FR2669379A1 - DOSING PUMP FOR LIQUID PRODUCTS. - Google Patents

Abstract

Dosing pump for liquid products contained in a container, a filter (5) is provided near the neck of the container, to purify the outside air entering the container at each dose. The pump comprises, a first lower valve (9, 21) for the admission of liquid into the metering chamber (13), a second valve (19, 20) for controlling the dose of liquid delivered, and a third valve (6, 7) for checking the safety of the pump closing.

Description

1 2669379

  DOSING PUMP FOR LIQUID PRODUCTS

  The invention relates to a metering pump for

liquid products.

  The principle of metering pumps is well known and these are used in different fields

since many years.

  They consist of a cylindrical chamber of determined volume and a pusher integral with a piston that can move inside this chamber, this assembly being mounted on a container containing the product

that we want to distribute.

  A double valve system allows the expulsion of the contents of this chamber when the user depresses the pusher the lower valve is then closed and the upper valve open, then the suction filling of this chamber when the pusher is released and it goes up under the action of a spring the lower valve

  being then open and the upper flap closed.

  These pumps have a first drawback related to

the atmospheric pollution.

  As the product is dispensed, its volume in the bottle decreases and it creates in the free space thus formed a depression that opposes

  gradually filling the chamber.

  To compensate for this phenomenon it is necessary to

  allow air to enter the bottle.

  This obligation to let in air is a major drawback in the use of pumps, especially when they are used to dispense products sensitive to oxygen, bacteria, or

  generally to outdoor pollution.

  This is the case for pharmaceuticals,

cosmetics or food.

  Solutions to solve this problem have been

  proposed and some are used.

  This is in all cases to prevent air from entering the bottle and put the product to distribute in a container whose volume decreases as and when

of its use.

  This variable volume container may consist of a flexible bag placed in another rigid container, or

  a rigid container in which moves a piston.

  The outside air enters the rigid container but remains outside the flexible bag or displaceable piston. In both cases the piston or the walls of the bag are sucked by the formed depression and, the air can not enter, the volume of the container is always adapted to the

volume of product remaining.

  The disadvantages of these devices are well known: their technology is difficult to implement, their cost is high, their use on the filling lines

is delicate.

  Metering pumps of known type have a

  second disadvantage related to the nature of the upper valve.

  When the upper valve has a lip of a floating piston movable in front of a hole of the axial piston connected to the pusher, sealing is ensured when the pump

  is at rest, even if the container is lying down or turned over.

  But if the relative sliding of the floating piston and the axial piston is bad, the two pistons begin to rise while the valve remains open. The outside air then enters the chamber through the hole of the piston.

  axial pusher unobstructed by the lip of the floating piston.

  When the pump returns to rest, the chamber is filled in part by the liquid to be dispensed and partly by the outside air, and the dosage is distorted. When using the pump, the dose of product

liquid is not complete.

  When the upper valve is constituted by a ball, the valve is not likely to remain open during the filling operation of the chamber But if the container is coated, the valve opens and no longer ensures sealing at the level of pusher As a result, the liquid

can flow.

  A first object of the invention is to propose a dosing pump which avoids the risk of deterioration of the

  liquid product by atmospheric pollution.

  Another object of the invention is to provide a metering pump that does not have a product dosing defect or sealing in case of change of position of the container. The invention relates to a metering pump for liquid products contained in a container, comprising an axial piston driven by a spring, said axial piston having a central bore for conveying the liquid product to be distributed to the outlet channel carried by a pusher, said axial piston carrying a floating piston sliding in a metering chamber, characterized in that a filter is provided near the neck of the container, for purifying the outside air entering the

container at each dosage.

  According to another characteristic of the invention the pump comprises, a first lower valve for the admission of liquid into the metering chamber, a second valve for controlling the liquid dose delivered, and a third valve for controlling the

  closing safety of the pump.

