WO2004073876A1

WO2004073876A1 - Improved dispenser

Info

Publication number: WO2004073876A1
Application number: PCT/EP2004/001182
Authority: WO
Inventors: Pradeep Janardhan Nair; Sreehari Ramachandran Nair; Randhir Kumar Paul
Original assignee: Unilever Plc; Unilever Nv; Hindustan Lever Limited
Priority date: 2003-02-18
Filing date: 2004-02-06
Publication date: 2004-09-02

Abstract

A liquid container (LC) and dispensing assembly (DA), said dispensing assembly comprising an actuating member, an air pump, a liquid pump, each said pumps being concentric, and each said pumps having a reciprocating piston /plunger unit, each said pumps also comprising an inlet and a discharge; said actuating member adapted for operating said two pumps, and having an outflow channel having a dispensing opening, said channel connectable to said discharge of said pumps, air pump valve means adapted for sucking up air into the piston chamber of said air pump and to dispense air to the outflow channel, said air pump valve means present in the inlet and discharge of the air pump, liquid pump valve means adapted for sucking up liquid into the piston/plunger chamber of said liquid pump from said liquid container and to dispense liquid to the outflow channel, said liquid pump valve means present in the inlet and discharge of the liquid pump, said air pump valve means comprising means adapted such that the connection between the outflow channel and the air pump is blocked while air is being sucked in from atmosphere and when air is not sucked in the connection between the outflow channel and the air pump is opened, the said liquid pump valve means comprising means adapted to block the connection between the outflow channel and the liquid pump when liquid is being sucked up by the piston/plunger chamber of the liquid pump and when liquid is not sucked in to open the connection between the outflow channel and the liquid pump.

Description

Improved Dispenser

Field of the Invention

The present invention relates to a dispenser for dispensing an air-liquid mixture such as a foam dispenser used for dispensing liquids in particular in the form for various end use/applications. The foam dispenser is especially useful for use in delivering foam products such as liquid soap, shower foam, shaving foam and the like.

Background Art

Foaming pumps and aerosols are well known to dispense the liquids in the form of foam. Such aerosols/fearners usually involve a dispensing assembly consisting of two pumps basically a liquid pump and an air pump which feed in the liquid and the air to a mixing chamber wherefrom the foamed liquid is delivered through a dispensing head. Importantly, the dispensing head is spring biased to an usual no- discharge position. As and when foamed discharge is desired, the dispensing head/activating means is pressed down against its spring bias to actuate the liquid pump and air pump in a manner such that during the downward motion of dispensing head, the air from the air pump and liquid from the liquid pump are forced into a mixing zone and thereafter traverses a foam passage to be finally discharged in the form of a foam. After the dispensing is over, the activating member is released and it automatically retracts upwards due to its spring bias to its original position when the communication between the air pump and the liquid pump with the mixing chamber is cut-off by and the dispenser restored to its no-discharge state.

US 5429279 discloses an apparatus including a mixing chamber for mixing together pressurized gaseous and liquids constituents, the mixing chamber including a lower region and an upper region, separate feed connections for the pressurized constituents of a mixture to be formed, a discharge connection for discharging the formed mixtures to a chamber, wherein at least one of the separate feed connections includes passages in a wall of the mixing chamber, a spring located in the lower region of the mixing chamber biased against a pressure element located in the upper region of the mixing chamber, wherein the pressure element and an inner wall of the upper region of the mixing chamber define an annular space around the pressure element, wherein the passages comprise a porous part in the wall of the mixing chamber that open into the annular space around the pressure element in the upper region of the mixing chamber and comprises an inlet for a pressurized gaseous constituents and wherein the lower region of the mixing chamber comprises an inlet for a pressurized liquid component .

