The object of the present invention is to satisfactorily solve the problems existing in the prior art.
According to the invention, said object is achieved by a pump: it comprises a substantially cylindrical pump body which defines inside it a metering chamber, has at its lower end an inlet equipped with a valve and at its upper end a discharge orifice on the one hand and a piston on the other hand. The piston can cooperate with elastic return means external to the dosing chamber, in which it moves between an upper stop and a lower end-of-travel stop. The piston has a central core and a coaxial liner. The central core is connected to the lower end of an axial hollow rod, the upper end of which protrudes outside the metering chamber. Said bush is connected to said hollow stem by an elastic joint which ensures, on the one hand, a sealing contact with the inner wall of said dosing chamber and, on the other hand, forms, together with said central core, an annular discharge channel which can be opened by displacement of said bush with respect to said central core. The upper end of the pump body is closed by a collar which on the one hand forms an upper stop for the piston with its inner surface and on the other hand serves as a lower support for the return means with its outer surface. The collar has a central bore in which the hollow rod connected to the piston moves. The pump of the invention is characterized in that said bush comprises an upper ring intended to be sealingly engaged in a ring groove on the inner surface of said collar.
According to a useful feature of the invention, the collar comprises a flared lower skirt having an annular element on its inner surface opposite the central core for sealing contact with the central core when the discharge channel is closed.
According to a particular embodiment of the invention, the joint comprises a central hoop mounted by radial tightening on the axial hollow rod, the hoop being connected to the bushing by an elastically deformable spacer ring.
According to another alternative, the collar is constituted by a central sleeve having a stop for snapping into the upper part of the pump body and a peripheral pressure plate for fixing to the upper edge of the pump body.
According to a particular embodiment of the invention, said hollow rod and said central core are realized in a single piece.
According to a first solution, the hollow rod is separated from the central core by a plurality of transverse slots. The transverse groove communicates with the discharge passage.
According to a second variant, the axial hollow rod is connected to a nozzle outside the metering chamber.
Preferably, the spacer ring of the joint of the bush is arranged substantially opposite the opening of the transverse groove and has a certain inclination.
Preferably, said nozzle has a peripheral annular shoulder defining an upper bearing surface for supporting said return means of the piston.
Alternatively, said shoulder extends downwardly with a cylindrical wall in which said central sleeve of said collar guides the movement of said cylindrical wall, both of which together form a housing for said return means.
According to a further feature of the present invention, the pump body has a bore defining a vent hole located above the piston and above the lower edge of the liner.
Additionally, the end of the liner may be beveled so that its surface sealingly contacts and scrapes against the inner wall of the metering chamber.
In another variant, the side surface of the central core and the inner surface of the bush opposite thereto are parallel to each other, while being inclined with respect to the axis of the pump.
Preferably, said central core has a lower portion in the shape of a truncated cone which can enter a cavity matching the profile of the lower portion of the pump body, below the lower stop plane of the piston, to force the opening of said discharge channel under pressure when the pump is initially started.
The pump of the invention achieves a good seal without the use of gaskets, which makes it compatible in terms of odour with perfumes and aromatic cosmetics.
The seal thus obtained also allows the pump of the invention to be used upside down without causing leakage of the formulation.
The assembly of the constituent parts of the pump can be carried out in a single simple operation, which allows the manufacturing and packaging steps to be fully automated, thus making it possible to increase production efficiency.
Furthermore, the return means of the piston are arranged outside the metering chamber, which makes it possible to reduce the volume of the pump portion inside the container, thus making it possible to fill a greater volume of the container with the formulation.
The invention will be better understood from a reading of the following description in conjunction with the drawings. In the drawings:
The pump shown in figure 1 is used to dispense perfume or cosmetics and medicaments from a container.
The pump comprises a substantially cylindrical pump body which defines a metering chamber 11 in its interior.
The pump body 1 of the pump is intended to be sealingly fixed to the neck C of the container.
