Blower unit for pneumatic mixers and apparatus for the pneumatic mixing of granules, powders and/or liquids comprising said blower unit

A blower unit for pneumatic mixers, comprising: a hollow element internally defining a duct, extending between an input section and an output section, for the passage of an air flow between said sections, wherein said input section can be connected to a source of pressurised air and said output section can be connected to a manifold of a pneumatic mixer; a shutter suitable to shut off said airflow through said output section in a controlled manner; an actuator connected to the shutter and configured to regulate the position of the shutter; the hollow element has a first end portion, at said output section, that can be reversibly coupled to a corresponding end portion of the manifold and wherein the blower unit further comprises first reversible connecting means to establish a reciprocal connection between the end portions.

This application is the National Phase of International Application PCT/IB2018/054361 filed Jun. 14, 2018 which designated the U.S.

This application claims priority to Italian Patent Application No. 102017000071761 filed Jun. 27, 2017, which application is incorporated by reference herein.

The present invention relates to the field of industrial mixers for liquids and/or granular materials, in particular powders.

In particular, the present invention relates to a blower unit for the pneumatic mixing of liquids and/or granular materials, in particular powders, and an apparatus for the pneumatic mixing of granules and/or liquids comprising said blower unit.

Pneumatic apparatuses are known for the mixing of liquids and/or granular materials in which a hopper has the function of receiving the substances to be mixed; these are normally introduced through an opening in the upper part thereof. The outer surface of the hopper is connected to a plurality of blower units fed by one or more pressurized air ducts. The blower units comprise a shutter and an actuator to operate it and are angularly staggered on the outer surface of the hopper so as to provide a sufficiently spread blowing and stirring action throughout the mass of material contained in the hopper.

The mixing action is caused by impulsive airflows inside the hopper generated by the synergistic action of the pressurised air source and the blower units. “Impulsive airflows” is intended to mean airflows of particularly short duration and particularly high pressure, such as to cause stirring and mixing of the contents of the hopper.

It is known that in pneumatic mixing apparatuses the effectiveness and efficiency of the mixing action depends on the characteristics of the impulsive airflows and on the properties of the substances contained in the hopper, which define the physical response thereof to the aforesaid impulsive airflows. Properties of the substances contained in the hopper which define the physical response thereof to the impulsive airflows include: the weight of the various substances, the particle size of the granular matter, the presence of liquid substances and the viscosity of any liquid substances.

The characteristics of the impulsive airflows are determined by the properties of the mixing apparatus and the related pneumatic mixing process. The aforesaid properties therefore have a direct impact on the effectiveness and efficiency of the pneumatic mixing process and include, for example:the duration of the impulsive airflows and of the intervals therebetween;the pressure upstream of the shutter;the number of blower units;the direction along which the blower units blow inside the hopper;the shape of the shutter inside the blower unit and of any stop surface shaped complementarily thereto;the position and motion of the shutter, controlled by the actuator.

Disadvantageously, the integration between the hopper, blower units, and internal components of the blower units, actuators and delivery duct proposed by the prior art makes it impossible to quickly replace one or more of these components in order to obtain desired flow characteristics or for any repairs.

Currently, the adaptation of the mixing apparatus to operating conditions different from the design conditions and the repair of any damaged parts involve the replacement of entire parts of the hopper, in particular of the lower shell with all the blower units connected thereto and the actuators operating them.

Moreover, disadvantageously, the removal and replacement of the entire blower or of some parts thereof is complex, laborious and often only feasible by personnel with specific skills. Even the regulation of the blower's operating components cannot be implemented simply in terms of time and costs.

The foregoing compromises the ability to easily adapt the apparatus to the mixing of different substances depending on the case and to repair it if necessary; this drawback greatly restricts the conditions and effectiveness of use of a pneumatic mixing apparatus.

In this context, the technical task underlying the present invention is to provide a blower unit for pneumatic mixers, as well as an apparatus for the pneumatic mixing of granules, powders and/or liquids comprising such a blower, which overcome the above-mentioned drawbacks of the prior art.

