EP3924096A1

EP3924096A1 - Dispensing machine for fluid products, and components thereof

Info

Publication number: EP3924096A1
Application number: EP20713089.9A
Authority: EP
Inventors: Edoardo Rossetti; Marco Rossetti
Original assignee: ALFA Srl
Current assignee: ALFA Srl
Priority date: 2019-02-14
Filing date: 2020-02-13
Publication date: 2021-12-22
Also published as: IT201900002165A1; WO2020165822A1

Abstract

A dispensing machine for fluid products comprises a support structure with a rotary table which carries a plurality of pumping units coupled to respective fluid product reservoirs. Each pumping unit comprises a pump and a delivery valve connected to each other. The dispensing machine further comprises a dispensing operating area with a valve actuator and a pump actuator, adapted to couple respectively with the valve and the pump of a pumping unit positioned at the dispensing operating area following a rotation of the rotary table. The dispensing machine for fluid products further comprises a further plurality of reservoirs of fluid products coupled to pumping units provided with delivery ducts leading to a fixed nozzle assembly arranged at the dispensing operating area. A dispensing assembly for a rotary table-type fluid dispensing machine comprises a pumping unit with a reciprocating, volumetric pump and a valve assembly coupled to the volumetric pump. A pump actuator and a valve actuator are provided for coupling respectively the volumetric pump and the valve assembly from opposite sides of the pumping unit along a substantially radial direction of the rotary table in a dispensing operating area of the dispensing machine for fluid products. A pump for a dispensing assembly of a dispensing machine for fluid products comprises a cylindrical pumping chamber inside which slidingly reciprocates a piston for sucking fluid from a suction duct and feeding fluid into a delivery duct. The piston includes a larger diameter section and a smaller diameter section movable in synchronism with respect to each other to feed a certain flow of fluid proportional to the larger diameter section of the piston. The two sections are movable in opposition to supply a fluid flow proportional to the difference between the two sections of the piston. A valve for a dispensing assembly of a dispensing machine for fluid products comprises a delivery duct, a recirculation duct and a delivery opening. A selector disc is operable from a position in which the delivery duct is in communication with the recirculation duct, to a position in which the delivery duct is in communication with a delivery nozzle of the valve leading to the delivery opening. A check valve for use in a pumping unit of a dispensing machine for fluid products comprises a rigid dome-like structure with a top wall surrounded by a plurality of holes arranged in a circle. The check valve also comprises a corresponding dome-like membrane with a fluid passage on the top of the dome. The passage corresponds to the top wall of the rigid structure so as to be closed when the dome-like membrane rests against the rigid dome-like structure, and be open when the dome-like membrane is spaced from the rigid dome-like structure so as to allow a flow of fluid through the passage in the dome-like membrane and the holes on the rigid structure, the passage for fluid on the top of the dome being preferably a through hole.

Description

DISPENSING MACHINE FOR FLUID PRODUCTS, AND COMPONENTS THEREOF

Field of the invention

The present invention relates to a dispensing machine for fluid products such as colorants and the like, for the extemporaneous production of finished paints.

The invention has been developed particularly but not exclusively in relation to a dispensing machine of a rotating type, in which the colorant dispensing takes place in a sequential way.

The invention has been also developed particularly but not exclusively in relation to a dispensing unit for said dispensing machine for fluid products.

The invention has been also developed particularly but not exclusively in relation to a delivery pump for said dispensing machine for fluid products.

The invention has been also developed particularly but not exclusively in relation to a delivery valve for said dispensing machine for fluid products.

The invention has been also developed particularly but not exclusively in relation to a check valve for use in said dispensing machine for fluid products.

Technological background

There are known machines for dispensing colorant products and similar products intended for production of finished paints having a desired chromatic tone. In particular, the colorant dispensing machines comprise a plurality of reservoirs for fluid colorants, also known as universal colorants, which through pumps of various types are dispensed in predetermined amounts and mixed to a base paint.

In the traditional art of so-called tintometric systems, the base paint is prepared at the factory and made available inside canisters to the point of sale. The canisters with the base paint are opened when required and placed on the dispensing machine. Colorants dispensed by the dispensing machine are added to the base paint according to a precise formulation to obtain a finished paint having the required chromatic tone. Pastel colour shades are obtained using a base paint of a white colour, whilst dark and intense colour shades are generally obtained using a base paint which is not pigmented and therefore is of a neutral or transparent colour .

The known dispensing machines are of the type with simultaneous dispensing or of the type with sequential dispensing. In the first case the dispensing nozzles of the colorants are grouped in a common region, called nozzle centre, in such a way that the pumps which deliver the colorants can be activated at the same time to dispense simultaneously the colorants required within the canister arranged below the nozzle centre. The dispensing machines for sequential delivery are configured to deliver the colorants within the canister in a desired sequence. The sequential machine can have a fixed nozzle centre like the machines for simultaneous dispensing, or they can provide a movement thanks to which each individual nozzle for dispensing the desired colorant is brought in sequence above the canister, to deliver one colorant after the other. The movement can be of the translational type or rotating type.

A sequential-type colorant dispensing machine typically comprises a rotating table or carousel on which delivery units are mounted in a circular arrangement, each of which comprises a reservoir of colorant coupled to a piston pump provided with a delivery valve. An actuator is mounted in a fixed delivery station. By rotating the carousel, the delivery units with the desired colorants can be progressively brought to the delivery station, where the actuator can be coupled to the pump of the delivery unit for extracting a given quantity of colorant from the respective reservoir and dispense it in a container placed at the delivery station so that it is under the delivery valve of the delivery unit.

The rotating sequential dispensing machines of the known type have various disadvantages, especially in terms of performance and precision of delivery, and with regard to the reliability of the components. Moreover, the rotating sequential dispensing machines of the known type are adapted to only deliver colorants and cannot therefore be used for the production of paints which involve the delivery of components different from colorants, as described for example in WO 2018/134749 of the same applicant.

Summary of the invention

It is the purpose of the present invention to solve the problems of the prior art. One aim of the invention is to provide a dispensing machine that provides a fast and precise dispensing, for both large quantity of fluid product and very small amounts thereof. Another aim of the invention is to provide a dispensing machine that is economical and reliable. Another aim of the invention is to provide a dispensing machine which is suitable for the delivery both of colorants and other fluid products for the production of paints, for example according to the teachings of WO 2018/134749 of the same applicant.

In order to achieve these and other aims, the object of the invention is a dispensing machine of the rotating type, having the features indicated in the appended claims. The invention relates also to a delivery unit for such a dispensing machine for fluid products. The invention also relates to a delivery pump for said dispensing machine for fluid products. The invention also relates to a delivery valve for said dispensing machine for fluid products. The invention also relates to a check valve for use in said dispensing machine for fluid products. According to a first aspect, there is described a dispensing machine for fluid products comprising a support structure with a rotating table. The rotating table can carry a plurality of pumping units. The pumping units can be coupled to relative reservoirs of fluid products. Each pumping unit can comprise a pump and a delivery valve coupled to each other. The dispensing machine can comprise an operative delivery zone. A pumping unit can be positioned in correspondence of the operative delivery zone following a rotation of the rotating table. A valve actuator can be provided in the operative delivery zone. The valve actuator can be adapted to be couple to the valve of a pumping unit. A pump actuator can be provided in the operative delivery zone. The pump actuator can be adapted to be coupled to the pump of a pumping group. The dispensing machine for fluid products can comprise a further plurality of reservoirs for fluid products coupled to pumping units provided with delivery ducts that lead to a group of fixed nozzles arranged in correspondence of the operative delivery zone.