EP 0613728 Bl proposes a foam dispensing pump container having an elastic valve member which is disposed inside an upper wall of an air piston having at least one suction hole and which includes a cylindrical wall portion, an outer thin annular valve portion extending outwardly from the cylindrical wall portion and an inner thin annular valve portion extending inwardly from the cylindrical portion. The elastic valve member is mounted such that its cylindrical wall portion is in contact at least in part with an inner surface of a portion of the upper wall between the suction hole and an air passage, the outer thin annular valve portion is in contact, at its outer annular rim portion, with an inner surface of such portion of the outer wall that extends outwardly beyond the suction hole, and the inner thin annular valve portion is in contact, at its inner annular rim portion with an outer annular projection which is formed below the air passage and on an outer surface of a wall of a liquid piston. Such an elastic valve as proposed in this prior art construction is adapted to serve as a double acting shut-off device for the air pump which could function as the valve means for opening and closing the communication of the air chamber with the atmosphere and also to open and close the passage of the air from the air chamber to the mixing chamber as and when required.

However, such elastic/resilient dual shut-off component used in the above EP' 728 had problems since the same chaplet valve with two lip portions was used to open and close the air chamber communication with the atmosphere and the mixing zone with resulting problems of non-uniform and delayed operations of the chaplet valve for the above purposes leading to improper, non-uniform and uncontrolled closing and opening of the communication of the air-chamber with respect to the atmosphere and the mixing chamber and consequential problems of achieving uniform mixing and discharge. Importantly, considering that such dispensers sometime involve dispensing of sticky materials, the problems of sticking of the chaplet valve with respect to any component resulted in affecting the opening and closing of both the air chamber communication with the atmosphere as well as the mixing zone leading to further complexities in operation.

US 6053364 is targeted to avoid the limitation of EP' 728 and instead of the elastic dual shut-off valve means the system of US' 364 provided for the double acting shut-off device formed by the assembly of the annular air piston, a sealing ring fastened to the actuating member, and a flanged protecting driver portion of the liquid piston wherein during the downward motion of the actuating member, the sealing ring blocked the passage of the air chamber to the atmosphere while opening the communication of the air chamber with the mixing zone and when the actuating member is released to retract upwards to its usual position, the annular air piston and the flanged protruding driver portion of the liquid piston close together to seal-off the connection of the air chamber to the mixing chamber and in the process open the communication of the air chamber to the atmosphere by releasing the seal ring block therebetween.

Such a shut-off mechanism is supposed to take care of problems of the resilient elastic component of the prior EP' 728.

WO 00/78629 Al discloses an aerosol dispensing a liquid, in particular in the form of a foam which is directed to provide for a design which is supposed to take care of problems of contamination of the contents of the dispensing assembly by blocking entry of water or other contaminants from outside into the dispensing assembly. However, the valve means proposed in this prior art to open and close the communication of the air chamber with respect to the atmosphere and the mixing chamber is again an elastic dual shut-off variety proposed in EP' 728.

It would be apparent from the above state of art that while the basic features of such foaming pumps / aerosols are common to all involving the liquid pump comprising a liquid chamber, liquid pump piston, inlet to liquid pump, non return valve to inlet liquid, outlet from the liquid pump and non return valve for outlet liquid as well as the basic units of the air pump consisting of air chamber, air pump piston, inlet air pump, non return valve to inlet air, outlet from air pump and non return valve for outlet air , there has been a constant endeavor in the art to improve such aerosol/foamers by providing more efficient mechanisms for air and liquid delivery to the mixing chamber , the intake of the air from the atmosphere by said air chamber and liquid chamber as well as the intake of the liquid from the liquid chamber. It is important to maintain desired operational pressure in the air and liquid chamber to facilitate the process of foamed discharge from the aerosol/foamer . Thus, it is well apparent that the valve means used in such systems and its combination and functions in relation to the air pump and the liquid pump govern the efficiency of the foamers/ aerosol used as foam dispensers.

Objects of the Invention

It is thus the basic object of the invention to provide for improvement in dispensers for dispensing air-liquid mixtures such as foaming pumps / aerosols of the type discussed above, which would specifically avoid the problems of existing systems such as the dual-action resilient valve/chaplets usually used as communication means for the air chamber with the atmosphere and with the mixing zone, to thereby ensure better and uniform mixing of air-liquid and its dispensing.

