Patent Publication Number: US-2012037268-A1

Title: Device for the metered dispensing of liquid or viscous products and method for implementing this device

Description:
The present invention relates to a metering dispenser device for dispensing at least one liquid or viscous product from product tanks, each associated with a product, and in which the quantity of product dispensed is measured by its weight. The invention also provides a method of implementing the device. 
     TECHNICAL FIELD 
     Products for personal or home use by consumers, such as detergents, laundry additives, shampoos, or food products such as oils, beverages, are usually made available in packages that are discardable, and thus for single use. Such packages represent a large fraction of the cost of the final product. That type of distribution generates a large amount of waste that needs to be processed, thereby giving rise to considerable amounts of economic and environmental cost, since waste management is becoming ever more complex and expensive. 
     For several years, there has been growing sensitivity to the problem of durable management of natural resources and of the harmful economic and health consequences resulting from large quantities of waste. It has become essential to search for economic models that consume less energy, that generate less greenhouse-effect gas, and that are less expensive in terms of natural resources. 
     In this context, it is important, whenever possible, to provide alternative solutions to distributing products in single-use packaging and to make it possible for products to be distributed in bulk with packages that are reusable. Such alternative solutions must nevertheless be economically viable, without involving extra cost, they should satisfy hygiene requirements, they should enable the products to be delivered reliably, and they should not give rise to drawbacks in use for the consumer. 
     PRIOR ART 
     There are various known proposals for devices and methods for dispensing products in bulk by using containers that are reusable by the client, but known proposals do not give full satisfaction since they do not make it possible simultaneously to monitor: firstly the presence of a container under the filler nozzle while also monitoring sealing between the filler nozzle and the container for filling; and secondly the maximum acceptable filling level so as to avoid any overflow with loss of product, possibly while also monitoring for the presence of foam, where necessary. Furthermore, none of the known devices reliably guarantees that no drops of product can escape from the filler nozzle in the event of malfunction of the machine or of the container being absent from under the filler nozzle. Furthermore, known filler devices are not suitable for genuinely metered dispensing of products, since the client cannot select the quantity of product to be purchased, nor can the client use containers of different types, since the client must bring a container of determined type that is adapted to the device. 
     Document DE-GM 9108409.1 discloses an automatic device, intended more particularly for supermarkets, for filling reusable containers brought by clients, and in which clients can themselves fill the containers they have brought with a liquid product. A metering pump ensures that a predetermined quantity of product is conveyed from the product tank directly into the clients&#39; containers. That device uses an expensive pumping and control system, particularly since the flexible hose inserted into the container for filling is provided with a stop device that depends on level. 
     Document EP 0 640 556 discloses a similar device for filling containers, in particular with cleaning products or food products, taken from a tank. By using a vacuum pump, the filler product is conveyed firstly into a measuring chamber, and then after being measured, the predetermined quantity of product is conveyed by gravity into the container. 
     Document DE 4 315 422 A1 discloses a similar filling device that also uses technology based on measuring volume and that serves solely for delivering a predetermined quantity of product. 
     Document GB 1 357 953 discloses a foam detector device for dispensers of beverages, in particular beer, in which the liquid is delivered directly via an outlet orifice of the tank. A spherical float ( 16 ) closes the outlet orifice when the tank is empty or nearly empty. In the event of foam forming in the tank, the liquid level drops, and the float closes the outlet orifice, thereby interrupting the dispensing of the liquid and preventing the foam from escaping. 
     Document U.S. Pat. No. 4,911,212 discloses a device for filling reusable bottles, the device having specific means ( 24 ) for centering the head ( 36 ) of the filler nozzle ( 30 ), which means both center the nozzle under the filler nozzle of the tank before filling and maintain the bottle in this position during filling. 
     Document WO 93/22235 discloses a device for detecting foam, which device comprises a capacitive detector ( 11 ) detecting the value of the dielectric constant of the content of the beer delivering pipe as a function of the amplitude and the frequency of oscillation created in an electrostatic field by a captive electrode. A foam bleed valve ( 14 ) is incorporated in a stop valve ( 13 ) of the ball valve type. 
     None of the above-mentioned known devices is fitted with a system for monitoring the presence of a container and for monitoring sealing between the filler nozzle and the container for filling, and that is adaptable to all types of packaging and that also includes a device for monitoring the level of filling. Known foam detector devices involve stopping filling. None of the known devices enables a client to select the quantity of product that the client desires to purchase, since they deliver a predetermined quantity of product. 
