WO2002083318A2

WO2002083318A2 - Dispensing pump

Info

Publication number: WO2002083318A2
Application number: PCT/IB2002/001134
Authority: WO
Inventors: Stefano Santagiuliana
Original assignee: Taplast Spa
Priority date: 2001-04-10
Filing date: 2002-04-09
Publication date: 2002-10-24
Also published as: EP1379336B1; ES2235032T3; DE60202359T2; AU2002253430A1; EP1249278A1; EP1379336A2; WO2002083318A3; DE60202359D1

Abstract

A delivery pump for fluids is disclosed comprising: a pump body (3) connected to a container (C); a first piston (5) having a second cylindrical wall (52) and an annular lip (53) protruding therefrom; a second hollow piston (7) coaxial to the first piston (5) and having a bottom member (6) provided with annular grooves (62, 63) co-operating with the first piston (5) to define sealing zones; elastic means (16) returning the pistons to rest after a delivery; an intermediate body (9) inside the pump body provided with an annular groove (92) facing the first piston. The edges (521, 522) of the second cylindrical wall (52) and the edge (531) of the annular lip (53) define three sealing zones, each having a sealing profile formed by at least two surfaces co-operating with corresponding surfaces belonging to each annular groove (62, 63, 92) provided in the bottom member and in the intermediate body.

Description

DISPENSING PUMP

The present invention relates to a delivery pump to be coupled to the neck of a container, particularly adapted to deliver fluids of food products, liquid detergents, creams or perfumes. It is well known that requirements of hygienic and practical character led to a wide spread on the market of containers for fluids provided with delivery devices actuated manually by the user.

The delivery pumps of the prior art generally comprise a hollow body defining a suction/compression chamber for the fluid to be delivered, communicating with the container interior through a suction duct.

A first tight piston is slidingly coupled to the hollow body. Said tight piston in its turn is slidingly and coaxially coupled to one end of a second piston internally provided with a tubular chamber.

The tubular chamber of the second piston communicates with outside through a delivery duct and with the suction/compression chamber through one or more holes made on a bottom member of the second piston.

Said holes are shut through two annular edges belonging to the first piston and coupled to corresponding grooves made on the bottom member of the second piston. Valve means generally consisting of metal balls, interposed between the suction/compression chamber and the container interior, regulate inflow and outflow of fluid to and from the chamber.

Finally, elastic means, generally consisting of helical springs, interposed between the hollow body and the pistons warrant return of said pistons to the rest position when delivery is over.

In operation the user acting on the piston loads the elastic means and compresses the liquid contained in the suction/compression chamber at the same time bringing the first piston to its top dead centre so as to move away the annular edges of the bottom member. This action allows outflow of the liquid contained in the suction/compression chamber to the delivery duct.

When the first tight piston reaches the bottom of the suction/compression chamber, the thrust action of the elastic means by the user is terminated.

Consequently, the second hollow piston directly connected to said elastic means, is returned upwards and draws together the first tight piston that closes in this way the communication between the suction/compression chamber and the tubular chamber of the second piston.

Under these conditions the elastic return of the piston generates a vacuum inside the suction/compression chamber opening the suction ducts of the liquid from the container so as to allow inflow of liquid inside the chamber and therefore a subsequent delivery of the pump.

The efficiency of suction and also the good operation of the pump in the ^* subsequent delivery stage, is caused by the seal obtained by the couple of annular edges of the first piston and the characteristics of the material used for the their manufacture.

A first limitation of the above mentioned designs consists in that said pumps have a limited efficiency of liquid suction from the container.

This is substantially due to the fact that the delivery pump in its rest position has the elastic means keeping the two annular surfaces compressed one against the other thus causing a progressive opening of said surfaces, more particularly when the direction of the thrust force of the elastic means is not coaxial to the symmetry axis of the edges of the sealing surfaces.

It has to be added that the assembled pump in rest conditions during the transport and stockage phases, undergoes considerable thermal stresses increasing and accelerating wear of the sealing surfaces. This can cause leakage of liquid from the container inside to the pump exterior without actuation of the pump.

