EP0345132A1 - Precompression dosing pump with improved priming action - Google Patents

Abstract

An especially useful precompression metering pump belonging to the prior art is difficult to prime because of the high compressibility of the air initially contained in its chamber. In order to overcome this difficulty in its operation, the present invention provides, next to the pump's usual output valve, elastic means 20 and at least one cylindrical part 10, which supplementary components form a second output valve. <??>In one particular embodiment, these two latter components are housed one on top of the other inside the outlet channel 33 of the pump-activating rod 31. To this end they press when at rest against, respectively, a constriction 32 in the form of a spur and a shoulder 34, both of which are formed in this channel. In the course of normal operation, it is the pump's differential piston 4 which draws back, so that the metering pump operates just as in the prior art. In the priming phase, however, the actuating rod 31 can be driven fully in, with the result that the part 10 lifts off the constriction 32. This modification thus makes it possible to expel the air initially contained inside the pump chamber 23 to the outside. <IMAGE>

Description

The present invention relates to an improvement of a precompression dosing pump which improves 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.

The five parts forming the pump of the prior art are:
a tower 1 having a base 11 to adapt to the neck of the reservoir, or container, of product and to be tightly secured thereto by complementary means (also not shown),
- a pump body 2, the top 21 of which snaps into the previous 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 integral with 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 in Figure 2 and defined as we will see later. The piston 3 also extends upwards and 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 extends 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 differential piston 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 a sealing lip 43 below. 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 towards 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 its pressure increase considerably as a result of the forced reduction 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 vertical force capable of opposing that of the spring 5. The needle 41 then withdraws from the constriction 32 and provides a passage to the outside for 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 point of this type of precompression metering pump. 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 2,133,529 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 FIG. 2, the gadroon 25 then causes the local raising of the skirt 42 so that air can escape towards the interior of the pump body 2 which communicates with the reservoir. 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.

More specifically, it relates to an improvement improving the priming of a precompression dosing pump used for the emission of a liquid product or pastes, 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 to isolate and pressurize 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 a channel outlet opening at a free end of said rod,
- a differential piston housed in said pump chamber to interrupt 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 with said differential piston and said actuating rod so as to constitute, within said outlet channel, a first outlet valve reserved for the emission of said product as well as a second outlet valve allowing the evacuation into the atmosphere 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 pâteaux 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 figure 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 figure 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 phase of emitting the liquid product or pasta to be dispensed;
• - Figures 4 to 6 show in longitudinal section a precompression metering pump comprising a first variant of this 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 represented in FIGS. 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 this 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 of the same axis as 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 so 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 which in fact comprises a good section of the previous 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 conforming to 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 the creep of the materials modifying the securing conditions whether they consist of a force fit or a snap-on.

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 ′ connected 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 reservoir 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 through the pressure exerted on the step 44 and opposing the return force of the spring 5. The ring 10 therefore remains all the better maintained at 103 against the lug 32 than 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 pressurized product 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 latching 312 or any other connecting means 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 now 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 isolated by means of an upper skirt 46 specially provided 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 rest against the constriction 32 of the channel 33 inside the rod 31. As the equivalent elastic means 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 identical movement of the piston 4. It can for example be pr ecompressed.

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. Here 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 succeeds in compressing 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 disengagement of the upper skirt 46 of the piston 4. In place of the spring 20, the upper part of the cylindrical part 10 comprises 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 to the 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 (30)