     Finally, documents U.S. Pat. No. 6,578,763 and U.S. Pat. No. 7,083,093 disclose a method of filling containers with a liquid product from a tank of a dispenser appliance, and also the appliance itself. According to those documents, clients may themselves refill an originally empty container with the same product and pay only for the volume of product, without paying the price for the reused container. The quantity of filler product and the price are determined in advance and are identical for all clients. The product is dispensed by means of a nozzle provided at the bottom end of a movable duct, small dispenser tubes being provided inside said movable duct, each being used with one product or one product component. A system for removing overflow is provided by means of a small tube connected to a projecting collar surrounding the outlet nozzle. The formation of foam is avoided or limited by the fact that the nozzle is lowered into the container for filling until it touches the bottom of said container. That method and that device present the drawback of being adapted for filling only a predetermined quantity of liquid and for requiring the use of a container of origin that is checked by reading bar codes on the container. In addition, that method does not reliably guarantee that the product is genuinely delivered into the container, e.g. in the event of the container being poorly positioned under the nozzle. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Consequently, an object of the present invention is to provide a metering dispenser device for dispensing at least one liquid or viscous product from product tanks, each of which is associated with a product, and in which the quantity of dispensed product is measured by means of its weight, it being possible for clients to select the quantity of product they desire to purchase, that dispenses the product under good conditions of hygiene while guaranteeing that the product cannot be delivered if no container is present, or in the event of malfunction of the machine associated with a loss of electrical or pneumatic power, that monitors the presence of the container under the nozzle and also monitors sealing between the nozzle and the container for filling, that monitors the maximum acceptable filling level so as to avoid any overflow of product and any risk of soiling, that monitors the presence of foam and that provides a device for preventing or limiting the formation of foam in association with flow rate regulation, that is suitable for being manufactured and installed at a cost that is economically viable, and that is easy for the client to use. Furthermore, the device must be capable of being used with liquid products that present different coefficients of viscosity. The device must also guarantee a high level of reliability in measuring the quantity of product that is delivered, independently of temperature and pressure conditions. The device should advantageously be of the multi-product type, enabling a plurality of different products to be dispensed. 
     The invention also provides the method of using the metering dispenser device. 
     In order to achieve this object, the invention provides a metering dispenser device for dispensing at least one liquid or viscous product from product tanks, each allocated to a product, with the quantity of dispensed product being measured by its weight, the device being characterized in that it comprises:
         a vertically-movable motor-driven filler nozzle connected to a product delivery duct, itself connected to the product tank, and engageable in the container for filling;   a tray on which to stand the container for filling;   a selector for selecting the desired type of product and/or quantity of product;   a device for detecting the container for filling and for monitoring sealing between the filler nozzle and the container for filling, which device co-operates with a feed of gas under pressure and a pressure detector;   scales arranged under the tank of product in order to determine the quantity of product delivered by measuring the quantity of product remaining in the tank and co-operating with a controller for regulating and monitoring the dispensing of product;   a centrifugal pump or a pressurizing device for causing the product to be conveyed from the product tank into the container for filling;   a device for monitoring the maximum acceptable filling level; and   a payment ticket dispenser.       

     Provision is advantageously made for this device also to include a device for detecting the presence of foam, which device is associated with a filling rate regulator. 
     This metering dispenser device presents the advantage of guaranteeing three essential functions, namely: firstly detecting the presence of a container for filling and monitoring sealing between the filler nozzle and the container so as to prevent the filling process so long as sealing is not established or so as to interrupt the filling process in the event of a loss of pressure as a result of a lack of sealing; secondly monitoring the maximum acceptable level of product in the container, thereby preventing any overflow of product and avoiding any risk of soiling; and thirdly monitoring the presence of foam with the rate of filling being regulated as a function of the quantity of foam that is detected so as to avoid any overflow of foam without interrupting the delivery of product. 
     The metering dispenser device in accordance with the invention makes it possible to dispense liquid or viscous products in bulk with users themselves selecting the quantity of product they desire to purchase, and with the quantity of product that is dispensed being measured by the weight of said product. Measuring weight presents the advantage of weight being the only physical magnitude that is insensitive to external conditions of pressure and temperature. This type of measurement also makes it possible to comply with the requirements of European Directive IPFA No. 2004/22/EC relating to automatic weighing instruments. 
     In accordance with the invention, the filler nozzle is made up of three concentric tubes that serve to convey a flow of the gas under pressure and a flow of the product for dispensing. According to the invention, the inner tube serves to inject gas under pressure into the container, the middle tube disposed at a certain distance around the inner tube serves to introduce the product into the container, and the outer tube disposed at a certain distance around the middle tube serves to exhaust the gas under pressure. The filler nozzle is vertically movable as a whole and the inner tube is vertically movable relative to the middle tube and the outer tube. 
     In accordance with the invention, there is provided a probe for detecting the maximum acceptable level of product, the probe being arranged inside the inner tube and being secured thereto so as to move together with said inner tube. 
     According to another characteristic of the invention, the inner tube, the middle tube, the outer tube, and the probe are electrically insulated from one another. In the closed position of the middle tube, said inner tube and said middle tube are at the same electrical potential, thereby making it easier to establish and maintain sealing contact. 
     Still in accordance with the invention, the bottom end of the outer tube is provided with a part in the form of a nipple that is secured to said outer tube, presenting an annular outside surface that slopes conically inwards and that comes into contact with the neck of the container for filling. The sloping annular outside face of the end part in the form of a nipple that comes into contact with the neck of the container for filling may be covered in an elastic material in order to improve sealing between the filler nozzle and the container. 
     In accordance with the invention, the middle tube and the inner tube together with the probe for detecting the maximum acceptable level of product project from the bottom end in the form of a nipple of the outer tube, thus making it possible to avoid any risk of the product rising into the tube for exhausting the gas under pressure. 