In particular, it is an object of the present invention to provide a blower unit for pneumatic mixers, which is capable of improving the versatility of the pneumatic mixing apparatus. This improvement relates to one or more of the following characteristics: the machine downtime during an intervention to replace one or more internal components, the possibility to replace certain internal components with equivalents having different characteristics, the level of technical specialisation required of the personnel in charge of the adaptation intervention, the possibility of the user of the apparatus to carry out the adaptation intervention with internal or own resources, without contacting specialized external personnel.

The specified technical task and object are substantially achieved by means of a blower unit for pneumatic mixers and an apparatus for the pneumatic mixing of granules, powders and/or liquids including such a blower unit, comprising the technical features set out in one or more of the accompanying claims.

With reference toFIGS. 1, 2 and 3, the blower unit object of the invention is generally indicated by1, and its main components are: a hollow element2, a shutter3and an actuator4connected to the shutter3to regulate the position thereof, i.e. to regulate the maximum travel thereof understood as a shift from a closed condition of the shutter to a maximum opening position, which can be predefined, as will be better specified below.

The hollow element2, preferably having a monolithic structure, is a body internally defining a manoeuvring volume for housing the shutter3and for the passage of the mixing air. In particular, the hollow element2internally defines a duct5, shown inFIGS. 1 and 2, configured for the passage of a flow of air or other inert gases between an input section6and an output section7.

The hollow element2internally defines a chamber8, in which the shutter3is slidably arranged so as to translate along an axis of translation “A” thereof, and a lateral delivery duct9extending between the input section6and the chamber8in a direction preferably incident to the axis of translation “A” of the shutter3.

The chamber8extends between a rear region10of the hollow element2, to which the actuator4is applied, and the aforesaid output section7. In some embodiments, the chamber8has a rotationally symmetric, preferably cylindrical shape. In the illustrated example, the symmetry axis of the chamber8coincides with the translation axis “A” of the shutter.

The hollow element2can be connected to a source of pressurised air at the input section6. In the illustrated embodiment, the lateral duct9, preferably of circular cross-section, has the function of establishing a flow connection between the pressurised air source and the chamber8.

Preferably, the connection between the hollow element2and the pressurised air source is carried out by means of removable connecting members11. In this case, the hollow element2has, at the input section6, an ending12, which can be reversibly coupled, for example, to a corresponding ending (not shown) of a duct for supplying pressurised air “B”. In at least one embodiment, the ending12has the shape of a flange.

According to the configuration shown inFIG. 1, the duct5is defined by the lateral duct9and a portion of the chamber8, in particular a front portion thereof facing the output section7.

Still more preferably, the ending12has a seat13for housing a gasket14, which is adapted to seal the connection between the ending12of the hollow element2and the above-mentioned ending of the supply duct “B”. In at least one embodiment, the removable connecting members11comprise tightening mechanisms, which are configured to cause the ending12and the corresponding ending of the supply duct “B” to move towards one another. In particular, in the embodiment illustrated in the accompanying figures, the removable connecting members11comprise a tightening ring11a(visible in detail inFIG. 3A), which can be tightened by means of a threaded knob11b.

Advantageously, the hollow element2can also be reversibly connected to a manifold “C” (identified as the hidden line inFIGS. 1, 2 and 3) of a pneumatic mixer at the output section7by means of first reversible connecting means15a. The aforesaid manifold “C” defines a protrusion of the pneumatic mixer, in particular of the lower part of a hopper “T” of the mixing apparatus, and has the function of connecting the blower unit1to the hopper “T”.

The hollow element2has, at the output section7, a first end portion16athat can be reversibly coupled to a corresponding end portion “C1” of the manifold “C”. In at least one embodiment, the first end portion16aof the hollow element2and/or the end portion “C1” of the manifold “C” have the shape of a flange.

Preferably, the first end portion16ahas a first seat17afor housing a first gasket18aadapted to seal the connection between the hollow element2and the manifold “C” of the pneumatic mixer.

Still more preferably, the first reversible connecting means15acomprise first tightening means configured to cause the first end portion16aand the manifold “C” to move towards one another so as to compress said first gasket18a. In the embodiment illustrated in the accompanying figures, the first reversible connecting means15acomprise a ring, which can be tightened by means of a threaded knob, similar to that shown inFIG. 3A.

With reference to the shutter3, it has the shape of a piston comprising an elongated rod19and a flared or tapered head portion20, preferably in the shape of a truncated cone. In at least one embodiment ofFIGS. 1 and 2, the shutter3has a rotation symmetry axis. In the embodiment ofFIGS. 1 and 2, the rotation symmetry axis of the shutter coincides with its translation axis “A”.