According to a particular aspect, the further plurality of reservoirs for fluid products and pumping units, and the group of nozzles, can be mounted on a carriage. The carriage can be extractable. The carriage can be normally located underneath the rotating table.

According to another particular aspect, the rotating table can comprise a toothing on its outer edge which mesh with a pinion of a motor that selectively carries out the rotation of the rotating table.

According to another aspect, there is described a dispensing group for a dispensing machine for fluid products of the type with a rotating table. The dispensing unit can comprise a pumping unit. The pumping unit can comprise a volumetric pump. The volumetric pump can be a reciprocating volumetric pump. The pumping unit can comprise a valve assembly. The valve assembly can be coupled to the volumetric pump. A pump actuator can be provided which can be coupled to the volumetric pump. A valve actuator can be provided which can be coupled to the valve assembly. It can be envisaged that the pump actuator and the valve actuator are coupled at opposite sides of the pumping unit. It can be envisaged that the coupling of the pump actuator and/or the coupling of the valve actuator occur along a substantially radial direction of the rotating table. It can be envisaged that the coupling occurs in an operative delivery zone of the dispensing machine for fluid products.

Preferably, the pump actuator can comprise a push member. The push member can be axially movable in the radial direction of the rotating table for selectively engaging with one end of the pump.

Preferably, the pump actuator can comprise a magnetic attachment member. Preferably, the magnetic attachment member can selectively engage to a metallic end of a piston of the pump .

Preferably, the pump actuator can comprise a position sensor. The position sensor can identify the engagement position of the pump actuator with the end of the pump.

Preferably, the valve actuator can comprise an operation gear. The operation gear can be operated in rotation to engage a gear of the valve unit for selecting the operating modes of the dispensing machine. Preferably, the toothing of the operation gear is interrupted along a sector corresponding to a zero position in which the pumping units on the rotating table are free to pass in front of the valve actuator without interfering with the gear.

According to another aspect, there is described a pump for a dispensing unit of a dispensing machine for fluid products. The pump can comprise a pumping chamber, preferably a cylindrical one. In the pump, preferably inside of the pump chamber, a piston can reciprocally slide to draw fluid from a suction duct and to introduce fluid in a delivery conduit. Preferably, the piston can comprise a section with a greater diameter and a section with a smaller diameter. The greater diameter section and the smaller diameter section can be movable in synchronism with respect to each other in order to feed a determined fluid flow rate which is proportional to the section of larger diameter of the piston. The greater diameter section and the smaller diameter section can be movable in opposition to feed a fluid flow rate which is proportional to the difference between the two sections of the piston.

Preferably, the greater diameter section and the smaller diameter section can be connected to each other through an elastic element. Preferably, the elastic element can push the smaller diameter section extending it away from one end of the greater diameter section. Preferably, the extension thrust occurs until the smaller diameter section abuts against an end wall of the pumping chamber. From that point on, a further advancement of the piston can determine the compression of the elastic element and the advancement of only the greater diameter section, whereas the smaller diameter section can remain in abutment against the end wall of the pumping chamber.

Preferably, the piston can be externally covered or enveloped by a bellows. Preferably, the bellows can also have a portion of greater diameter and a portion with a small diameter. According to another aspect, there is described a valve for a dispensing unit of a dispensing machine for fluid products. The valve can comprise a delivery duct, a recirculation duct and a delivery opening. The valve can comprise a selector disc, which can be actuated from a position in which the delivery duct is in communication with the recirculation duct, to a position in which the delivery duct is in communication with a delivery nozzle of the valve which opens into the delivery opening.

Preferably, the valve can comprise a primary delivery nozzle and a precision delivery nozzle of a smaller size than the primary delivery nozzle. Preferably, the selector disc can be operable to bring alternately the primary dispensing nozzle or the precision delivery nozzle at the delivery opening, so as to put the delivery duct in communication with the one or the other of the delivery nozzles, respectively.

Preferably, the selector disc can be brought to a position in which the at least one nozzle is in communication upstream with the delivery duct while downstream it is closed or in communication with the recirculation duct, so as to be able to discharge the pressure of the fluid in the circuit by providing a suction through the delivery duct.

Preferably, the selector disc can be operated in rotation through a gear integral therewith.

According to another aspect, there is described a check valve for use in a pumping unit of a dispensing machine for fluid products. The check valve can comprise a rigid dome structure with a top wall surrounded by a plurality of holes arranged in a circle. The check valve can comprise a dome shaped membrane with a passage for a fluid on the top of the dome. Preferably, the passage can correspond to the top wall of the rigid structure so as to be closed when the dome shaped membrane rests against the rigid dome structure, and to be open when the dome membrane is spaced from the rigid dome structure so as to allow a flow of fluid through the passage in the dome-shaped membrane and the holes on the rigid structure. Preferably, the passage for a fluid on the top of the dome is a through hole.

According to another aspect, there is described a dispensing machine for fluid products which can comprise a support structure with a rotating table which carries a plurality of pumping units coupled to relative reservoirs of fluid products. Preferably, the dispensing machine can comprise at least one dispensing unit of the type mentioned above, and/or at least one pump of the type mentioned above, and/or at least a valve of the type mentioned above, and/or at least a check valve of the type mentioned above.

According to another aspect, there is described a method for dispensing fluid products through a machine of the type referred to above.

Brief description of the drawings

Further characteristics and advantages will become apparent from the following detailed description of a preferred embodiment, with reference to the appended drawings which are given by way of non limiting example, in which:

- Figure 1 is a perspective view of a dispensing machine for fluid products embodying aspects of the present invention, in which the external covering panels of the machine have been removed for clarity of illustration;

Figure 2 is a plan view of a dispensing unit of the dispensing machine of Figure 1;

- Figure 3 is a longitudinal section according to line III- III of Figure 2;

- Figure 4 is an exploded view of the pumping unit forming part of the dispensing unit of Figure 2;

- Figure 5 is a top view of the pumping unit of Figure 4;

- Figure 6 is a section according to line VI-VI of Figure 5;

- Figure 7 is an enlarged sectional view of a detail of the fastening system of the pumping unit to the motor for actuating the pump;

- Figure 8 is an enlarged sectional view of a detail of the position sensor of the pumping unit;

- figures 9 and 10 illustrate two different positions of the piston of the delivery pump for fluid product;

- Figure 11 is a sectional view on an enlarged scale of the delivery valve in a primary delivery position;

- Figure 12 is an exploded view of a first check valve of the pumping unit associated to the delivery nozzle of the delivery valve shown in Figure 11;

- Figure 13 is a sectional view on an enlarged scale of the delivery valve in a position of precision delivery;

- Figure 14 is a sectional view on an enlarged scale of a second check valve of the pumping unit, associated with the intake duct of the pumping unit;

- Figure 15 is an exploded view of the valve of Figure 14;

Figures 16 and 17 are exploded views according to two different perspectives of the delivery valve of the pumping unit ;

- Figures 18, 19 and 20 show plan views of three components of the delivery valve of figures 16 and 17;

- Figures 21, 22 and 23 show the flow of fluid product which passes through the delivery valve of figures 16 and 17 in a condition of recirculation of the fluid product;

- Figures 24A and 24B show two different positions which the dispensing valve assumes in an operative sequence of primary delivery;

- Figures 25A and 25B show two different positions which the dispensing valve assumes in an operative sequence of precision delivery; and

- Figures 26A - 26D are bottom views of the coupling between a pumping unit and the actuator in a sequence of operating steps from a recirculation position to a position of precision delivery.