     According to another characteristic of the invention, the bottom end of the inner tube is provided with a nozzle head presenting the shape of a projecting annular collar having its top surface sloping downwards and outwards and including annular sealing elements. Said nozzle head located at the bottom end of the movable inner tube for injecting gas under pressure and presenting the shape of a projecting annular collar is provided on its inside with at least two downwardly-sloping radial ducts for passing the gas under pressure. The bottom end of the nozzle head is closed by an end part that serves to insulate the probe electrically relative to the nozzle head and to the inner tube, and from which the bottom end of the probe for detecting the maximum acceptable level projects a little. 
     In a variant of the invention, the nozzle head located at the bottom end of the movable inner tube for injecting gas under pressure is constituted by two portions having the shape of superposed annular projecting collars disposed at a certain distance one above the other, the upper collar being secured to the inner tube for injecting gas under pressure and the lower collar being secured to the probe for detecting the maximum acceptable level of product so as to define between them a continuous annular orifice for passing the gas under pressure. 
     According to another characteristic of the invention, the sealing between the filler nozzle and the container for filling is monitored throughout the filling process by injecting gas under pressure through the inner tube of the filler nozzle, the outer tube for exhausting gas under pressure being provided at its top end with a rated valve enabling the pressure to be maintained throughout the pressurized gas circuit. In the event of the pressure dropping as a result of a loss of sealing between the outer tube of the filler nozzle and the container for filling, a pressure detector issues a signal triggering the rise of the inner tube together with the nozzle head and the interruption of the filling process. 
     Still in accordance with the invention, in the raised position of the inner tube and the nozzle head relative to the middle tube, corresponding to the position prior to delivering the product into the container, said nozzle head comes into contact with a counterbore provided in the inside wall of the middle tube for introducing the filler product in order to close said middle tube and prevent the product being delivered, while in the lowered position of the inner tube and the nozzle head relative to the middle tube, corresponding to its position after sealing has been established between the filler nozzle and the container for filling, the nozzle head is disengaged from the bottom end of the middle tube so that the annular orifice thereof is thus open in order to enable the filler product to flow into the container, the filler product being directed by the sloping top surface of the nozzle head in the form of a projecting annular collar towards the side wall of the container. 
     According to another characteristic of the invention, the maximum acceptable level of the product inside the container for filling is established by measuring the electrical resistance between firstly the inner tube for injecting the gas under pressure or the nozzle head or the middle tube, and secondly the probe for measuring the maximum acceptable level of product and arranged inside said inner tube in such a manner as to stop the filling process when the maximum acceptable level of product is reached. 
     According to another characteristic of the invention, the presence of foam is detected by measuring the electrical resistance between firstly the middle tube for introducing the product and/or the inner tube and/or the nozzle head, and secondly the outer tube for exhausting the gas under pressure, the filling rate being determined as a function of the quantity of foam that is detected. 
     Still in accordance with the invention, the product is conveyed from the tank into the container for filling by a centrifugal pump or by a pressurizing device. 
     According to another characteristic of the invention, the quantity of product delivered is determined by the scales located under the product tank continuously measuring the difference between the weight of product in the tank at the beginning of the product delivery process and the measurement instant, corresponding to the quantity of product that has already been delivered at that instant. 
     In a preferred variant of the invention, the tray on which the container for filling stands is constituted by a balance that measures the tare weight of the container at the beginning of the filling cycle and that measures the final weight at the end of the filling cycle in order to calculate the quantity of product that has been delivered into the container by taking the difference. Two measurements are then made of the quantity of product that has been delivered, i.e. one by the scales located under the product tank and the other by the balance on which the container for filling stands. 
     Still in accordance with the invention, a plurality of independent product tanks may be provided, each co-operating with a dedicated filler nozzle with which it forms a module by construction, and the nozzle corresponding to the selected product is put into place by a translation or rotation system. This variant of the invention corresponds to a multi-product dispenser. 
     In accordance with the invention, the method of using a metering dispenser device for dispensing liquid or viscous products from a product tank, in which the quantity of dispensed product is measured by its weight, is characterized by the following steps, when there is provided a simple tray on which the container for filling is stood and the quantity of product that has been delivered is measured solely by the scales located under the product tank:
         the user placing a container for filling onto a tray under the orifice for passing the filler nozzle, in order to trigger the launching of the automatic filling cycle;   the user actuating the selector arranged on the structure of the dispenser appliance in order to select the product and/or the desired quantity of product;   putting the filler nozzle corresponding to the selected product into position;   lowering the filler nozzle and introducing it into the container for filling, the lowering movement of the nozzle being triggered by pressing on the selector arranged on the structure of the dispenser appliance;   injecting gas under pressure into the container for filling in order to monitor the establishment of sealing between the filler nozzle and the container and the maintenance of sealing throughout the filling process;   triggering the operation of the centrifugal pump or of the pressurizing device in order to cause the product to be conveyed from the tank into the container;   triggering the operation of the scales placed under the tank of product in order to measure continuously the difference between the weight of product in the tank at the beginning of the product delivery process and at the measurement instant, corresponding to the quantity of product that has already been delivered at that instant;   optionally putting into operation the device for detecting the presence of foam and serving to regulate the filling rate;   putting into operation the device for monitoring the maximum acceptable level of product in order to prevent any overflow of product from the container;   lowering the inner tube with its nozzle head to disengage the bottom orifice of the middle tube and begin delivering the product;   stopping the filling process either when the requested quantity has been delivered, or on receiving a signal emitted by the device for monitoring the maximum acceptable filling level, or in the event of sealing being lost between the filler nozzle and the container, by raising the inner tube together with the nozzle head;   cleaning firstly by wiping by the sealing elements located in the grooves in the peripheral surface of the nozzle head and secondly by blowing gas under pressure through the sloping radial ducts formed in the nozzle head;   raising the filler nozzle into its retracted position inside the structure of the dispenser appliance;   an electronic device putting into form all of the information, including the result of calculating the price to be paid for sending to a printer; and   the user withdrawing the filled container and the ticket giving the information relating in particular to the quantity of product that has been delivered, the price to be paid, information about the product, its traceability, and the store.       

