MC200005A1 - Injection pump for dye dispensing machine - Google Patents

Description

Description of the designated industrial invention:

Injection pump for dye dispensing machine

The designated industrial invention relates to the field of dye dispensing machines, in particular those comprising an injection pump system.

Such machines are used to dispense a predetermined quantity of colorants, which are mixed, according to predefined formulas, with white or neutral base products to obtain finished paints of various colors. Generally, the quantities of colorants used represent only a small percentage of the weight or volume of the final paint. Thus, the slightest variation in the amount of colorant administered can produce final shades that are completely different from one another.

The primary requirement in the dye dispensing machine sector is to provide highly precise and repeatable dosages to ensure consistent results. Modern injection-type dispensing machines consist, at a minimum, of a reservoir for each dye, a pump with a movable piston located in a cylinder, and a valve that alternately connects the inside of the cylinder to the reservoir or to a dispensing line. When the piston rises, the dye is drawn into the cylinder through the valve. The valve is then switched to connect the cylinder to the dispensing line. Lowering the piston then forces the dye out of the cylinder and into the dispensing line.

distribution. The amount of dye distributed thus depends on the movement of the piston and the diameter of the cylinder.

In dye dispensing, the requirements for precision and stability depend on numerous factors, including the piston-cylinder assembly and the precise positioning of the piston during its suction and dispensing motion. The piston-cylinder assembly generally requires rigorous control of the dimensional and geometric data of both components, as well as the selection of sliding and sealing gaskets to prevent any dye leakage along the cylinder walls.

The precise definition of the piston's trajectory, and thus the quantity of dye drawn in and dispensed in a single pass, is addressed differently in this type of machine, through mechanical systems that include, for example, an end-of-stroke stop and can be fixed in a predetermined position to prevent the piston from rising beyond a certain point. An example of such a solution is illustrated in US patent 5511695, which highlights a dual-control adjustment method. In this method, a first, more superficial adjustment can be made via a pivot inserted into a series of equidistant notches, while a second, more precise adjustment is achieved using a threaded element that can be held at predefined angles.

The major drawback of current injection-type dispensing machines of the type mentioned above is that, to guarantee high accuracy and consistent repetition of dispensed doses, regular and rather expensive maintenance of the system is required.

A proper seal between the piston and cylinder is essential. In particular, most machines of this type require periodic replacement, for example every six months, of the piston-cylinder assembly seals. Furthermore, the need for precise dimensional and geometric tolerances of the cylinder and piston results in high manufacturing costs.

On the other hand, if one wants to obtain high precision and continuity in the distribution of the product, it is then practically impossible or, at the very least, strongly discouraged to manufacture the injection pump with plastic materials, which are, it is true, relatively inexpensive, easy and quick to handle, but which cannot guarantee the indispensable precision, which can be obtained, for example, with steel.

Furthermore, the adjustment systems of current machines of this type are sometimes insufficient to guarantee the precise dosing of the amount of colorant needed to obtain the desired paint color. In any case, the steps in the piston's movement between the two successive adjustment notches are small and subtle. It is generally impossible to accurately ensure that the piston stroke reaches an intermediate position between two successive notches. Moreover, the adjustment steps of the piston's movement are usually indicated in the unit of measurement referring to the quantity of colorant dispensed. Consequently, it is difficult to change the unit of measurement to adapt the machine to the requirements of different markets, as this would require modifying the machine's very structure.

For example, in the aforementioned US patent 5511695, the position of the notches,

The adjustment pivot and the pitch of the adjustment notches, which are inserted into them, are closely linked to the adjustment of the distribution of the product itself, which is partially carried out in fluid ounces.

If we want to convert the settings into another unit of measurement, for example into cubic centimeters, it would then be necessary to modify not only the screen printing on the body of the machine but also the distance between the notches and the pitch of the adjustment notches.

From a practical point of view, given the costly nature of the modifications mentioned above, it is virtually impossible to "localize" a dye dispensing machine that would adapt to the requirements of the markets and various consumers.

The invention aims to solve the various problems posed by current dispensing machines. In particular, it seeks to provide an injection-type dispensing machine that guarantees precise and consistent results without requiring constant and costly handling. A second objective of the invention is to present a simple and economical dispensing machine that can be mass-produced, even using plastic, without the need for detailed control of dimensional and geometric tolerances. Furthermore, the invention aims to guarantee the dispensing of colorants in the required quantity and in the chosen unit of measurement.

In order to achieve the objectives described above, the various properties of the invention, relating to a dye dispensing machine of the injection type, are presented in the following claims.

However, additional features and advantages relating to the said invention will be raised by the subsequent description of a more suitable manufacturing version, with reference to the drawings in the appendix, given purely by way of non-exhaustive example, and in which:

- Figure 1 shows a side view of an injection pump of a dye dispensing machine based on said invention

- Figure 2 is a longitudinal section of the injection pump of Figure 1.

Referring to the diagrams, a pump (10) comprises a base support (11) in which is disposed an access conduit (12) for the dye, which is generally connected to a dye reservoir (not shown), and a distribution conduit (13). A valve (14), actuated by a lever (21) or similar component, alternately connects either the access conduit (12) or the distribution conduit (13) with the internal chamber (15) of a flexible-walled pumping element, which, in the embodiment shown and illustrated, is a bellows (16). The bellows (16) is contained within a tubular control body (17) whose lower end (18) is fixed to the base support (11).