Detailed Description

With reference now to Figurel, a dispensing machine for fluid products comprises a support structure 1 comprising a platform 2 which supports a rotating table or carousel 3. On the rotating table 3 are mounted reservoirs 4 of fluid products. Each reservoir 4 is coupled to an underlying pumping unit 5. A motor 6 is coupled to the rotating table 3, for example by means of a pinion meshing with a toothing 3' made on the periphery of the rotating table 3 to selectively drive in rotation the rotating table 3, preferably in both directions of rotation so as to bring the desired pumping unit 5 at an operative delivery zone 10 placed on the front of the dispensing machine. The dispensing machine can be provided with an extractable carriage 7. On the carriage 7 there can be mounted extractable reservoirs 8 of fluid products connected to pumps 9 with delivery ducts which lead together in a nozzle centre 11. The reservoirs 8 of fluid products have preferably a volume which is greater than the reservoirs 4 placed on the rotating table 4, and they allow to produce paints by delivering products which complete those paints for example according to the teachings of WO 2018/134749 by the same applicant. The products which complete the paints are generally delivered in higher quantities than the colorant contained in the reservoirs 4 on the rotating table 3, which typically are needed in small volumetric amounts to provide the desired colour shade to the finished paint.

A support plane 12 which is adjustable in height is adapted to support a canister into which fluid products are delivered to obtain the desired paint. The support plane is arranged below the nozzle centre 11. When the carriage 7 is inserted in the dispensing machine, the support plane 12 is arranged below the operative zone 10, in such a way that the desired fluid products contained in the reservoirs 4 can be delivered in the desired amounts in a canister resting on the support plane 12. If the extractable carriage 7 is not provided, the support plane 12 can be mounted directly on the support structure 1 of the dispensing machine.

With reference now to Figures 2 and 3, it is shown in enlarged scale the dispensing unit of the dispensing machine for fluid products, comprising one of the pumping groups 5 positioned at the operative delivery zone 10. The pumping unit 5 comprises a pump 14. The pump 14 is a volumetric pump, preferably of the reciprocating type, and will be described in further detail hereinbelow. The pump 14 communicates with a suction duct through an inlet 16. The suction duct communicates with a respective reservoir of fluid product 4. The pumping unit 5 comprises a valve assembly 18. The pump 14 communicates with the valve assembly 18, which can be switched into different positions, so as to deliver to the outside, for example in a canister located therebelow and resting on the plane 12, the fluid product pumped by the pump 14, or to recirculate the fluid product returning it to the reservoir 4.

A motor unit 20 is mounted in the operating area 10. The motor unit 20 is fixedly mounted on the base structure of the dispensing machine. The motor unit 20 comprises a motor 22 for actuating the pump 14, which is preferably a stepper motor. The motor unit 20 comprises a mechanism 24 which converts the rotating motion of the motor 22 into a linear motion. The motor unit 20 is arranged to couple selectively to a pump 14 which is located in the operating area 10. In particular, the mechanism 24 comprises a coupling member 26 on the motor side, arranged to couple selectively to a corresponding coupling member 28 on the pump side. Selective coupling between the coupling element 26 on the motor side and the coupling member 28 on the pump side can take place by mechanical coupling, for example by means of a bayonet mount or the like, or other fastenings of that kind. As an alternative or in addition, the coupling can take place in a magnetic or electromagnetic way.

In the operating delivery zone 10 a valve actuator unit 30 is mounted. The valve actuator unit 30 is placed opposite to the motor unit 20 with respect to the pumping unit 5. The valve actuator unit 30 is arranged to be coupled with the valve assembly 18 to actuate it and therefore adjust the way it operates, as will be better described hereinbelow. The valve actuator unit 30 is fixedly mounted on the base structure of the dispensing machine. The valve actuator unit 30 comprises a motor 32, preferably a stepper motor. The valve actuator unit 30 includes an actuator mechanism 34 coupled to the motor 32. The actuator mechanism 34 is designed to couple with the valve assembly 18 of the pumping unit which is located in the operating area 10, so as to control the selective opening thereof. The valve actuator unit 30 comprises at least one position sensor 36 to detect and signal the position of the actuator mechanism 34, in particular the position of a zero-indicating rod 35 coupled to the motor 32. In particular, the position sensor 36 can detect and signal an initial reference position of the valve actuator mechanism 34.

The actuator mechanism 34 comprises an operation gear 38. The operation gear 38 is controlled by motor 32, to which it can be coupled with the interposition of transmission members, such as for example, a gear 37 keyed on the drive shaft 33 of the motor 32 and meshing with the operation gear 38. Naturally the operation gear 38 could be coupled to the motor 32 either directly or with the interposition of other transmission members such as for example a belt transmission.

The operation gear 38 has a set of external teeth, for example a toothing with straight teeth. The toothing of the operation gear 38, as will be revealed more clearly below, is interrupted for a certain portion of its extension, preferably but not exclusively about an arc of 90°. In the portion of the interrupted toothing, the operation gear 38 has a flat horizontal tongue 38', whose height is less than the height of the teeth of the operation gear 38. The interruption of the toothing of the operation gear 38 allows the pumping units 5 to pass in front of the valve actuator 30 during the rotation of the rotating table 3, without interfering with the operation gear 38. In fact, during the rotation of the rotating table 3 the operation gear 38 has its section devoid of teeth, provided with the tongue 38', facing the pumping units 5. In this position, shown in Figures 2 and 3, the tongue 38' is free to slide without interference within a corresponding horizontal slot 39' of a toothed sector wheel 39 of the valve unit 18. Starting from this position, when a pumping unit 5 is stopped in front of the valve actuator 30 in the operating area 10, the operation gear 38 can be rotated in such a way that its toothing meshes with the toothed sector wheel 39 of the valve unit 18, so as to be bring the latter in the desired position according to the requested operation, as will be better described in the following .