The object of the present invention is to overcome the above mentioned limitations and drawbacks. A first object of the invention is to provide a pump insensitive to mechanical and thermal stresses underwent during the transport and stockage phases so as to warrant always a perfect sealing condition.

Another object is to provide a pump keeping the suction efficiency substantially constant with time. A further object is to provide a delivery pump having a suction efficiency higher than the prior art pumps.

Still a further object is to provide a pump that after its use can be completely and immediately recycled without requiring any previous dismantling operation to separate different incompatible materials. An additional object is to provide a pump which is particularly easy to be used and reliable.

A last but not least object is to provide a very cheap pump of easy construction and assembly, suitable for the mass production. Said objects are attained by a delivery pump for containers of fluids to be delivered that according to the main claim comprises:

- a pump body connected through connection means to the neck of a container containing a liquid to be delivered, said pump body defining a first generally cylindrical chamber adapted to receive the liquid coming from inside said container, said first chamber being provided with valve means to put said first chamber in communication with said liquid container;

- a first piston having a first annular wall sliding on the cylindrical surface of said first chamber, said first piston having a second generally cylindrical wall, internal relative to said first annular wall, and an annular lip protruding from said second wall and facing said cylindrical chamber;

- a second hollow piston coaxial with said first piston so as to define a second tubular chamber, said second piston being connected at one end with a liquid delivery duct and having at the other end a bottom member rigidly connected to said second piston, said bottom member being provided with one or more holes putting said tubular chamber in communication with said first chamber of said pump body and having annular grooves co-operating with said first piston to define sealing zones;

- elastic means adapted to return said first piston and said second piston to the rest position after the liquid delivery operation;

- an intermediate body arranged inside said pump body, said intermediate body defining a cylindrical cavity on which said second piston is sliding and having an annular groove facing said first piston, and is characterised in that the edges of said second cylindrical wall and the edge of said annular lip of said first piston define three sealing zones, each zone having a sealing profile formed by at least two surfaces co-operating with corresponding surfaces belonging to each annular groove made in said bottom member and said intermediate body.

According to the invention the seal required to prevent leakage of liquid when the pump is at rest, is obtained by providing three sealing zones acting at the same time, with the provision that each sealing device has at least two active surfaces, that is two annular sealing zones. According to a preferred embodiment of the invention this is obtained by the particular frustum conical configuration of the edges of the first piston. The presence of three different sealing zones warrants that the liquid of the container when the pump is at rest, does not leak even in case of turning the container upside down.

Moreover, the invention surprisingly allows to obtain delivery pumps having a higher suction efficiency relative to the traditional pumps, substantially constant with time.

Still surprisingly, according to carried out tests the pump of the invention resulted to be insensitive to long inoperative periods. The foregoing objects and advantages will be better understood from the following description of a preferred embodiment given as an illustrative non limiting example and shown in the accompanying sheets of drawings in which:

- Fig. 1 is a sectional view of the delivery pump of the invention applied to a container in the rest position;

- Fig. 2 is an enlarged view of a portion of the pump of Fig. 1 ; - Fig. 3 is a sectional view of the pump of the invention at start of the operative stage;

- Fig. 4 is an enlarged view of a portion of Fig. 3;

- Figs. 5 to 9 are each a sectional view showing different constructional versions of some elements of the pump of Fig. 1 ; and - Fig. 10 is a sectional view of the pump of the invention during the operative stage.

The delivery pump of the present invention is shown in Fig. 1 where it is generally indicated with numeral 1. The pump is provided with means 2 for the removable coupling to the neck O of a container C containing the fluid F to be delivered.

