PRESSURE TRANSDUCER

A pressure transducer, particularly to be installed in liquid pumping devices, comprising a cup-shaped container from the bottom of which a connector protrudes for connection to a pressurized duct; the connector and the bottom are traversed by a through hole for the passage of fluid inside the transducer to a pressure sensor; the transducer comprises elements for locking the pressure sensor in a single possible orientation inside the container and elements for preventing the extraction of the pressure sensor to from the container.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the cited figures, the transducer according to the invention, generally designated by the reference numeral10, comprises a cup-shaped container11, from the bottom12of which an externally threaded connector13protrudes for connection to a pressurized duct. The connector13and the container11are both conveniently traversed by a through hole14for the passage of fluid inside the transducer10to a pressure sensor15. More precisely, the container11and the connector13are provided monolithically, as shown clearly in the sectional views ofFIGS. 3 and 4.

The pressure sensor15comprises a flat functional element16, which is made of ceramic and is substantially disc-shaped, with a cavity that forms an internal membrane-type portion17of limited thickness, and an electronic board18that is installed on the flat functional element16at right angles to the internal membrane-type portion17and is connected thereto. In particular, an electric circuit, specifically a Wheatstone bridge45, is embedded in the internal membrane-type portion17and protrudes from it with four pins46, shown inFIGS. 1 and 4, by means of which the connection to the electronic board18is established. Said internal membrane-type portion17is subjected to the pressure of the fluid that enters the transducer10through the through hole14and the electronic board18is preset to transduce the pressure that acts on the internal membrane-type portion17and therefore the electrical variation in the Wheatstone bridge, and to send its signal to a processing and control device of the pumping device.

The pressure sensor15must be accommodated in a specific position inside the container11in order to ensure a stable connection of the electronic board18to a connector that connects it to an external signal control and processing device.

In this regard, the electronic board18acts as plug, which conveniently has an engagement portion18athat enters the connector. Advantageously, the transducer10comprises means19for locking the pressure sensor15in a single possible orientation within the container11, which comprise a cup-shaped intermediate element20that supports the pressure sensor15and enters with it the container11along the longitudinal axis21of the latter, according to a single possible orientation, since it is provided externally, on a wall thereof that is shaped complementary to the cavity of the container11, with a raised portion22which, during insertion, slides in a corresponding slot23of the container11. Vice versa, in an alternative embodiment, not shown here, the container can be provided with a raised portion that protrudes inward and the cup-shaped intermediate element on the other hand can have a corresponding complementarily shaped slot within which the raised portion of the container slides during insertion.

More precisely, in this embodiment the cup-shaped intermediate element20has two mutually opposite crescent-shaped walls24aand24b, the first of which bears the raised portion22on its outer side. Both crescent-shaped walls24aand24bhave, on the inner side of the curvature, two mutually opposite guides25(only one of which is clearly visible inFIG. 1) and the intermediate cup-shaped element20conveniently has an opening on its bottom, which is not visible in the accompanying figures, so that this last element and the pressure sensor15are associated by sliding of the electronic board18in the two mutually opposite guides25.

Moreover, the transducer10also comprises means26for preventing the extraction of the pressure sensor15from the container11.

In particular, said extraction-preventing means26comprise a pivot27that is inserted transversely in the container11through an insertion slot28(shown inFIG. 5) and passes through the electronic board18at an adapted window29provided therein (shown inFIG. 1).

More particularly, the pivot27consists of a plate that passes through the container11from one side to the opposite side and the cup-shaped intermediate element20is provided with a cantilever element30between the two crescent-shaped walls24aand24b,which is folded toward the center, proximate to which it has, at its free end, two teeth31that engage by snap action the pivot27, each entering a corresponding seat32of the pivot27.

Conveniently, the pivot27, in its plate-like shape, has for insertion a grip head33that identifies uniquely the side thereof for insertion in the container11, an insertion slot28of suitable dimensions which is larger than its opposite one corresponding to the head.

The container11advantageously has a hexagonal cross-section and the transducer10comprises also a plug34, also having a hexagonal cross-section, which closes the container11on the opposite side with respect to the side for association with the duct.

The plug34is coupled to the container11by snap-acting quick engagement means35that consist of two mutually opposite tabs36which protrude from a last portion37of the container11and of which only one is visible inFIGS. 1 and 5, said tabs entering by snap action corresponding slots38provided in two opposite faces39of the plug34. These two faces39are rendered elastically deformable for the insertion of the tabs36, being provided conveniently with two parallel cuts in the insertion direction.

The plug34is provided in an upward region with an opening40for the passage of the connectors that connect the electronic board18to the external processing and control device of the pumping device. The placement of the plug34according to the correct orientation, so that the opening40is in the correct position to ensure connection, is ensured by a protrusion41(shown inFIGS. 1 and 6) of the container11on its outer wall, so as to correspond to the slot23, on which the plug34slides with a complementarily shaped recess, not shown, in order to be connected to the container11in a single possible orientation.

Conveniently, the transducer10is also provided with two gaskets of the O-ring type, both of which are clearly visible inFIGS. 1,3and4.

Observing the cross-sections shown inFIGS. 3 and 4, it can be noted that the container11has, at the bottom12, a portion42for association with the flat functional element16. The association portion42enters the cavity of the flat functional element16to arrange itself so that the through hole14is at the internal membrane-type portion17.

A first gasket43is interposed between said association portion42and the flat functional element16in order to prevent the fluid that enters the transducer10through the through hole14from reaching the electronic part.

A second gasket44is arranged on the connector13, at the bottom12of the cup-shaped container11, for connection of the transducer10to the duct.

The use of the transducer according to the invention is as follows in its assembly.

The pressure sensor15is inserted in the cup-shaped intermediate element20, with the electronic board18in the two mutually opposite guides25, and they are inserted together in the container11after the first gasket43has been placed on the association portion42. These elements are oriented so that during insertion the raised portion22slides within the slot23.

After this, the pivot27is inserted transversely in the container11through the insertion slot28and passes through the electronic board18, passing through the window29. In this manner extraction of the pressure sensor15from the container11is prevented. Furthermore, during insertion the pivot27engages by snap action the cup-shaped intermediate element20, accommodating in the seats32the teeth31of the cantilever element30, and in this manner any accidental exit of the pivot27is prevented.

Finally, the transducer10is closed with the plug34, which is caused to slide appropriately with its recess on the protrusion41and is applied in a unique position on the container11, so that the electronic board18can be connected to the external device through the opening40.

The transducer10thus assembled is ready to be installed on the duct.

It should be noted that the transducer10according to the invention can be assembled easily and quickly, ensuring the association of the parts in unique orientations in order to ensure the correct operation thereof.

It should also be noted that the components are mutually associated without threaded parts but only by means of sliding guides and parts that engage by snap action, reducing significantly the overall space occupation of the transducer.

In practice it has been found that the invention achieves the intended aim and objects, providing a pressure transducer that is compact and easy to use both during assembly and during installation within the pumping device, thanks to the way in which its parts are associated and thanks to its hexagonal external contour.

One advantage of the transducer in fact arises from its hexagonal contour, which allows screwing and unscrewing it to and from the duct with a simple hex wrench instead of clamps or other special tools.

Another advantage arises from constructive simplicity, which leads to low costs and therefore to the possibility of installing the transducer even in circuits for which the use of pressure-controlled switches was provided previously.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may furthermore be replaced with other technically equivalent elements.

In practice, the materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.

The disclosures in Italian Patent Application No. PD2012A000373 from which this application claims priority are incorporated herein by reference.