1. Improvement improving the priming of a precompression dosing pump used for the emission of a liquid or pasty product, said pump comprising
- a pump body (2) having a bottom (22) communicating with a reservoir of said product and a top (21) open to the atmosphere,
a hollow piston (3) for isolating and pressurizing a pump chamber (23) within said pump body (2), said hollow piston (3) extending through said open top (21) of said pump body ( 2) into an actuating rod (31) pierced right through an outlet channel (33) opening at a free end of said rod (31),
- a differential piston (4) housed in said pump chamber (23) to interrupt the communication with said reservoir and / or said outlet channel (33),
- a return spring (5) for recalling said hollow (3) and differential (4) pistons, characterized in that a priming assembly (100) is further provided comprising elastic means (20) and at least one cylindrical part (10) which collaborates with said differential piston (4) and said actuating rod (31) in order to constitute, within said outlet channel (33), a first outlet valve reserved for the emission of said product as well as a second outlet valve allowing the evacuation into the atmosphere of the air initially contained in said pump chamber (23), said first valve being closed when said second valve is open and vice versa. 2. Improvement according to claim 1, characterized in that, while an external force is exerted on said actuating rod (31) to push said hollow piston (3) within said pump body (2), said first outlet valve opens when said pump chamber (23) admits sufficient pressure to move said differential piston (4) against the return force transmitted by said return spring (5), said second outlet valve opening, meanwhile, when said differential piston (4) abuts against said pump body (2), said elastic means (20) being less flexible than said return spring (5). 3. Improvement according to any one of claims 1 or 2, characterized in that said assembly (100) initiation of which said at least one cylindrical part (10) is constituted by a ring having a base, is housed with a game radial in said outlet channel (33) from said actuating rod (31) and retained by a stop between support means (34) and a lug (32) presented by said channel (33) and situated respectively on the side of said free end of said actuating rod (31) and the side of said pump chamber (23), the base of said ring pressing internally in a first annular contact zone (104) on said differential piston (4) to form said first outlet valve and externally in a second annular zone of contact (103) on said lug (32) to form said second outlet valve, the shape of said cylindrical part (10) of said differential piston (4) and of said rod (31) at said annular contact zones (103, 104) being adapted so that, when said differential piston (4) comes into abutment against said pump body (2), said actuating rod (31) can be pushed further within said pump body (2) and that said second annular contact zone (103) disappears. 4. Improvement according to claim 3, characterized in that said base of said ring is cut into a truncated cone while said lug (32) has the shape of a boss. 5. Improvement according to claim 3, characterized in that said base of said ring is planar while said lug (32) is a sealing lip oriented towards said free end of said actuating rod (31). 6. Improvement according to any one of claims 3 to 5, characterized in that said support means (34) consist of a narrowing of said outlet channel (33). 7. Improvement according to any one of claims 3 to 6, characterized in that said elastic means (20) consist of a precompressed spring. 8. Improvement according to any one of claims 3 to 5, characterized in that a hollow end piece (30) is secured by tight fitting in said free end of said actuating rod (31) so that it narrows the section of said outlet channel (33) and constitutes said support means (34) serving as a stop for said priming assembly (100). 9. Improvement according to claim 8, characterized in that said hollow end piece (30) has externally at least two annular spurs collaborating with at least two annular notches of said free end of said actuating rod (31) to be secured by snap-fastening . 10. Improvement according to claim 8, characterized in that said hollow end piece (30) protrudes outside said free end of said actuating rod (31) and is constituted by a more rigid plastic than that forming said first piston (3 ). 11. Improvement according to claim 10, characterized in that said end piece (30) has externally at least two annular spurs as well as a flange (37), said spurs anchoring inside said free end of said actuating rod (31) while said flange (37) is applied to said free end of said actuating rod (31). 12. Improvement according to any one of claims 8 to 11, characterized in that said end piece (30) is integral with said ring, said elastic means (20) being constituted by tongues connecting said end piece (30) and said ring. 13. Improvement according to claim 12, characterized in that said tongues are parallel to the axis of said outlet channel (33). 14. Improvement according to claim 12, characterized in that said tabs are wound in a spiral around the axis of said outlet channel (33). 