The shutter3can be connected to the actuator4and positioned so as to shut off the airflow through the output section7in a controlled manner.

In particular, an abutment element21, having at least one internal stop surface22a, is arranged in opposition to the shutter3. The internal stop surface22a, preferably with a truncated cone or convergent shape, is counter-shaped with respect to the head portion20of the shutter to define at least one hermetically closed configuration of the output section7.

The position of the shutter3, controlled by the actuator4, defines the opening and closing of a flow connection between the chamber8and the hopper “T” of the pneumatic mixing apparatus to which the blower unit1is connected through said manifold “C”. Furthermore, the possible intermediate positions of the shutter3can define the size of the passage section of the flow connection. In particular, the size of the aforesaid section is defined by the position of the head portion20of the shutter3with respect to the internal stop surface22a.

Advantageously, in order to be able to determine the intermediate positions of the shutter3, i.e. the travel of the shutter during the opening phase, adjustment means are arranged inside the actuator4to define the width of the output section7.

These adjustment means may either be of the manual type, for a variation in the output section7made by manual intervention on mechanical components of the actuator4, or of the automatic type, by means of a suitable electronic system, which operates on the actuator4under certain conditions.

The adjustment means therefore allow the flow to be controlled with an “additional” parameter with respect to the ON/OFF pressure and time parameters alone (opening and closing of the output section7), i.e. a control parameter representative of the width of the fluid passage section.

Advantageously, this parameter is thus controlled (as adjusted by manual or automatic intervention) independently of parameters of pressure and opening time of the output section (7).

The adjustment means therefore allow the parameter representative of the width of the passage section to be operated on, thus optimizing the flow and adjusting it according to the type of material to be mixed, i.e. according to the chemical nature of the material and the particle size of the powders.

Therefore, on the basis of each single mixing step, the individual flow control parameters are suitably adjusted in an independent manner in order to mix the powders in an optimal manner.

Preferably, the head portion20of the shutter3includes fluid-sealing means, in particular at least one gasket20a. The gasket20ais configured to seal said flow connection when the head portion20abuts against the internal stop surface22aof the abutment element21.

The respective shapes of the head portion20of the shutter3and of the internal stop surface22aand the position of the shutter can determine the characteristics of the flow of air flowing into the hopper “T” through the manifold “C”. Advantageously, the shutter3and/or the abutment element21are removable and replaceable so that they can be selected according to the desired type of flow.

In particular, the connection between the shutter3and the actuator4is reversible. In the illustrated embodiment, the rod19comprises an externally threaded end portion forming a screw19a, which can be screwed into a corresponding receiving portion of the actuator4.

Moreover, the abutment element21can be removed and/or replaced by disassembling the reversible connection between the blower unit1and the manifold “C”. In particular, the locking of the abutment element21is achievable by closing the first reversible connecting means15aso that, when tightened, the abutment element21remains trapped between the manifold “C” and the hollow element2.

In some embodiments, the abutment element21, when in use, is housed inside the manifold “C”. Preferably, the abutment element21has an outer surface that is shaped complementarily to the internal surface of the manifold “C”. Still preferably, the abutment element21also comprises fluid-sealing means, in particular at least one gasket21a, to define a fluid-tight housing inside said manifold “C”.

In the illustrated embodiment, at least one segment22bof the abutment element21has an increased radial dimension and is inserted in a corresponding increased diameter segment of the manifold “C”, which extends from the end portion “C1” of the manifold “C”, facing the hollow element2, up to an internal shoulder “C2”. In turn, the hollow element2has, on the output section7, an internal projection23such as to intercept and axially lock the abutment element21which, once assembled, remains locked at its increased diameter portion between said internal projection23and said internal shoulder “C2”.

In accordance with a different embodiment, not shown, the internal projection23may be defined by an inside diameter of the hollow element2(and in particular of the output section7) suitably selected to axially lock the abutment element21.

In some embodiments, the abutment element21comprises a rear body21band a front body21c, preferably joined by mutual interlocking. In particular, the rear body21bcomprises the above-described portion of the abutment element21configured for the locking between the internal projection23and the internal shoulder “C2”, whereas the front body21ccomprises the internal stop surface22a.