Figure 4 shows an exploded view of the pumping unit 5. The pump 14 comprises a body 40 with a substantially cylindrical cavity 42 which extends along a longitudinal axis X-X. The cavity 42 ends inside the body 40 with an end wall 41. The end wall 41 has a slight central projection 43. A piston 44 is mounted inside the cavity 42 and is slidably movable in the axial direction X-X. In the cylindrical wall 42a of the cavity 42, a radial opening 46 is formed which communicates with the reservoir of fluid product 4 through the suction duct. The inlet 16 is mounted on the radial opening 46. In the cylindrical wall 42a there is also formed a delivery channel 47 which opens into a delivery opening 49 made in the end wall 41 and communicates with the valve assemb1y 18.

In the radial opening 46 a check valve 48 is mounted, shown in enlarged scale in the details of Figures 14 and 15. The check valve 48 comprises an abutment ring 50, a dome shaped membrane 52 and a rigid body 54 also shaped like a dome. The rigid body 54 is provided with holes 55 for the passage of the fluid. Preferably the holes 55 are arc-shaped and are arranged in a circle with respect to the axis of the rigid body 54. In this way the rigid body 54 has a support central zone 56 in correspondence with a central notch 57 of the dome-shaped membrane 52. When fluid pressure is exerted by the rigid body 54 through the holes 55 to the dome-shaped membrane 52, the latter is moved away from the rigid body 54 and the fluid can pass through the central notch 57. In the configuration of the pump 14, this condition corresponds to the suction of fluid from the inlet duct through the inlet 16 following a suction stroke of the piston 44. When instead a fluid pressure is exerted in the opposite direction, that is, from the dome-shaped membrane 52 toward the rigid body 54, the fluid pressure pushes the dome-shaped membrane 52 against the convex wall of the rigid body 54 in such a way that the central notch 57 is closed by the central zone 56 of the rigid body 54, thus blocking the flow of fluid. This check valve is particularly effective and reliable, since there is no sliding between parts and no abrasion due to any solid particles present in the fluid.

The piston 44 comprises a pusher 60 end with an annular projection 62 for supporting a spring 64, preferably a coil spring wound in a spiral around the pusher 60, as shown also in Figure 6 and in the enlarged detail of Figure 7. The spring 64 facilitates the suction stroke of the piston 44, that is, its movement to the right in the drawings. An end plate 65 closes the body 40 and retains the piston 44 within itself. The coupling member 28 is fixed, preferably screwed, on the bottom of the pusher 60. A fin or wing 61 radially protruding from the pusher 60 is detected by a sensor 63 mounted on the mechanism 24 to accurately determine the end of stroke of the piston 44 when the mechanism 24 is coupled to the piston 44 by means of the coupling between the coupling member 26 on the motor side and the coupling member 28 on the pump side. Preferably but not restrictively, the sensor 63 is a photoelectric cell which senses the fin or wing 61 at a known predefined distance just before, for example one millimetre, the coupling position between the motor and the pump. From the moment of detection, the displacement of coupling member 26 on the motor side toward the coupling member 28 on the pump side proceeds for said known predefined distance. In a preferred embodiment of the invention, the coupling member 26 on the motor side is a permanent magnet, whilst the coupling member 28 on the pump side is a metal block which can be coupled magnetically to said permanent magnet.

A cup-shaped body 66, shown in enlarged scale in Figures 9 and 10, is mounted at the other end of the pusher 60, on the opposite side to the annular projection 62. The cup shaped body 66 is axially slidable on a cylindrical end 68 of the pusher 60. The cylindrical end 68 has its diameter smaller than the diameter of the pusher 60. The axial sliding movement of the body 66 is contrasted by the elastic bias of a spring 70, preferably a coil spring wound in a spiral around the cylindrical end 68 of the pusher 60.

The piston 44 moves inside a bellows 80 interposed between the pusher 60 and the cylindrical wall 42a of the cavity 42. The bellows 80 can extend and compress axially following the axial sliding of the piston 44. The bellows 80 comprises an end annular projection 82 locked in a fixed position between the body 40 of the pump and an annular projection 84 of the plate 65. The bellows 80 comprises a main portion 80a the diameter of which is close to the internal diameter of the cylindrical wall 42a of the cavity 42. On the side far from the annular projection 82, the bellows 80 has a short end portion 80b whose diameter is smaller than the diameter of the main portion 80a. The short portion 80b substantially corresponds in length to the length of the cup-shaped body 66. The end of the bellows 80 is closed by a thrust wall 86. The cup-shaped body 66 abuts the inner side of the thrust wall 86 under the bias of the spring 70. A cup 45 is mounted on the end of the chamber 42 so as to rest against the end wall 41. The cup 45 houses the portion 80b of the bellows 80, as shown in Figure 9. The body 45 can have guide ridges radially distributed on its inner wall, in order to guide the portion 80b of the bellows 80. In a variant, the cup 45 acts as reduction of the internal diameter of the cavity 42, to reduce the displacement of the pump in the condition of precision delivery, which will be described in the following. In this variant, the inner annular wall of the cup 45 is substantially smooth and has a diameter that is slightly larger than the diameter of the portion 80b of the bellows 80. In this way the pumping volumes are reduced, and the pump is more effective when it operates in suction, since there is a lower elastic effect of micronized air possibly present in the product fluid.

As can be seen in the enlarged detail of Figure 8, the mechanism 24 of the motor unit 20 comprises a pusher 90 with an internal thread 92 which is coupled to an actuating screw 94 fixed to the output shaft of the motor 22. The pusher 90 can slide but not rotate inside a fixed body 96. For example the pusher 90 and the fixed body 96 are coupled to each other by means of projections and longitudinal grooves. In this way, the rotating motion of the motor 22 is transformed into a linear motion of the pusher 90. At the end of the pusher it is fixed the coupling member 26. A position sensor 98, for example a photoelectric cell, detects the initial position of the pusher 90, when the coupling member 26 engages the coupling member 28 on the pump side. Preferably, the sensor 98 sees the displacement of pump during dispensing. The pusher 90 has an annular projection 99 (see Figure 3) which abuts the fixed body 96 and defines the maximum retraction of the pusher that allows to disengage the coupling member 26 on the side of the motor from the coupling member 28 on the pump side .

As shown in Figures 3 to 5, the valve assembly 18 comprises a valve support 100 mounted on the body 40 of the pump 14. The valve support 100 comprises a cylindrical inlet 102 that engages in a corresponding cylindrical seat 104 formed on the body 40. The cylindrical seat 104 is coaxial with the delivery duct 47. A sealing gasket 105 is mounted on the peripheral wall of the cylindrical inlet 102. A delivery duct 106 for fluid product is made coaxial with the cylindrical inlet 102. The delivery duct 106 preferably comprises a first duct portion 106a which extends horizontally in communication and on the extension of the delivery duct 47. The first duct portion 106a communicates with a second duct portion 106b that extends vertically up to the inlet of a valve 110. From the valve 110 a recirculation outlet 108 is connected through a duct to the reservoir 4 of fluid product.

The valve 110, more clearly visible in Figures 16 to 20 comprises a delivery hole 112. The delivery hole 112 is formed in the lower part of the valve 110, on a cover 114. The cover 114 has a substantially circular shape and the delivery hole is placed eccentric with respect to the cover centre. The cover 114 is provided with two wings 113 for it to be fixed to the valve support 100, for example by means of two screws 111. The delivery hole 112 has a smaller diameter at the upper face 114a of the cover 114, and a larger diameter at its lower face 114b. The delivery hole 112 is therefore flared downwards, so that the thickness of the wall of the cover 114 is as little as possible an obstacle to the flow of the fluid being delivered.