Yet another object of the present invention is directed to a selective combination and disposition of components of an aerosol/foaming pump, which would be simple to obtain and at the same time would be efficient in generating the desired air-liquid mix/foam out of the foaming pump/ aerosol.

Yet further object of the present invention is to provide for improvement in foaming pumps/ aerosols of the type discussed above, whereby the actuating components required for functioning of the foaming pump/ aerosol can be adapted such as to facilitate obtaining and assembling of such device and make it cost effective.

Summary of the Invention

Thus according to the present invention there is provided a dispenser for dispensing air- liquid mixture comprising:

a liquid container and dispensing assembly, said dispensing assembly comprising an actuating member, an air pump, a liquid pump, each said pumps being concentric, and each said pumps having a reciprocating piston /plunger unit, each said pumps also comprising an inlet and a discharge; said actuating member adapted for operating said two pumps, and having an outflow channel having a dispensing opening, said channel connectable to said discharge of said pumps, air pump valve means adapted for sucking up air into the piston chamber of said air pump and to dispense air to the outflow channel, said air pump valve means present in the inlet and discharge of the air pump, liquid pump valve means adapted for sucking up liquid into the piston/plunger chamber of said liquid pump from said liquid container and to dispense liquid to the outflow channel, said liquid pump valve means present in the inlet and discharge of the liquid pump, said air pump valve means comprising means adapted such that the connection between the outflow channel and the air pump is blocked while air is being sucked in from atmosphere and when air is not sucked in the connection between the outflow channel and the air pump is opened, the said liquid pump valve means comprising means adapted to block the connection between the outflow channel and the liquid pump when liquid is being sucked up by the piston/plunger chamber of the liquid pump and when liquid is not sucked in to open the connection between the outflow channel and the liquid pump, said air pump comprising: i) at least one ball valve means disposed with respect to a corresponding cavity in said air piston for atmospheric communication with the air chamber such that when the actuating member and the piston is in its usual no discharge position the cavity is open to allow entry of atmospheric air into said air chamber and when the said actuating member is pressed down the piston is also pressed downward whereby the ball means is adapted to block the cavity to thereby block the communications with the atmosphere and ii) a chaplet valve supported with respect to said air piston internally and having annular radially inwardly extending lip adapted to co-operate with the external of said liquid plunger such that when the actuating member is in its usual no discharge position , the piston position is such that the chaplet lip blocks the communication of the air chamber to the mixing zone therethrough the inside of the air piston and the outside of the liquid plunger and when the actuating member is pressed downwards, the air piston is also pressed down whereby the lip get displaced to allow entry of the air from the chamber to the discharge outlet .

In accordance with another aspect the present invention provides a foam dispenser comprising:

a liquid container and dispensing assembly, said dispensing assembly comprising an actuating member, a foamer, an air pump, a liquid pump, each said pumps being concentric, and each said pumps having a reciprocating piston/plunger unit, each said pumps also comprising an inlet and a discharge; said actuating member adapted for operating said two pumps, and having an outflow channel having a dispensing opening, said channel connectable to said discharge of said pumps and housing a mixing zone for mixing of air and liquid and a foamer, air pump valve means adapted for sucking up air into the piston chamber of said air pump and to dispense air to the outflow channel and into a mixing zone, said air pump valve means present in the inlet and discharge of the air pump, liquid pump valve means adapted for sucking up liquid into the piston/plunger chamber of said liquid pump from said liquid container and to dispense liquid to the outflow channel and further into said mixing zone, said liquid pump valve means present in the inlet and discharge of the liquid pump, said foamer means adapted to generate foamed discharge of the air-liquid mix; said air pump valve means comprising means adapted such that the connection between the outflow channel and the air pump is blocked while air is being sucked in from atmosphere and when air is not sucked in the connection between the outflow channel and the air pump is opened, the said liquid pump valve means comprising means adapted to block the connection between the outflow channel and the liquid pump when liquid is being sucked up by the piston/plunger chamber of the liquid pump and when liquid is not sucked in to open the connection between the outflow channel and the liquid pump, said air pump comprising: i) at least one ball valve means disposed with respect to a corresponding cavity in said air piston for atmospheric communication with the air chamber such that when the actuating member and the piston is in its usual no discharge position the cavity is open to allow entry of atmospheric air into said air chamber and when the said actuating member is pressed down the piston is also pressed downward whereby the ball means is adapted to block the cavity to thereby block the communications with the atmosphere and ii) a chaplet valve supported with respect to said air piston internally and having annular radially inwardly extending lip adapted to co-operate with the external of said liquid plunger such that when the actuating member is in its usual no discharge position, the piston position is such that the chaplet lip blocks the communication of the air chamber to the mixing zone therethrough the inside of the air piston and the outside of the liquid plunger and when the actuating member is pressed downwards, the air piston is also pressed down whereby the lip get displaced to allow entry of the air from the chamber to the discharge outlet .