  Other features emerge from the

  following description made with reference to the drawings

  attached to which can be seen: Figure 1: a sectional view of a first embodiment of a metering pump according to the invention in the rest position; Figure 2: a sectional view of the metering pump of Figure 1 during liquid distribution; Figure 3: a sectional view of the metering pump of Fig 1 during filling of the metering chamber; Figure 4 is a partial sectional view of a second embodiment of a metering pump according to the invention; Figure 5 is a partial sectional view of a third embodiment of a metering pump according to the invention; Figure 6: a partial sectional view of the pump

  metering device of Fig 5 during filling of the container.

  Referring to Fig 1, there is shown the body 15 of a rigid container containing the liquid to be dispensed The neck of this container is capped by a cup 4, with the interposition of a seal 42 The cup 4 has a central passage in which freely slides an axial piston 3 substantially cylindrical and having a bulging portion 31 capable of abutting under a

  narrowing 41 of the central passage of the cup 4.

  In the vicinity of its upper end, the axial piston 3 has an annular widening 32 capable of

  to abut on the narrowing 41.

  The axial piston 3 has a central bore 17 opening only at its upper end in the form of a valve seat 20 for receiving a ball

  19 acting as upper valve.

  The upper end of the axial piston 3 is capped by a pusher 2 having a blind central bore 22 facing the valve seat 20, and a channel 18 for dispensing the liquid to be dispensed. This pusher has a skirt capable of sliding freely in a part. cylindrical of the cup 4, or around this cylindrical portion. Inside the container 15, a sleeve 16 is snapped onto the cup at the seal 42 This sleeve consists of three cylindrical parts and a tip, also cylindrical, which are of decreasing diameters The first part 43 the sleeve 16 extends a little below the cup 4 and defines between its bottom 44 and the cup 4 a space in which is housed a ring-shaped filter 5 The bottom 44 is pierced with holes 12 which communicate the outside and inside the

container 15.

  The second portion 45 of the sleeve 16 defines a metering chamber 13 The third portion 46 of the sleeve 16 provides guidance of a spring 8 and its bottom comprises a valve seat 21 for a ball 9 acting as a lower valve below the valve seat 21, the sleeve ends with a nozzle 47 on which is fixed a dip tube 14 whose free end is at the bottom

of the container 15.

  The spring 8, whose lower end is guided by the sleeve 16, has its upper end applied under the lower end of the axial piston 3. It is compressed when a user presses on the pusher 2, and returns the axial piston 3 and the pusher 2 towards the

  high when the pressure on the pusher is released.

  In the vicinity of the lower end of the axial piston 3 is disposed a diametrical hole 6 which passes through the central bore 17 and can thus establish a communication between this bore 17 and the chamber 13 The diametrical hole 6 passes through the axial piston in a zone 49 of reduced diameter, between the bulged portion 31 and a lower annular enlargement 48 which serves as a stop

support for the spring 8.

  In this area 49 of reduced diameter is mounted a floating piston 1 which slides on the one hand on the zone 49 of the axial piston 3, on the other hand on the second portion 45 of the sleeve 16 The floating piston 1 has a cylindrical ring 50 capable to apply under the cup 4 On the zone 49 of the axial piston, the floating piston 1 carries a lip 7 able to seal both ends

diametrical hole 6.

  The operation of the metering pump according to the invention is as follows starting from the position of

rest of fig 1.

  The user presses the pusher 2 and the axial piston 3 begins to descend by compressing the spring 8, the ball 9 being applied to its seat 21 While the floating piston 1 remains stationary, the axial piston 3 descends and the diametral hole 6 The liquid contained in the chamber 13 can then pass through the diametrical hole 6 in the central bore 17, then lift the ball 19 from its seat 20, pass into the blind bore 22 of the pusher 2 and from there. in the outlet channel 18 of the liquid. The swollen portion 31 of the axial piston 3 arrives at the floating piston 1 and drives it downwards, displacing the liquid from the chamber 13 through the hole 6, the bore 17 and the channel 18. This is the arrangement of FIG. When the enlargement 32 of the axial piston 3 reaches the narrowing 41 of the cup 4, a dose of liquid has

was delivered through channel 18.