The internal chamber (15) of the bellows (16) is preferably completely closed except for an opening (22) in the bottom (23) for a contact port (24) with the valve (14). The bottom (23) of the bellows (16) is fixed to the body of the support (11), while the upper end (25) is fixed to a movable, airtight plate (26) located inside the tubular body (17). Because the internal chamber (15) of the bellows is closed at its upper end, it is unnecessary for the plate (26) to be airtight to the walls of the

tubular control body (17), which never comes into contact with the coloring product and can therefore be made with freely selected material, including plastic.

In the recommended embodiment of the invention, the bellows (16) has a plurality of relatively rigid walls (27) articulated by hinges (22). If the bellows is made of plastic, for example Teflon or a similar material, the hinges (28) can be plastic hinges made from the rigid walls (27) of the bellows.

On the tubular control body (17), two vertical notches (19) are made, from which appendages (20) protrude from the plate (26). These are connected in a U-shape to a slider (30), which is fixed to the outside of the tubular body and slides on a straight rail (40). It can be selectively locked in various positions by means of a braking device preferably controlled by two pushbuttons (41).

A position sensor, linear encoder, or similar device is fixed to the slider (30) so as to raise the position of the slider itself, and thus of the plate (26), relative to the rail (40). The sensor may contain one or more transducers of a generally known design, which are resistive in nature and have a large capacitance, linear differential inductors, photoelectric transducers, encoders, or similar devices.

Naturally, the configuration illustrated in the diagram is given only as an example; the sensor can be fixed in other positions, for example between the tubular body (17), depending on the physical properties of the sensor itself, the financial advantages, and the relative cost-effectiveness of manufacturing the pump (10). The position signal recorded by the sensor is sent to an electrical circuit including a viewer (31), for example, of the seven-segment type illustrated in the figure. Despite the bellows (16), which already provides a substantially linear relationship between the axial displacement of the slider (30) and the volume of the chamber (15), the electronic circuit allows for the correction of any non-linear behavior of the bellows, particularly related to the state of extension and compression.

The electronic circuit allows, in particular, the conversion, via internal conversion tables, of the linear displacement index of the slider (30) or the plate (26). This index is read from the sensor and converted into the volume index of dye contained in the compartment (15), or into a corresponding value indicated in the chosen units of measurement. Furthermore, using current techniques for reading and measuring the displacement of the plate (26), and the sensor attached to the slider (30), it is possible to obtain a precise indication—unless the sensor has a higher physical resolution—of the derived quantity of dye contained in the compartment (15), thus achieving a higher degree of accuracy in obtaining the final paint color. The consistency of the results is ensured by the fact that the moving parts of the pump (10) are not in contact with the dye, which remains confined within the channels of the base support and inside the bellows (16).

In any case, despite the absence of the electronic system, it is possible to obtain high dosing accuracy by adapting one of the current measurement systems relating to the 170 quantities to be distributed, which are based, for example, on graduated gauges or a similar system, thanks to the fact that the pump does not have sliding joints.

Thus, following the above description, it can easily be seen that the injection pump of the said invention is not subject to wear and tear and, consequently, offers the necessary precision and consistency in the quantity of dye dispensed, without requiring costly pump maintenance. Its simple construction and ease of use make this pump a particularly suitable model, although not exclusively so, for use on small, manually operated dye dispensing devices.

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All forms of updating and implementation characteristics may vary widely from what has been described and illustrated above, without departing from the scope and principle of said invention.

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Claims (10)

Demands 1. Injection pump for dye dispensing machine, comprising an internal pumping chamber (15) and selectively actuable valves (14) to alternately connect the pumping compartment (15) with an access conduit (12) and a distribution conduit (13) of a dye, characterized in that it comprises a pumping part with walls (27,28) at least partially flexible which define the pumping compartment of moving parts (26,30) selectively causing the extension and folding of the walls in order to bring the internal pumping chamber (15) from a minimum volume to a desired maximum volume, and vice versa. 2. Injection pump according to the description in point 1, characterized in that the pumping part is a bellows (16). 200 3. Injection pump according to the description in point 2, characterized in that the bellows (16) has a plurality of relatively rigid walls (27) articulated to each other by hinges (28). 205 4. Injection pump as described in point 3, characterized by the fact that the bellows (16) is located during extension and compression inside a tubular body (17). 11 5. Injection pump according to the description in point 4, characterized in that the tubular body is fixed to a base support (11) in which are located the valves (14) and the access (12) and distribution (13) conduits of the dye. 6. Injection pump according to the description in point 2, characterized in that the actuation parts (26,30) include a movable plate (26) fixed to the first end (25) of the bellows. 7. Injection pump according to the descriptions of points 4 and 5, characterized in that a second end (23) of the bellows, on which is located an opening (22) intended for the passage of the dye, is fixed symmetrically to the end of the tubular body (17) which is in turn fixed to the base support (11). 8. Injection pump for a dye dispensing apparatus, comprising a basic structure (11), a tubular body (17) within which is defined a pumping chamber (15) and selectively actuable valves (14) for connecting the pumping chamber (15) to the access conduit (12) and the distribution conduit (13) for a dye, respectively. The internal passage chamber is characterized in that it comprises actuable parts (26, 30) which selectively cause an increase or decrease in the volume of the pumping chamber to reach a minimum volume and vice versa, by means of sensors detecting the displacement of the operating means (26, 30) and transmitting a position signal to an electronic circuit which has display means (31). 9. Injection pump according to point 7, characterized in that the electronic circuit has the capacity to process the signal from sensors in order to translate the measurement referring to the linear position of the operating means (26, 30) into a corresponding value. Such values are indicated by the display means (31). 10. Dye dispensing apparatus, comprising at least one injection pump (10) according to one of the above-stated claims.