Dosing machines for dosing fluid products

Abstract

A dosing machine for dosing fluid products, comprising: a plurality of containers, which have corresponding vertical longitudinal axes and are arranged to contain corresponding fluid products; a plurality of rotating stirring elements, which are located in the corresponding containers and can be operated to rotate by means of corresponding electric motors; and a dispensing head, which has a plurality of nozzles connected to the corresponding containers, each container is associated with a corresponding height measuring device, the height measuring device comprising: a float, which accommodates a permanent magnet and moves freely in the container; a magnetic detector, which is arranged outside the container and includes a plurality of magnetic sensors spaced apart from each other in the vertical direction, and each magnetic sensor is arranged to detect changes in the magnetic field caused by the passage of the float near it; and a control unit, which analyzes the signals provided by the magnetic sensors to detect the fluid height in the container and the periodic passage of the float near one or more magnetic sensors.

Description

Technical Field

[0001] The invention relates to a dosing machine for dispensing metered quantities of a fluid product.

[0002] The invention is particularly aimed at developing its application to dosing machines for dispensing dyes for preparing paints. In the following description reference will be made to this specific field of application without loss of generality. Background Art

[0003] The dosing machine for distributing the dyestuff for preparing coating usually comprises a plurality of containers with vertical axis to accommodate the corresponding dyestuff. The dosing machine comprises a distributing head with a plurality of nozzles connected with the corresponding containers. A plurality of distributing pumps supply the dosing quantity of dyestuff from the container to the corresponding nozzle of the delivery head.

[0004] The container is usually provided with corresponding stirring means which keep the dye contained inside the container in motion according to a predetermined period in order to avoid the formation of stratification, sedimentation, scaling and the like.

[0005] In these dosing machines it is important that the level of the dye contained in the various containers is always above a pre-set minimum level in order to prevent the dispensing pump from sucking in air.

[0006] The height of the dye inside the container is usually determined by the control unit of the dosing machine by means of a calculation which subtracts the gradually dispensed volume from the initial volume set by the operator. The operator must set the volume of dye contained in each container on the machine control panel after each refilling operation. During operation, the machine control unit gradually subtracts the dispensed volume from the initial volume of each container and provides an estimate of the height of the fluid present in each container.

[0007] This system allows to achieve acceptable accuracy, provided that the operator accurately indicates the height reached after each reloading operation.

[0008] Systems that determine the height of the dye based on calculating the volume dispensed are susceptible to human error, which may result in a deviation between the calculated height and the actual height.

[0009] For example, an error by the operator in estimating the volume of dye contained in the container at the end of reloading, or an error in the value entered into the machine control panel, may result in the complete emptying of the container, with the risk of causing the associated dispensing pump to draw in air.

[0010] In some cases, an operator may intentionally set an incorrect value for the effective level into the machine control system to force dosage even when the dye level is below a level at which the machine control system prohibits further dispensing.

[0011] For these reasons, a system for detecting the level of dye in a container of a dosing machine that does not require human intervention is desired.

[0012] On the other hand, most known systems for measuring the level of liquids in containers cannot be used in dosing machines because they would interfere with the rotating stirring device that keeps the dye in motion inside the container and because the physicochemical properties of the dye limit the type of detection system that can be used. Summary of the invention

[0013] The object of the present invention is to provide a metering machine to overcome the problems of the prior art.

[0014] This object is achieved according to the invention by a dosing machine having the features that form the subject of embodiments of the present application.

[0015] The examples of the present application form part of the entirety of the disclosure provided herein with respect to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention will now be described in detail with reference to the accompanying drawings, given purely by way of non-limiting examples, in which:

[0017] Figure 1 is a perspective view of a metering machine with some parts removed;

[0018] Figure 2 Is Figure 1 A perspective exploded view of a container for a fluid product indicated by arrow II in FIG.

[0019] Figure 3 yes Figure 2 An axial cross-sectional view of a container;

[0020] Figure 4 and 5 yes Figure 3 Cross-sectional views of the container at different positions.

[0021] It should be understood that the various figures may not be reproduced to the same scale and that some components may be removed in order to simplify the understanding of the figures. DETAILED DESCRIPTION

[0022] refer to Figure 1 , numeral 10 indicates a metering machine for dispensing metered quantities of a fluid product, such as, for example, a dye for preparing a paint.

