figure 16 illustre la phase d'amorçage.

The present invention will now be described with the aid of drawings which illustrate five particular variants of its embodiments. These are given by way of example and should not limit the improvement envisaged here to the parts shown in these drawings. In particular, they can be replaced by all the technical equivalents which will appear to those skilled in the art. In the drawings:

• Figures 1 to 3 show in longitudinal section a precompression dosing pump of the prior art to which the present invention applies. In Figure 1, the pump is at rest; in FIG. 2, it is in the priming phase and, in FIG. 3, it is in the emission phase of the liquid or pasty product to be dispensed;
• Figures 4 to 6 show in longitudinal section a precompression metering pump comprising a first variant of the present improvement. If the pump assembly is drawn in the rest position in Figure 4 and in the priming phase in Figure 5, Figure 6 shows only a detail of the inner channel of the corresponding actuating rod;
• Figures 7 and 8 show in longitudinal section a precompression metering pump comprising a second variant of the present improvement. The rest and priming positions are respectively shown in Figures 7 and 8;
• Figure 9 shows the section of a mold adapted to the actuating rod of the precompression dosing pump of Figures 7 and 8;
• Figures 10 and 11 show in longitudinal section a precompression metering pump comprising a third variant of the present improvement. Figures 10 and 11, which both show the pump in the rest position, are distinguished by a particular arrangement of the pump of Figure 11 which grants it in known manner progressive intake properties;
• Figure 12 shows the section of a mold adapted to the actuating rod of the precompression dosing pump of Figures 10 and 11;
• Figures 13 and 14 show in longitudinal section a precompression metering pump comprising a fourth variant of the present improvement. At rest in FIG. 13, the priming is carried out in FIG. 14;
• Figures 15 and 16 show in longitudinal section a precompression metering pump comprising a fifth variant of the present improvement. Figure 15 shows the rest position while Figure 16 illustrates the priming phase.

In each of these figures, equivalent parts have been given the same number. This applies in particular to the five cylindrical elements of common axis forming the precompression dosing pump of the prior art already described: the spinner 1 and the pump body 2 fixed on the tank, the first hollow piston 3, the piston differential 4 and the spring 5 movable within the pump body 2. As will appear later all the modifications made within the framework of the present invention relate to the needle 41 of the differential piston 4 and the rod 31 of the first piston 3 hollow. They amount to the introduction of at least one additional part (which receives the number 10) as well as elastic means 20 tending to repel this part relative to the rod 31 or the needle 41 or even to distance these last two elements l of each other.

Thus a first variant of this improvement, shown in Figures 4 to 6, shows compared to the prior art an enlargement of the channel 33 inside the rod 31 downstream of the throttle 32. The latter is then reduced to an annular lug to which reference 32 will now be reserved. A ring 10 is housed in the enlarged section of the channel 33 as well as a cylindrical spring 20, both like the channel 33 and placed with a radial clearance one behind the other. On one side, the ring 10 abuts at the level of the outer ring 103 of its base on the lug 32. On the other hand, the spring 20 is supported on a shoulder 34 of the rod 31 corresponding to the passage of the widening of the channel 33 to its traditional size at the outlet of the rod. The stiffness of the spring 20 must moreover be significant so that everything takes place, in the use phase of the pump, as in the previous state (cf. FIG. 3). If necessary, it is a precompressed spring. In fact, when the actuating rod 31 is pressed, it now transmits its movement to the piston 4 via the contact between the needle 41 and the internal crown 104 of the base of the ring 10 (cf. FIG. 6) . Then, the precompression of the product resulting in the withdrawal of the needle 41, it is this contact which is destroyed while the product fuses outside, passing between the conical top of needle 41 and ring 10.

However, during priming, things happen differently. Indeed, as has already been mentioned in the description of the prior art, the high compressibility of the air initially contained in the pump chamber 23 makes it possible to lower the piston 4 until it comes into abutment at its lower recess 45 against the sleeve 24. However, the relative position of the crowns 103 and 104 of the cylindrical piece 10 as well as the shape of the lug 32 of the rod 31 (see Figure 6) allow to push even more deeply the actuating rod 31. If, therefore, the user presses fully on the rod 31, that is to say until the base of the hollow piston 3 meets the step 44 of the differential piston 4, he can compress the spring 20 and thus breaking the tight contact established so far between the outer ring 103 of the ring 10 and the lug 32. The compressed air then finds a passage between the ring and the rod to the outside of the reservoir. It is therefore evacuated from the pump chamber 23. The priming conditions are now met as mentioned above without any air being introduced into the container.

