EP0377536B1 - Check valve for introducing a liquid to be sprayed to a pump chamber, and its use - Google Patents

Abstract

Some precompression pumps currently used for spraying a liquid include a non-return valve formed by a gasket (3) held captive between the base of the pump body (1) and a sleeve (2). This non-return valve determines the extent to which the pump chamber (19) is isolated from or put into communication with a supply of liquid, as a function of whether the gasket (3) bears against the base of the pump body (1) or against the sleeve (2), closing a central hole through the pump body or being held off a central hole through the sleeve. In order to make valve operation more reproducible the present valve has the following features: the base of the pump body (1) is in the form of a cup (18) of small slope; the side wall (28) of the sleeve (2) flares from the end (26) of the sleeve (2) and has a local swelling (27), with the side wall (28) being of reduced thickness on either side of the swelling (27 ); and the end (26) of the sleeve (2) includes a tongue (25) and two ribs (2b), the tongue (25) and the ribs (2b) extend from the side wall (28) of the sleeve (2) all they way to its central hole (2a), the tongue (25) is diametrically opposite the swelling (27) and it is thickest adjacent to the central hole (3a), the ribs (2b) are disposed symmetrically about the diameter passing through the swelling (27) and the tongue (25) such that each of them forms an acute angle with the diameter on either side of the swelling (27).

Description

The present invention relates to a non-return valve used for the admission into a pump chamber of a liquid to be vaporized. More precisely, this valve is designed to open and close in a particularly reproducible manner from one actuation of the pump to another. It is advantageously used with certain precompression pumps of the kind disclosed by American patent US 4 245 967.

We describe below the corresponding prior art pump in order to clearly define the role of the valve in question here. This recall will also highlight the shortcomings of the intake valves used so far. For this, reference will be made to the longitudinal section presented with the drawings of this specification in FIG. 1. It indeed shows a precompression pump intended to be crimped tightly by means of a capsule 10 and seals 9a and 9b on a tank (not shown). When activated, this pump must be kept vertical in the position shown.

This is how the precompression pump of the prior art is essentially protected by a pump cylinder 1. The throttled end 12 of this cylinder 1 communicates (generally by a dip tube not shown) with the reservoir of liquid to be emitted. Between the end 12 and the hollow body 11 of the cylinder 1 is arranged a non-return valve in this case comprising a cylindrical seal 3 as well as a sleeve 2 for guiding the seal 3. A piston 5 circulates inside the body 11. It is provided with outer sealing lips 5a. These determine with the non-return valve the pump chamber 19 which is thus isolated in the lower part of the body 11. The piston 5 receives, in a central recess 5b, a rod 4 with a blind inner channel 4a which opens out laterally through an orifice 4b. The rod 4 and the piston 5 are also designed such that a spring 7 allows, by its compression, a relative movement of the rod 4 and the piston 5. Thus the orifice 4b can pass from the position shown in Figure 1, in which it is closed by the piston 5, in a position where it communicates with the pump chamber 19. Within the latter are finally arranged a return spring 8 which is more flexible than the spring 7 as well as a ring 6 which has the essential function of ensuring a very good seal between the piston 5 and the rod 4.

When a user presses on the rod 4, he first of all causes, by means of the spring 7, the descent of the piston 5 within the body 11 of the pump cylinder 1. However, this movement remains extremely limited. Indeed the seal 3 is applied against the bead protruding at the base of the body 11 and isolates the chamber 19 pump. The incompressibility of the liquid which it contains therefore stops the stroke of the piston 5 while the pressure in the chamber 19 increases. The action of the user then results in essentially compressing the spring 7. This in fact occurs when the pressure in the pump chamber 19 has reached a certain threshold in relation to the stiffness of the spring 7. This threshold justifies the designation of precompression pump, because as soon as it is exceeded, the chamber 19 is placed in communication with the outside via the orifice 4b and the channel 4a and the liquid flows. It is then the turn of the spring 8 to compress while the volume of the chamber 19 decreases. The emission of the liquid continues in this way until the base 6a of the ring 6 comes into abutment against the surface of the sleeve 2.