It has been found by way of the present invention that the above combination of the ball closure valve and the internally extending single lip chaplet valve to open and close the communication of the air chamber with the atmosphere and the mixing chamber respectively is advantageous since it effectively takes care of the problems of dual-actuating double lip elastic valve usually used in the art. In particular, the combination proposed by way of the present invention avoids the problem of use of the chaplet having annular contact with the piston surface of the dual actuating chaplet of the prior art. As discussed- above due to such annular contact of the chaplet of the prior art which is avoided by the combination of the ball and ingle lip chaplet of the present invention, the problems of delay in reverse stroke due to sticking of the chaplet to the piston surface is avoided. The ball and cavity valve used functions more efficiently as the same cannot have any problems of sticking of chaplet. This provides for more effective control over the entry of air in the air chamber and maintaining desired pressure requirement to work the system efficiently. Importantly, the combination proposed in the invention advantageously combines a ball closure for the air entry into the air chamber with the single lip chaplet valve for opening and closing the communication of - li ¬

the air chamber with respect to the mixing zone/discharge outlet. Importantly, the single lip chaplet provides for a more secured operation, assembling and effective working in relation to the piston motion.

Advantageously, the system of the invention while providing for a more effective functioning of foamer/aerosol also takes care of reducing the number of components for the system whereby it would be made more simple and cost effective to obtain and assemble. In this respect, the system of the invention makes effective use of a modified combination of a liquid plunger and liquid seal whereby additional component liquid piston assembly used in the prior art involving locator, lock and seat is avoided.

The actuating head used in the dispenser comprises an outlet passage and a dispensing opening. The outlet passage provides the space to accommodate foamer. The actuating head is adapted such that when it is pressed with the result the pistons of air pump and the liquid pump respectively moves downwards the volumes of the corresponding piston chambers are reduced. Liquid and air are then dispensed to the mixing chamber. This can be varied according to requirement .

Preferably, a closure is used to attach dispensing assembly and liquid container in a liquid tight manner.

A dip-tube can be provided with the liquid pump to serves as a siphon to reach the bottom of liquid container. This dip tube should be adapted to extend to close to the bottom of liquid container to serve as an effective inlet for the - Il ¬

liquid pump. The foamer server to allow the passage of the air and liquid mixture from the mixing chamber, through two small meshes to make the foam dense. This dense foam is forced into the outlet passages and exits from the opening provided in the head.

Preferably, a locator is used as a movable component in the liquid pump to generate compression and vacuum in liquid chamber .

The air piston is adapted to move up and down in air chamber coupled to the actuating head. The main movable component use to generate compression and vacuum within the air chamber. It is also adapted to house the single lip chaplet valve, which have a flexible-sealing component comprising annular resilient sealing lip. The piston is further provided with cavity adapted for incoming air from the atmosphere and a corresponding ball valve is also provided in the cavity to work as NRV for incoming air.