As provided in Figure 6 for details of this first variant, the base of the ring 10 is cut into a truncated cone. This favors in particular the contact 103 of its outer ring against a lug 32 having the simple form of a boss. This also results in a self-centering of the ring 10 on the conical top of the needle 41 which guarantees the contact 104 of its inner crown even if the parts have played a little. It is finally advantageous that the two ends of the ring are cut identically. In this way, the parts are assembled without having to pay attention to the direction of introduction of the ring 10 into the rod 31.

This operation is in truth dependent on the tightness of the contact 103 made between the ring 10 and the lug 32. In particular, the latter should be manufactured with care so that, its slight elasticity helping, the ring 10 pushed back by the spring 20 applies to it suitably. However, the rod 31 is usually molded in a plastic material in one piece with the first hollow piston 3. The existence of both the shoulder 34 and the lug 32 within the channel 33 then makes the operation delicate. In fact, the mold must include a central finger conforming to the shape of the channel 33. This finger therefore has a wider intermediate section. Also when it is forcibly removed from the molded part, this section rubs against the lug 32 and deforms it. A similar stress is then imposed on it when the ring 10 and the spring 20 are put in place. Finally, experience shows that pin 32 is found if damaged that it is no longer able to collaborate satisfactorily with the ring 10.

Thus a second variant of this improvement is developed according to Figures 7 and 8. It differs from the previous essentially by the shape of its rod 31 of actuation. On one side is provided a main part which closely resembles the first piston 3 described so far and which in fact comprises a good section of the preceding rod 31. Its inner channel 33 also has the lug 32. However, the shoulder 34 is absent. Instead, the canal widens a little more. The rod 31 is further amputated from its thinned end portion. This is because the latter is now offered by a nozzle 30 which fits at the end of the channel 33 of the main room. The shoulder 34 is then determined by the base of the end piece 30 which narrows the passage to the outside.

In order to properly attach the end piece 30 to the main part of the first piston 3, the outer surface of the end piece 30 preferably comprises two stages of annular spurs. These can either snap into two grooves in the wall of the channel 33 (not shown), or anchor directly in this wall as long as the material of the main part lends itself to it. In the latter case, the end piece 30 advantageously has an external flange 37. This is then used to adjust the final degree of insertion of the nozzle 30 into the channel 33.

Thus, the manufacturing by molding of the main part is carried out without difficulty. As schematically indicated in FIG. 9, the mold comprises for example two dies. A first matrix 6 comprises a central finger 61 matching the shape of the transmission channel 33 from the free end of the main part forming the rod 31 to the lug 32. A second matrix 7 comprises a boss 71 conforming to the part piston 3 proper and also going up to lug 32. By moving these two dies away from each other (see the arrows in FIG. 9), the manufacturer thus manages to release the main part without requesting the pin 32. We note that, in this embodiment, the pin 32 admits rather the shape of a sealing lip that this mode of molding allows to achieve with the desired quality. To obtain a rod 31 rendering the same services as that of FIGS. 4 to 6, it then suffices to introduce the ring 10 and the spring 20 one after the other through the free end of the main part. , then snap on the end piece 30 molded elsewhere. During this final assembly operation, the lug 32 is not further stressed so that the subsequent user can have full confidence in its sealing qualities.

According to another embodiment of this second variant, the end piece 30 can be made in one piece with the ring 10. The elasticity necessary for push the latter against the lug 32 is then advantageously provided by molded tabs between the base of the nozzle 30 and the upper surface of the ring 10. These are, as the case may be, parallel to the axis of revolution of the assembly and bend towards the surface of the channel 33 or else arranged in a spiral and approach each other. It goes without saying that this second embodiment is very convenient in terms of mounting the pump since three elements can thus be assembled in a single operation.