It is then that the user stops pressing on the rod 4. The stiffer spring 7 first returns to its initial shape causing the rod 4 to rise within the recess 5b of the piston 5. The passage to the outside through the hole 4b and the channel 4a therefore closes. Then the spring 8 relaxes in turn and the pump chamber 19 is put under vacuum. It follows a suction of the seal 3 towards the top of the guide sleeve 2. This connects the chamber 19 and the interior of the liquid tank. The latter is then admitted into the chamber 19 passing around the joint 3. Ribs 2b carried by the top of the sleeve 2 in fact prevent the joint 3 from closing its central hole 2a. When the pump chamber 19 has returned to its original size and is again filled with liquid, the pressures are balanced on either side of the seal 3. For the valve of the prior art shown in FIG. 1, it is then hoped that gravity will bring the seal 3 against the cord 1a of the base of the body 11, thereby isolating the chamber 19 of the pump for subsequent actuation.

However, the return of gasket 3 to its place is not systematically carried out according to theory. Often the seal 3 is placed at an angle within the sleeve 2. When the precompression pump is actuated again, the pump chamber 19 remains in communication with the reservoir of liquid to be vaporized. The pressure within the chamber 19 therefore does not rise so that the spring 7 is not compressed and the passage for the emission of the liquid does not become free. This malfunction occurs especially when it comes to pumping a gas (for example when priming the pump). In this case, the seal 3 tends to remain sticking to the top of the sleeve 2 by skin effect (such as the appearance of static electricity).

It goes without saying that, from the user's point of view, the resulting random operation is hardly engaging. It can even be prohibitive for pharmaceutical products requiring careful dosing. For the manufacturer of such pumps, it also poses a problem. In fact, all the pumps are tested before being placed on the market. However, the test usually used to assess their performance is to operate the pump three times while it is mounted on an air tank. The depression thus created in the tank is taken as a criterion of good or bad functioning. Often pumps are thus eliminated, the seal 3 of which has not returned correctly in the presence of air, but which would have given all satisfaction in the presence of the liquids for which they are intended. The high rate of waste therefore constitutes a serious shortfall for the manufacturer.

Thus, the intake valve of the present invention aims to significantly reduce the randomness of its operation, especially in the presence of gas. In particular, its seal 3 must be able to return systematically to its place in order to effectively close the communication 13 between the reservoir and the pump chamber 19.

• un cylindre de pompe comportant intérieurement un étranglement séparant un corps et une extrémité, ledit corps protégeant ladite chambre de pompe tandis que ladite extrémité communique avec un réservoir dudit liquide,
• une douille creuse ayant un fond percé d'un trou central et une paroi latérale adaptée pour être emboîtée de façon étanche dans ledit corps de sorte que ladite douille déterimine avec ledit étranglement un logement,
• un joint en forme de disque adapté à prendre place avec jeu dans ledit logement,

caractérisé en ce que:

• ledit étranglement admet, du côté dudit corps, la forme d'une cuvette de faible inclinaison,
• ladite paroi latérale de ladite douille s'évase intérieurement depuis ledit fond de ladite douille et présente localement un renflement, ladite paroi latérale de ladite douille étant moins épaisse de part et d'autre dudit renflement,
• ledit fond de ladite douille comporte une languette et deux nervures, ladite languette et lesdites nervures s'étendant depuis ladite paroi latérale de ladite douille jusqu'audit trou central de ladite douille, ladite languette étant en outre diamétralement opposée audit renflement et plus épaisse près dudit trou central de ladite douille, lesdites nervures étant par ailleurs disposées symétriquement par rapport au diamètre passant par ledit renflement et ladite languette de sorte qu'elles s'étendent en faisant un angle aigu avec ledit diamètre de part et d'autre dudit renflement.