The cover 114 has an annular rim 115 that projects with respect to the upper face 114a so as to form a seat 116 for a recirculation disc 118. The recirculation disc 118 is locked in rotation in the housing seat 117 for example by peripheral notches 120 formed in its edge that fit into respective teeth 121 projecting from the annular rim 115. In the recirculation disc 118 it is formed an outlet hole 122 for the fluid that is coaxial with the delivery hole 112 on the closure cover 114. Similarly to the delivery hole 112, the outlet hole 122 also has a smaller diameter at the upper face 118a of the recirculation disc 118, and a greater diameter at its lower face 118b. The outlet hole 122 is therefore flared downwards such as the delivery hole 112 on the cover 114, also in this case to reduce the interference of the thickness of the recirculation disc 118 with the flow of fluid being delivered. The diameter of the outlet hole 122 in correspondence of the lower face 118b of the recirculation disc 118 is preferably equal to, or less than the diameter of the delivery hole 112 at the upper face 114a of the cover 114, so as to provide an overall outlet port for the fluid that progressively widens downwards starting from the upper face 118a of the recirculation disc 118. On the upper face 118a of the recirculation disc 118 there is a recirculation channel 124. The recirculation channel 124 is in the form of an arc whose extent is substantially equal to 180° and is preferably in a diametrically opposite position with respect to the outlet hole 122. The depth of the recirculation channel 124 is smaller than the thickness of the recirculation disc 118.

Above and coaxially to the recirculation disc 118, the toothed sector wheel 39 is mounted, inside which a distributor disc 126 is fixed. To this effect, the distributor disc 126 has some peripheral teeth 128 that fit into respective notches 129 formed on a cylindrical inner wall of the toothed sector wheel 39. The toothed sector wheel 39 is provided with external teeth 130 that extend along two toothed sectors 130a, 130b adjacent and symmetrical with respect to a diametrical axis X ' -X ' which defines the centred position which the valve assembly 18 initially assumes when it is in the operating area 10. The X ' -X ' axis is parallel to the axial axis X-X of the pump 14. Some teeth 130 closer to the diametrical axis X ' -X ' have a slot 131 on their head. The notches 131 as a whole form the notch 39' in which the tongue 38' can pass with a play if the toothed sector wheel 39 is correctly aligned with the operation gear 38. In case of an error which prevents the notch 39' to be aligned with the tongue 38' when the pumping unit arrives in the operating area 10, at least one of the teeth 130 without a notch 131 would hit the tongue 38', thus pushing the operation gear 38 in rotation and consequently moving the zero rod 35 from its centred position on the sensor 36. The movement of the zero rod 35 without the motor 32 being activated determines an error condition, which is signalled by the dispensing machine .

On the upper face 126a of the distributor disc 126 are formed a primary delivery channel 132 and a precision delivery channel 133. These two primary delivery and precision delivery channels 132, 133 extend in the shape of an arc to an extent of little less than 90° each. They preferably have an angular extent equal or approximately equal to each other. They also have a depth which is approximately equal to each other, and less than the thickness of the distributor disc 126. They have a width equal or approximately equal to each other, for example preferably of about 3 mm. At a distal end 132a of the primary delivery channel 132 a primary delivery nozzle 134 is formed. The primary delivery nozzle has a relatively large diameter, preferably but not necessarily of 3 mm (see also Figure 11) .

Immediately upstream of the primary delivery nozzle 134 a check valve 135 is mounted, which is shown in an enlarged section in Figure 11 and in an enlarged perspective view in Figure 12. The check valve 135 comprises a rigid body 136 shaped like a dome with a plurality of peripheral holes 137 and a dome-shaped membrane 138 with a central hole 139. The check valve 135 operates in a similar way to the check valve 48 described above and illustrated in Figures 14 and 15. When a fluid pressure is exerted from the rigid body 136 through the peripheral holes 137 on the dome-shaped membrane 138, the latter is pushed at a distance from the rigid body 136 and the fluid can pass through the central hole 139. In the configuration of the valve 110, this condition corresponds to the delivery of fluid from the pump 14 through the delivery duct 106a following a thrust movement of piston 44. When a fluid pressure is exerted in the opposite direction, that is, from the dome-shaped membrane 138 to the rigid body 136, the fluid pressure pushes the dome-shaped membrane 138 against the lower convex wall of the rigid body 136 in such a way that the central hole 139 is closed by the rigid body 136 thus blocking the flow of fluid. As mentioned above, this check valve is particularly effective and reliable, since there is no sliding between parts and no abrasion due to any solid particles present in the fluid. This check valve provided with a central hole 139 is further advantageous, because the presence of the hole reduces pressure drops compared to check valves of the known type.

Naturally, although the examples of check valves described and illustrated are particularly advantageous, the dispensing machine could make use of check valves of the known type. Moreover, the primary delivery nozzle 134 could also be devoid of any check valve.

At about halfway along the precision delivery channel 133, a precision delivery nozzle 140 is formed. As it can also be seen in the section of Figure 13, the precision delivery nozzle 140 preferably has a short end section 140a whose diameter at the lower face 126b of the distributor disc 126 is preferably of 1.2 mm, whereas the diameter thereof at the upper face 126a of the distributor disc 126 is equal to or approximately equal to the width of the precision delivery channel 133, preferably about 3 mm. Beside the precision delivery nozzle 140, at a distal end 133a of the precision delivery channel precision 133, a recirculation hole 142 is provided. The recirculation hole 142 preferably has a diameter greater than that of the precision dispensing nozzle 140, and preferably equal to or approximately equal to the width of the precision delivery channel 133.

Above the distributor disc 126, a pressure disc 144 is mounted which is fixed with respect to the valve assembly 18. The pressure disc 144 has a delivery hole 145 and a recirculation hole 146. The components of the valve 110, that is to say the pressure disc 144, the distributor disc 126 and the recirculation disc 118, are kept in contact with each other thanks to compression springs 148 which press on pressure disc 144. The faces of the discs making up the valve 110 have made with a high planarity precision in to avoid leakage of fluid between one disc and the other. The faces of the discs making up the valve 110 are preferably made of a very hard material, for example a ceramic material, to resist wear even after many operating cycles, during which the distributor disc 126 is made to oscillate by the toothed sector wheel 39 while sliding on the recirculation disc 118 and on the pressure disc 144, respectively.