The pump comprises a hollow body 3 defining a first suction/compression chamber 4 for the fluid F to be delivered, communicating with the interior of container C through a suction duct 4a. A first tight piston 5 is slidingly coupled to the hollow body 3, said piston being slidingly and coaxially coupled also to a bottom member 6 connected to a second piston 7, internally provided with a tubular chamber 8. More particularly the first piston 5 has a first annular wall 51 slidingly engaged on the cylindrical surface 31 of the first suction/compression chamber 4. Said piston 5 is provided with a second generally cylindrical wall 52 of a smaller diameter that the first wall 51. An annular lip 53 protrudes from the cylindrical wall 52 and extends to the first cylindrical chamber 4 of the pump body 3 starting from a generally flat annular surface 54 that as it ^* will be explained hereinafter, acts as a striker for drawing said first piston 5 during pump operation. Inside said first piston 5 there is a second piston 7 with a tubular cavity 8 connected at its first end to the delivery duct 12 of the pump and at the other end to a bottom member 6 rigidly connected to said second piston.

In the embodiment of Fig. 2 the annular bottom member 6 is rigidly connected to the second piston 7 through a snap connection of two annular cavities made on said bottom member conjugated with corresponding protrusions made on the tubular bottom portion of the piston 7. The bottom member 6 has a set of holes 61 putting the tubular chamber 8 of the second piston 7 in communication with the first cylindrical chamber 4 when the pump is in the working position, as shown in Figs. 3 and 4, that is when the bottom member 6 is spaced from the lower lip 521 of the cylindrical wall 52 of the first piston 5.

The bottom member 6 has also two lower and upper annular grooves 62 and 63 respectively, co-operating with corresponding annular edges belonging to the second cylindrical wall 52 and the annular lip 53 of the first piston when the pump is at rest and is returned by elastic means generally indicated with numeral 16.

Said elastic means 16 consist of a bellows spring 40 fully made of plastic material and having a perimetral spiral ridge 41. Said bellows spring is connected at one side to the delivery cap 13 and at the other side to the pump connection means 2. The delivery cap 13 is rigidly connected also to the last part of the second piston 7 so that when the pump is manually actuated, exerting with fingers a pressure on the delivery cap and therefore on the bellows 40, the piston 7 is drawn downwards and consequently the annular flat surface 71 of such a piston goes into contact with the annular surface 54 of the first piston drawing it downwards. In such a way as shown in Fig. 4, an annular opening 14 is created through which the previously pumped fluid present in the first chamber 4 is transferred through the holes 61 , inside the tubular chamber 8 of piston 7 and to the outside through said chamber and the duct 12. Valve means provided on the bottom of the chamber 4, generally indicated with numeral 17 and constituted in this embodiment by a ball 42 made of plastic material, prevent back flow of liquid into the container C during ^* compression of the bellows 40 corresponding to delivery of fluid into the delivery duct 12. Indeed, the ball 42 is pushed to the hole 43 so as to hinder return of liquid stored in the first chamber 4 inside container C. On the contrary the ball 42 is lifted by vacuum when piston 5 returns upwards when action of manual pressure is ended, while liquid from interior of container C enters again chamber 4 ready for a new delivery. According to the embodiment of the invention shown in Fig. 1 , the second piston 7 is guided in its stroke by the cylindrical part 91 of an intermediate body 9, which is arranged inside the pump body 3. The intermediate body 9 may be structurally separated from the pump body 3 or moulded as a single piece with the pump body 3. Said intermediate body 9 has also a groove 92 that as explained hereinafter, co-operates with the annular edge of the second cylindrical wall

52 of the first piston 51.

According to the invention, when the pump is at rest, therefore, when the bellows 40 is not pressed downwards, by an external action, three sealing zones are provided in the pump, warranting that the liquid ready for delivery does not leak from the first chamber 4 nor from container C through the air recovery holes indicated with numeral 15.