     In accordance with a preferred variant implementation of the invention, when provision is made for the tray on which the container for filling is stood to be constituted by a balance and the quantity of product that has been delivered is measured firstly by the scales located under the product tank and secondly by said balance on which the container is stood, the method of using a metering dispenser device for dispensing liquid or viscous products from a product tank, in which the quantity of dispensed product is measured by its weight, is characterized by the following steps:
         the user placing a container for filling onto a balance under the orifice for passing the filler nozzle, in order to establish the tare weight of the container and trigger the launching of the automatic filling cycle;   the user actuating the selector arranged on the structure of the dispenser appliance in order to select the product and/or the desired quantity of product;   putting the filler nozzle corresponding to the selected product into position;   lowering the filler nozzle and introducing it into the container for filling, the lowering movement of the nozzle being triggered by pressing on the selector arranged on the structure of the dispenser appliance;   injecting gas under pressure into the container for filling in order to monitor the establishment of sealing between the filler nozzle and the container and the maintenance of sealing throughout the filling process;   triggering the operation of the centrifugal pump or of the pressurizing device in order to cause the product to be conveyed from the tank into the container;   triggering the operation of the scales placed under the tank of product in order to measure continuously the difference between the weight of product in the tank at the beginning of the product delivery process and at the measurement instant, corresponding to the quantity of product that has already been delivered at that instant;   optionally putting into operation the device for detecting the presence of foam and serving to regulate the filling rate;   putting into operation the device for monitoring the maximum acceptable level of product in order to prevent any overflow of product from the container;   lowering the inner tube with its nozzle head to disengage the bottom orifice of the middle tube and begin delivering the product;   stopping the filling process either when the requested quantity has been delivered, or on receiving a signal emitted by the device for monitoring the maximum acceptable filling level, or in the event of sealing being lost between the filler nozzle and the container, by raising the inner tube together with the nozzle head;   cleaning firstly by wiping by the sealing elements located in the grooves in the peripheral surface of the nozzle head and secondly by blowing gas under pressure through the sloping radial ducts formed in the nozzle head;   raising the filler nozzle into its retracted position inside the structure of the dispenser appliance;   using the balance to measure the final weight of the quantity of product delivered;   comparing the measurements of the quantity of product delivered as taken by the scales and by the balance;   an electronic device putting into form all of the information, including the result of calculating the price to be paid for sending to a printer; and   the user withdrawing the filled container and the ticket giving the information relating in particular to the quantity of product that has been delivered, the price to be paid, information about the product, its traceability, and the store.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described in detail for purely indicative purposes in the following description. 
         FIG. 1  is an axial section view of a metering dispenser device in accordance with the invention in a waiting position retracted inner the structure of the dispenser appliance. 
         FIG. 2  is an axial section view of a metering dispenser device in accordance with the invention having its filler nozzle in the lowered position for detecting the container to be filled. 
         FIG. 3  is an axial section view of a metering dispenser device in accordance with the invention having its filler nozzle in the filling position. 
         FIG. 4  is an axial section view of a larger scale of the bottom end of the filler nozzle, the inner tube and the nozzle head being in the raised position. 
         FIG. 5  is an axial section view of a larger scale of the bottom end of the filler nozzle, the inner tube and the filler head being the lowered, filling position. 
         FIG. 6  is an axial section view of a metering dispenser device in accordance with the invention in which the foam detector device is in operation. 
         FIG. 7  is an axial section view of a metering dispenser device in accordance with the invention in which the device for monitoring the maximum acceptable level is in operation. 
         FIG. 8  is an axial section view of the nozzle head. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The metering dispenser device in accordance with the invention serves to dispense liquid or viscous products in bulk with users themselves selecting the quantities they desire to purchase, said dispensed quantities of product being measured by the weight of said product. Instead of selecting a quantity of product, a user may also select the amount to spend in order to acquire the product. The metering dispenser device is housed in a structure ( 2 ) of a dispenser appliance, which includes in particular a tray ( 6 ) on which to stand the container ( 5 ) that is to be filled, and a product selector (not shown in the figures). The product (P) is conveyed from the product tank (not shown in the figures) into the container ( 5 ) for filling by means of a centrifugal pump or by a device for applying pressure. 