  The user then releases the pressure on the pusher 2 and the spring 8 returns the axial piston 3 towards

the top.

  The ball 19 falls back on its seat 20.

  The zone of reduced diameter 49 of the axial piston 3 slides in the floating piston 1 which remains stationary and the diametrical hole 6 is masked by the lip 7. This results in a depression in the chamber 13 and the ball 9 rises from its seat 21 to leaving the liquid contained in the container 15 up through the dip tube 14 to the chamber 13 The axial piston 3 continues to rise and its lower annular enlargement 48 reaches the edge of the lip 7 and drives the floating piston 1 up, This accentuates the depression in the chamber 13 and the liquid call by the dip tube 14 This is the arrangement of Fig 3 The liquid rising in the chamber 13, its level in the container 15 decreases, which creates a depression in the container 15 The outside air passes between the skirt of the pusher 2 and the cylindrical portion of the cup 4, then between the axial piston 3 and the cup 4, then through the filter 5, then through the inlet holes 12 air filt In this way, as long as the floating piston 1 rises, the compensation in the container 15 of the volume of liquid filling the chamber 13 with filtered air is ensured. At the end of the upward movement, the part bulge axial piston 3 abuts under the narrowing 41 of the cup, the ring 50 of the floating piston 1 also abuts under the cup 4 to ensure a kind of seal, and the ball

9 falls back on his seat 21.

  The air-passed filter 5 that enters the container can be sterilizing to stop bacteria and keep the product sterile. It can also be designed to capture oxygen from the air in case the liquid product of the container needs to be protected from oxidation It can finally, in a general way, be able to stop any external pollution and to let

  the container only perfectly pure air.

  This filter can be made of paper, fabric, plastic material, a material impregnated with a liquid, and in general, any material capable of stopping the

  or unwanted components in the air.

  Referring to Figure 4, we can see a slightly different arrangement of the filter 5, all other elements of the pump being the same and therefore not shown The cup 4 is still in place on the neck of the container 15 It carries on the one hand the sleeve 16, on the other hand a body 10 having holes il of external air intake During the ascent of the axial piston 3 and the floating piston 1, the outside air passes between the piston axial 3 and the body 10, then through the holes 11 of outside air intake, then by the filter 5 and finally, through the holes 12 of filtered air intake, in the

container 15.

  In the embodiment of FIG. 5, the body is above the cup 4 and the filter 5 is between them. The outside air inlet holes 11 are still in the body 10, but it is the cup 4 who presents the

24 holes of filtered air intake.

  Under these holes 24 is provided in the container 15, a valve 23 preventing leakage of the liquid product to

through the filter 5.

  According to this embodiment, the liquid product to be dispensed can be introduced into the container through the filter. FIG. 6 represents the filling operation, in which the pusher 2 is replaced by a filling head 25 comprising a tubing 27 for applying the vacuum to the container via the axial piston, and a tubing 26 for injecting the liquid into the container

  through the filter 5, the valve 23 being open.

  The pump according to the invention, in addition to the filtering of the outside air, has the advantage of having a system of valves preventing leakage of liquid product when the container is coated, for example with a ball 19 on a valve seat 20 and a floating piston 1 whose lip 7 closes the diametrical hole 6 of the axial piston 3, the risk of external air entering through

the axial bore 17 is discarded.

Claims (2)

  1 metering pump for liquid products contained in a container, comprising an axial piston driven by a spring, said axial piston having a central bore for conveying the liquid product to be distributed to the outlet channel carried by a pusher, said axial piston carrying a floating piston sliding in a metering chamber, characterized in that a filter (5) is provided near the neck of the container, for purifying the air   outside penetrating into the container at each dosage.   2 Pump according to claim 1, characterized in that it comprises: a first lower valve (9,21) for the admission of liquid into the metering chamber (13), a second valve (19, 20) for the control the liquid dose delivered, and a third valve (6, 7) for the control of   the closing safety of the pump.