A seat means is provided to give passage to the liquid and provide support for lock and spring. It also provides restricted movement to the steel ball.

A spring means is provided for biasing the actuating member to the usual no discharge position. It also takes care of returning the pistons to its initial position and provides the force required for performing the seal to the steel ball. A steel ball is used to seal the liquid chamber in compression stroke so that no flow takes place with respect to the liquid container in this stroke. It also prevents back flow of liquid soap that is sucked during suction stroke from the liquid container.

The details of the invention its objects and advantages are explained hereunder in greater detail in relation to non- limiting exemplary illustrations of a foaming device/ aerosol of the invention in relation to the accompanying figures wherein:

Figure 1 is a sectional illustration of the foam dispenser of the invention with the actuator head in its usual position of no discharge.

Figure 2 is a sectional illustration of the foam dispenser of the invention showing the disposition of the components with the actuator head pressed down in the position to dispense the contents from the container in the form of a foam;

Reference is invited to figure 1, hich illustrates an embodiment of the foamer in accordance with the present invention. As clearly illustrated in said figure, the foamer is basically comprised of the liquid container (LC) , which at the top supports the dispenser assembly (DA) . The dispenser assembly is comprised of the actuating head member (HA) having a central discharge passage (DP) . The actuating head cooperates with the air pump and the liquid pump and for the purpose the same is operatively linked at its lower end to the annular piston (AP) of the air pump. The plunger means (PM) of the liquid pump is also operatively connected to the internal portion of the air piston such that by actuation of the actuating head the air piston and the - Il ¬

liquid plunger can both be moved downwards required to carry out the dispensing operation.

Importantly, in accordance with the present invention the air chamber (AC) of the air pump is adapted to open and close operative connection with the atmosphere by provision of cavity (CA) in the shoulder region of the annular piston. A cooperating ball valve (BV) is provided with respect to cavity such that in the usual condition (no discharge) the ball provides for opening of the cavity to allow entry of the air from the atmosphere into the air chamber as indicated by arrows in the figure and further also into the liquid container. The actuating head is spring biased to be maintained in a no discharge condition when such ball valve is open for entry of atmospheric air into the air chamber. As and when the actuating head is pressed down, the same also presses down the piston and in the process the ball closures blocked the cavity of the air piston thereby blocking the communication of the air chamber with the atmosphere. Importantly, in accordance with the present invention, the operative communication between the air chamber and the mixing zone (MZ) is adapted to be opened and closed by means of a single lip chaplet valve (CV) . As illustrated in said figure, in the usual no discharge position of the actuating head, the single lip, which is radially inwardly extending, is adapted to close the communication of the air chamber to the mixing zone there between the inside of the piston and the external surface of the liquid plunger. For the purpose, a flanged radial outward protruding portion (RO) is provided on the plunger outer surface, which co-operates with the lip of the chaplet valve to block the air chamber passage to the mixing zone.

As and when the discharge is required and the actuating head is pressed down, the piston while blocking the cavities for communication with the atmosphere opens up the chaplet valve for passage of the air from the air chamber to the mixing zone.

The liquid pump in the system of the invention is comprised of a hollow plunger (HP) the plunger at its lower end cooperates with a sealing valve (SV) to open and close the communication of the plunger inside and the liquid contents of the liquid container entering the liquid pump. A ball means seal (BMS) is provided in the dip tube formed lower end of the liquid pump which when pressed by the sealing member blocks the operative connection of the liquid contents in the container and the inside of the liquid pump. Thus during the usual no discharge position of the actuating head, the liquid plunger and the sealing means are forced upwards whereby the ball means seal (BMS) get lifted to allow entry of liquid from the container to the liquid pump. When the actuating head is pressed down for discharge of liquid, the plunger is also pressed down along with the sealing means to thereby block the operative connection between the liquid container and the liquid pump. In such condition, the plunger inside is maintained in operative connection with the liquid contents in the liquid pump, which is forced under pressure through the plunger inside into the mixing zone.