     As can be seen in  FIGS. 1 to 7 , the metering dispenser device in accordance with a preferred embodiment of the invention has a motor-driven filler nozzle ( 1 ) that is vertically movable and that engages in the neck of the container ( 5 ) for filling. In the embodiment shown in the figures, the filler nozzle ( 1 ) is made up of three concentric tubes ( 10 ), ( 20 ), ( 30 ), with the inner tube ( 10 ) serving to inject a gas under pressure into the container ( 5 ), the middle tube ( 20 ) that is located at a certain distance around the inner tube ( 10 ) serving to introduce the product (P) into the container ( 5 ), and the outer tube ( 30 ) located at a certain distance around the middle tube ( 20 ) serving to exhaust the gas under pressure. The direction of the gas stream under pressure is marked by arrows A, and the direction of the stream of product (P) by arrows B. 
     The inner tube ( 10 ) for injecting a gas under pressure is connected to a delivery duct ( 16 ) for delivering said gas under pressure, and it serves to convey said gas under pressure into the container ( 5 ) for filling. Said inner tube ( 10 ), e.g. made of copper, serves to ground the nozzle head ( 11 ) provided at its bottom end. The inner tube ( 10 ) is vertically movable relative to the middle tube ( 20 ) and to the outer tube ( 30 ) that are not movable relative to each other. Inside the inner tube ( 10 ) there is arranged a probe ( 40 ) for detecting the maximum acceptable level of the product, which probe is secured to the inner tube ( 10 ) and moves together therewith. The probe ( 40 ), e.g. made of stainless steel, serves to pick up electric potential for the purpose of detecting the maximum acceptable level of the product (P) in the container. The product-introduction middle tube ( 20 ) together with the inner tube ( 10 ) for introducing gas under pressure and including the probe ( 40 ) for detecting the maximum acceptable level of product project from the bottom end of the outer tube ( 30 ) for exhausting gas under pressure, thus serving to avoid any risk of the product rising into the tube for exhausting gas under pressure. 
     The product-introduction middle tube ( 20 ) that conveys the product (P) into the container ( 5 ) for filling is connected to a product delivery duct ( 21 ) that is itself connected to a product tank (not shown in the figures) feeding said nozzle with product (P). The middle tube ( 20 ), e.g. made of stainless steel, serves to ground the product (P) found inside it and also to ground the inside tube ( 10 ) for injecting gas under pressure, with electrical contact taking place via the sloping top surface ( 12 ) of the nozzle head ( 11 ) and the corresponding shoulder ( 24 ) of the counterbore ( 22 ) of the middle tube ( 20 ), or via the product (P) itself. 
     The outer tube ( 30 ) for exhausting gas under pressure is provided at its bottom end with a part ( 31 ) in the form of a nipple that is assembled to said outer tube ( 30 ), e.g. by screw fastening. The nipple ( 31 ) presents an outer annular surface ( 32 ) that slopes inwards in conical manner and comes into contact with the neck of the container ( 5 ) for filling in order to establish and maintain sealing contact between the container ( 5 ) and the filler nozzle ( 1 ). In a particularly advantageous variant embodiment, the sloping annular outside surface ( 32 ) of the nipple-forming end part ( 31 ) is covered in an elastic material, e.g. rubber, thereby making it easier to establish and maintain sealing contact between the container ( 5 ) and the filler nozzle ( 1 ). The outer tube ( 30 ) and the nipple ( 31 ) assembled on said outer tube ( 30 ) are both made of electrically conductive material, the outer tube ( 30 ) being made of aluminum, for example, and the nipple ( 31 ) of brass. The nipple ( 31 ) serves to pick up the electric potential in order to detect the formation of foam (M) in the container ( 5 ). The outer tube ( 30 ), which is not connected to ground, serves to conduct the electric potential of the nipple to the wire connection point provided on a coupling ( 91 ) in the drive means for driving the filler nozzle ( 1 ). 
     The inner tube ( 10 ), the middle tube ( 20 ), the outer tube ( 30 ), and the probe ( 40 ) are electrically insulated relative to one another, respectively by the support head ( 92 ), the end part ( 15 ) of the nozzle head ( 11 ), and the coupling ( 91 ) that are all made of insulating material. 
     As shown in greater detail in  FIGS. 4 and 5 , the inner tube ( 10 ) includes at its bottom end a nozzle head ( 11 ) secured to said inner tube ( 10 ). Said nozzle head ( 11 ) is assembled with the inner tube ( 10 ) by screw fastening, for example, an O-ring ( 17 ) providing sealing between the inner tube ( 10 ) and the nozzle head ( 11 ). The nozzle head ( 11 ) is in the form of a projecting annular collar having its top surface ( 12 ) sloping downwards and outwards so as to direct the flow of product (P) towards the side wall of the container. In grooves formed in the outer peripheral face of the nozzle head ( 11 ) there are provided annular sealing elements ( 13 ), more particularly O-rings, that provide sealing between the nozzle head ( 11 ) and the inside face of the middle tube ( 20 ) for introducing the product. Said nozzle head ( 11 ) is provided on its inside with at least two radial ducts ( 14 ) sloping downwards a little and enabling the gas under pressure to pass from the inner tube ( 10 ) into the container ( 5 ), as shown more particularly in  FIGS. 5 and 8 . In a preferred embodiment of the invention, eight radial ducts ( 14 ) are provided for passing the gas under pressure, the ducts being arranged in a star configuration. The bottom end of the nozzle head is closed by a part ( 15 ), e.g. made of Teflon, that serves to insulate the probe electrically relative to the nozzle head ( 11 ) and the inner tube ( 10 ), the bottom end of the probe ( 40 ) projecting a little from said end part ( 15 ). 