[0023] The machine 10 comprises a frame 12 supporting a plurality of containers 14 which, during use, are filled with respective dyes.

[0024] The machine 10 comprises a delivery head 16 having a plurality of nozzles connected to respective containers 14 by means of a dosing circuit comprising a plurality of conduits and a plurality of dispensing pumps which draw the quantities of dye to be dosed from the containers 14 and send them to the respective nozzles of the delivery head 16. Figure 1 In the embodiment of the present invention, the metering circuit is not shown for the sake of simplicity of representation. The metering circuit itself is known and is outside the scope of the present invention.

[0025] The dye supplied by the metering circuit is dispensed from the delivery head 16 into a container (not shown) resting on a base 17 where it is mixed with a diluent (water or solvent) to prepare a coating.

[0026] Reference Figure 2 and 3 , each container 14 has an elongated shape along a longitudinal axis A. The containers 14 are arranged in the frame 12 of the machine 10 such that the respective longitudinal axis A is oriented vertically.

[0027] Each container 14 has a side wall 20 , for example cylindrical, a bottom wall 22 and an upper opening 24 , through which the container 14 can be filled with a fluid product, such as, for example, a dye.

[0028] The bottom wall 22 of the container 14 has at least one opening associated with a valve 30. In the case of a dosing circuit where the suction and recirculation share the same line, only one opening may be provided. Conversely, two openings may be provided when the suction and recirculation are on different lines. In addition, in each container 14, a second shut-off valve 32 may be provided to cut off the dye in the case of a container replacement during maintenance operations.

[0029] Reference Figure 3-5 Each container 14 includes a corresponding stirring element 34 rotatable around a corresponding longitudinal axis A, which keeps the dye moving inside the container 14 according to a predetermined period to avoid sedimentation, stratification or deposition of the dye. The stirring element 34 includes a central tubular member 36 elongated in the longitudinal direction A and a plurality of blades 38 protruding radially from the central tubular member 36. The stirring element 34 is driven to rotate around the axis A by an electric motor 42, which can be associated with a gear box located below the bottom wall 22 of the container 14.

[0030] refer to Figure 2-5 Each container 14 is associated with a height measuring device 44 , which is arranged to measure the height of the fluid inside the corresponding container 14 .

[0031] Each height measuring device 44 comprises a float 46 which is arranged inside the container 14 and which houses a permanent magnet 48. The permanent magnet 48 may be, for example, an iron-boron-neodymium magnet (or the like) having a significant magnetic field strength.

[0032] The float 46 is completely unrestrained by the stirring element 34 and any other structures present inside the container 14, and is therefore free to move inside the container 14. During operation, the float 46 is urged by the rotatable stirring element 34 to rotate about the longitudinal axis A of the container 14. Figure 4 and 5 As can be seen in FIG. 1 , rotation of the blade 38 in direction B or rotational movement of the fluid within the container 14 causes the float 46 to move about the longitudinal axis A.

[0033] The float 46 has a specific weight so that it is always close to the free surface of the dye. The float 46 can have any shape, such as a spherical or cylindrical shape. In a direction perpendicular to the longitudinal axis A of the container 14, the float 46 occupies most of the distance between the central tubular member 36 of the stirring element 34 and the side wall 20 of the container 14 to prevent the float 46 from getting stuck between the inner edge of the blade and the outer surface of the central tubular member 36.

[0034] Each height measuring device 44 includes a magnetic detector 50 arranged outside the container 14. The magnetic detector 50 can be fixed, for example, on the outer surface of the side wall 20 of the container 14. The magnetic detector 50 can be glued, screwed or co-molded on the outer surface of the side wall 20 of the container 14. The magnetic detector 50 can extend along a generating line of the outer surface of the container 14. Depending on the specific situation, the magnetic detector 50 can extend over the entire effective length of the container 14, or only at the lower part of the container 14.

[0035] The magnetic detector 50 includes a plurality of magnetic sensors 52 spaced apart from each other in a direction parallel to the longitudinal axis A of the container 14. The magnetic detector 50 may include a strip printed circuit 54 on which the magnetic sensors 52 are arranged. The magnetic sensors 52 may be spaced apart at regular intervals (e.g., approximately 1-3 cm) in a direction parallel to the longitudinal axis A of the container 14.

