Pump for regenerating a decalcifying device of a dishwashing machine (bitron s.p.a.) gas monkey monster truck


As is known, a decalcifying device comprises a chamber containing substances with water-softening properties, in particular ion exchange resins, through which the water supplied to the dishwashing machine is made to pass so that it is decalcified.

According to known methods, for example those described in EP 2 564 752 and EP 1 497 491, the inflow of the brine into the chamber containing substances with water-softening properties is controlled by means of a pump, such as a membrane-type pump, which is positioned on a conduit connecting the salt reservoir to the aforementioned chamber.

In particular, EP 2 564 752 describes a membrane-type or peristaltic pump activated by a gear motor, the specific structure of which is not even outlined and which imparts a reciprocating motion to a piston connected to the respective membrane, such that no part of the gear motor is connected to the membrane. The gear motor is moreover housed in a casing which is clearly separate from the body in which the respective brine inflow/outflow conduits are formed, such that no part of the gear motor is associated to said body.

A pump (FIGS. 1 and 2) comprises a body 10, typically of plastics material, in the lower portion of which an inflow conduit 16 provided with a one-way valve 18 and an outflow conduit 12 provided with a one-way valve 14 are defined. As is shown in the figures, the conduits 12, 16 are offset. In a manner which is known per se and not shown in the figures, the inflow conduit 16 is connected to a salt reservoir in which a regenerating brine is formed, whereas the outflow conduit 12 is connected to a chamber containing substances with water-softening properties of a decalcifying device of a dishwashing machine.

At the top, the body 10 comprises a hollow case 20, preferably of plastics material, within which a solenoid 22 having a vertically oriented longitudinal axis 24 is housed. The case 20 is shaped substantially in the manner of a parallelepiped and has, inter alia, an upper wall 26 and a lower wall 28 parallel to one another.

A core is mobile along the axis 24 and, in general, has a part of plastics material which is slidingly associated to the body 10 and to which a member of magnetic material, such as iron, capable of interacting with the electromagnetic field generated by the solenoid 22 is assembled/co-moulded. In the shown embodiment of the invention, the core is formed by a bar 30 of plastics material, whose lower portion is surrounded by a sleeve 32 of magnetic material fixed to the bar 30. In an alternative embodiment of the invention which is not shown in the figures, a member of magnetic material may be incorporated, for example by means of co-moulding, within the bar 30 of plastics material. An initial portion 34 of the outflow conduit 12 is moreover coaxial with the downward continuation of the axis 24, and forms a right angle with a subsequent portion 36 which is parallel with the inflow conduit 16.

The bar 30 of the core has an upper end associated to the case 20 through a passage 38 formed in the wall 26, which acts as upper guide of the movement of said core. Analogously, the wall 28 of the case 20 is provided with a further passage 40 acting as lower guide of the movement of the sleeve 32 of the core. The bottom surface of the bar 30 has a T-shaped projection 42 connected to a centre portion of a membrane 44, the peripheral portion of which is fixed to the body 10.

A helical spring 46, which acts as return elastic means of the core, is arranged coaxially around the upper portion of the bar 30 between the upper end of the sleeve 32 and the lower surface surrounding the passage 38 of the wall 26 of the case 20.

FIG. 3 shows the electrical supply circuit of the solenoid 22. As is shown therein, the alternating supply current passes through a half-wave rectifier diode 48. In addition, a capacitor 50, preferably having a capacity not greater than 3 μF (as well as not zero), is arranged in parallel to the solenoid 22 to attenuate the supply current.

During operation of the pump (FIG. 1), the flow of electric current through the solenoid 22, together with the return action of the spring 46, causes a reciprocating movement of the core to which the membrane 44 is connected, thereby activating the flow of the brine from the inflow conduit 16 towards the outflow conduit 12. As is shown in the figures, the movement of the core takes place in air, such as to avoid a priori a situation in which said core may come into contact with the pumped liquid. This movement is very silent since the coupling of the core with the upper and lower guides described above may be realized with high precision. The silent nature of the movement is further promoted by the features of the electrical supply circuit of the solenoid 22, which tend to dampen induced vibrations.

When the pump is not active (FIG. 2), the mouth of the initial portion 34 of the outflow conduit 12 is closed by the centre portion of the membrane 44 which ensures the water-tightness in both directions between the inflow and outflow conduits 16, 12.

The only difference with respect to the pump described above consists in the fact that the membrane 44 also acts as lower guide of the movement of the core, which—contrary to that shown above—passes with not insignificant play 51 through the passage 40 formed in the lower wall 28 of the case 20.

In this case, the return elastic means consist of a first spiral spring 52 having a first end fixed to a circumferential projection 54 protruding from the upper wall 26 of the case 20 and a second end 56 fixed to the bar 30 of the core. The spring 52 also acts as upper guide of the movement of the core.

In this case, a safety conduit 60 for discharging the brine is formed in the body 10. In the case of accidental breakage of the membrane 44, the brine can be discharged through the conduit 60 without coming into contact with the electromagnetic parts of the pump, thereby avoiding the risk of damaging them.

Clearly, without departing from the principle of the invention, the constructional details and the embodiments may be greatly varied with respect to that described purely by way of example, without thereby departing from the scope of the invention as defined in the accompanying claims. In particular, a pump according to the present invention can be used in any desired decalcifying device with or without a monolithic body of plastics material, the hydraulic circuit of which provides that the step of regenerating the ion exchange resins is activated by a pump positioned on a conduit for connecting the salt reservoir, in which the regenerating brine is formed, to the resin-containing chamber.