     In a variant embodiment that is not shown in the figures, the nozzle head ( 11 ) located at the bottom end of the movable inner tube ( 10 ) for injecting gas under pressure is made up of two portions in the form of superposed annular projecting collars, located at a certain distance one above the other, the upper collar being secured to the inner tube for injecting gas under pressure and the lower collar being secured to the probe for detecting the maximum acceptable level of the product so as to define between them a continuous annular orifice for passing the gas under pressure. 
     As shown in  FIG. 1 , the filler nozzle ( 1 ) in the waiting and rest position is retracted inside the structure ( 2 ) of the dispenser appliance. 
     As shown more particularly in  FIGS. 2 and 4 , when the nozzle head ( 11 ) and the inner tube ( 10 ) for injecting gas under pressure are in the raised position relative to the middle tube ( 20 ) for introducing the product, this corresponding both to the rest position of the nozzle and to the position for injecting gas under pressure, said nozzle head is engaged in the middle tube ( 20 ) and comes into contact with the shoulder ( 24 ) of a counterbore ( 22 ) provided in the inside wall of said middle tube ( 20 ) so as to close said middle tube and prevent the product being delivered. Contact between the surfaces ( 24 ) and ( 12 ) also serve to provide electrical contact. Electrical contact may also be provided between the inner tube ( 10 ) and the middle tube ( 20 ) via the product (P) itself, if the product is conductive. 
     As shown more particularly in  FIGS. 3 and 5 , when the nozzle head ( 11 ) and the inner tube ( 10 ) for injecting gas under pressure are in the lowered position relative to the middle tube ( 20 ) for introducing the product, which position corresponds to the filling position after sealing has been established between the filler nozzle ( 1 ) and the container ( 5 ) for filling, the nozzle head is disengaged from the bottom end of said middle tube ( 20 ) so that its annular orifice ( 23 ) is thus opened in order to enable the filler product to flow into the container, the filler product (P) being directed by the sloping top surface ( 12 ) of the nozzle head ( 11 ) that is in the form of an annular collar projecting towards the substantially vertical side wall of the container ( 5 ). 
     In the embodiment shown, the filler nozzle ( 1 ) is assembled at its top end with a coupling ( 91 ) that enables all of the fitted parts making up the nozzle ( 1 ) to be electrically insulated, and that is itself actuated by an actuator ( 9 ). The inner tube ( 10 ) is mounted at its top end on a support head ( 92 ), e.g. made of Teflon or of any other material that is rigid and insulating, thereby enabling the incoming stream of gas under pressure to be placed between the inner tube ( 10 ) and the probe ( 40 ), and enabling the probe ( 40 ) to be electrically insulated relative to the inner tube ( 10 ). The actuator ( 9 ) serves to raise and lower the assembly comprising the support head ( 92 ), the inner tube ( 10 ), the probe ( 40 ), and the nozzle head ( 11 ) in co-operation with a compression spring ( 90 ) so as to enable the product (P) to be introduced and to flow. More particularly, the actuator ( 9 ) compresses the compression spring ( 90 ) to cause the assembly comprising the support head ( 92 ), the inner tube ( 10 ), the probe ( 40 ), and the nozzle head ( 11 ) to pass into the lowered, working position that enables the product (P) to flow, and causes said assembly to rise into the rest position in the event of the flow of product being interrupted or stopping. In the context of the invention, provision may also be made for any other suitable means for actuating the filler nozzle ( 1 ), e.g. a rack system co-operating with a motor, or indeed a magnetic field. 
     The metering dispenser device in accordance with the invention proposes simultaneously: firstly monitoring the presence of a container ( 5 ) under the filler nozzle ( 1 ) and providing sealing between said filler nozzle and the container ( 5 ) for filling; and secondly monitoring the maximum acceptable level of product in the container, thereby avoiding any risk of overflow. When a foam detector device of the invention is also provided, the metering dispenser device in accordance with the invention serves not only to monitor sealing and the maximum acceptable level of product, but also to monitor the formation of foam in association with a filling rate regulator, with the flow rate of the product (P) being reduced in the event of foam forming. 