To this end, a non-return valve is proposed for admitting a liquid to be vaporized into a pump chamber, said valve being formed by the collaboration of three elements:

• a pump cylinder internally comprising a constriction separating a body and an end, said body protecting said pump chamber while said end communicates with a reservoir of said liquid,
• a hollow socket having a bottom pierced with a central hole and a side wall adapted to be fitted in leaktight manner in said body so that said socket deterimates with said constriction a housing,
• a disc-shaped seal adapted to take place with play in said housing,

characterized in that:

• said constriction admits, on the side of said body, the shape of a bowl of slight inclination,
• said side wall of said socket flares internally from said bottom of said socket and locally has a bulge, said side wall of said socket being thinner on either side of said bulge,
• said bottom of said sleeve has a tongue and two ribs, said tongue and said ribs extending from said side wall of said sleeve to said central hole in said sleeve, said tongue being further diametrically opposite said bulge and thicker near said central hole of said socket, said ribs being moreover arranged symmetrically with respect to the diameter passing through said bulge and said tongue so that they extend at an acute angle with said diameter on either side of said bulge.

Other characteristics of a valve according to the present invention are set out in the dependent claims collected below. They also refer to advantageous uses of the present valve in association with known pumps.

During tests carried out on precompression pumps of the kind described above, this valve has been shown to be particularly effective. When checking the pumps according to the method mentioned above, the waste rate dropped significantly. In addition, the doses emitted from one stroke to the next proved to be particularly regular. Finally, the pumps fitted with the valve of the invention operate in reverse, which is impossible with the gravity valves of the prior art.

• la figure 1 est une coupe longitudinale d'une pompe à précompresion comprenant un clapet d'admission de l'art antérieur,
• la figure 2 est une coupe longitudinale d'un cylindre de pompe pour accueillir une pompe à précompression similaire à celle de la figure 1, mais pourvu d'un siège de clapet de sorte qu'il constitue un premier élément d'un clapet d'admission selon une forme de réalisation de la présente invention,
• la figure 3 est une coupe longitudinale d'une douille de guidage constituant un deuxième élément d'un clapet d'admission selon une forme de réalisation de la présente invention,
• la figure 4 est une vue de dessous de la douille de guidage de la figure 3,
• la figure 5 est une coupe longitudinale d'un joint constituant un troisième élément d'un clapet d'admission selon une forme de réalisation de la présente invention,
• les figures 6 à 8 sont des coupes longitudinales d'un même clapet d'admission selon une forme de réalisation de la présente invention. Sur la figure 6, le joint est montré alors qu'il vient d'être placé à l'intérieur d'un cylindre de pompe et de sa douille de guidage. Les figures 7 et 8 illustrent repectivement les phases d'émission du produit contenu dans la chambre de pompe et d'admission du produit dans la chambre.

The valve for the admission into a pump chamber of a liquid to be vaporized according to the present invention will now be described with the aid of an example allowing a better understanding of its embodiment. For this, reference is made to the accompanying drawings. On these:

• FIG. 1 is a longitudinal section of a precompression pump comprising an intake valve of the prior art,
• Figure 2 is a longitudinal section of a pump cylinder for accommodating a precompression pump similar to that of Figure 1, but provided with a valve seat so that it constitutes a first element of a valve admission according to an embodiment of the present invention,
• FIG. 3 is a longitudinal section of a guide sleeve constituting a second element of an intake valve according to an embodiment of the present invention,
• FIG. 4 is a bottom view of the guide sleeve of FIG. 3,
• FIG. 5 is a longitudinal section of a gasket constituting a third element of an intake valve according to an embodiment of the present invention,
• Figures 6 to 8 are longitudinal sections of the same inlet valve according to an embodiment of the present invention. In Figure 6, the seal is shown when it has just been placed inside a pump cylinder and its guide sleeve. FIGS. 7 and 8 respectively illustrate the phases of emission of the product contained in the pump chamber and of admission of the product into the chamber.

The pump cylinder 1 in FIG. 2 is very similar to that used in the prior art which is illustrated in FIG. 1 and mentioned above. The only differences to be noted are located at the base of the body 11, at the place where it is connected to the constricted part 12 of the cylinder 1. In fact, the support cord 1a is not present here. Instead, the base of the body 11 has a smooth inner wall 18. It is however slightly sloping, determining a bowl inclined from 1 to 6 ° approximately. The communication 13 between the reservoir of liquid to be vaporized and the pump chamber 19 also has a different section from that of the prior art. On either side of a cylindrical section, truncated cones widen the communication 13 both on the side of the pump chamber 19 and on the side of the throttled part 12 inside the tank.

