Patent Publication Number: US-11047083-B2

Title: Liquid dispensing device, particularly for dispensing washing agents in a washing machine

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage of International Application No. PCT/IB2018/051382 filed Mar. 5, 2018, claiming priority based on Italian Patent Application No. 102017000025159 filed Mar. 7, 2017. 
     The present invention relates in general to liquid dispensing devices, for example dispensing devices for washing agents such as detergents or rinsing agents in washing machines, such as dishwashers or washing machines. 
     In particular, the present invention relates to a dispensing device for a liquid, comprising
         A reservoir within which a holding chamber for a liquid is defined, said chamber being capable of communicating with the outside of the reservoir through an outlet opening for liquid dispensing;   a ram movable within the holding chamber and capable of assuming a forward end-of-stroke position, in which the ram engages a seat formed at the outlet opening and blocking fluid communication between the holding chamber and the outside of the holding chamber, and a backward end-of-stroke position in which the ram is removed from the seat, wherein a variable volume working chamber capable of communicating with the holding chamber is defined between the ram and the seat; and   non-return valve means arranged at the outlet opening and downstream of the seat, said non-return valve means being open or closed when difference between fluid pressure upstream thereof and fluid pressure downstream thereof is higher or lower than a predetermined value, respectively;   wherein during the stroke of the ram from the forward end-of-stroke position to the backward end-of-stroke position the liquid flows from the holding chamber to the working chamber, and during the stroke of the ram from the backward end-of-stroke position to the forward end-of-stroke position the liquid is compressed within the working chamber and, upon opening of the non-return valve means, is dispensed out from the working chamber through the outlet opening;   wherein the device further comprises actuating means arranged at the outside of the reservoir and capable of contactlessly controlling motion of the ram.       

     In the dispenser according to the invention it is not necessary to provide openings in the reservoir walls to allow mechanical elements to operate on the ram. Technical problems related to the construction of hydraulic sealing systems are therefore avoided, and therefore the configuration of the reservoir is significantly simplified. 
     In some embodiments, it is also advantageous to have the valve means and/or the ram disposed removably inside the reservoir, for example positioned in a removable cap. 
     In this way, the problems of washability of the entire volume and of the entire surfaces that come into contact with detergents are overcome. A characteristic of liquid detergents which is not very functional at automatic dosages is in fact that after a certain time of exposure to the air or in use, they tend to change their viscosity until they reach the solid state. In this case, having an object completely washable in the parts that come into contact with the detergent, and having an easily accessible inner volume solves the problems for the restoration of the functions. 
    
    
     
       Further features and advantages of the invention will become apparent from the detailed description that follows, provided purely by way of non-limiting example with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a dispensing device according to the invention; 
         FIGS. 2 and 3  are schematic and sectional views of the device, in two different operating positions; 
         FIGS. 4 and 5  are perspective views of some components of the dispensing device; 
         FIGS. 6 and 7  are side elevation and plan views, respectively, of a dispensing device according to a further embodiment; 
         FIGS. 8 and 9  are schematic and sectional views of the device in  FIGS. 6 and 7 , in two different operating positions. I 
     
    
    