In order to obtain such a result and with reference to the liquid present in chamber 4 for another delivery, when the pump is at rest as shown in Figs. 1 and 2, the grooves 62 and 63 of the bottom member 6 co-operate with the annular edge 521 of the second cylindrical wall 52 of piston 5 and the annular edge 531 of the annular lip 53 also of piston 5, respectively. A perfect seal is warranted because in each of the two edges 521 and 531 there are at least two surfaces co-operating with corresponding surfaces belonging to each groove 62 and 63 with the clear purpose to ensure a perfect seal even in presence of deformation of the annular surfaces. Indeed, it is clear that a double sealing surface can offer a greater sealing warranty in comparison with a single surface. This is the reason why in the embodiment shown in Figs. 1 and 2 the edges have a frustum conical profile while the grooves belong to surfaces that in view of their shape define together with the surface of the annular edges at least a double sealing ring. More particularly, in the enlarged view of Fig. 2, the surfaces 521a and 521b of the edge 521 create two sealing rings with corresponding ^* surfaces 63a and 63b of the groove 63. In this way, any possible pouring from chamber 4 to chamber 8 and therefore leakage of liquid is clearly prevented.

In is also avoided that a possible residual liquid contained in chamber 8 can come out and fill the space inside the bellows 40 or other spaces and finally come out from cap 13. As to the possibility that fluid F through the air recovery holes 15 may reach the pump outside, this is prevented by the second cylindrical wall 52 and its lower and upper edges 521 and 522 respectively. As already mentioned, the lower edge 521 co-operates with a corresponding groove 62 of the bottom member 6, while the upper edge 522 co-operates with a corresponding groove 92 of the intermediate member 9. Also the edge 522 and the groove 92 have the same features, in the sense that the profile of edge 522 defines at least two sealing zones on the groove 92. It is clear that in this condition a possible pouring of fluid from inside the container C to the pump outside is prevented by the tight closure effected by the second wall 52 of the first piston and the tight seals so created. In has also to be pointed out that as the wall 52 is cylindrical, the sealing zones of the lower and upper edges 521 and 522 are arranged along the same vertical line and therefore any possible warping action of the edges of the cylindrical wall 52 due to dissymmetry of distribution of the elastic forces causing the first piston 5 to return is avoided. The presence of three discrete sealing zones and of at least two sealing surfaces in each zone essentially ensures to the pump of the invention the tightness that remains stable with time and avoids deterioration due to possible deformation of the piston edges.

A first constructional version of the sealing zones is shown in detail in Figs. 4 and 6. Such a version is different from the preceding embodiment because the sealing edges of the cylindrical wall 52 have each the curved profile instead of a frustum conical one.

More particularly, in Fig. 5 each surface 21 b, 20b belonging to the edge 521 of the cylindrical wall 52 and 21a, 20a belonging to a corresponding groove 62 is constituted by a parabola stretch. The version of Fig. 6 provides that surfaces 22a, 23a and 22b, 23b of each edge and each groove belong to an arc of circle.

As an alternative, the two surfaces may have one a curved profile and the ^* other a rectilinear profile or vice-versa as shown in Figs. 7 and 8. Another constructional version shown in detail in Fig. 9 is different from the preceding one because the sealing surfaces of the edges of the cylindrical wall 52 and of each conjugated groove define four discrete annular sealing zones instead of only two as in the preceding embodiments. Indeed, a first couple of seals is obtained conjugating the surfaces 26a with 26b and surfaces 27a with 27b while another couple is obtained conjugating surfaces 24a with 24b and 25a with 25b.

It is clear that increase of the number of sealing surfaces corresponds to a greater suction efficiency of the pump.

It is to be pointed out that the delivery pump 1 is fully made of plastic material making it immediately and totally recyclable. In this connection it has to be pointed out that the plastic material used for making the first piston 5 has special mechanical features allowing to obtain an optimal seal.

In operation the user acting on piston 7 loads the elastic means 16 and compresses the fluid F contained in the suction/compression chamber 4. The first piston 5 is then moved to its top dead centre as shown in Fig. 3, thus moving the annular edge 52 away from groove 62 and allowing outflow of fluid F to the delivery duct 12 along the path indicated with numeral 50. When the piston 7 reaches the bottom of the suction/compression chamber 4, it is released by the user thus allowing the elastic means 16 to return it to the starting rest position shown in Fig. 1.