     Monitoring for the presence of a container ( 5 ) for filling under the filler nozzle ( 1 ), and establishing sealing between the filler nozzle and the container ( 5 ) for filling and maintaining sealing throughout the filling process, are provided by injecting gas under pressure into the container ( 5 ). By way of example, the gas may be compressed air injected under at a maximum pressure of 10 bars, and preferably at about 6 bars. The gas could equally well be a technical gas that also serves to protect the filler product. This gas under pressure arrives via a delivery duct ( 16 ) into the inner tube ( 10 ) and it penetrates via the ducts ( 14 ) of the nozzle head ( 11 ) into the container ( 5 ), with some of the gas under pressure then escaping via the outer tube ( 30 ) and the duct ( 34 ) for exhausting said gas under pressure, as shown more particularly in  FIGS. 2 and 3 . A pressure detector or a flow meter serves to measure the pressure or the flow rate of the air. Once the desired pressure guaranteeing sealing has been achieved, authorization is given to deliver the product by opening the bottom end of the middle tube ( 20 ). Sealing between the filler nozzle ( 11 ) and the container ( 5 ) for filling is monitored throughout the filling process by injecting gas under pressure. The outer tube ( 30 ) for exhausting the gas under pressure is provided at its top end with a calibrated valve (not shown in the figures) serving to maintain the pressure throughout the circuit for gas under pressure. In the event of the pressure dropping as a result to a loss of sealing between the outer tube ( 30 ) of the filler nozzle ( 1 ) and the container ( 5 ) for filling, a pressure detector issues a signal causing the inner tube ( 10 ) to rise together with the nozzle head ( 11 ), thereby causing the filling process to be interrupted. It is thus not possible for the product to be delivered in the event of a lack of sealing, and it is not possible for drops of product to escape from the middle tube ( 20 ). This safety device is particularly important when delivering a chemical such as fertilizer or a product such as wine that might splash onto and stain the user of the dispenser device. After an accidental stoppage of the dispenser, delivery of the product may be restarted after the user has repositioned the container and sealing between the neck of the container ( 5 ) for filling and the outer tube ( 30 ) has been re-established. In addition, maintaining the pressure throughout the product delivery cycle has the effect of “breaking up” the foam and of reducing the formation thereof, since the compressed air injected by the inner tube ( 10 ) passes through the foam before being exhausted via the outer tube ( 30 ). 
     The monitoring of the maximum acceptable level of product in the container serves to avoid any risk of the product overflowing and soiling the surroundings. The maximum acceptable level of the product inside the container ( 5 ) for filling is established by measuring electrical resistance, which varies depending on the nature of the product present between two electrodes, one constituted by the inner tube ( 10 ) for injecting gas under pressure or the nozzle head ( 11 ) or the middle tube ( 20 ), and the other by the probe ( 40 ) for measuring the maximum acceptable level of product and located inside said inner tube ( 10 ), projecting a little from the bottom end ( 15 ) of the nozzle head ( 11 ) and coming into contact with the product, so as to cause the filler nozzle to be raised and the filling process to be stopped once the maximum acceptable level of product has been reached. Thus, for example, if the user has placed a 1.5 liter (L) container on the tray, but has requested 2 L of product to be delivered, then product delivery is stopped automatically when the product reaches the top level of the container. The price invoiced is then the price corresponding to the quantity of product that is actually delivered and not that corresponding to the requested quantity of product. 
     Monitoring the presence of foam may be particularly useful for products that tend to foam, such as detergent or wine. The presence of foam (M) is detected by measuring electrical resistance, which varies depending on the kind of product present, the measurement being made between two electrodes that are constituted firstly by the middle tube ( 20 ) for introducing the product and/or the inner tube ( 10 ) and/or the nozzle head ( 11 ), and secondly by the outer tube ( 30 ) for exhausting the gas under pressure, with the filling rate being determined as a function of the quantity of foam that is detected. When the presence of foam is detected, product delivery continues but at a slower rate. The formation of foam is also reduced by the configuration of the nozzle, more particularly by the fact that the flow of product (P) is directed towards the side wall of the container ( 5 ) by the downwardly-sloping top surface ( 12 ) of the nozzle head ( 11 ) in the form of a projecting annular collar. 
     In accordance with the invention, the quantity of product that is delivered is determined by scales located under the tank of product and continuously measuring the difference in the weight of product in the tank from the beginning of the product delivery process to the measurement instant, this corresponding to the quantity of product that has already been delivered at said instant. 
     In a variant embodiment of the invention, a second measurement of the quantity of product that has been delivered is also made. The stand tray ( 6 ) of the metering dispenser device having the container ( 5 ) for filling standing thereon is constituted by a balance that measures the tare weight of the container at the beginning of the filling cycle and that measures the final weight at the end of the filling cycle in order to calculate the weight of product in the container by taking the difference. Two measurements are thus taken in parallel of the quantity of product that has been delivered, one by the scales located under the product tank and the other by the balance on which the container for filling is placed. 
     In some circumstances, it is advantageous for a single appliance to be capable of delivering different products as selected by the user. In the context of the invention, provision may be made for a plurality of independent product tanks, each co-operating with a dedicated filler nozzle with which it forms a module by construction. The user may select the product by actuating a selector arranged on the structure of the dispenser appliance. The nozzle corresponding to the selected product is then put into place by a system for movement in translation or rotation. 