Figures 21 - 23 illustrate the possibility of recirculation of the fluid which can be activated in an initial configuration of the valve 110 when it arrives in the operating delivery zone. In this initial recirculation configuration, a delivery pressure exerted by the pump 14 pushes the fluid through the delivery conduit 106 and through the delivery hole 145 in the pressure disc 144, in the direction of the arrow M in Figure 21. In this recirculation configuration, the fluid that flows through the delivery hole 145 flows into the primary delivery channel 132 on the distributor disc 126 in the direction of the arrow M' of Figure 22. The fluid is then directed along the primary delivery channel 132 toward its distal end 132a. The fluid therefore flows through the check valve 135 and is conveyed in the primary delivery nozzle 134. In the recirculation configuration, the primary delivery nozzle 134 opens into an end of the recirculation channel 124 on the recirculation disc 118. The fluid therefore enters into the recirculation channel 124 in the direction of the arrow M" of Figure 23. The fluid flows through the recirculation channel 124 and comes out through both the recirculation hole 142 and the precision delivery nozzle 140 on the distributor disc 126, traveling in the opposite direction with respect to the delivery, according to arrows R' and R" of Figure 23. After it has gone through the recirculation hole 142 and the precision delivery nozzle 140 on the distributor disc 126, the fluid is collected in the precision delivery channel 133 from which it emerges through the recirculation hole 146 on the pressure disc 144, in the direction of the arrow R in Figure 21. From the recirculation hole 146, the fluid is pushed toward the recirculating output 108 on the valve support 100, from which it is directed toward the reservoir 4 of fluid product. The recirculation of fluid obtained in this way is particularly effective and improved with respect to the prior art, since it allows to move all the fluid in the reservoir instead of only the portion closer to the suction duct, as generally occurs in the prior art machines. Preferably, the pumping the fluid in the recirculation configuration takes place at low speed, just to keep refreshed the colorant inside the pump 14. For example, with just a quantity of about 1 - 1.5 cc it is possible to recirculate the fluid through all the inner ducts of the pump 14 and the valve assembly 18 up to the recirculation outlet 108. One of the advantages of the described recirculation configuration is that of being able to recirculate the fluid through the precision delivery nozzle 140 in the opposite direction with respect to the precision delivery, that is, from its smaller diameter 140a at the lower face 126b to its larger diameter at the upper face 126a of the distributor disc 126, so as to always keep the precision dispensing nozzle 140 well free from possible sediments and thus ensuring maximum performance in terms of precision and repeatability. A possible sediment downstream of the precision delivery nozzle 140 that fails to pass through the smaller diameter hole 140a at the lower face 126b would be in any case readily pushed along the direction of the arrow R' in the hole 142, which has a much greater diameter than that of the precision delivery nozzle 140 and through which the most part of the fluid product flows in the recirculation condition .

The operation of the toothed sector wheel 39 by the valve actuator unit 30 allows to select different positions of the distributor disc 126, to obtain different functional configurations of the valve 110 according to the operating requirements .

Figures 24A and 24B show two steps of the selection of the distributor disc 126 to perform the primary delivery of a fluid product through the primary delivery nozzle 150.

As can be seen in Figure 24A, the toothed sector wheel 39 can be rotated anticlockwise, as seen from the above, at a primary delivery angle 150, preferably equal to or approximately equal to 80° with respect to the initial recirculation position described above and identified by the axis X ' -X ' . This rotation brings the distributor disc in a primary delivery configuration, in which the delivery nozzle 134 is aligned with the primary outlet hole 122 on the recirculation disc 118 and with the delivery hole 112 on the cover 114. In this way the thrust of the piston 44 of the pump 14 causes the delivery of the fluid product. In particular, the fluid product exits the pump 14 through the delivery duct 106, passes through the delivery hole 145 on the pressure plate 144 in the direction of the arrow M of Figure 21, passes through the check valve 135 and the primary delivery nozzle 134 on the distributor disc 126 and is dispensed to the outside through the outlet hole 122 on the recirculation disc 118 and with the delivery hole 112 on the cover 114, typically within a canister located under the valve assembly 18.

The presence of check valves 48, 135 on the inlet 16 of the suction duct of the fluid and on the primary delivery nozzle 134 respectively, allows to activate the pump 14 in a reciprocating manner for more than one cycle, so as to deliver or recirculate an amount of fluid which is a multiple of its displacement, without it being necessary to perform any operation on the valve 110. In fact, when the delivery stroke of the piston 44 arrives at its end, the piston 44 can be operated in suction to collect further fluid from the reservoir. In this condition, the check valve 48 opens, allowing a corresponding amount of fluid to pass from the reservoir to the cavity 42 of the pump 14. At the same time, the depression caused by the piston 44 in delivery conduit 106 does not provoke any suction of fluid from the valve 110 toward the pump 14, thanks to the closing of the check valve 135. On the contrary, when the piston 44 is activated for delivery and exerts a pressure on the fluid contained in the cavity 42, the check valve 48 closes and prevents the fluid to pass through the inlet 16 and return to the reservoir. On the contrary, the check valve 135 opens and allows the fluid to flow through the primary delivery nozzle 132. The fluid in the cavity 42 is therefore pushed through the delivery duct 106 through the check valve 135 and the primary delivery nozzle 134 so as to be dispensed to the outside in the case where the distributor disc 126 is in the primary delivery configuration of Figure 24A, or so as to be recirculated in the reservoir in the case where the distributor disc 126 is in the recirculation position of Figure 19.

Before passing from the recirculation configuration of the valve 110, illustrated in the figures 18 - 20, to the primary delivery configuration shown in Figure 24A, it is possible and preferable to pass through a pressure releasing configuration, shown in Figure 24B. In fact, in the recirculation configuration the circuit inside the valve 110 accumulates a certain pressure due to the pressure losses that the fluid encounters in the passage through the various components of the valve 110 starting from the delivery duct 106. When dispensing of a fluid is required, a direct passage from the recirculation configuration of figures 18 - 20 to the primary delivery configuration of Figure 24A would cause the release of the accumulated pressure through the primary delivery nozzle 134, with the consequent uncontrolled leak of a small, however indeterminate amount of fluid from the outlet hole 122 which would compromise the precision of delivery by the pumping unit 5. To prevent, or in any case minimize this effect, the toothed sector wheel 39 can be rotated by a vent angle 151 to release the pressure from the delivery duct 106 and from the circuits inside the valve 110. The vent angle 151 is about equal to 40° with respect to the axis X ' -X ' , in a clockwise direction seen from above. Following such a rotation, the distributor disc 126 is disposed in such a way that the primary delivery nozzle 134 faces an end of the recirculation channel 124 of the recirculation disc 118, while the other end of the recirculation channel 124 remains at least in communication with the recirculation hole 142 formed in the precision delivery channel 140. In turn, the precision dispensing channel 140 moves in such a way as to be in communication with the overlying delivery hole 145 in the pressure plate 144. In this configuration, a small suction movement of the pump 14 allows to release the pressure of the fluid in the circuit which, starting from the delivery duct 106, runs generally without hindrances through the delivery hole in the pressure disc 144, the precision delivery channel 133 and at least the recirculation hole 142 in the distributor disc 126, the recirculation channel 124 in the recirculation disc 118, up to the primary delivery nozzle 134, passing through the check valve 135 which is actuated in counter pressure so as to discharge the fluid pressure also in the primary delivery channel 132.