Thus, during the downward motion, the air from the air chamber and the liquid from the liquid chamber is forced through the mixing zone and further into the foamer to be dispensed as a foamed product .

Importantly, in accordance with the present invention, the combination of the ball closure for the cavity of the air piston communicating with the atmosphere and the single lip chaplet provide for effective and fast operation of the dispensing assembly. The problems of sticking and / or delay in activation of the dual shut-off double lip chaplet used for the purpose under the prior art is avoided by the above selective combination.

The operation of the dispensing unit is further explained hereunder in relation to figures 1 and 2.

Htep — 1 (For discharge o£ foamed product -Figure 2)

The actuating head is first pressed when the air and liquid piston moves downwards. The volume of air and liquid pump chamber decreases and pressure increases. Due to increase in pressure the ball like NRV get closed i.e. no interaction with the liquid container take place. The ball in the piston cavity seats perfectly to its position so that no interaction with atmosphere takes place. The lip of the chaplet for outgoing air to the mixing chamber get deactivate so the air, which is initially sucked in air pump chamber, comes out from the opening provided in the actuating head to the atmosphere via outlet passage and the foamer. Lock that is provided for outgoing from liquid chamber to the mixing chamber gets deactivated so that air, which is initially inhaled in liquid chamber, comes out from the opening provides in the actuating head. STEP - 2 (For return to no discharge position-Figure 1)

When actuating head is released the dispensing assembly will return to its starting position by restoring force of the spring. During this return movement volume of air chamber and liquid chamber increases and pressure decreases. Due to the decrease in pressure the ball like NRV open and the liquid pump chamber will fill with liquid from the liquid container.

Also the ball in the piston cavity seats-off from its position so that air can come to the air pump chamber. The lip of the chaplet for outgoing air is activated so that no air can flow to the mixing chamber. Lock that is provided for outgoing from liquid chamber to the mixing chamber get activated so that no liquid can pass from the liquid chamber. A vent opening is also provided in air pump, which is used to supply air to the interior of the liquid container in order to compensate for the amount of liquid, which has been used from the liquid container while the air pump chamber fills with air.

STEP-3 (For subseq ent discharge -Figure 2)

When actuating head is pressed again the air and the liquid piston moves downwards. With the result the volume of the air pump chamber and liquid pump chamber decreases and pressure increases. The ball in the piston cavity seats perfectly to its position so that no interaction with atmosphere takes place. Due to increase in pressure, lock that is provided for outgoing from liquid chamber to the mixing chamber deactivated so that liquid, which is inhaled in liquid chamber, comes out to the mixing chamber. The lip of the chaplet for outgoing air to the mixing chamber deactivate so that air, which is inhaled in air pump chamber, comes out to the mixing chamber. In the way from liquid chamber to mixing chamber some restricted passage are given and the air also coming to mixing chamber via the specific passage. This arrangement is provided to make the swirl to the incoming liquid and air so that turbulence is generated there and mixing of liquid and air will take place. After that this passes through the foamer where two meshes are provided, these meshes makes the foam dense.

This foam ultimately comes out to the outlet passage and leaves the dispensing opening.

It is thus possible by way of the present invention to provide for improvement in foaming pumps / aerosols of the type discussed above, which would avoid problems of existing systems such as the sticking of dual lipped resilient chaplets and/or delay in reverse stroke of the dispenser subsequent to dispensing. Importantly, the improved foaming pumps/ aerosols of the invention advantageously makes effective use of a ball closure and single lip chaplet combination whereby the said problems of dual lip chaplets to open and close communications of the air chamber with respect to the atmosphere and the mixing chamber could be controlled better thereby maintaining proper and effective pressure levels inside the chamber for effective function of the foam/dispenser. Importantly, the selective combination and disposition of components of an aerosol/foaming pump would make it simple and cost effective to obtain and at the same time would be efficient in generating the desired foamed products out of the pump/aerosol of the invention.