The lower end of the pump body 1 has an inlet 10 with a valve 12. The valve is here a ball valve.
The upper end 1b of the pump body 1, which is open for the insertion of a piston 2, is provided with a discharge hole 20 a.
The orifice 20a leads to a closable passage 20 for the discharge of the formulation in the metering chamber 11.
The piston 2 is movable between an upper stop and a lower end-of-travel stop of the metering chamber 11 and is returned to the stop position by a helical spring 4 arranged outside the metering chamber 11.
The piston 2 comprises a central core 21 connected to the lower end 23a of an axial hollow rod 23, the upper end 23b of which protrudes outside the metering chamber 11.
In the illustrated embodiment, the hollow rod 23 and the central core 21 are one single piece.
A bushing 22 coaxially encloses the central core 21, which bushing 22 is an insert connected to the hollow rod 23 by means of an elastic joint 24.
According to a variant not shown in the figures, the central core 21, the hollow rod 23 and the bush 22 are realized in a single piece. The liner 22 ensures, on the one hand, a sealing contact with the inner wall of the metering chamber 11 and, on the other hand, forms, together with the central core 21, an annular channel 20.
The bush 22 has a flared lower skirt 22a having an annular member 220 on its inner surface facing the central core 21. The ring member 220 is intended to sealingly contact the central core 21 when the discharge passage 20 (fig. 1 and 3) is closed.
The hollow stem 23 is separated from the central core 21 by a number of transverse slots 230, the transverse slots 230 communicating with the discharge channel 20.
The side surface of the central core 21 and its inner surface facing the bush 22 are parallel to each other and inclined with respect to the axis of the pump.
The articulation 24 comprises a central hoop 24b, which is mounted by radial tightening on the axial hollow rod 23, above the central core 21.
The band 24b is connected to the liner 22 by an elastically deformable spacer ring 24a so that the liner 22 can move relative to the central core 21.
The bush 22 also comprises an upper collar 22b, extending on the extension of the lower skirt 22 a; a spacer ring 24a separates the skirt 22a from the collar 22 b.
The upper end of the pump body 1 is closed by a collar 3, whose inner surface forms the upper stop of the piston 2 and whose outer surface acts as the lower support for a spring 4, by means of stop means.
The collar 3 is constituted by a central sleeve 33 having a central hole 30 in which the hollow rod 23 connected to the piston 2 moves. The height of the band 24b is substantially equal to the height of the aperture 30 which matches the profile of the respective upper edge of the band.
When the pump is at rest as shown in figure 1, the collar 22b of the liner 2 sealingly engages in an annular groove 31 on the inner surface of the collar 3.
The inner surface of the annular ring 22b is slightly inclined to the axis of the pump, while its outer surface is substantially parallel to said axis.
Likewise, the inner side wall 31a of the groove 31, opposite the inner surface of the collar 22b, is slightly curved towards the axis of the pump, so as to ensure mutual sliding contact of the two opposite surfaces and to ensure the guiding of the collar 22a in the groove 31 in the up-stop position.
In the latter case, the upper edge of the collar 22b does not contact the bottom of the groove 31, to avoid deformation of the bush 22. However, the inner surface of the collar 22b is in sealing contact with the inner side wall 31a of the groove 31.
In addition, the end of the inner side wall 31a of the groove 31 is in tight contact against the upper surface of the spacer ring 24. In this way, in the upper stop position of the piston, the upper stop of the piston 2 provides a double seal against the possible accidental leakage of the formulation at the vent holes 13 located above the lower edge of the skirt 22 a.
When the pump is used upside down, the groove 31 forms a barrier for receiving the formulation which may overflow through the aperture 13 into the interior of the metering chamber 11. On the central sleeve 33 of the collar 3, at the level of the upper part 1b of the pump body 1, there is a sealing stop 33 a. The sleeve also has a peripheral pressure plate 33b intended to be fixed to the upper edge of the pump body 1.
