Diaphragm pump and a receptacle fitted therewith

Details Diaphragm pump and a receptacle fitted therewith Diaphragm pump and a receptacle fitted therewith

2000-07-10

2001-10-23

Shaver, Kevin (Department: 3754)

Dispensing

With discharge assistant

With movable nozzle interconnected therewith

C222S207000, C222S321100, C222S321200, C222S321700

Reexamination Certificate

active

06305581

ABSTRACT:

The present invention relates to a pump and to a receptacle containing a liquid, for example a cosmetic cream, and fitted with such a pump.
BACKGROUND OF THE INVENTION
French patent 2 728 809 discloses a pump comprising a pushbutton displaceably mounted on a support which is secured to the receptacle containing the substance to be dispensed, the pushbutton having a circularly cylindrical central duct provided with radial openings at its bottom end, the support defining an annular pump chamber of variable volume around said duct. A diaphragm made of elastomer is mounted on the support. The diaphragm has a circularly symmetrical central portion in the form of a sleeve that is open at its top end and closed at its bottom end. The central duct of the pushbutton is inserted in the diaphragm until it bears against the end wall of the sleeve. The diaphragm constitutes a resilient return member enabling the pushbutton to be returned to its initial position after a quantity of substance has been dispensed.
During the return movement of the pushbutton, the diaphragm presses against the central duct and isolates the pump chamber from the radial openings of the central duct so at to prevent air returning into the pump chamber.
Such a pump presents the advantage of having only a small number of parts and thus of being of relatively low cost to manufacture.
Nevertheless, that known pump does not provide complete satisfaction, and the Applicant company has observed, in particular, difficulties in priming.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention seeks to improve the reliability of the operation of a pump of the above-defined type, i.e. comprising a moving member mounted to move relative to a support, the moving member having a central duct into which the substance to be dispensed penetrates via at least one opening, the support co-operating with the moving member to define a variable volume pump chamber around said central duct, the pump also having a diaphragm having a central portion in which said central duct is inserted, the diaphragm being organized in such a manner as to isolate the pump chamber from the opening(s) of the central duct when the volume of the pump chamber increases and the substance is sucked into it.
The invention achieves this by at least one of the central duct and the central portion of the diaphragm including an annular bulge that is suitable, when the volume of the pump chamber increases, for bearing in leakproof manner on the other of the central portion and the central duct of the diaphragm, so as to isolate the pump chamber from the opening(s) of the central duct.
In other words, the above-mentioned bulge ensures that the annular passage formed around the central duct between the pump chamber and the opening(s) of the central duct is closed during the suction stage.
The surface of the diaphragm which bears on the central duct to ensure said closure is slightly stretched as a result of the presence of the bulge, such that low air pressure in the pump chamber can suffice to break the sealing between the diaphragm and the central duct.
This makes the pump easier to prime.
In addition, it is generally desirable to use a relatively hard elastomer to make the diaphragm, enabling a relatively high return force to be obtained without having to prestress the diaphragm to excess, the drawback of prestressing the diaphragm too much being the risk of rupturing the diaphragm in the long term.
However, the use of a harder elastomer tends to increase priming difficulties since the diaphragm deforms less easily.
The invention enables the influence of the modulus of elasticity of the material constituting the diaphragm on the operation of the pump to be reduced to some extent, and thus enables a harder elastomer to be used so as to reduce the prestress of the diaphragm while maintaining the desired spring effect.
To make manufacture easy by molding plastics material, the bulge is preferably formed on the inner surface of the central portion of the diaphragm.
The bulge thus formed on the central portion of the diaphragm bears in sealed manner on the central duct so as to isolate the pump chamber from the opening(s) of the central duct, at least while the volume of the pump chamber is increasing.
Advantageously, when at rest, the bulge also bears in sealed manner on the central duct.
In a variant, the bulge is formed on the outer surface of the central duct.
When the bulge is formed on the inner surface of the diaphragm, one or more hollow or projecting portions in relief are advantageously formed on the central duct, remote from the bulge when the moving member is in the high position, and reaching the bulge at the end of the down stroke of the moving member, the portions in relief being organized in such as manner as to facilitate the creation, at that moment, of a passage between the pump chamber and the opening(s) of the central duct.
The portion(s) in relief is/are in the form of one or more ribs formed on the outer surface of the central duct, for example.
In a particular embodiment, the central portion of the diaphragm includes a base comprising an inner stud that is organized so as to engage in the bottom end of the central duct.
Such a stud enables the bottom end of the central portion of the diaphragm to be held relatively stable on the bottom end of the central duct.
In a particular embodiment, the diaphragm has a flexible lip suitable firstly for isolating the pump chamber from the source of substance when the volume of said pump chamber decreases, and secondly for enabling substance to enter into said pump chamber when the volume thereof increases.
In a particular embodiment, said flexible lip is connected to the central portion of the diaphragm by forming a downwardly open annular trough, and the support includes an inner skirt having its top end bearing against the end wall of said trough to retain the diaphragm when the moving member is moved downwards to decrease the volume of the pump chamber.
Preferably, said inner skirt has openings at its top end, the openings being of a height that is less than the height of the flexible lip, said openings enabling the substance to reach the pump chamber when the volume thereof increases and the flexible lip moves away from the inner skirt.
In a particular embodiment, the central portion of the diaphragm is connected at its top end to an annular portion whose width and thickness are selected in such a manner as to improve retention of the diaphragm when said central portion is stretched.
Preferably, the thickness of the above-mentioned annular portion, prior to the diaphragm being assembled in the pump, is greater than or equal to the thickness of the diaphragm in its central portion.
Preferably, the above-mentioned annular portion, prior to the diaphragm being assembled in the pump, is at least 1.5 times wider than it is thick, and preferably twice as wide as it is thick.
One of the flexible lip and the inner skirt preferably includes an annular bulge that is suitable for bearing on the other of the inner skirt and the flexible lip so as to isolate the pump chamber from the inside of the receptacle when the volume of the pump chamber decreases.
In a particular embodiment, the flexible lip includes an annular bulge on its inner surface that is suitable for bearing in sealed manner on the inner skirt so as to isolate the pump chamber from the source of substance at least when the volume of the pump chamber decreases.
At rest, the annular bulge advantageously bears in sealed manner on the inner skirt.
The flexible lip advantageously includes, above said annular bulge, a preferred deformation zone that is preferably constituted by a thin zone.
In a variant, the inner skirt includes on its outer surface an annular bulge that is suitable for bearing in leakproof manner on the flexible lip so as to isolate the pump chamber from the source of substance when the volume of the pump chamber decreases.
In a particular embodiment, the height of the above-mentioned flexible lip is greater than or equal to the height of

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