Patent Description:
Such types of pumps are used for example for pumping sauces, jams, etc., containing solid parts (for example solid parts of tomatoes in a sauce, solid parts of fruit in jams).

The use of a piston pump is known for pumping such types of products to a homogeniser. Typically the piston is driven by a connecting rod-crank system, driven by a camshaft or crankshaft. One drawback of such a solution is related to the overall dimensions of such a shaft.

A further drawback is related to the fact that the law of motion followed by the piston is rigid and pulsating according to sinusoidal law such as to create accelerations and decelerations in the flow, which are thus not flexible and therefore not adaptable to the specific needs which may arise from time to time.

The pulsations in the flow generate pressure pulses.

The document <CIT> discloses a pump for delivering animal food which piston is driven by a balls screw shaft.

In this context, the technical task underlying the present invention is to offer a pumping apparatus and a method which allow the dimensions to be optimised. In addition, the present solution allows to improve the operating flexibility of the pumping apparatus.

The defined technical task and the specified objects are substantially achieved by a pumping apparatus and a method for pumping a fluid containing solid parts comprising the technical features set forth in one or more of the appended claims.

Further features and advantages of the present invention will become more apparent from the following indicative, and hence non-limiting, description of a preferred, but not exclusive, embodiment of a pumping method and an apparatus, as illustrated in the accompanying drawings, in which:.

In the accompanying drawings, reference number <NUM> indicates a pumping apparatus for pumping a food fluid containing solid parts. Such a fluid is typically viscous, e.g., sauces, jams etc. Suitably the solid parts can reach longitudinal dimensions up to <NUM> millimetres.

The apparatus <NUM> comprises a pumping assembly <NUM>. The pumping assembly <NUM> in turn comprises a jacket <NUM> and a piston <NUM> which is movable alternately backwards and forwards in the jacket <NUM> in order to pump and suction the fluid. The jacket <NUM> is substantially cylindrical. Suitably, it is made of stainless steel. Suitably, the pumping assembly <NUM> comprises three lubrication points. All the parts of the pumping assembly <NUM> in contact with the product are made of FDA certified material.

The apparatus <NUM> further comprises an electric motor <NUM> driving said pumping assembly <NUM>. Preferably, the electric motor <NUM> is an induction motor with a circular crown stator. Suitably, the electric motor <NUM> is an asynchronous motor (typically three-phase) or a DC motor or a brushless motor. The motor <NUM> comprises a rotor <NUM> and a stator <NUM>. The stator <NUM> suitably surrounds at least a part of the rotor <NUM>. The stator <NUM> comprises electrical windings for generating a rotating magnetic field which rotates the rotor <NUM>. Suitably, the electric motor <NUM> is a commercial motor. Suitably, the electric motor <NUM> is servo-ventilated. Suitably, the electric motor <NUM> comprises/is coupled to a frequency converter. Such a frequency converter allows the rotation speed of the rotor <NUM> to be adjusted. For example, such a converter allows to adjust the rotation speed of the rotor <NUM> instant by instant. This allows considerable flexibility of use. For example, it allows to control the acceleration and deceleration ramps of the rotor <NUM> and/or the piston <NUM>. Suitably, the pumping assembly <NUM> comprises a position control system of the piston <NUM>. The position of the piston <NUM> along the jacket <NUM> is thus understood. This typically occurs by means of an encoder. Preferably, such a control system (e.g., the encoder) is applied to the motor <NUM> (in particular the rotor) or to the piston <NUM> or to another portion of a motion transmission system from the motor <NUM> to the piston <NUM>.

Advantageously, the position control system of the piston <NUM> is operatively associated with the frequency converter. The frequency converter is suitably actuated as a function of the position of the piston <NUM> detected by the control system. Thereby, the speed of the piston <NUM> can be controlled as the position of the piston varies along the stroke thereof. In particular, the frequency converter allows the piston to follow specific acceleration and/or deceleration profiles straddling the inversion of the motion of the piston <NUM> itself.

The apparatus <NUM> further comprises means for managing the acceleration ramps of the piston <NUM>. This is done by electronic control of the axes, which prevents water hammers in the downstream circuit. The electric motor <NUM> is therefore capable of controlling the acceleration ramps.