Furthermore, the end piece 30 is preferably made of a fairly rigid plastic material. It is indeed the part of the first hollow piston 3 which is directly actuated. Often, a pusher, itself rigid, covers it in order to facilitate this manipulation by the user. The transmission of the force between the pusher and the end piece 30 is thus made more secure. However, the main part of the first hollow piston 3 has sealing lips 35 and 36 allowing it to circulate in leaktight fashion along the pump body 2. It is therefore preferable to use a relatively flexible plastic material to constitute it. Thus a rigid material is found in contact with a flexible material and it is not said that the corresponding connection is sufficiently solid and the remainder in spite of the aging of the dosing pump to support the thrust transmitted to the tip 30 by the elastic means 20. In the long run, a separation of the tip is in fact to be feared, fatigue or creep of the materials modifying the conditions of subjugation whether they consist of a force fit or a snap-in.

To mitigate this risk, a third variant of the present improvement has been devised. It is shown in Figures 10 and 11 which show that the first piston 3 is formed in this version of two hollow cylinders 300 and 310 engaged one in the other. The inner cylinder 300 has a sealing lip 36 oriented towards the bottom 22 of the pump body in order to slide in leaktight manner within the pump body 2. It extends upwards into a rod pierced with a central channel 33 for the product issue. About halfway up the channel 33 projects an annular lug 32 advantageously having the shape of a sealing lip oriented towards the outlet of the channel 33.

The external cylinder 310 comprises, in this embodiment, also a sealing lip 35 oriented towards the upper end 21 of the pump body in order to slide in leaktight manner within the pump body 2. In a more characteristic manner the present invention, it extends upward into a rod. The latter surrounds the rod of the inner cylinder 300 and thins above it into a hollow end portion 37 extending from the channel 33.

Advantageously, a free space 320 is provided between the end of the rod of the inner cylinder 300 and the thinning of the outer cylinder 310. In addition, a crown 34 protrudes opposite the channel 33 at the base of the terminal part 37 of the rod of the outer cylinder 310. This ring 34 has different radial channels 311 connecting the free space 320 with the channel 33.

Advantageously, an annular notch 312 is formed at the outer root of the rod of the inner cylinder 300. Likewise, an annular boss is provided at the inner root of the rod of the outer cylinder 310. In this way, the two cylinders can be made integral by snap-fastening when their respective rods are engaged one on the other.

In this third variant, a priming assembly 100 is presented. It could just as easily be used in the two variants described above in place of the ring 10 and elastic means 20. This assembly 100 is in fact made up of two identical rings 10 and 10 ′ linked together by a partition 20 cylindrical with the same axis as the rings. In the absence of external stresses, the latter corresponds for example to a thin hollow cylinder of the same internal diameter as the rings 10 and 10 '. Its small thickness also allows its elastic bending so that it can take the shape of a barrel shown in the drawings. It is however less flexible than spring 5.

In fact, the priming assembly 100 is housed within the channel 33. If a radial clearance is maintained, the assembly 100 is therein compressed axially between the end portion 37 of the rod of the outer cylinder 310 and the annular lug 32 which both provide support. The upper ring 10 'rests on the entire surface of its section against the crown 34 of the terminal part 37. The lower ring 10 is applied, for its part, against the lug 32 in a very localized zone 103 which, the elasticity of the parts helping, guarantees a tight contact.

This third variant of the present improvement works more or less like the previous two. During its priming, after the differential piston 4 has been lowered until it comes into abutment against the sleeve 24 of the pump body 2, the first hollow piston 3 can still be depressed so that its inner cylinder 300 rests against the step 44 Consequently, the top of the needle 41, which is applied in a sealed manner on the edge 104 of the ring 10, pushes the latter upwards. It follows that the contact 103 between this ring 10 and the lug 32 of the transmission channel 33 is broken. Now there is a passage between the pump chamber 23 and the exterior via, first of all, the gap between the periphery of the ring 10 and the wall of the channel 33 and, then, the channels 311 of the crown 34. This mechanism therefore allows the evacuation of the air initially contained in this chamber 23.

Note that due to the relative elasticity of the exterior cylinder 310, the compression of the user also has the effect of deforming this cylinder 310 in a barrel, making the free space 320 disappear between the latter and the cylinder 300 interior. This phenomenon, combined with that described above, results in increased bending of the partition 20 which strengthens the seal of the needle contact 41-ring 10 at 104.