The transverse slot 230 opens laterally on the hollow rod 23, opposite the connecting curve 24c between the collar 24b and the spacer 24a of the joint 24.
However, due to the slope 240, the groove is never blocked by the curved portion 24 c.
Outside the metering chamber 11, an axial hollow rod 23 is connected to a nozzle 5, for example by nesting and spring-braking. The nozzle 5 has a peripheral annular shoulder 51 which forms an upper bearing surface for the spring 4. The shoulder 51 extends downwards in the direction of the collar 3 by a cylindrical wall 52 in which the central sleeve 33 guides the movement, which together form a housing 54 for the spring 4.
The end of the skirt 22a of the liner 22 is inclined and its outer surface 220a ensures sealing contact of the sealing surface of the piston 2 with the inner surface of the metering chamber 11 as the piston moves.
In fig. 2a and 2b, the piston is moving downwards in the metering chamber 11 under the effect of the thrust manually exerted on the nozzle 5 by the spray head T.
If the pump has been started, the metering chamber 11 is filled with formulation, said thrust being transmitted by the incompressible liquid formulation to the chamber wall of the metering chamber 11, in particular to the skirt 22a of the connecting liner 22.
The liner 22 is now the only movable part of the metering chamber 11.
The thrust acting on the liner 22 then causes it to move upwards along the inner wall of the metering chamber (see figure 2b) due to the elastic deformation of the hinge 24.
As a result of the movement of the bushing, the annular member 220 is caused to separate from the side surface of the central core 21, thereby opening the annular discharge channel 20.
As the piston 2 continues to descend, the end surface 220a of the skirt 22a scrapes against the wall of the metering chamber 11, causing the formulation to pass through the passage 20 and then, in turn, through the transverse groove 230, the hollow stem 23 and the spout 5 until it is expelled by the spray nozzle B of the spray head T.
When the lower edge of the skirt 22a comes into contact with the lower stop formed by the shoulder 14 of the lower part of the pump body, all the volume initially occupied by the formulation in the metering chamber is evacuated, except for the remaining volume in the cavity 15 of the lower part of the pump body 1.
At this point, as shown in FIG. 3, the spring 4 is compressed and the cylindrical wall 52 is pressed into the chamber 54.
At this point, no thrust is applied to the bush 22, which is then pivoted downwards by the elastic return action of the joint returning to its original shape and position.
The ring 220 thus comes back onto the central core 21 closing the channel 20.
As the spray head T and spout 5 are released, spring 4 is released, cylindrical wall 52 withdraws upwardly under the guidance of sleeve 33, the piston in metering chamber 11 rises back, and the product in the container is drawn into the pump chamber through orifice 10 via open valve 12.
This process is continued until the piston returns to its rest position at the upper stop position, in which the collar 22b of the bush 2 is sealingly engaged in the groove 31 of the collar 3 (see figure 1).
Fig. 4a and 4b relate to the start-up phase of the pump.
In fact, after manufacture, assembly and filling of the formulation, the container R is filled with the formulation, but only with air in the metering chamber 11.
The effect of the first descent of the piston 2 is therefore to compress the air in the metering chamber 11. After a certain pressure difference is reached, the bushing 22 will move upwards and the ring element 220 will separate from the central core 21, thereby opening the channel 20.
The compressed air is then expelled from the passageway 20, the slot 230, the hollow stem 23, the nozzle 25 and the nozzle B.
Since the central core 21 has a lower portion 21a in the shape of a truncated cone, which can enter the cavity 15 of the piston 2 with a matching profile below the level of the lower stop 14, the discharge channel 20 can be forced open under pressure, so that all the air in the metering chamber 11 is expelled.
The condition of the piston 2 in the down position causes the passage 20 to be opened for a short time, corresponding to the time required for the chamber 15 to deflate.
Then, the spray head T is released, and the relaxation of the spring 4, the closing of the channel 20 and the lifting back of the piston 2 create a vacuum in the metering chamber 11, thus achieving the first filling of the pump by sucking in the preparation from said container.