The present invention has the subject of a pressure differential electronic transducer device, in particular for a fluid circuit.

The object of the present invention is to make a compact electronic pressure transducer device that is able to detect both an absolute pressure and a difference between two pressures.

This and other objects are accomplished according to the invention with an electronic pressure transducer device comprising a hollow rigid casing having a first (8, 8a) and a second (10, 10a) fluid intake opening and wherein a first (18') and a second (18") transduction chamber are defined, in which are mounted, respectively, a first element resiliently suspended in the casing and movable with respect to the casing due to a first fluid pressure introduced through the first opening, and a second element equally resiliently suspended in the casing and movable with respect to the casing due to a second fluid pressure introduced through the second opening; said first and second element being arranged to generate an inductance and the configuration being such that said inductance is variable as a function of the values of said pressures or of their difference.

Further characteristics and advantages of the invention will become clear from the following detailed description, given purely as a non-limiting example, with reference to the attached drawings, in which: figure 1 is a perspective view of a transducer device according to the invention; figure 2 is a section view of the device along the line II-II of figure 1; and figure 3 is a section view of a variant of the device according to the invention.

In figure 1 an electronic pressure transducer device is wholly indicated with T.

Such a device T has a hollow rigid casing 1 comprising an upper shell 2 coupled with a lower shell 4 and a lateral lid 6 connected to said upper 2 and lower 4 shells. The upper 2 and lower 4 shells and the lid 6 are advantageously made with a moulded plastic material.

Figure 2 illustrates a section view, along the line II-II of figure 1, of the transducer device T.

The upper shell 2 has a tubular fitting 8 on top inside which an upper fluid intake passage 8a is defined.

The lower shell 4 also has a tubular fitting 10 inside which a lower fluid intake passage 10a is defined.

The passages 8a and 10a are connected to respective upper 12 and lower 16 fluid inlet chambers.

The upper shell 2 and the lower shell 4 define a first transduction chamber 18', separated in a fluid-tight manner from the inlet chambers 12 and 16 respectively through an upper membrane 20 and a lower membrane 22.

Inside the first transduction chamber 18' a coil 24 is inserted comprising an essentially tubular reel support 24a on which a coil 24b is made. The support 24a is resiliently suspended inside the first transduction chamber 18' through a first upper helicoidal spring 26 and an opposing first lower helicoidal spring 28. Said springs 26 and 28 comprise an electrically conductive material.

The support 24a cooperates with the upper membrane 20 and is movable with respect to the first transduction chamber 18' due to a first fluid pressure that enters into the device T through the upper fluid intake passage 8a.

Inside the first transduction chamber 18' there is also a reaction corp 36 that in the illustrated example is substantially shaped like an inverted cup, placed stationary in use in the lower shell 4. The reaction corp 36 defines a second transduction chamber 18", separated in a fluid-tight manner from the lower inlet chamber 16 from the lower membrane 22. The reaction corp 36 is maintained operatively integral to the lower shell 4 by the first lower spring 28 and extends inside the support 24a.

The first transduction chamber 18' and the second transduction chamber 18" are placed in communication with one another, for example through a hole present in the reaction corp 36, so as to equalise the pressures present inside the two chambers 18' and 18".

Inside the second transduction chamber 18" a ferromagnetic core is arranged, wholly indicated with 30. Said core 30 comprises a tubular support 30a that carries an element made of ferromagnetic material 30b.

The ferromagnetic core 30 is resilient Iy suspended in the second transduction chamber 18" through a second upper spring 32 and a second lower spring 34 arranged in the lower inlet chamber 16.

The core 30 is coupled with the lower membrane 22.

The second upper spring 32 is arranged between the end of the ferromagnetic core 30 opposite the lower membrane 22 and the reaction corp 36, and it is therefore opposite the second lower spring 34.

The ferromagnetic core 30 is arranged partially compenetrated inside the coil 24 and is movable with respect to the first transduction chamber 18', inside the support 24a of the coil 24, due to a second fluid pressure that enters into the device T through the lower fluid intake passage 10a.

The compenetration degree of the ferromagnetic core 30 in the coil 24 depends upon the values of such first and second fluid pressures, or their difference, and correspondingly the value of the inductance of the coil 24b depends upon it.

The device T also comprises an electronic elaboration circuit 38 that comprises a support plate 40 and a plurality of electronic components 42. The circuit 38 is housed in a lateral recess 48 defined by the upper 2 and lower 4 shells and communicating with the first transduction chamber 18'. Said lateral recess 48 is closed by the lateral lid 6.

The support plate 40 is connected stationary in use to the upper 26 and lower 28 springs through respective first ends 26a and 28a of said springs 26 and 28.