When the user stops pressing the first piston 3, the partition 20 immediately seeks to return to its initial shape. It follows the very rapid restoration of contact 103 between the ring 10 and the lug 32 so that the pump chamber 23 is found completely isolated from the outside. As it is also isolated from the tank thanks to the sealing lips 43 of the skirt 42 circulating on the sleeve 24, the increase in its volume as the return spring 5 relaxes, causes the development of a depression within it. In the embodiment of Figure 10, the depression can reach a substantial value thanks to the presence in particular of the sealing lip 35 of the cylinder 310 outside of the piston rod 3 which prevents any infiltration of air. At the same time, a suction force urges this lip 35 and effectively opposes the separation of the two cylinders 300 and 310 forming the first piston 3 that the assembly 100 would otherwise tend to cause. This strengthens their connection at the snap 312 and, in some cases, can even make the latter useless.

As soon as the pistons have returned to their high position in FIG. 10, the passage offered between the skirt 42 and the sleeve 24 allows filling of the pump chamber 23 with the aid of the product sucked in from the reservoir by vacuum. The barrel deformation of the outside cylinder 310 of the first piston 3 has long since disappeared, the assembly 100 having pushed the crown 34 from the first moments of the pistons rising.

A new actuation of the first piston 3 results this time in the compression of the product trapped in the pump chamber 23. Indeed, the return spring 5, more flexible, is always stressed in the first place. And while with the depression of the pistons 3 and 4, its length decreases, the volume of the pump chamber 23 drops. The sealing lip 43 of the skirt 42 circulating on the sleeve 24 as well as the sealing lip 36 of the cylinder 300 inside the first piston 3 also guarantee the insulation of the chamber 23 so that the pressure of the product trapped in her breast is growing. This then causes the differential piston 4 to be withdrawn by the intermediary of the pressure which is exerted on the step 44 and opposes the restoring force of the spring 5. The ring 10 therefore remains all the better maintained at 103 Against the lug 32 that the cylinder 310 outside tends to deform in a barrel and compress the priming assembly 100. It is rather the turn of contact 104 with the needle 41 to break. The product under pressure then fuses between the needle 41 and the ring 10 to gain the exterior via the central holes of the ring 10, of the partition 20, of the ring 10 ′ and finally of the terminal part 37 of the cylinder 310 outside.

The emission continues in this way until the differential piston 4 comes into abutment against the sleeve 24 at the level of the recess 45. The pump chamber 23 which therefore ceases to decrease in volume, sees its pressure drop. The latter soon becomes unable to further oppose the return spring 5 so that the differential piston 4 rises and that the contact 104 of its needle 41 with the ring 10 is restored. The user noting that the product is no longer emitted, releases his effort again and the pump chamber 23 is not long in filling with product as at the end of priming, thus preparing the dose for subsequent actuation .

The first hollow piston 3 which has just been described lends itself to molding without disadvantage for the quality of the lug 32. For example, FIG. 12 very schematically shows how its internal cylinder 300 could be produced. It would suffice to use a two-part mold. A first part 6 would have in hollow the imprint of the outer surface of the cylinder 300 and, projecting in the center of the latter, a first finger 61 conforming to the internal shape of the channel 33 downstream of the lug 32. A second part 7 of the mold would, in turn, have a second finger 71 matching the interior shape of the channel 33 upstream of the lug 32. By pulling part 6 to the right of Figure 12 and part 7 to the left, the cylinder 300 find naked without the pin 32 does not suffer from friction.

It is understood that a comparable molding system can be used to make the cylinder 310 outside of the first piston 3. Before it is assembled to the cylinder 300 inside, the priming assembly 100 is engaged in the latter downstream of the lug. For this purpose, the assembly 100 is advantageously reversible. This is the case of the assembly 100 which has just been described and which comprises two identical rings 10 and 10 ′ while only the ring 10 in contact with the lug is useful for the proper functioning of the pump. Then, the assembly is completed by engaging the outer cylinder 310 on the inner cylinder 300 and causing them to snap, if necessary.

The third variant described hitherto with reference to FIG. 10 involves two sealing lips carried by the first hollow piston 3. We have seen that each of them is active in a different phase of the pump's operation: the lip 36 of the inner cylinder 300 participating in the isolation of the pump chamber 23 during the compression of its contents and the lip 35 of the outer cylinder 310 guaranteeing the development of a significant depression in chamber 23. However, the metering pump of the prior art is sometimes arranged in such a way that, during the raising of the pistons, its chamber 23 is the place of a depression of lesser importance. To this end, French patent 2,558,214 filed in 1984 by the company VALOIS provides for example one or more bores 48 in the differential piston 4. These are provided with thin lips 47 projecting from the step 44 and acting as a non-return valve. Thus, their presence does not in any way modify the phase of pressurizing the pump chamber 23. On the other hand, when its volume increases, the bores 48 practically immediately place the chamber 23 in communication with the reservoir, and this well before the skirt 42 leaves the sleeve 24.