The elastic return of piston 7 generates a vacuum inside chamber 4 opening the suction ducts 4a for fluid F. At the same time, the first piston 5 returns to its bottom dead centre 10 closing the delivery duct 12 thus allowing inflow of fluid F inside chamber 4, making pump 1 ready for the subsequent delivery. It is important to note that the proposed solution is applicable to any type of delivery pump whether configured for operation as a simple distributor, as atomiser or foamer pump.

From the foregoing it is clear that the described delivery pump attains the intended objects.

Although the invention was described with reference to the accompanying sheets of drawings, in the constructional stage it may undergo ^* constructional modifications falling within the same inventive principle set forth in the appended claims.

Claims

1) A delivery pump for fluids comprising:

- a pump body (3) connected through connection means (2) to the neck of a container (C) containing a liquid to be delivered, said pump body defining a first generally cylindrical chamber (4) adapted to receive the liquid coming from inside said container, said first chamber being provided with valve means (17) to put said first chamber in communication with said liquid container;

- a first piston (5) having a first annular wall (51) sliding on the cylindrical surface (31) of said first chamber, said first piston having a second generally cylindrical wall (52), internal relative to said first annular wall, and an annular lip (53) protruding from said second wall and facing said cylindrical chamber (4);

- a second hollow piston (7) coaxial with said first piston (5) so as to define a second tubular chamber (8), said second piston being connected at one end with a liquid delivery duct (12) and having at the other end a bottom member (6) rigidly connected to said second piston (7), said bottom member (6) being provided with one or more holes (61) putting said tubular chamber (8) in communication with said first chamber (4) of said pump body and having annular grooves (62, 63) cooperating with said first piston (5) to define sealing zones;

- elastic means (16) adapted to return said first piston and said second piston to the rest position after the liquid delivery operation;

- an intermediate body (9) arranged inside said pump body, said intermediate body defining a cylindrical cavity (91) on which said second piston is sliding and having an annular groove (92) facing said first piston, characterised in that the edges (521 , 522) of said second cylindrical wall (52) and the edge (531) of said annular lip (53) of said first piston define three sealing zones, each zone having a sealing profile formed by at least two surfaces co-operating with corresponding surfaces belonging to each annular groove (62, 63, 92) made in said bottom member and said intermediate body.

2) The pump according to claim 1 characterised in that the edges (521 , 522) of said second cylindrical wall and the edge of said annular lip (531 ) of said first piston (5) and the corresponding grooves (62, 63, 92) cooperating with said edges have a substantially frustum conical profile.

3) The pump according to claim 1 characterised in that the edges of said second cylindrical wall and the edge of said annular lip of said first piston have a substantially curved profile and co-operate with corresponding grooves (62) compatible with said profiles and vice-versa (Fig. 7, Fig. 8).

4) The pump according to claim 1 characterised in that the edges of said second cylindrical wall (52) and the edge of said annular lip (53) of said first piston each define with the corresponding grooves, four annular sealing zones (Fig. 9).

5) The pump according to claim 1 characterised in that the upper edge (522) of said second cylindrical wall (52) of said first piston (5) cooperates with the annular groove (92) made in said intermediate body and the lower edge (521) of said second cylindrical wall (52) of said first piston co-operates with the first annular groove (62) made in said bottom member.

6) The pump according to claim 1 characterised in that the edge (531) of said annular lip (53) co-operates with a second annular groove (63) made in said bottom member. 7) The pump according to claim 1 characterised in that said annular lip (53) of said first piston has a generally flat annular surface (54) in contrast with a corresponding annular protrusion (71) of the outer surface of said second hollow piston (7) so that said second piston draws said first piston during the liquid delivery phase of said pump. 8) The pump according to claim 1 characterised by having one or more openings (65) for air passage between said liquid container and the outside, said opening being arranged above the top dead centre of said first piston.

9) The pump according to claim 1 characterised in that said elastic means (16) consist of a bellows spring (40) made of plastic material.

10) The pump according to claim 9 characterised in that said bellows spring (40) has at least a spiral ridge (41).

11) The pump according to claim 1 characterised in that said valve means (17) comprise a ball (42) made of plastic material.