The apparatus <NUM> can suitably further comprise a speed adapter <NUM> operatively interposed between the electric motor <NUM> and said pumping system <NUM>. The speed adapter <NUM> allows to provide a different angular speed in output relative to the input speed given by the rotor <NUM> of the electric motor <NUM>. The adapter <NUM> is a mechanical system, typically geared. The speed adapter <NUM> is typically a speed reducer. It therefore allows to provide a power take-off at the output with a lower angular speed relative to that of a rotor of the electric motor <NUM>. The reducer can also be integrated/combined in the electric motor <NUM> so as to define a gear motor.

Suitably, said speed adapter <NUM> (in particular said reducer) has a power output (typically by means of a drive shaft) in a direction orthogonal to that of the input of the rotor <NUM>.

The pumping assembly <NUM> comprises a drive shaft <NUM> actuated by said adapter <NUM>. The drive shaft <NUM> comprises a groove <NUM> extending spirally. Such a groove <NUM> extends along at least one section of a radially outermost side surface of the drive shaft <NUM>.

The pumping assembly <NUM> comprises a driven actuator <NUM> which is slidable forwards and backwards. Suitably, the driven actuator <NUM> is a linear actuator. It suitably translates forwards and backwards moved by the drive shaft <NUM>. The driven actuator <NUM> comprises a recess <NUM> extending spirally about at least one section of said actuator <NUM>. The recess <NUM> is at least partially facing the groove <NUM>.

The pumping assembly <NUM> comprises a plurality of rolling elements <NUM> which engage in both said groove <NUM> and in said recess <NUM>. Such rolling elements <NUM> are typically spheres. It is thereby possible to transfer the motion from the drive shaft <NUM> to the driven actuator <NUM>. A rotary motion of said drive shaft <NUM> may then be transferred into a forward or return stroke of said driven actuator <NUM>.

Suitably, the drive shaft <NUM> with the groove <NUM>, the driven actuator <NUM> with the recess <NUM>, the rolling means <NUM> define a ball recirculation system. In particular, they define a system known in other applications as a recirculating ball screw.

The driven actuator <NUM> is constrained to the piston <NUM>. Preferably they are assembled together. In particular, the piston <NUM> could be integral with the driven actuator <NUM>. Possibly, the piston <NUM> and the driven actuator <NUM> could also be a single monolithic body. As a function of the rotation direction of the drive shaft <NUM>, the driven actuator <NUM> moves in one direction or the other.

The rotor <NUM> is rotatable about a first axis <NUM> which is orthogonal to a second axis <NUM> along which said driven actuator <NUM> and said drive shaft <NUM> extend. In particular, the actuator <NUM> translates along said second axis <NUM>. The second axis <NUM> also identifies a translation direction of the piston <NUM>. The driven actuator <NUM> is typically coaxial with the drive shaft <NUM>. Suitably, the driven actuator <NUM> surrounds the drive shaft <NUM>. The driven actuator <NUM> preferably surrounds and is positioned externally to said drive shaft <NUM>. The driven actuator <NUM> comprises a cavity in which said drive shaft <NUM> protrudes. However, there could be an opposite solution in which the drive shaft <NUM> surrounds at least one section of the driven actuator <NUM>. Suitably, the drive shaft <NUM> and the driven actuator <NUM> define a telescopic structure. As a function of the rotation direction of the drive shaft <NUM>, such a telescopic structure lengthens or shortens. In particular, as a function of the rotation direction of the drive shaft <NUM>, an insertion or extraction of one between the shaft <NUM> or the actuator <NUM> relative to the other is caused. In the solution illustrated in the accompanying figures, an extraction of the actuator <NUM> from the shaft <NUM> corresponds to a pumping stroke of the piston <NUM>. Similarly, an insertion of the actuator <NUM> into the shaft <NUM> corresponds to a suction stroke of the piston <NUM>. Suitably, the stroke of the piston <NUM> is adjustable by acting on the control of the electric motor <NUM>. Suitably, the maximum stroke of the piston <NUM> is comprised between <NUM> and <NUM> metres.