With this type of dosing pump of the prior art, the sealing lip 35 of the outer cylinder 310 is no longer useful. As shown in FIG. 11, it is then preferable to eliminate it in order to reduce the friction of the first hollow piston 3 on the pump body 2 and thus authorize the use of a more flexible return spring 5. Instead, a simple annular rim 35 can be provided. If its diameter is less than that of the interior of the pump body 2, the flange 35 must remain suitable for contact with the tower 1 in the pump rest position. This contact is indeed useful at the stop of the first hollow piston 3 determining its high position. It may also be necessary to isolate the tank from the outside when an air vent 13 is otherwise provided. It is understood, however, that the molding of the rim 35 with the external cylinder 310 does not present any particular difficulty. The constitution of the first hollow piston 3 in two parts even allows easy adaptation to this second type of metering pump since the inner cylinder 300 and the priming assembly 100 remain, for their part, unchanged. Their respective molds therefore apply to all of the dosing pumps mentioned here. Note, however, that in this embodiment, the snap-fastening 312 or any other means of connection is essential in order to keep the two cylinders 300 and 310 integral, especially during the raising of the pistons to which no suction is no longer opposed. .

With the fourth variant of the improvement presented here, it is the shape of the differential piston 4 and more precisely of its needle 41 which is essentially modified. As shown in Figures 13 and 14, the needle 41 is roughly replaced by a cylindrical piece 10 of the same axis as that of the pump and which fits inside the piston 4 reduced in this case to its skirt 42 and its tier 44. The base of the cylindrical part 10 is full. It is provided on the outside with a rim 101 which allows the spring 5 to press it against the piston 4. Thus, during use, the part 10 is made integral with the piston in order to reproduce the operating mode of the anterior pumps. The upper part of the part 10 has an internal channel 105 opening directly into the channel 33 of the rod 31 of the piston 3. This internal channel 105 communicates with another channel 102, horizontal, located approximately halfway up the part cylindrical 10. When the latter is fully engaged in the piston 4, that is to say in the normal use phase of the pump, this horizontal channel 102 is insulated by an upper skirt 46 provided specially in the upper part of the piston 4. Finally, a cylindrical spring 20 bears against this upper skirt 46. It surrounds the head of the cylindrical part 10 so as to bear moreover against the throttle 32 of the channel 33 inside the rod 31. Like the elastic means equivalents provided by the previous variant, the spring 20 must be hard so that at least at the start of the stroke of the actuating rod 31, the descent of the latter does indeed cause an identical movement of the p iston 4. It can for example be precompressed.

Thus, as in the prior art, the depression of the rod 31 drives the piston 4 towards the inside of the pump thanks to the stop offered by the throttle 32. The product put under pressure in this way ensures the withdrawal of the piston 4 as well as the cylindrical piece 10 which is then gripped by the upper skirt 46 having, for this purpose, a hook shape. In the priming phase, the insertion of the actuating rod 31 can be carried out further. Again, the air from the pump chamber 23 does not hinder its descent until the piston 4 comes into abutment on the sleeve 24. The user then manages to compress the spring 20. This results in a relative movement of the cylindrical part 10 relative to the piston 4 and the release of the upper skirt 46 (cf. FIG. 14). The compressed air can then flow through the channels 102, 105, then 33 and be evacuated outside the tank, which is the end sought after.

The fifth variant of the improvement illustrated by FIGS. 15 and 16 is very close to the previous one. In particular, the cylindrical part 10 is almost entirely reproduced with the rim 101, the channels 102 and 105 ... The difference lies only in the elastic means which allow, at the end of the first depression of the actuating rod 31, to cause the release of the upper skirt 46 of the piston 4. In place of the spring 20, the upper part of the cylindrical part 10 has fins with a lower bevel. The upper skirt 46 can then be deformed when its hook-shaped edge rises on the beveling under the effect of external compression. The air in this case flows between the fins as far as channel 102.