As in the prior art, the lower part of the pump cylinder 1 has a recess 17 to receive a guide sleeve 2 with a good fit. This is however done differently. Figures 3 and 4 show the form adopted in the context of the present invention. It should be emphasized, before continuing with its description, that it is represented here on a scale different from that of FIG. 2. Its scale is also extremely magnified compared to its actual size corresponding more to 6mm in diameter for 4mm in diameter. height.

The sleeve 2 according to an embodiment of the present invention in fact admits the appearance of a hollow cylinder having a lower part 21 wider than its upper part 22 (cf. FIG. 3). The sectional recess between these two parts determines a shoulder 23 against which the return spring 8 comes to bear. The interior of the socket 2 likewise has a wider section at the level of the lower part 21 (see recess 29) than at the level of the upper part 22 (see recess 24). A central hole 2a connects all of the recesses.

The shape of the internal walls of the lower recess 29 is particularly advantageous in the context of the present invention (cf. FIG. 4). In general, the side wall 28 flares internally towards the base of the sleeve 2 at an angle of approximately 4 °. However, it locally has a small internal bulge 27. On either side of this bulge, it should also be noted that the wall 28 is somewhat less thick. The bottom 26 of the recess 29 is, meanwhile, flat. It also has three protrusions. A tongue 25 diametrically opposite the bulge 27 starts from the side wall 28 and goes to the central hole 2a. The section in FIG. 3 specifies that this tongue 25 is thicker near the hole 2a. Its face inclines for example 15 ° relative to the plane of the bottom 26. Furthermore two ribs 2b also extend from the side wall 28 to the central hole 2a. They are arranged symmetrically with respect to the diameter passing through the center of the tongue 25 and that of the bulge 27. Their respective axis also makes an acute angle with this diameter (of about 40 ° for example). In the embodiment illustrated in Figure 4, the side wall 28 is slightly thinner along the small arc located between the two ribs 2b.

Within the recess 29 of the socket 2, it is planned to have a seal 3. This is presented in section in FIG. 5 on the same scale as the socket 2 in FIGS. 3 and 4. It is in makes a small disc of elastomer or plastomer, the faces 31 of which are flat. The stamping conditions of this type of joint often cause the appearance of a meniscus on its edge 32.

When all of the three elements which have just been described separately are mounted, the valve of the invention is then formed. Figures 6 to 8 show how it works. When the seal 3 has just been placed in the recess 29, it is therefore surrounded by air. It then rests at the bottom of the bowl 18 of the body 11 of the pump cylinder 1 (cf. FIG. 6). When the pump is primed and the seal 3 is on the contrary bathed in liquid, it nevertheless retains more or less this same position. Certainly, its material generally absorbs a certain amount of liquid and increases in volume. However, in this embodiment of the present invention, swelling on the order of 10% is perfectly tolerable. The joint 3 remains relatively free to move and thus retains all the characteristics of a gravity joint. Besides, it may prove advantageous to ballast this joint. With an increased mass, it will therefore be able to close more quickly the inlet valve of the pump chamber 19 which it constitutes in collaboration with the pump cylinder 1 and the socket 2 in accordance with the mechanism described in the following paragraph.

In the pressure build-up phase in the pump chamber 19, the seal 3 is applied against the bowl 18 as indicated in FIG. 7. The large contact surface thus created ensures perfect sealing of the seal 3. No trapped liquid in room 19 can therefore not return to the tank. In the vacuum phase of the pump chamber 19, the seal is lifted by suction. It then takes the form illustrated in FIG. 8. The part of the seal 3 held by the tongue 25 remains practically in place while the seal 3 is also applied against the ribs 2b. The product can then be admitted into the pump chamber 19 by flowing through the hole 13, then bypassing the edge 32 of the seal 3 and finally passing between the ribs 2b to the central hole 2a of the sleeve 2. The bulge 27 ensures the release of this flow path even in the case of a horizontal displacement of the joint 3. In addition, the smaller thickness of the side wall 28 of the sleeve 2 near this bulge prevents the appearance too high pressure drops during this flow. Finally, when the chamber 19 is again full, the seal 3 easily returns to the position illustrated in FIG. 7. Indeed, the general flaring of the side wall 28 of the sleeve 2 limits the possible contact surface with the joint 3. The latter therefore does not risk adhering to or catching on the socket and returns more surely against its seat formed by the bowl 18.