     With reference to  FIGS. 1 to 5 , a dispensing device for liquids is shown, indicated as a whole with reference numeral  1 . The device  1  can, for example, be a device for dispensing a washing agent such as a detergent or a rinse agent in a washing machine, such as a dishwasher or a washing machine. 
     The device  1  essentially comprises a reservoir  3 , inside which a holding chamber  3   d  is obtained for storing the liquid, and a cap  11  mounted on the reservoir  3 . The reservoir  3  can be a plastic element consisting of two parts coupled to each other, for example by means of thermal welding processes, but it can also be made in a single part, for example by means of blowing processes. 
     The cap  11  is sealably mounted at a filling mouth  3   g  of the reservoir  3 . The cap  11  comprises a head  12  and a hollow shank  14  which extends axially from the head  12 , inside the holding chamber  3   d . A seal  15  is arranged on the side of the cap  11  facing the shank  14  and is adapted to be compressed between the head  12  of the cap  11  and a wall of the reservoir  3  around the mouth  3   g , when the cap is mounted on the reservoir. Through the head  12  of the cap, a plurality of openings or through outlet holes  12   b  are formed. The closure of the cap can be screw or bayonet, as in the illustrated example, by means of radial projections  12   a  formed on the perimeter of the cap head  12  which engage corresponding grooves formed on the perimeter of the filling mouth  3   g  of the reservoir  3 . 
     The shank  14  comprises a radially outer tubular wall  14   a , on which a pair of longitudinally opposed longitudinal slits  14   b  is formed, and a radially inner tubular wall  14   c , coaxial with the radially outer tubular wall  14   a  and having a smaller longitudinal extension than it. The cavity inside the radially inner tubular wall  14   c  is in communication with the outlet openings  12   b  formed on the head  12  of the cap  11 . 
     The end of the shank  14  away from the cap head  12  is inserted in a centering collar  3   h  formed in the bottom of the reservoir  3 . 
     Inside the shank  14 , a ram  16  is guidably mounted. The ram  16  comprises a guide part  16   a , slidably inserted inside the radially outer tubular wall  14   a  of the shank  14  and provided with guide protrusions  16   b  inserted in the slits  14   b , and a ram end portion  16   c  provided with longitudinal grooves  16   d  on the lateral surface thereof. At the top of the ram end portion  16   c  is a membrane  17  of deformable material, e.g. elastomeric material. The membrane  17  is fixed to the ram end portion  16   c  at the centre thereof, while it is free to bend peripherally. 
     At a forward end-of-stroke position of the ram  16 , the ram end portion  16   c  is designed to abut against a seat  14   d  formed on the inner side of the radially inner tubular wall  14   c . The seat  14   d  is positioned at a predetermined distance from the free end of the radially inner tubular wall  14   c . Between the seat  14   d  and the free end of the radially inner tubular wall  14   c , a chamber  14   e  is thus defined surrounded by a continuous wall, that is to say, without lateral openings. 
     A permanent magnet  18  is fixed to the ram  16 , positioned in such a way as to have a polarity oriented parallel to the direction of movement of the ram  16 . 
     The permanent magnet  18  is designed to contactlessly interact with a pair of permanent control magnets  21 ,  22  arranged outside the reservoir  3 , on the other side of the bottom wall thereof. However, other means are possible to contactlessly control the ram  16 , in particular means based on electromagnets able to create static or variable electromagnetic fields. However, other means for contactlessly controlling the ram  16  are possible, in particular means based on electromagnets capable of generating static or variable magnetic fields. 
     The control magnets  21 ,  22  are arranged in such a way as to have a polarity oriented parallel to the direction of movement of the ram  16 . One of them,  21 , hereinafter referred to as the retraction magnet, points a pole towards the magnet  18  opposite the pole which the magnet  18  points towards the magnet  21 . The other,  22 , hereinafter referred to as the advancing magnet, points a pole towards the magnet  18  of sign identical to that of the pole which the magnet  18  points towards the magnet  22 . 
     The control magnets  21 ,  22  are supported by a movable support member  23 , for example rotating about an axis y parallel to the direction of movement of the ram  16 . With respect to such a support member  23 , the magnets  21  and  22  occupy angularly distinct positions, in particular diametrically opposite positions. However, this arrangement is not mandatory, as a configuration in which the magnets can be moved alternately is also contemplated. 
     The support member  23  is mounted on a support structure (not shown), integral with the reservoir  3  or independent of it, and receives motion from an actuator  24 , for example a rotary actuator or a linear actuator. 
     A unidirectional non-return valve device  30  is positioned at the head  12  of the cap. This device  30  is positioned in the cavity delimited by the radially inner lateral wall  14   c , between the seat  14   d  and the outlet openings  12   b . The non-return valve device  30  is conventionally provided with elastic means which urge the shutter in a closed position. The valve device  30  is therefore configured to be open or closed when the difference between a fluid pressure upstream thereof (i.e. in the chamber  14   e ) and a fluid pressure downstream thereof (i.e. at the outlet openings  12   b ) is respectively greater than or less than a predetermined value (determined in substance by the elastic means). 
     In the retracted end position shown in  FIG. 2 , the ram  16  is substantially resting against the bottom wall of the reservoir  3 , and is held in this position due to the magnetic attraction between the magnet  18  of the ram  16  and the retraction magnet  21  which are positioned opposite each other. 
     As a result of a control signal sent by a control unit to the actuator which controls the support member  23 , the actuator controls the rotation of the support member  23  so as to bring the advancing magnet  22  in front of the magnet  18  of the ram  16  ( FIG. 3 ). 