In one embodiment not expressly shown in the figures, at least one of the two bodies21b,21cis made of two complementary pieces, for example in the form of two half-rings, to promote mutual assembly with and disassembly from the other of the two bodies21b,21c.

In an alternative embodiment, not shown, the abutment element21can alternatively be housed and locked, partially or totally, with the same procedures described above, inside the hollow element2.

In accordance with a further aspect of the invention, the actuator4can be reversibly connected to the rear region10of the hollow element2, by means of second reversible connecting means15b. Preferably, the hollow element2has, at said rear region10, a second end portion16bthat can be reversibly coupled to a corresponding end surface of the actuator4. In at least one embodiment, the coupling between the hollow element2and the actuator4is achieved by juxtaposing respective flanges.

Preferably, at least one from among the actuator4and the second end portion16bof the hollow element2is provided with a second seat17bfor housing a second gasket18b, said second reversible connecting means15bbeing configured to cause the actuator4and the second end portion16bof the hollow element2to move towards one another so as to compress said second gasket18b. In the embodiment illustrated in the accompanying figures, the second reversible connecting means15bcomprise a tightening ring, which can be tightened by means of a threaded knob, similarly to what is shown inFIG. 3A.

Preferably, the actuator4is of the linear type, in particular of the pneumatic type.

In the embodiment illustrated inFIGS. 1 and 2, the actuator4is configured to cause the shutter3to translate along the axis “A”.

In possible alternative embodiments, not shown, the shutter3and the abutment element4can be positioned so as to shut off the input section6or an intermediate section of the duct5in a controlled manner.

Still in possible alternative, non-shown embodiments of the blower unit1, the actuator4is of the rotary type. In this case, the shutter3and the abutment element21form a rotary valve configured to shut off the flow in the duct5in a controlled manner.

In other embodiments, not shown, the actuator4and preferably also the shutter3are removable and/or replaceable, whereas the connection between the hollow element2and the manifold “C” or the connection between the hollow element2and the pressurised air source is fixed.

FIG. 4shows an apparatus for the pneumatic mixing of granules, in particular powders or granules and liquids, made in accordance with the present invention, comprising: a hopper “T”, adapted to contain granules and/or liquids and provided, on an outer surface thereof, with a plurality of protrusions forming manifolds “C”; a plurality of blower units, of the type indicated by1inFIGS. 1, 2 and 3, which can be connected to said manifolds “C”, and at least one pressurised air supply system.

The hopper “T” preferably has a shape converging downwards. It is suitable to receive the material to be mixed from an opening “T1” in the upper part and to deliver it through an openable-on-command hole “T2” in the lower part.

In some embodiments, not shown, a metering system is connected or can be connected to the lower part of the hopper “T”. The function of said metering system is to ensure the controlled discharge of the material contained inside the hopper “T”.

The manifolds “C” are of the type described above, preferably with a circular cross-section, similar to the manifold “C” shown by the dashed line inFIGS. 1, 2 and 3. They are suitable to be reversibly connected to the blower units1with the means and the methods described above and to define a flow connection between the aforementioned blower units1and the inside of the hopper “T”.

The pressurised air supply system comprises a plurality of supply ducts “B” that can be connected, preferably in a reversible manner, to the input section6of the blower units1with the means and the methods described above.

In some embodiments, the pressurised air supply system comprises an intake “P”, which can be connected to a pressurised air source external to the pneumatic mixing apparatus.

In other embodiments, not shown, the pressurised air supply system also includes a compressor, acting as a source of pressurised air.

In the embodiment ofFIGS. 4 and 5, the pressurised air supply system also includes a common line “R” adapted to distribute the pressurised air to the individual supply ducts “B”; preferably, the aforementioned common line “R” has an annular shape. Still preferably, the aforesaid supply ducts “B” can be reversibly connected to the common line “R”, in particular by means of tightening rings similar to those described above and illustrated inFIG. 3A.

In some embodiments, the materials of the blower unit1and mixing apparatus, except the ga{acute over ( )} skets, are metal alloys, preferably steels and in particular corrosion-resistant steels. Some minor components, such as the shutter3and the counterhead21, are preferably made of polymeric materials for greater lightness and practicality.