• augmentation de près de 70% de la surface de contact du joint 3 et de la base du corps 11 par l'utilisation d'une cuvette 18 au lieu d'un cordon 1a d'appui;
• maintien vertical du joint 3 par une languette 25;
• guidage horizontal du joint 3 par un renflement 27 latéral;
• limitation du contact éventuel entre le joint 3 et la paroi latérale 28 de la douille 2 grâce à l'évasement de cette paroi;
• élargissement local du chemin d'écoulement par une épaisseur moindre de la paroi latérale 28 de la douille 2.

This is how the present invention implements several improvements of the prior art:

• increase of nearly 70% of the contact surface of the seal 3 and the base of the body 11 by the use of a bowl 18 instead of a support cord 1a;
• vertical maintenance of the joint 3 by a tongue 25;
• horizontal guiding of the joint 3 by a lateral bulge 27;
• limitation of the possible contact between the seal 3 and the side wall 28 of the sleeve 2 thanks to the flaring of this wall;
• local widening of the flow path by a smaller thickness of the side wall 28 of the sleeve 2.

• meilleure étanchéité du clapet fermé et élimination des difficultés de réalisation du cordon 1a d'appui;
• assurance du retour du joint 3 dans sa position de repos. En particulier, ce retour ne fait plus uniquement appel à la gravité et élimine donc les effets de peau qui sont susceptibles de s'opposer à elle;
• réduction des pertes de charge lors de l'admission du produit dans la chambre 19 de pompe.

Each of these improvements improves, among other things, a particular aspect of the operation of the intake valve:

• better sealing of the closed valve and elimination of the difficulties of producing the support cord 1a;
• assurance of the return of the seal 3 in its rest position. In particular, this return no longer only uses gravity and therefore eliminates the skin effects which are liable to oppose it;
• reduction in pressure losses during the admission of the product into the pump chamber 19.

• 34 cm de remontée du liquide avec un clapet de l'art antérieur,
• contre 73 cm de remontée avec un clapet selon la présente invention.

En recommençant l'essai, la pompe munie de l'ancien clapet a abouti à 41 cm alors qu'avec le présent clapet, les 73 cm ont été reproduits exactement.All in all, the results obtained are very conclusive. For example, during a test consisting in sucking a colored liquid in a column surmounted by a precompression pump, ten actuations of the pump determined:

• 34 cm of liquid rise with a valve of the prior art,
• against 73 cm of ascent with a valve according to the present invention.

By repeating the test, the pump fitted with the old valve resulted in 41 cm while with the present valve, the 73 cm were reproduced exactly.

The present non-return valve for admission into a pump chamber is particularly advantageous when used in combination with both a pump without return air and a deformable container. Indeed, although it has not been mentioned so far, the pump shown in axial section in Figure 1 includes an air intake. In other words, its cylinder 1 is pierced with an opening 14 (also shown in FIG. 2) disposed at a height such that the peripheral sealing lip 5a of the piston 5 is always below it. Thus, when the piston 5 returns to the rest position, air can be admitted into the container (not shown) on which the pump is crimped in a sealed manner. And, in this way, the liquid which is still there in reserve, is it maintained at atmospheric pressure.

However, there are liquids, such as for example drugs, which bear bad contact with the ambient air. The current trend is then to package them in containers whose deformable envelope is hermetically closed by a distribution pump. It is therefore without air intake (that is to say, its cylinder 1 has no opening 14). And any expulsion of liquid is accompanied by a loss of volume of the container, the envelope of which deforms as a result. However this envelope most of the time offers some resistance to deformation. It follows the maintenance of the interior of the container at a pressure P₀ lower than atmospheric pressure, the internal depression being of course all the more marked as the envelope is deformed.