As can be seen in Figure 25A, the toothed sector wheel 39 can be rotated in a clockwise direction as seen from above by a precision delivery angle 152, which is preferably equal to or approximately equal to 80° with respect to the initial recirculation position described previously and defined by the axis X ' -X ' . The precision delivery angle 152 is substantially equal and opposite to the primary delivery angle 150 with respect to the initial recirculation position defined by the axis X'-X' . This rotation brings the distributor disc in a precision dispensing configuration, in which the precision delivery nozzle 140 is aligned with the outlet hole 122 on the recirculation disc 118 and with the delivery hole 112 on the cover 114. Similarly to what has been described above with reference to the primary delivery, the thrust of the piston 44 of the pump 14 causes the delivery of the fluid product, which in this case can be very precise through the precision delivery nozzle 140 which is smaller than the primary delivery nozzle 134. Also in this case, before passing from the recirculation configuration of the valve 110, illustrated in the figures 18-20, to the precision delivery configuration illustrated in Figure 25A, it is possible and preferable to pass through a pressure release configuration, shown in Figure 25B. To avoid the problems linked to the accumulation of pressure in the delivery circuit which have already been mentioned above, the toothed sector wheel 39 can be rotated by a vent angle 151' to release the pressure from the delivery duct 106 and from the internal circuits of the valve 110. The vent angle 151' is equal to about 40° with respect to the axis X ' -X ' , in an anticlockwise direction as seen from the above. Following such a rotation, the distributor disc 126 is disposed in such a way that the precision delivery nozzle 140 is closed at the bottom by the recirculating disc 118. In this configuration, a small suction movement of the pump 14 allows to discharge the pressure of the fluid up to the prevision delivery nozzle 140.

The precision delivery in the configuration of the valve 110 shown in Figure 25A is particularly advantageous when is accompanied by a precision pumping of the pump 14. The precision pumping of the pump 14 is obtained thanks to the provision of the cup-shaped body 66 and the two portions 80a and 80b of the bellows covering 80. During the primary pumping, the pump 14 is operated in such a way that the piston 44 moves along the cavity 42 alternatively on a path which goes from the retracted position, in which the volume inside the cavity 42 is maximum, to a forward position of primary pumping, illustrated in Figure 9, in which the thrust wall 86 of the bellows 80 arrives in abutment against the end wall 41 of the cavity 42 and in particular against its central slight projection 43. The displacement of primary delivery of the pump 14 is defined by the transverse area of the main portion 80a of the bellows 80, multiplied by the length of the primary delivery stroke of the piston 44. In the primary dispensing condition, the delivery resolution of the pump 14 is given by the minimum travel distance of the piston 44 following the minimum obtainable rotation of the motor 22, typically equal to one step or, depending on the control which is used, half step or a fourth of a step. To obtain a much higher resolution, the piston 44 is pushed beyond the position of maximum primary delivery illustrated in Figure 9, so that the cup-shaped body 66 moves backwards against the bias of the spring 70. In this way, the end portion 80b of the bellows 80 is compressed, while its main portion 80a continues to advance. In this condition, the volume of fluid moved is proportional to the difference between the cross-sectional area of the end portion 80b and that of the main portion 80a, that is, it is equal to the area of the circular crown defined by the difference of the diameters of the two portions 80a, 80b. This design of the pump 14 allows to obtain both large flow rates of fluid when the piston 44 is actuated in its primary dispensing stroke, and very high accuracy of delivery of small quantities of fluid when the piston 44 is actuated with the end section thereof in continuous contact with the end wall, wherein the thrust area of the fluid in the cavity 42 is reduced only the circular crown which is the difference in the diameters of portions 80a, 80b of the bellows 80.

Figures 26A-26D show a bottom view of the coupling between the valve actuator unit 30 and the pumping unit 5, and in particular the valve 110, in a sequence of operating steps from a recirculation position to a precision dispensing position, and the subsequent return to the recirculation position. For the sake of simplicity of illustration the intermediate step of releasing the pressure of the circuit is omitted .

In the configuration shown in Figure 26A, the pumping unit 5 is facing the valve actuator unit 30 in the operating area 10. In this position, corresponding to the recirculation position of the valve 110, the motor unit 20 is coupled with the piston 44, which is first pushed forward so as to cause the recirculation of the fluid product. The piston 44 is made to advance until it is brought to the position of precision dispensing and high resolution, illustrated in Figure 9 in which the thrust wall 86 of the bellows 80 comes to abut the end wall 41 of the cavity 42.

In this recirculation position, the zero rod 35 is positioned in correspondence of the sensor 36, which thus recognizes the initial position of the valve actuator unit 30 wherein the operation gear 38 faces the toothed sector wheel 39 without interference between the respective toothings, and with the tongue 38' inserted in the notch 29'. Subsequently, as can be seen in Figure 26B, the operation gear 38 is actuated in a clockwise rotation (seen from below) for such an angle as to cause a first contact between the respective teeth of the operation gear 38 and the toothed sector wheel 39. At this point, a further rotation in a counterclockwise direction causes the operation wheel 38 meshing with the toothed sector wheel 39, which begins to rotate. From the meshing start position of Figure 26B, the toothed sector wheel 39 can be rotated by 40° to reach the vent position to release the residual pressure as described above. In the vent condition, the pump 14 is driven slightly in suction for releasing the pressure in the circuit of the valve 110, as described above. Then, as shown in Figure 26C, the operating gear 38 is rotated in a clockwise rotation (seen from below) for such an angle as to bring the toothed sector wheel 39 in the position of precision delivery, described above in detail with reference to Figure 25A. In this configuration, the pump 14 can be operated to deliver the desired quantity of fluid product. Preferably, at the end of the dispensing, before returning to the recirculation position, the pump 14 is operated again slightly in suction in order to draw the drop inside the delivery nozzle so as to leave the assembly in a clean position. The operating gear 38 is rotated clockwise to bring the toothed sector wheel 39 in the recirculation position. In the return operation, the operating gear wheel 38 is rotated by a certain angle beyond the zero position, as shown in Figure 26D, up to the point where the teeth of the two wheels enter again in contact with each other, but on the opposite side with respect to the delivery rotation just concluded. This allows to correctly align the teeth of the toothed sector wheel 39, correcting slight displacements thereof with respect to the precise initial recirculation position. The operation gear 38 is finally brought back to the initial position shown in Figure 26A, by actuation of the valve actuator 30 which moves the zero rod 35 to the position detected by the sensor 36, which corresponds to the recirculation position of the toothed sector wheel 39. In this condition the tongue 38' is inserted with play in the notch 39' on the front teeth of the toothed sector wheel 39, in such a way that the pumping unit can be released from the working area 10 following a rotation of the rotating table 3, to leave room for another pumping unit.

By symmetrically inverting the rotations of Figures 26A- 26D is is possible to obtain the sequence of operating steps for the primary delivery. The primary delivery of fluid can be made with a high flow rate by virtue of the relatively large displacement of the pump 14 and to the dimensions of the delivery channels, including the size of the primary delivery nozzle 134 which is relatively big having, as mentioned above, a diameter preferably equal to or approximately equal to 3 mm. At the end of the delivery operations, during a certain number of cycles of the pump 14, the valve 110 is brought again in the recirculation configuration by actuating the valve actuator 30 which brings back the zero rod 35 to the position detected by the sensor 36, shown in Figure 22A.