[0036] Each magnetic sensor 52 is arranged to detect changes in the magnetic field caused by the passage in the vicinity of a permanent magnet 48 housed in the float 46. The magnetic sensor 52 may be, for example, a Hall Effect sensor.

[0037] Each height measuring device 44 comprises a control unit 56 which analyses the signal provided by the magnetic sensor 52. The control unit 56 can be arranged at the lower part of the printed circuit 54. All control units 56 of the various height measuring devices 44 are connected to a central control unit of the metering machine, for example via a controller area network (CAN) bus or a similar data transmission system.

[0038] The control unit 56 can detect the level of the fluid in the container based on the sensor 52 detecting the change in the magnetic field caused by the passage of the permanent magnet 48 housed in the float 46 in its vicinity.

[0039] An advantageous consequence is that, during operation, the float 46 moves about the axis A and, using the same height measuring device 44 , it is also possible to effectively diagnose a possible failure of the stirring element 34 .

[0040] In fact, the control unit 56 is able to detect the periodic passage of the float 46 near the one or more magnetic sensors 52. In the event that the stirring element 34 is blocked due to a mechanical or electrical fault, the float 46 does not periodically pass near the magnetic sensors 52. In this case, the control unit 56 does not detect the periodic variation of the magnetic field on the one or more magnetic sensors 52, which allows the diagnosis of the failure of the stirring element 34.

[0041] This diagnostic capability is highly appreciated by users, as this type of failure often goes unnoticed but is a potential source of problems as it can cause the dye to gradually dry out.

[0042] In fact, each container 14 is provided with its own control unit 56 which makes it possible to selectively activate the stirring elements 34 of the various containers 14. The possibility of selectively activating the stirring elements 34 of the various containers 14 can be useful in the case of dyes which, due to their chemical and rheological properties, cannot withstand frequent stirring cycles, or which, on the contrary, require more frequent cycles than other dyes.

[0043] Of course, without affecting the principle of the invention, the details of structure and of the embodiments may vary widely with respect to what is described and illustrated, without thereby departing from the scope of the invention as defined by the appended claims.

Claims

1. A dosing machine for dosing fluid products, include: - a plurality of containers (14) having respective vertical longitudinal axes (A) and configured to contain respective fluid products; - a plurality of rotating stirring elements (34) located inside respective containers (14) and operatively rotated by respective electric motors (42); as well as a dispensing head (16) having a plurality of nozzles connected to corresponding containers (14), Characterized in that each of the containers (14) is associated with a respective height measuring device (44), the height measuring device comprising: a float (46) containing a permanent magnet (48) and arranged inside the respective container (14), wherein the float (46) is free to move inside the container (14) and is moved during operation by the respective stirring element (34) about the vertical longitudinal axis (A) of the container (14); a magnetic detector (50) arranged outside the container (14) and comprising a plurality of magnetic sensors (52) spaced apart from each other in the vertical direction and each configured to detect a change in the magnetic field caused by the passage of the float on its proximal side (46); and - a control unit (56) which analyses the signals provided by the plurality of magnetic sensors (52) to detect the level of the fluid inside the container (14) and the periodic passage of the float (46) in the vicinity of one or more of the magnetic sensors (52).

2. The metering machine according to claim 1, It is characterized in that The magnetic detector (50) comprises a strip printed circuit (54) on which the magnetic sensor (52) is arranged.

3. The metering machine according to claim 1, It is characterized in that The magnetic detector (50) is fixed to the outer surface of the side wall (20) of the corresponding container (14).

4. The metering machine according to claim 1, It is characterized in that The magnetic detector (50) extends along a generation line of a side wall (20) of a corresponding container (14).

5. The metering machine according to claim 1, It is characterized in that The magnetic detector (50) extends over the entire active length of the respective container (14) or only over a portion of the active length.

6. The metering machine according to claim 1, It is characterized in that The float (46) occupies a majority of the distance between the central tubular member (36) of the stirring element (34) and the side wall (20) of the container (14) in a direction perpendicular to the longitudinal axis (A) of the container (14).

7. The metering machine according to claim 1, It is characterized in that A control unit (56) associated with a respective container (14) is configured to selectively actuate a respective stirring element (34).

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