ELECTRIC PUMP

This invention relates to an electric pump, in particular an oscillating slider type electric pump, that can be used, for example, in machines for the preparation of drinks such as coffee and the like.

As is known, in various machines it is necessary to move fluids such as water or the like, it is possible to use the so-called "oscillating slider pumps", wherein a movable element is oscillated (that is, moved with an alternating movement) along an axis of movement usually rectilinear: putting this movable element in the presence of the liquid, the movement of the element causes a movement of the liquid and consequently a flow of fluid.

Where it is necessary to measure the flow rate of the fluid generated by the pump just described, it is known from the prior art that a so-called "flow meter", which in turn is made from numerous structural variations, is inserted in the system downstream of the pump.

Generally, the flow meters used in association with oscillating slider pumps are based on the presence of a bladed element immersed in the flow downstream of the pump: the bladed element is set in rotation about a respective keying axis and this same speed of rotation is used as signal correlated with the flow rate.

The aforesaid prior art, whilst it is widely used, has several drawbacks.

First of all, the presence of foreign bodies in the flow to be measured causes an increase in the fluid dynamic resistance, and this results in an oversizing of the pump (as well as the onset of undesired turbulence in the system for moving the fluid) .

Moreover, the need to mount a flow meter outside the electric pump makes it necessary to increase the total number of elements of a flow system, thereby increasing the total costs and increasing the assembly times.

This invention therefore aims to provide an electric pump which can overcome the above-mentioned drawbacks. Mainly, the aim of this invention is to provide an electric pump which has a simple and compact structure, and which can also integrate various functions as well as the mere generation of the "push" for the fluid.

The aim of this invention is also to provide an electric pump which simplifies the assembly operations of a flow system and reduces the structural complexity. This invention therefore aims to provide an electric pump which minimises the "flow losses" inside the pipes of the system.

The technical purpose indicated and the aims specified are substantially achieved by an electric pump having the features described in one or more of the accompanying claims.

An electric pump will now be described in further detail with reference to the accompanying drawings, which illustrate a preferred embodiment of the invention, without restricting the scope of the inventive concept, and in which:

- Figure 1 is a perspective view of a first variant of the electric pump according to the invention;

- Figure 2 shows a longitudinal cross section of the electric pump of Figure 1;

- Figure 3 is a perspective view of a second variant of the electric pump according to the invention;

- Figure 4 shows a longitudinal cross section of the electric pump of Figure 3;

- Figure 5 is a perspective view of a third variant of the electric pump according to the invention;

- Figure 6 shows a longitudinal cross section of the electric pump of Figure 5;

- Figure 7 is a perspective view of a fourth variant of the electric pump according to the invention;

- Figure 8 shows a longitudinal cross section of the electric pump of Figure 7;

- Figure 9 is a perspective view of a fifth variant of the electric pump according to the invention; and

- Figure 10 shows a longitudinal cross section of the electric pump of Figure 9;

With reference to the accompanying drawings, the numeral

1 denotes the oscillating slider electric pump according to this invention, substantially comprising a main body

2 (which traditionally defines a channel 2a having an inlet opening and an outlet opening opposite the inlet opening, in the direction of flow of the fluid inside the channel 2a) ; there is also a propulsive element 3 housed in the main body 2 (and which is designed to move a flow 3a of fluid, whether it is water or the like) . The propulsive element 3 is put into action by appropriate actuator means 4, which act on the latter for moving it according to alternative rectilinear movements along an operational axis 3b; at the same time, there are means 5 for measuring a flow rate (conveniently active on the aforementioned flow 3a) through the channel 2a.

Advantageously, in this invention the measuring means 5 are positioned outside the channel 2a (or in other words, they do not encroach in the inner space defined by the channel 2a with mechanical protrusions) and they are designed to determine a flow rate through the channel 2a by measuring parameters of an electromagnetic nature associable with the flow 3a.

Entering into detail, it may be noted that the measuring means 5 are designed to measure parameters of an electromagnetic nature associable with the alternative rectilinear movements of the propulsive element 3 which in turn comprises at least one sensitive electromagnetic portion (or in other words, comprises a ferromagnetic or paramagnetic material).

The principle on which this invention is based is therefore that of measuring a variation in electromagnetic quantities associated with the movement of the propulsive element, which due to its movement generates the flow of fluid.

It should also be noted that the principles of variation of the operational conditions of the propulsive element 3 may be chosen according to the requirements at the time: for example, it is possible to vary the stroke of the propulsive element 3 (and, therefore, vary the fluid flow rate generated by the electric pump 1) by varying the pressure downstream and/or upstream of the channel 2a, or, alternatively, it is also possible to vary the stroke (and, therefore, the flow rate) by varying the electric power supply frequency.

The measurement of the variations in electromagnetic quantities associated with the movement of the propulsive element is correlated with the flow rate generated, and, consequently, these measurements of the variations may be used for generating a signal correlated with the flow rate.

Returning to the structure of this invention and referring to one of the embodiments illustrated in the accompanying drawings, it may be seen that the measuring means 5 comprise at least one measuring element 5a (for example, a winding or coil) positioned downstream of the channel 2a: the measuring element 5a can be conveniently located close to the outlet opening of the main body 2, even though according to the requirements at the time it may be located in other parts of the electric pump 1 (as described in more detail below) .

Thanks to the presence of the measuring element 5a, the measuring means 5 are designed to measure a first electromagnetic induction variation, which as shown depends on the moving towards/away of the propulsive element with respect to the measuring element 5a.