     In a first embodiment, a stationary stand tray ( 6 ) is provided on which the container ( 5 ) for filling is stood, and the quantity of product actually delivered is measured by the scales placed under the tank(s) of product(s). The operation of the metering dispenser device in accordance with the invention then comprises more particularly the following steps:
         the user placing a container ( 5 ) for filling onto a tray ( 6 ) under the orifice ( 3 ) for passing the filler nozzle ( 1 ), in order to trigger the launching of the automatic filling cycle;   the user actuating the selector arranged on the structure ( 2 ) of the dispenser appliance in order to select the product and/or the desired quantity of product;   putting the filler nozzle corresponding to the selected product into position;   lowering the filler nozzle ( 1 ) and introducing it into the container ( 5 ) for filling, the lowering movement of the nozzle being triggered by pressing on the selector arranged on the structure of the dispenser appliance;   injecting gas under pressure into the container for filling in order to monitor the establishment of sealing between the filler nozzle ( 1 ) and the container ( 5 ) and the maintenance of sealing throughout the filling process, the direction of the stream of gas under pressure being indicated by arrows A;   triggering the operation of the centrifugal pump or of the pressurizing device in order to cause the product (P) to be conveyed from the tank into the container ( 5 );   triggering the operation of the scales placed under the tank of product in order to measure continuously the difference between the weight of product in the tank at the beginning of the product delivery process and at the measurement instant, corresponding to the quantity of product that has already been delivered at that instant;   optionally putting into operation the device for detecting the presence of foam and serving to regulate the filling rate;   putting into operation the device for monitoring the maximum acceptable level of product in order to prevent any overflow of product from the container ( 5 );   lowering the inner tube ( 10 ) with its nozzle head ( 11 ) to disengage the bottom orifice ( 23 ) of the middle tube ( 20 ) and begin delivering the product, the direction of the product steam being indicated by arrows B;   stopping the filling process either when the requested quantity has been delivered, or on receiving a signal emitted by the device for monitoring the maximum acceptable filling level, or in the event of sealing being lost between the filler nozzle ( 1 ) and the container ( 5 ), by raising the inner tube ( 10 ) together with the nozzle head ( 11 );   cleaning firstly by wiping by the O-rings ( 13 ) located in the grooves in the peripheral surface of the nozzle head ( 11 ) and secondly by blowing gas under pressure through the sloping radial ducts ( 14 ) formed in the nozzle head ( 11 );   raising the filler nozzle ( 1 ) into its retracted position inside the structure ( 2 ) of the dispenser appliance;   an electronic device putting into form all of the information, including the result of calculating the price to be paid for sending to a printer; and   the user withdrawing the filled container ( 5 ) and the ticket giving the information relating in particular to the quantity of product that has been delivered, the price to be paid, information about the product, its traceability, and the store, the ticket possibly including in particular a bar code including the above information.       

     In a preferred variant of the invention, the stand tray ( 6 ) is constituted by a balance that, in parallel with the measurement performed by the scales placed under the tank(s) of product(s), measures the quantity of product actually delivered. The operation of the metering dispenser device in accordance with this embodiment of the invention comprises more particularly the following steps:
         the user placing a container ( 5 ) for filling onto a balance ( 6 ) under the orifice ( 3 ) for passing the filler nozzle ( 1 ), in order to establish the tare weight of the container and trigger the launching of the automatic filling cycle;   the user actuating the selector arranged on the structure ( 2 ) of the dispenser appliance in order to select the product and/or the desired quantity of product;   putting the filler nozzle corresponding to the selected product into position;   lowering the filler nozzle ( 1 ) and introducing it into the container ( 5 ) for filling, the lowering movement of the nozzle being triggered by pressing on the selector arranged on the structure of the dispenser appliance;   injecting gas under pressure into the container for filling in order to monitor the establishment of sealing between the filler nozzle ( 1 ) and the container ( 5 ) and the maintenance of sealing throughout the filling process, the direction of the stream of gas under pressure being indicated by arrows A;   triggering the operation of the centrifugal pump or of the pressurizing device in order to cause the product (P) to be conveyed from the tank into the container ( 5 );   triggering the operation of the scales placed under the tank of product in order to measure continuously the difference between the weight of product in the tank at the beginning of the product delivery process and at the measurement instant, corresponding to the quantity of product that has already been delivered at that instant;   optionally putting into operation the device for detecting the presence of foam (M) and serving to regulate the filling rate;   putting into operation the device for monitoring the maximum acceptable level of product in order to prevent any overflow of product from the container ( 5 );   lowering the inner tube ( 10 ) with its nozzle head ( 11 ) to disengage the bottom orifice ( 23 ) of the middle tube ( 20 ) and begin delivering the product, the direction of the product steam being indicated by arrows B;   stopping the filling process either when the requested quantity has been delivered, or on receiving a signal emitted by the device for monitoring the maximum acceptable filling level, or in the event of sealing being lost between the filler nozzle ( 1 ) and the container ( 5 ), by raising the inner tube ( 10 ) together with the nozzle head ( 11 );   cleaning firstly by wiping by the O-rings ( 13 ) located in the grooves in the peripheral surface of the nozzle head ( 11 ) and secondly by blowing gas under pressure through the sloping radial ducts ( 14 ) formed in the nozzle head ( 11 );   raising the filler nozzle ( 1 ) into its retracted position inside the structure ( 2 ) of the dispenser appliance;   using the balance ( 6 ) to measure the final weight of the quantity of product delivered;   comparing the measurements of the quantity of product delivered as taken by the scales and by the balance in order to verify that the two measurements are consistent and that the operation has taken place correctly;   an electronic device putting into form all of the information, including the result of calculating the price to be paid for sending to a printer; and   the user withdrawing the filled container ( 5 ) and the ticket giving the information relating in particular to the quantity of product that has been delivered, the price to be paid, information about the product, its traceability, and the store, the ticket possibly including in particular a bar code including the above information.