Suitably, the axial position of the drive shaft <NUM> is fixed along said second axis <NUM>. Instead, the actuator <NUM> moves, in particular translates, along said axis <NUM>. In this regard, the pumping assembly <NUM> comprises a guiding means which inhibits the rotation of said driven actuator <NUM> allowing the translation thereof along the second axis <NUM>.

The pumping system <NUM> comprises an outer casing <NUM> which wraps around at least a part of the drive shaft <NUM> and the driven actuator <NUM>. The motor <NUM> is external to the casing <NUM>. The motor <NUM> is also external to the jacket <NUM>. The casing <NUM> is suitably external, preferably adjacent, to the jacket <NUM>.

The pumping assembly <NUM> comprises a pumping chamber <NUM> positioned in said jacket <NUM> and in which the fluid is suctioned and pumped by said piston <NUM>.

The pumping assembly <NUM> comprises an intake valve <NUM> which, in an open configuration, permits the entry of said fluid into the pumping chamber <NUM>. The pumping assembly <NUM> comprises a delivery valve <NUM> which, in an open configuration, permits the pumping of the fluid present in the pumping chamber <NUM>. Suitably, the intake valve <NUM> and/or the delivery valve <NUM> is/are ball valves. The suction valve <NUM> and the delivery valve <NUM> are pneumatically controlled. The suction valve <NUM> and the delivery valve <NUM> are remotely controlled. In particular, remotely controlled pneumatic means are present for controlling the valves <NUM> and <NUM>. In an alternative solution, the valves <NUM>, <NUM> could be operated in another manner, for example by a solenoid. The use of remotely controlled valves is interesting, as it facilitates large passage sections. In particular, the intake valve <NUM>, if open, has a passage section which is at least <NUM>% (preferably <NUM>%) of the section of the intake duct immediately upstream of the valve <NUM>. Similarly, the delivery valve <NUM> allows to free a passage section which is at least <NUM>% (preferably <NUM>%) of the section of the delivery duct immediately downstream of the valve <NUM>. This is useful for facilitating the passage of solid parts. The jacket <NUM> can suction axially and pump orthogonally to a movement direction of the cylinder <NUM>. But also vice versa. The pumping assembly <NUM> has reversible operation.

The driven actuator <NUM> comprises an annular sleeve <NUM> which wraps around a section of said drive shaft <NUM> and in which said rolling elements <NUM> are contained. The jacket <NUM> extends axially for less than <NUM>/<NUM> of a stroke of the driven actuator <NUM>.

Suitably, the pumping apparatus <NUM> also comprises an additional pumping assembly <NUM> suitably actuated by an additional electric motor <NUM>. This description for the pumping assembly <NUM>, for the electric motor <NUM> and the reciprocal interactions thereof can be respectively repeated for the additional pumping assembly <NUM>, for the additional electric motor <NUM> and the reciprocal interactions thereof.

Suitably, the additional pumping assembly is a pump provided with a piston which moves alternately along a direction parallel to the second axis <NUM> described above. Suitably, the pumping assembly <NUM> and the additional pumping assembly <NUM> are side by side. The use of two pumping assemblies allows to give greater regularity to the fluid flow rate. In fact, when the pumping assembly <NUM> is in the suction step, the pumping assembly <NUM> will be in the pumping step.

Advantageously, the additional electric motor <NUM> comprises a frequency converter which allows the rotor speed to be promptly adjusted as a function of a signal provided by a piston position control system of the additional pumping assembly <NUM>.

Suitably, the frequency converter of the motor <NUM> and the frequency converter of the motor <NUM> are able to control the movement of the piston of the pumping assembly <NUM> and the piston of the pumping assembly <NUM> so as to have a compressive fluid flow rate processed by the sum of the pumping assembly <NUM> and the pumping assembly <NUM> which is constant over time (regardless of the inversion of the motion of the respective pistons). The frequency converter of the motor <NUM> and the frequency converter of the motor <NUM> are therefore synchronised.

An object of the present invention is also a system <NUM> for treating a food fluid containing solid particles. In fact, such a system <NUM> comprises a pumping apparatus <NUM> having one or more of the features described previously.