15. Improvement according to any one of claims 8 to 14, characterized in that said hollow piston (3) is manufactured in a mold consisting of at least two dies (6, 7), one of said dies having a finger (61 ) conforming to said outlet channel (33) from said lug (32) to said free end of said rod (31), demolding is effected by removing said finger (61) through said end. 16. Improvement according to any one of claims 3 to 5, characterized in that said hollow piston (3) is formed by a hollow inner cylinder (300) and a hollow outer cylinder (310), said cylinders (300, 310) being adapted to fit into each other, said lug (32) projecting from the interior wall of said interior cylinder (300) while said support means (34) consist of a thinned section of said cylinder ( 310) outside. 17. Improvement according to claim 16, characterized in that said inner cylinder (300) comprises a sealing lip (36) directed towards said pump chamber (23) for sliding in leaktight manner within said pump body (2) . 18. Improvement according to claim 17, characterized in that said cylinders (300, 310) of said hollow piston (3) are provided with connecting means (312) enabling them to be made integral. 19. Improvement according to claim 18, characterized in that said connecting means (312) of said cylinders (300, 310) of said hollow piston (3) consist of an annular notch formed on the outer surface of said inner cylinder (300) and in an annular boss carried by the inner surface of said outer cylinder (310), said notch and said boss being adapted to snap when said cylinders (300, 310) are engaged one on the other. 20. Improvement according to any one of claims 17 to 19, characterized in that said outer cylinder (310) comprises a sealing lip (35) directed towards the top (21) open of said pump body (2) to slide in leaktight manner within said pump body (2). 21. Improvement according to claim 18 or claim 19, said metering pump being provided with a valve (47) for complementary admission opening from the start of the ascent of the pistons (3, 4), characterized in that said outer cylinder (310) has a rim (35) extending towards the top (21) open from said pump body (2) and sliding with play within said pump body (2). 22. Improvement according to any one of claims 16 to 21, characterized in that said external cylinder (310) has a thinned end portion (37), an internal base of which is adapted, during the engagement of said cylinders (300, 310 ) one on the other, coming opposite the interior of said interior cylinder (300) to constitute said support means (34) of said channel (33). 23. Improvement according to claim 22, characterized in that a ring (10 ′) identical to said at least one cylindrical part (10) constituted by said ring is also housed in said channel (33), downstream of said elastic means ( 20). 24. Improvement according to claim 23, characterized in that said inner base of said end portion (37) of said outer cylinder (310) has a surface substantially equal to the section of said rings (10, 10 ′) so that one or the other of said rings (10, 10 ′) can be applied thereto. 25. Improvement according to claim 24, characterized in that said elastic means (20) consist of a thin cylindrical partition integral with said rings (10, 10 ′) and of the same internal diameter as said rings (10, 10 ′). 26. Improvement according to claim 25, characterized in that said inner base of said end portion (37) of said outer cylinder (310) projects into a crown; in that, when said cylinders (300, 310) of said hollow piston (3) are engaged one on the other, said inner cylinder (300) extends to the surface of said crown so that a free space (320) exists at the end of said interior cylinder (300) corresponding to the thickness of which protrudes said crown; and in that radial channels (311) are provided in said ring to communicate said free space (320) with said channel (33). 27. Improvement according to any one of claims 16 to 26, characterized in that said inner cylinder (300) is produced in a mold consisting of at least two dies (6, 7), one of said dies (6, 7) having a finger (61) conforming to the interior of said interior cylinder (300) up to said lug (32), the release takes place by removing said finger (61) from the end of said interior of said cylinder (300) interior opposite said lug (32) so that said finger (61) does not rub on said lug (32). 28. Improvement according to any one of claims 1 or 2, characterized in that said at least one cylindrical part (10) comprises a solid lower part provided with an outer rim (101), an upper part pierced with a channel vertical (105) communicating with a horizontal channel (102) located approximately half of its height, said part (10) fitting into said differential piston (4) so that said flange (101) blocks its ascent in said differential piston (4) and that an upper skirt (46) provided with a hook-shaped rim presented by said differential piston (4) covers said horizontal channel (102) and forms said second outlet valve, said first valve outlet being constituted by the top of said at least one cylindrical part (10) resting on a constriction (32) presented by said channel (33) outlet of said rod (31) and in that said elastic means (20 ) oppose the relative displacement of the actuator rod (31) ement and said differential piston (4). 29. Improvement according to claim 28, characterized in that said elastic means (20) consist of a spring, preferably precompressed, surrounding the upper part of said cylindrical part (10) and resting on said upper skirt (46) of said piston (4) and on said throttle (32) of the channel (33) of said actuating rod (31). 30. Improvement according to claim 28, characterized in that said elastic means (20) collaborate with bevelled fins carried by said upper part of said cylindrical part (10).

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