The dispensing machine described above is particularly advantageous because it allows a precision dispensing with a very high resolution. The high resolution can be obtained thanks to the possibility of operate the pump in the precision condition, in which the volume of the pumped fluid is substantially proportional to the area of the circular crown between the larger section and the smaller section of the piston and the bellows on the outside thereof. This is facilitated also by the possibility of delivering through the precision delivery nozzle which has a very small diameter.

In the dispensing machine described above the delivery nozzles remain always clean and recirculation of the fluid product in the reservoir takes place up to the last droplet. The suction operation of the pump before and after the delivery maintains the valve and the delivery nozzles clean.

The dispensing machine described above advantageously does not need a periodic calibration. This is due to the fact that the delivery circuits for the colorants are not long, the pumping unit is substantially not subject to wear and moreover the delivery occurs substantially at ambient pressure .

The dispensing machine described above allows a high operation flexibility, being it capable to supply a same fluid product both in large quantities with high flow rate to reduce the dispensing times, and in very small amounts with high precision and resolution. These particularities of the dispensing machine allow to provide a compact machine, with limited overall dimensions, and yet capable of delivering both into relatively big canisters, for example having a volume of 15 litres, and in very small canisters, used for samples, for example of 100 cc. An advantage of the present dispensing machine with respect to rotating machines of the known type is the possibility of completely recirculating the fluid product in the reservoirs. In the rotating dispensing machines of the known type the recirculation of the colorant takes place only in a zone close to the intake pipe from the reservoir to the pump. In the present dispensing machine the fluid product in each reservoir is recirculated through a dedicated recirculating duct, preferably connected to the reservoir far from the suction duct. In this manner it is favoured the complete recirculation of the fluid product, which favours the elimination of air from the fluid product.

Naturally, without prejudice to the principle of the invention, the embodiments and details of construction can be widely varied with respect to what has been described and illustrated, without thereby departing from the scope of the present invention.

Claims

1. A dispensing machine for fluid products comprising a support structure with a rotary table which carries a plurality of pumping units coupled to respective fluid product reservoirs, each pumping unit comprising a pump and a delivery valve connected to each other, the dispensing machine further comprising a dispensing operating area with a valve actuator and a pump actuator, adapted to couple respectively with the valve and the pump of a pumping unit positioned at the dispensing operating area following a rotation of the rotary table, the dispensing machine for fluid products further comprising a further plurality of reservoirs of fluid products coupled to pumping units provided with delivery ducts leading to a fixed nozzle assembly arranged at the dispensing operating area.

2. A dispensing machine according to claim 1, wherein the further plurality of reservoirs for fluid products and pumping units, and the nozzle assembly, are mounted on an extractable carriage normally arranged below the rotary table .

3. A dispensing machine according to claim 1, wherein the rotary table comprises a toothing on its outer edge which engages with a pinion of a motor which selectively actuates the rotation of the rotary table.

4. A dispensing assembly for a rotary table-type fluid dispensing machine, comprising a pumping unit with a reciprocating, volumetric pump and a valve assembly coupled to the volumetric pump, a pump actuator and a valve actuator being provided for coupling respectively the volumetric pump and the valve assembly from opposite sides of the pumping unit along a substantially radial direction of the rotary table in a dispensing operating area of the dispensing machine for fluid products.

5. A dispensing assembly according to claim 4, wherein the pump actuator comprises a pushing member movable axially in the radial direction of the rotary table for selectively coupling with one end of the pump.

6. A dispensing assembly according to claim 5, wherein the pump actuator comprises a magnetic coupling member which selectively engages with a metallic end of a pump piston.

7. A dispensing assembly according to claim 5 or 6, wherein the pump actuator comprises a position sensor for detecting the engagement position of the pump actuator with the end of the pump .

8. A dispensing assembly according to any one of claims 4 to 7, in which the valve actuator comprises an operation gear operated in rotation to engage with a gear of the valve assembly to select the operating modes of the dispensing machine .

9. A dispensing assembly according to claim 8, wherein the toothing of the operation gear is interrupted along a sector corresponding to a zero position in which the pumping units on the rotating table are free to pass in front of the valve actuator without interfering with the operation gear.

10. A pump for a dispensing assembly of a dispensing machine for fluid products, comprising a cylindrical pumping chamber inside which slidingly reciprocates a piston for sucking fluid from a suction duct and feeding fluid into a delivery duct, wherein the piston includes a larger diameter section and a smaller diameter section movable in synchronism with respect to each other to feed a certain flow of fluid proportional to the larger diameter section of the piston, and movable in opposition to supply a fluid flow proportional to the difference between the two sections of the piston.

11. A pump according to claim 10, wherein the larger diameter section and the smaller diameter section are connected to each other through an elastic element which biases the smaller diameter section at one end of the larger diameter section to extend the smaller diameter section until it abuts against an end wall of the pumping chamber.

12. A pump according to any one of claims 10 to 11, in which the piston is covered by a bellows also having a larger diameter portion and a smaller diameter portion.

13. A valve for a dispensing assembly of a dispensing machine for fluid products, comprising a delivery duct, a recirculation duct and a delivery opening, a selector disc being operable from a position in which the delivery duct is in communication with the recirculation duct, to a position in which the delivery duct is in communication with a delivery nozzle of the valve leading to the delivery opening.

14. A valve according to claim 13, wherein the valve comprises a primary delivery nozzle and a precision delivery nozzle having dimensions smaller than the primary delivery nozzle, the selector disc being operable to bring either nozzle in correspondence with the delivery opening and bring the delivery duct in communication with said delivery nozzle, respectively .

15. A valve according to claim 13 or 14, in which the selector disc can be moved to a position in which the at least one nozzle is in upstream communication with the delivery duct while downstream it is either closed or in communication with the recirculation duct, so as to be able to discharge the fluid pressure in the circuit by suctioning through the delivery duct.

16. A valve according to any one of claims 13 to 15, in which the selector disc can be rotated by means of a gear integral therewith.

17. A check valve for use in a pumping unit of a dispensing machine for fluid products, comprising a rigid dome-like structure with a top wall surrounded by a plurality of holes arranged in a circle, the check valve also comprising a corresponding dome-like membrane with a fluid passage on the top of the dome, the passage corresponding to the top wall of the rigid structure so as to be closed when the dome-like membrane rests against the rigid dome-like structure, and be open when the dome-like membrane is spaced from the rigid dome-like structure so as to allow a flow of fluid through the passage in the dome-like membrane and the holes on the rigid structure, the passage for fluid on the top of the dome being preferably a through hole.

18. A dispensing machine for fluid products comprising a support structure with a rotary table which carries a plurality of pumping units coupled to respective fluid product reservoirs, further comprising at least a dispensing assembly according to any one of claims 4 to 9, and/or at least a pump according to any one of claims 10 to 12, and/or at least a valve according to any one of claims 13 to 16, and/or at least a check valve according to claim 17.