These five variants which illustrate some embodiments of the improvement of the invention, clearly show their common point. During priming, as it is possible to abut the differential piston 4 and to push the actuating rod 31 even deeper, the user then causes the compression of elastic means which are not used during the actual use of the pump. The relative movement of the parts thus caused results in the opening of a path allowing the air initially contained in the pump chamber to be evacuated outside the container. During the first rise of the actuating rod, the pump chamber is found in depression, which promotes its filling with product which will be emitted during a subsequent actuation of the pump.

Claims (28)

1. A precompression metering pump for dispensing a liquid or a paste, said pump comprising:
      a pump body (2) having a bottom (22) communicating with a tank of said substance and a top (21) open to the atmosphere;
      a hollow piston (3) for isolating a pump chamber (23) inside said pump body (2), and for putting it under pressure, said hollow piston (3) extending via said open top (21) of said pump body (2) in the form of an actuator rod (31) which is pierced from end to end by an outlet channel (33) opening out to a free end of said rod (31);
      a differential piston (4) received in said pump chamber (23) in order to interrupt communication between said tank and said outlet channel (33);
      a return spring (5) for returning said hollow piston (3) and said differential piston (4);
      the metering pump being characterized in that it is further provided with a priming assembly (100) including resilient means (20) and at least one cylindrical part (10) which co-operates with said differential piston (4) and said actuator rod (31) in order to constitute a first outlet non-return valve reserved for dispensing said substance, said cylindrical part (10) also co-operating with said actuator rod (31) in order to constitute a second outlet non-return valve enabling the air initially contained in said pump chamber (23)to be evacuated within said outlet channel (33), said first non-return valve being closed when said second non-return valve is open, and vice versa.
2. A metering pump according to claim 1, wherein said resilient means (20) are stiffer than said return spring (5), so that, while an external force is being exerted on said actuator rod (31) in order to urge said hollow piston (3) into said pump body (2), said first outlet non-return valve opens when said pump chamber (23) gives rise to sufficient pressure to displace said differential piston (4) against the return force transmitted by said return spring (5), said second outlet non-return valve opening when said differential piston (4) comes into abutment against said pump body (2).
3. A metering pump according to claim 1 or 2, wherein said priming assembly (100) in which said at least one cylindrical part (10) is constituted by a ring having a base, is received with radial clearance inside said outlet channel (33) of said actuator rod (31), and is held in place by abutment between thrust means (34) and a lug (32) provided by said channel (33) and respectively situated adjacent to said free end of said actuator rod (31) and adjacent to said pump chamber (23), the base of said ring bearing internally in a first annular contact zone (104) against said differential piston (4) in order to form said first outlet non-return valve and externally in a second annular contact zone (103) against said lug (32) in order to form said second outlet non-return valve, the shapes of said cylindrical part (10), of said differential piston (4), and of said rod (31) in said annular compact zones (103, 104) being such that when said differential piston (4) comes into abutment against said pump body (2), said actuator rod (31) can be pushed down further into said pump body (2) and said second annular contact zone (103) disappears.
4. A metering pump according to claim 3, wherein said base of said ring is frustoconically shaped and said lug (32) is convexly curved.
5. A metering pump according to claim 3, wherein said base of said ring is plane, whereas said lug (32) is constituted by a sealing lip directed towards said free end of said actuator rod (31).
6. A metering pump according to any one of claims 3 to 5, wherein said thrust means (34) are constituted by a narrowing of said outlet channel (33).
7. A metering pump according to any one of claims 3 to 6, wherein said resilient means (20) are constituted by a precompression spring.
8. A metering pump according to any one of claims 3 to 5, wherein a hollow end fitting (30) is fixed in sealed manner in the free end of said actuator rod (31), thereby reducing the cross-section of said outlet channel (33) and constituting said thrust means (34) serving as the abutment for said priming assembly (100).
9. A metering pump according to claim 8, wherein said hollow end fitting (30) has at least two external annular serrations cooperating with at least two annular notches in said free end of said actuator rod (31) in order to snap fasten therewith.
10. A metering pump according to claim 8, wherein said hollow end fitting (30) extends beyond the free end of said actuator rod (31) and is made of a plastic material which is more rigid than the material forming said first piston (3).
11. A metering pump according to claim 10, wherein said end fitting (30) has at least two external annular serrations together with a collar (37), said serrations biting into the inside of said free end of said actuator rod (31) and said collar (37) bearing against the free end of said actuator rod (31).