In this case, this seal 3 allows the interior of the container to be isolated from the pump chamber. During the transient phase of admission to the chamber, the latter is in fact at a pressure P₂ which is much more below atmospheric pressure than the pressure P₀ prevailing in the container (| P₂ |> | P₀ |). We can also admit that the envelope) due to its inertia, firstly follows the decrease in the volume of its content so that P₀ is maintained in the container throughout the admission. However, when the chamber is filled and as a result, the pressure P₀ tends to equalize on either side of the joint, the envelope seeks to resume its original shape. This results in increasing the depression in the container where a pressure P₁ is established such that | P₀ | <| P₁ |. The seal 3 is therefore sucked against the bowl 18 while it helps maintain P₀ in the pump chamber. This has the happy effect of reducing the stress on the sealing lip 5a of the piston 5 which, by its function, is ill-suited to insulation in the event of internal depression. The air-conditioned packaging assembly is then made more efficient.

Claims (10)

1. A non-return valve for admitting a liquid to be sprayed into a pump chamber (19), said valve being constituted by cooperation between three components:
      a pump cylinder (1) having an internal narrowing (12) separating a body (11) and an end, said body housing said pump chamber whereas said end is in communication with a supply of said liquid;
      a hollow sleeve (2) having an end pierced by a central hole (2a) and a side wall (28) suitable for being received in sealed manner inside said body such that said sleeve and said narrowing together define a housing (29); and
      a gasket (3) in the form of a disk suitable for being received with clearance inside said housing;
      the non-return valve being characterized in that
      said narrowing is shaped, on its side adjacent said body (11), in the form of a cup (18) of small slope;
      said side wall (28) of said sleeve (2) flares from said end (26) of said sleeve (2) and is locally provided with a swelling (27), said side wall (28) of said sleeve (2) being of reduced thickness on either side of said swelling (27); and
      said end (26) of said sleeve (2) includes a tongue (25) and two ribs (2b), said tongue (25) and said ribs (2b) extending from said side wall (28) of said sleeve (2) to the central hole (2a) of said sleeve (2), said tongue (25) being diametrically opposite said swelling (27) and being of increased thickness adjacent to said central hole (3a) of said sleeve (2), said ribs (2b) being symmetrically disposed about a diameter passing through said swelling (27) and said tongue (25) so that each of them forms an acute angle with said diameter on respective sides of said swelling (27).
2. A valve according to claim 1, characterised in that said slope of said cup (18) lies in the range 1° to 6°.
3. A valve according to claim 1 or 2, characterized in that said side wall (28) of said sleeve (2) flares with an angle of 4° relative to the normal to said end (26) of said sleeve (2).
4. A valve according to any one of claims 1 to 3, characterized in that said reduced thickness of said side wall (28) of said sleeve (2) extends on either side of said swelling (28) between said ribs (2b).
5. A valve according to any one of claims 1 to 4, characterized in that said acute angle between each of said ribs (2b) and said diameter passing through said swelling (27) and said tongue (25) is approximately 40°.
6. A valve according to any one of claims 1 to 5, characterized in that said tongue (25) has a face sloping at 15° relative to said end (26) of said sleeve (2).
7. A valve according to any one of claims 1 to 6, characterized in that said gasket (3) is constituted by an elastomer or a plastomer which swells in the presence of liquid, with said gasket (3) increasing by up to 10% in volume.
8. A valve according to any one of claims 1 to 7, characterized in that said gasket (3) is constituted by an elastomer or a plastomer which is ballasted so that its mass is sufficient for ensuring that said gasket (3) moves inside its housing under the effect of gravity.
9. Utilization of the non-return valve of any preceding claim, characterized in that said body (11) of said pump cylinder (1) receives a precompression pump.
10. Utilization according to claim 9, characterized in that said pump has no air intake and in that said pump is fixed in sealed manner on a receptacle including a deformable envelope for receiving said liquid.

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