     Due to the magnetic repulsion between the magnet  18  of the ram  16  and the advancing magnet  22 , the ram  16  advances towards the seat  14   d  with the membrane  17 . When the membrane  17  begins to engage the free end of the radially inner tubular wall  14   c , the compression of the liquid inside the chamber  14   e  causes the opening of the non-return valve device  30  and therefore the delivery of the liquid, for example dispensing a detergent into the washing chamber of a dishwashing machine. The movement of the ram ends when the membrane  17  reaches the seat  14   d . At the end of the ram advancement, the non-return valve  30  is closed, determined by its elastic means. Overall, a volume of liquid is therefore delivered substantially equal to the maximum volume of the chamber  14   e  upstream of the seat  14   d  (determined by the distance between the seat  14   d  and the free end of the radially inner tubular wall  14   c ). 
     As a result of another control signal sent by the actuator which controls the support member  23 , the actuator controls the rotation of the support member  23  so as to bring the retraction magnet  21  in front of the magnet  18  of the ram  16  ( FIG. 2 ). 
     Due to the magnetic attraction between the magnet  18  of the ram  16  and the retracting magnet  21 , the ram  16  withdraws with the membrane  17  towards the retracted end position. The closure of the non-return valve device  30 , which occurred at the end of the ram advancement step, prevents liquids outside the reservoir from entering the reservoir  3 . For example, in the case of a dishwashing machine, the water circulating in the washing chamber C of the machine is prevented from entering the reservoir  3 ; at the same time, the ram is prevented from suctioning the detergent pushed forward by the previous movement into the reservoir. At the beginning of the retraction movement, the membrane  17  bends peripherally as a result of contact with the radially inner tubular wall  14   c  and/or the thrust of the liquid in the grooves  16   d  on the ram end portion  16   c , allowing the liquid present in the holding chamber  3   d  to reach the chamber  14   e  adjacent to seat  14   d . The membrane  17  returns to its non-deformed configuration when the ram  16  is retracted by such an extent as to bring the membrane  17  out of the chamber  14   e  adjacent to the seat  14   d . The movement of the ram  16  ends when the bottom wall of the reservoir is reached. To prevent the ram from hitting the bottom wall of the reservoir in a noisy manner, a damping chamber  3   m  (delimited at the top by a dashed line in  FIG. 3 ) is provided at the bottom of the reservoir, inside which the liquid opposes a resistance to the retraction of the ram. This is ensured by a lateral wall around the damping chamber  3   m  (in this case provided by one end of the shank), in which calibrated passages (not visible in  FIG. 3 ) are obtained which allow the liquid in the damping chamber  3   m , compressed by the ram  16  during the backward movement of the latter, to exit into the holding chamber  3   d  of the reservoir. 
     With the retraction of the ram, a new quantity of liquid is loaded into the chamber  14  ready to be delivered in a subsequent movement. 
     In the case of a dishwashing machine, generally the volume of detergent needed for a machine cycle can reach 40/50 cm 3 , then the movement of the ram which delivers only a small part of the volume at each cycle (for example 2/3 cm 3 ) must be repeated in a series of pulses until the expected quantity is reached. 
     Although advantageous for the washability of the reservoir, the configuration in which the ram and the valve device are positioned inside the removable cap is not mandatory. For example, it is possible to conceive an embodiment in which such components are partially or completely positioned outside the cap. Being in this case the function of supporting the components provided by parts obtained in the body of the reservoir, the cap would only maintain the closing function. 
     With reference to  FIGS. 6 to 9 , a further embodiment of the invention is now illustrated. The same reference numbers have been assigned to elements corresponding or equivalent to those already described in the above embodiment. 
     In the device in  FIGS. 6 to 9 , the body of the reservoir  3  is formed by two distinct parts  3   a  and  3   b , which will be indicated below as base and cover. The base  3   a  and the cover  3   b  are removably fixed together, for example by screws. Between the parts  3   a  and  3   b  of the reservoir, a seal  3   c  is interposed. 
     In base  3   e , a duct  3   e  is formed for loading the liquid into the holding chamber  3   d . In a manual loading embodiment, the duct  3   e  can be closed with a removable cap. In an automated loading embodiment, the duct  3   e  can be provided to be connected to a supply system. 
     The cover  3   b  comprises a head  12  and a hollow shank  14  which extends axially from the head  12 , inside the holding chamber  3   d . Through the cap head  12  there is formed a through outlet hole or opening  12   b.    
     The shank  14  comprises a tubular wall  14   a , on which a slit or opening  14   b  is formed which puts the interior of the shank  14  in communication with the rest of the holding chamber  3   d . The slit  14   b  extends in such a way as to leave a portion  14   a ′ of the tubular wall  14   a , closer to the outlet opening  12   b , free of lateral openings, that is, in other words, which continuously surrounds the cavity inside the tubular wall  14   a . The cavity inside the tubular wall  14   a  is in communication with the outlet opening  12   b  formed on the head  12  of the cover  3   b.    
     The end of the shank  14  away from the cover head  3   b  is inserted in a centering seat  3   h  formed in the bottom of the reservoir  3 . 
     Inside the shank  14 , the ram  16  is guidably mounted. At a forward end-of-stroke position of the ram  16 , the ram end portion  16   c  is designed to abut against a seat  14   d  formed on the inner side of the tubular wall  14   a . The seat  14   d  is positioned at a predetermined distance from the free end of the radially inner tubular wall  14   c . Between the seat  14   d  and the end of the continuous portion of tubular wall  14   a ′, a chamber  14   e  is thus defined. 
     A unidirectional non-return valve device  30  is positioned at the head  12  of the cover. This device  30  is positioned between the seat  14   d  and the outlet opening  12   b.    
       FIG. 9  also shows the damping chamber  3   m  (in this case provided by one end of the shank), in which a calibrated passage  3   n  is formed, which allows the liquid in the damping chamber  3   m , compressed by the ram  16  during the backward movement of the latter, to exit into the holding chamber  3   d  of the reservoir. 
     For the remainder, the structure and operation of the device in  FIGS. 6 to 9  are substantially corresponding to those of the device in  FIGS. 1 to 5 . 
     Of course, without altering the principle of the invention, the embodiments and the construction details may vary widely with respect to those described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the appended claims.