12. A metering pump according to any one of claims 8 to 11, wherein said end fitting (30) is fixed to said ring, said resilient means (20) being constituted by tongues interconnecting said end fitting (30) and said ring.
13. A metering pump according to claim 12, wherein said tongues lie parallel to the axis of said outlet channel (33).
14. A metering pump according to claim 12, wherein said tongues wind spirally around the axis of said outlet channel (33).
15. A metering pump according to any one of claims 3 to 5, wherein said hollow piston (3) is constituted by a hollow inner cylinder (300) and a hollow outer cylinder (310), said cylinders (300, 310) being suitable for fitting one inside the other, said lug (32) projecting from the inside wall of said inner cylinder (300) whereas said thrust means (34) are constituted by a reduction in the cross-section of said outer cylinder (310).
16. A metering pump according to claim 15, wherein said inner cylinder (300) includes a sealing lip (36) directed towards said pump chamber (23) in order to slide in sealed manner within said pump body (2).
17. A metering pump according to claim 16, wherein said cylinders (300, 310) of said hollow piston (3) are provided with connection means (312) for fixing them together.
18. A metering pump according to claim 17, wherein said connexion means (312) for said cylinders (300, 310) of said hollow piston (3) are constituted by an annular notch provided in the outside surface of said inner cylinder (300) and an annular projection carried by the inside surface of said outer cylinder (310), said notch and said projection being adapted to snap fastened together when said cylinders (300, 310) are engaged one inside the other.
19. A metering pump according to any one of claims 16 to 18, wherein said outer cylinder (310) includes a sealing lip (35) directed towards the open top (21) of said pump body (2) in order to slide in sealed manner within said pump body (2).
20. A metering pump according to claim 17 or claim 18, provided with an additional admission non-return valve (47) opening when the pistons (3, 4) begin to rise, wherein said outer cylinder (310) includes a rim (35) extending towards the open top (21) of said pump body (2) and sliding with clearance within said pump body (2).
21. A metering pump according to any one of claims 15 to 20, wherein said outer cylinder (310) has a smaller sized terminal portion (27) whose inner base is suitable, when said cylinders (300, 310) are engaged one within the other, to face the inside of said inner cylinder (300) in order to constitute said thrust means (34) of said channel (33).
22. A metering pump according to claim 21, wherein a ring (10') identical to said at least one cylinder part (10) constituted by said ring is also received in said channel (33) downstream from said resilient means (20)
23. A metering pump according to claim 22, wherein said inner base of said terminal portion (37) of said outer cylinder (310) has an area substantially equal to that of the section of said rings (10, 10') such that either of said rings (10, 10') may bear thereagainst.
24. A metering pump according to claim 23, wherein said resilient means (20) are constituted by a thin cylindrical partition interconnecting said rings (10, 10') and having the same inside diameter as said rings (1à, 10')
25. A metering pump according to claim 24, wherein said inside base of said terminal portion (27) of said outer cylinder (310) projects as a seat; when said cylinders (300, 310) of said hollow piston (3) are engaged one inside the other, said inner cylinder (300) extends to the surface of said seat such that an empty space (320) exists at the end of said inner cylinder (300) corresponding to the thickness through which said ring projects; and radial slots (311) are provided through said seat in order to put said free space (320) into communication with said channel (33).
26. A metering pump according to claim 1 or claim 2, wherein said at least one cylindrical part (10) comprises a solid bottom portion provided with an outer rim (101), a top portion pierced by a vertical channel (105) communicating with a horizontal channel (102) situated approximately halfway therealong, said part (10) engaging in said differential piston (4) such that said rim (101) prevents it from rising through said differential piston (4), and such that an upper skirt (46) provided with a hook-shaped rim on said differential piston (4) covers said horizontal channel (102) and forms said second piston outlet non-return valve, said first outlet non-return valve being constituted by the top of said at least one cylindrical part (10) bearing against a choking step (32) presented in said outlet channel (33) of said rod (31),and in that said resilient means (20) oppose relative displacement between the actuator rod (31) and said differential piston (4).
27. A metering pump according to claim 26, wherein said resilient means (20) are constituted by a spring, preferably a precompressed spring, surrounding the top portion of said cylindrical part (10) and bearing against said upper skirt (46) of said piston (4) and also against said choking step (32) of the channel (33) of said actuator rod (31).
28. A metering pump according to claim 26, wherein said resilient means (20) co-operates with chamfered fins carried by said top portion of said cylindrical part (10).

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