The system <NUM> further comprises a fluid heating means <NUM> positioned downstream of said delivery valve <NUM>. There is no fluid homogenising valve or narrow gap present between the delivery valve <NUM> and the heating means <NUM>. More generally, and regardless of the presence of the heating means <NUM>, there is no fluid homogenising valve or narrow gap for crushing the solid parts.

An object of the present invention is further a pumping method for pumping a food fluid containing solid parts by means of a pumping assembly <NUM>. Suitably, such a method is implemented by a pumping apparatus <NUM> and/or a treatment system <NUM>.

The pumping assembly <NUM> comprises a jacket <NUM> and a piston <NUM> slidable alternately in the jacket <NUM>. Such a piston <NUM> alternately moves forwards and backwards in the jacket <NUM>. The movement of the piston <NUM> causes the pumping and/or suction of the fluid with respect to the jacket <NUM>.

The method comprises the step of actuating a drive shaft <NUM> of the pumping assembly <NUM> by means of at least one electric motor <NUM> and suitably a speed adapter <NUM>. The speed adapter <NUM> rotates the drive shaft <NUM> at a different angular speed relative to that of a rotor <NUM> of the motor <NUM>.

The method further comprises the step of transferring motion from said drive shaft <NUM> to a driven actuator <NUM> positioned in said pumping assembly <NUM> by means of a plurality of rolling elements <NUM>. The rolling elements <NUM> suitably engage:.

The driven actuator <NUM> is constrained to the piston <NUM>. The piston <NUM> suctions and pumps the fluid.

The method can optionally comprise the step of pumping the fluid to a heating means <NUM> of said fluid without passing it through a homogenising valve or narrow gap intended to crush said solid parts.

Suitably, the pumping method for pumping a food fluid containing solid parts is implemented by means of at least:.

However, the pumping assembly <NUM> and the additional pumping assembly <NUM> could follow different profiles of the flow rate - time curve.

The present invention achieves important advantages.

First of all, it allows to obtain a pump which is optimised in the components thereof, while at the same time minimising the overall dimensions. In particular, it has a predominant longitudinal dimension, but a limited height and width (the solution exemplified in the accompanying figures has a longitudinal length of about <NUM> metres, a width of about <NUM> metres and a height of less than <NUM> metres; it can allow a flow rate of about <NUM>,<NUM> litres/hour with a pressure of about <NUM> bar).

Claim 1:
A system for treating a food fluid containing solid parts comprising:
- the food fluid containing said solid parts;
- a pumping apparatus for pumping the food fluid containing solid parts in turn comprising:
i) a pumping assembly (<NUM>) comprising a jacket (<NUM>) and a piston (<NUM>) that is movable alternately in the jacket (<NUM>) in order to suction and pump the fluid;
ii) an electric motor (<NUM>) driving said pumping assembly (<NUM>);
iii) a speed adaptor (<NUM>) operatively interposed between the electric motor (<NUM>) and said pumping assembly (<NUM>);
said pumping assembly (<NUM>) comprising:
- a drive shaft (<NUM>) actuated by said adaptor (<NUM>) and comprising a groove (<NUM>) extending spirally;
- a driven actuator (<NUM>) slidable forwards and backwards and comprising a recess (<NUM>) extending spirally about at least one section of said actuator (<NUM>);
- a plurality of rolling elements (<NUM>) that engage both in said groove (<NUM>) and in said recess (<NUM>) in order to transfer a rotary motion of said drive shaft (<NUM>) into a forward or return stroke of said driven actuator (<NUM>); said driven actuator (<NUM>) being constrained to said piston (<NUM>);
- a pumping chamber (<NUM>) positioned in said jacket (<NUM>) and in which the fluid is suctioned and pumped by said piston (<NUM>);
- an intake valve which, in an open configuration, permits the entry of said fluid into the pumping chamber (<NUM>) and a delivery valve which, in an open configuration, permits the pumping of the fluid present in the pumping chamber (<NUM>); characterised in that the intake valve and the delivery valve are actuated by a remotely controlled actuator.