The circuit 38 is connected to the coil 24b through respective second ends 26b and 28b of the upper 26 and lower springs 28, said second ends 26b and 28b being mobile in use and each connected to a respective end or terminal 24c and 24d of the coil 24b.

The circuit 38 is configured to detect the variation of the inductance of the coil 24 above described, said variation being indicative of the value of the first and second fluid pressure, or of the value of their difference. In a per sέ known manner, the circuit 38 can comprise an LC-type oscillating circuit, in which the inductive component at least partially consists of the inductance of the coil 24b.

The lower shell 4 finally has a lower opening 44 communicating with the lower inlet chamber 16 and equipped with a removable closure cap 46.

Preferably, the lower spring 34 is interposed between the lower membrane 22 and the removable cap 46.

The upper shell 2 and the lateral lid 6 finally define a seat 50 in which an electric connector 52 is inserted, connected to the electronic circuit 38.

Figure 3 illustrates a section view of a variant of the transducer device T. Elements that are identical or similar to those of the device of figure 2 are indicated with the same reference numerals.

The upper shell 2 has a tubular fitting 8 on top inside which an upper fluid intake passage 8a is defined. The lower shell 4 also has a tubular fitting 10 inside which a lower fluid intake passage 10a is defined.

The passages 8a and 10a are connected to respective upper 12 and lower 16 fluid inlet chambers.

The casing 1 defined by the upper shell 2 and by the lower shell 4 houses, stationary in use with respect to said shells 2 and 4, an essentially tubular reel support 25 in which are defined a first 18' and a second transduction chamber 18", which are separated in a fluid- tight manner from the associated inlet chambers 12 and 16 respectively through an upper membrane 20 and a lower membrane 22.

Inside the casing 1 a first and a second coil 24' and 24" are inserted comprising two coils 24b' and 24b" made on the support 25.

Inside each transduction chamber 18' and 18" a ferromagnetic core is also arranged, wholly indicated with 30' and 30", respectively. Said cores 30' and 30" comprise respective tubular supports 30a' and 30a" that carry respective elements made of ferromagnetic material 30b' and 30b".

The first ferromagnetic core 30' is resilient Iy suspended in the first transduction chamber 18' through a first upper helicoidal spring 26, arranged in the upper inlet chamber 12, and an opposing first lower helicoidal spring 28 interposed between the end of the first core 30' opposite the upper membrane 20 and a central portion 25a of the support 25.

The second ferromagnetic core 30" is resilient Iy suspended in the second transduction chamber 18' through a second upper helicoidal spring 32, interposed between the end of the second core 30" opposite the lower membrane 22 and the central portion 25a of the support 25, and an opposing second lower helicoidal spring 34 arranged in the lower inlet chamber 16.

The first core 30' is coupled with the upper membrane 20; the second core 30" is coupled with the lower membrane 22.

The first ferromagnetic core 30' is arranged in a partially compenetrated manner inside the first coil 24' and is movable with respect to the first transduction chamber 18', inside the support 25, due to a first fluid pressure that enters into the device T through the upper fluid intake passage 8a.

The second ferromagnetic core 30" is arranged in a partially compenetrated manner inside the second coil 24" and is movable with respect to the second transduction chamber 18", inside the support 25, due to a second fluid pressure that enters into the device T through the lower fluid intake passage 10a.

The compenetration degree of each ferromagnetic core 30', 30" in the respective coil 24', 24" depends upon the values of such first and second fluid pressures, or their difference, and correspondingly the value of the inductance of the respective coil 24b', 24b" depends upon it.

The device T further comprises an electronic elaboration circuit 38 that comprises a support plate 40 and a plurality of electronic components 42.

The circuit 38 is housed in a central recess 48a defined by the support 25.

The circuit 38 is connected to the coils 24' and 24" and is arranged to detect the variation of the inductance of the coils 24' and 24" above described, said variation being indicative of the value of the first and second fluid pressure, or of the value of their difference. In a per sέ known manner, the circuit 38 can comprise an LC-type oscillating circuit, in which the inductive component at least partially consists of the inductance of the coils 24b' and 24b".

The casing 1 finally has an upper opening 54 communicating with the upper inlet chamber 12 and a lower opening 44 communicating with the lower inlet chamber 16, each opening being equipped with a respective removable closure cap 56 and 46. Preferably, the upper spring 26 is interposed between the upper membrane 20 and the removable cap 56, the lower spring 34 is interposed between the lower membrane 22 and the removable cap 46.

The upper shell 2 and lower shell 4 finally define a seat 50 in which an electric connector 52 is inserted, connected to the electronic circuit 38.

Clearly, without affecting the principle of the finding, the embodiments and the details can be widely varied with respect to what has been described and illustrated purely by way of a non- limiting example, without for this reason departing from the scope of the invention as defined in the attached claims.