The generation of the signal correlated with the flow rate is performed advantageously by comparing the electromagnetic induction variation measured with respect to a predetermined reference value: according to the requirements at the time, this reference value can be analogue or digital, and can be pre-memorised in a storage unit of an electronic processing unit operatively associated with the electric pump 1 or generated by suitable hardware.

With particular reference to the latter possibility, the measuring means 5 can also comprise a reference element 5b (which may in turn be a coil/winding) designed to generate a corresponding electromagnetic signal: as just stated, the signal generated by the reference element 5b can be an electromagnetic induction reference value. By operatively associating the measuring element 5a and the reference element 5b, the measuring means 5 become designed to determine a flow rate of fluid by comparing the first electromagnetic induction variation and the electromagnetic induction reference value: in other words, comparing (for example, by subtraction) the electromagnetic signals measured at the terminals of the measuring element 5a and of the reference element 5b generates a signal linked to the effective "effect of movement of fluid in the unit of time" imparted by the movement of the propulsive element.

According to an optional feature of this invention, the reference element 5b can be a winding which causes the movement of the propulsive element 3: in other words, the reference element can comprise (or even coincide with) a propulsive inductive element 4a, as typically found on the electric pumps of the type according to this invention.

Alternatively, the reference element 5b can be a second inductive element positioned upstream of the channel 2a and preferably close to the inlet opening of the main body 2: in this configuration, the effects of the movement of the propulsive element 3 will be measured differently from the measuring element 5a and from the reference element 5b (which are located at different distances from the propulsive element 3): this allows electromagnetic inductions to be generated, in the measuring element 5a and in the reference element 5b, which are variable over time and always different instantaneously .

As stated above, the actuator means 4 can conveniently comprise a propulsive inductive element 4a, which is designed to move the propulsive element 3: in this configuration, the measuring element 5a and/or the reference element 5b can coincide with (or at the most comprise) the propulsive inductive element 4a.

In order to be able to process the signal deriving from the comparison between the various values coming from the measuring element 5a, from the reference element 5b or from the propulsive inductive element 4a, the electric pump 1 comprises an electronic circuit 6 for measurement and control: the circuit 6 is designed to measure at least electromagnetic induction values (coming from the aforementioned elements 5a and/or 5b and/or 4a) and to process a control signal as a function of the values measured.

The control signal can take various forms (analogue, digital, frequency modulated and other) and can be sent to control cards of the hydraulic system for the widest range of functions: the control signal could also be used as a feedback control parameter for self-ad usting the flow rate introduced by the electric pump 1 as a function of pre-defined operating logics.

It should be noted that the aforementioned feedback control method for the electric pump can also be implemented using devices having a structure different from that described above (or claimed hereunder) : for example, Hall effect sensors, resistive shunts, temperature sensors or others may be used (both for the measuring element 5a and for the reference element 5b) according to the requirements at the time.

More generally, it should be noted that the measurement of the variations in electromagnetic quantities, performed with the measuring means 5, can be both direct and indirect: for example, temperature sensors can be used obtain, by the well known laws of physics, the voltage drop or the instantaneous electrical resistance, and, consequently, it is possible to obtain (by subsequent processing or modelling) the parameters of interest .

It should also be noted that the relative arrangement of the various structural parts of this invention can be widely diversified, always, however, in such a way as to be able to achieve the measurement of the electromagnetic quantities according to this invention: for example, with reference to the drawings it may be seen how the measuring element 5a and/or the reference element 5b can be positioned "upstream" or "downstream" with respect to the propulsive element 3 or they can be coaxial and concentric (in other words, they can be positioned one inside the other but located at the same longitudinal coordinate with respect to the outflow axis) .

According to an optional feature of this invention, it is also possible to improve the reading capacity of the measuring element 5a (and/or, if necessary, of the reference element 5b) by inserting in the propulsive element 3 an electromagnetic induction amplifier, which in turn can comprise a neodymium magnet: this structural feature can also find use separately from the other features of this invention.

This invention also relates to a method of measuring the flow rate in an oscillating slider electric pump, comprising the following steps:

- first of all, measuring an electromagnetic quantity using a measuring element positioned coaxially to a flow (the electromagnetic quantity will preferably be a first value of electromagnetic induction measured at a flow point downstream of an oscillating slider electric pump) ;

comparing the electromagnetic quantity of the inductive element with a reference value (the latter can be an electromagnetic induction reference value pre- memorised or generated by a reference element measured at a flow point upstream of the oscillating slider electric pump) ; and lastly

- generating a a correlation signal as a function of the aforementioned comparison.

Preferably, the aforementioned comparing step is implemented by subtracting the first electromagnetic induction value from the reference electromagnetic induction reference value.

To complete the aforementioned method, the following steps can also be conveniently implemented:

- sending the correlation signal by electronic control means outside the electric pump; and/or

- varying at least one operational parameter of the electric pump according to the control signal, which in turn can be generated as a function of the correlation signal .

Conveniently, the aforementioned operational parameter can be, for example, a reciprocating motion speed of a propulsive element positioned inside the electric pump. The invention brings numerous advantages.

In fact, thanks to the particular structure of this device it is possible to generate a signal relative to the flow rate of fluid, which in turn may be post- processed by adequate "measurement and control electronics": moreover, the signal is generated according to a non-invasive method of reading the flow of fluid, thereby eliminating every possible source of turbulence or additional resistance in the flow.

Moreover, the operational integration achieved by this device allows a substantial reduction in the complexity and the assembly operations of a hydraulic system, with benefits on the final cost of the machinery in which the system operates . Lastly, it should be noted how this invention allows the production costs of the electric pump to be kept low, as well as not causing particular complications or modifications and retro-fitting adaptations on prior art machinery or systems, with advantages in terms of the overall production cost and the final price of the product .