Claims

1. A liquid container and dispensing assembly, said dispensing assembly comprising an actuating member, an air pump, a liquid pump, each said pumps being concentric, and each said pumps having a reciprocating piston /plunger unit, each said pumps also comprising an inlet and a discharge; said actuating member adapted for operating said two pumps, and having an outflow channel having a dispensing opening, said channel connectable to said discharge of said pumps, air pump valve means adapted for sucking up air into the piston chamber of said air pump and to dispense air to the outflow channel, said air pump valve means present in the inlet and discharge of the air pump, liquid pump valve means adapted for sucking up liquid into the piston/plunger chamber of said liquid pump from said liquid container and to dispense liquid to the outflow channel, said liquid pump valve means present in the inlet and discharge of the liquid pump, said air pump valve means comprising means adapted such that the connection between the outflow channel and the air pump is blocked while air is being sucked in from atmosphere and when air is not sucked in the connection between the outflow channel and the air pump is opened, the said liquid pump valve means comprising means adapted to block the connection between the outflow channel and the liquid pump when liquid is being sucked up by the piston/plunger chamber of the liquid pump and when liquid is not sucked in to open the connection between the outflow channel and the liquid pump, said air pump comprising: i) at least one ball valve means disposed with respect to a corresponding cavity in said air piston for atmospheric communication with the air chamber such that when the actuating member and the piston is in its usual no discharge position the cavity is open to allow entry of atmospheric air into said air chamber and when the said actuating member is pressed down the piston is also pressed downward whereby the ball means is adapted to block the cavity to thereby block the communications with the atmosphere and ii) a chaplet valve supported with respect to said air piston internally and having annular radially inwardly extending lip adapted to co-operate with the external of said liquid plunger such that when the actuating member is in its usual no discharge position , the piston position is such that the chaplet lip blocks the communication of the air chamber to the mixing zone therethrough the inside of the air piston and the outside of the liquid plunger and when the actuating member is pressed downwards, the air piston is also pressed down whereby the lip get displaced to allow entry of the air from the chamber to the discharge outlet .

2. A liquid dispensing assembly comprising an actuating member, an air pump, a liquid pump, each said pumps being concentric, and each said pumps having a reciprocating piston /plunger unit, each said pumps also comprising an inlet and a discharge; said actuating member adapted for operating said two pumps, and having an outflow channel having a dispensing opening, said channel connectable to said discharge of said pumps, air pump valve means adapted for sucking up air into the piston chamber of said air pump and to dispense air to the outflow channel, said air pump valve means present in the inlet and discharge of the air pump, liquid pump valve means adapted for sucking up liquid into the piston/plunger chamber of said liquid pump from said liquid container and to dispense liquid to the outflow channel, said liquid pump valve means present in the inlet and discharge of the liquid pump, said air pump valve means comprising means adapted such that the connection between the outflow channel and the air pump is blocked while air is being sucked in from atmosphere and when air is not sucked in the connection between the outflow channel and the air pump is opened, the said liquid pump valve means comprising means adapted to block the connection between the outflow channel and the liquid pump when liquid is being sucked up by the piston/plunger chamber of the liquid pump and when liquid is not sucked in to open the connection between the outflow channel and the liquid pump, said air pump comprising: i) at least one ball valve means disposed with respect to a corresponding cavity in said air piston for atmospheric communication with the air chamber such that when the actuating member and the piston is in its usual no discharge position the cavity is open to allow entry of atmospheric air into said air chamber and when the said actuating member is pressed down the piston is also pressed downward whereby the ball means is adapted to block the cavity to thereby block the communications with the atmosphere and ii) a chaplet valve supported with respect to said air piston internally and having annular radially inwardly extending lip adapted to co-operate with the external of said liquid plunger such that when the actuating member is in its usual no discharge position, the piston position is such that the chaplet lip blocks the communication of the air chamber to the mixing zone therethrough the inside of the air piston and the outside of the liquid plunger and when the actuating member is pressed downwards, the air piston is also pressed down whereby the lip get displaced to allow entry of the air from the chamber to the discharge outlet.