FR2707002A1 - Improved screened electrical sensor - Google Patents

Abstract

The present invention relates to a device of the sensor type, comprising: a sensor placed in a capsule (100), and a metallic screening casing (200) which surrounds the sensor capsule (100), characterised in that the metallic screening casing (200) is formed by a monobloc metallic element closed by folding over the sensor capsule (100) in order to pinch the latter elastically. The invention also relates to a sensor manufacturing method.

Description

 The present invention relates to the field of sensors, in particular force sensors, such as pressure sensors.

 The present invention relates, very particularly, but not exclusively, to the field of devices for measuring the intake pressure of the air / fuel mixture in a motor vehicle engine.

 Various devices have already been proposed comprising a piezoresistive transducer, generally a piezoresistive silicon transducer, capable of measuring the inlet pressure of the air / fuel mixture in a motor vehicle engine.

By way of nonlimiting example, mention may be made of the sensor sold by the company MOTOROLA under the reference MPX or else the sensor sold by the
SENSORTECHNICS company under the references SCC, SPX, SCX, etc ...

 These piezoresistive sensors generally comprise a capsule made of thermoplastic material which houses a structure of the Wheatstone bridge type with four elements implanted in a silicon wafer, so that the resistance of the elements of the bridge varies according to a pressure to be measured applied to the sensor. . The sensor therefore takes the form of a quadrupole supplied between two input terminals and delivering between its two output terminals a voltage proportional to the pressure to be measured. More precisely, the known sensors generally comprise an internal pressure reference so that the output voltage obtained between their terminals is proportional to the differential pressure between the reference pressure and the pressure to be measured.

 The sensor housing has a channel which ensures communication between the medium to be measured and the piezoresistive transducer.

 These sensors have already done great service.

 However, these sensors are fairly fragile and in particular very sensitive to mechanical vibrations, especially when used on motor vehicles.

 Furthermore, sealing on the sensor is not always easy to achieve.

 Document FR-A-2678066 describes a device intended to protect such a sensor with respect to mechanical vibrations and to ensure good sealing, which device comprises - two shells of flexible material defining in combination a chamber capable of accommodating the sensor capsule, while allowing the output wires of this sensor to pass, so that they are accessible outside the shells, and - a metal housing constituting a shield, formed of a casing and a cover comprising respective fixing means, designed to receive the two shells enveloping the sensor capsule and to compress them on the sensor output wires when the respective fixing means provided on the casing and on the cover are locked.

 The present invention now aims to further improve the known devices.

According to a first aspect the above object is achieved in the context of the present invention by means of a device of the type comprising
a sensor placed in a capsule, and
a metal shielding box which surrounds the sensor capsule, characterized in that the metal shielding box is formed by a one-piece metal element closed by folding over the sensor capsule to elastically pinch the latter.

 As will be explained in more detail below, the direct elastic clamping of the sensor capsule, obtained during the closing of the metal shielding case, makes it possible to almost completely eliminate the application of mechanical vibrations on the sensor. Direct elastic pinging also strengthens the seal.

 According to another advantageous characteristic of the present invention, the metal one-piece shielding casing is formed by stamping a sheet of steel.

 According to another advantageous characteristic of the present invention, the one-piece metal shielding casing has through passages for the electrical outputs of the sensor.

 According to another advantageous characteristic of the present invention, the one-piece metal shielding casing has elastic tabs projecting from its outer surface and which allow it to be fixed in an outer casing body.

According to a second aspect, the abovementioned object is achieved within the framework of the present invention by means of a manufacturing process comprising the steps which consist in
place a sensor capsule in a metal shielding box provided with through passages,
place the metal shielding box provided with the sensor capsule, in an external box body, and
introducing a coating resin into said outer casing body in order to immobilize the sensor capsule on the one hand in the metal shielding casing on the other hand immobilizing the metallic shielding casing in the outer casing body.

 Other characteristics, objects and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawings given by way of nonlimiting examples and in which - Figure 1 represents a sectional view axial view of a device according to the present invention according to the section plane referenced II in FIG. 2, FIG. 2 shows a top view of the same device before injection of the resin into the chamber of an outer casing body, - Figure 3 shows an end view of the same device, - Figure 4 shows a perspective view of the same device, - Figure 5 shows a sectional view of a metal shielding housing according to the present invention, before closing of it, - Figure 6 shows a partial top view of the same metal shielding box, - Figure 7 shows a top view of the same metal shielding box after closing, - Figure 8 shows a sectional view of the cover of the metal shielding box according to the cutting plane referenced VIII-VIII in Figure 7, - Figure 9 shows an end view of the same metal shielding box before closing , - Figure 10 shows a sectional view of a metal shielding box in accordance with the present invention receiving a sensor capsule, according to the cutting planes referenced XX in Figure 11, - Figure 11 shows a top view of the same metal shielding box equipped with a sensor capsule, - Figure 12 shows a top view of a spring plate used in the context of an alternative embodiment of the invention, - Figures 13 and 14 show two sectional views respectively orthogonal to each other according to the sectional planes referenced XIII-XIII and XIV-XIV in FIG. 12, of the same spring plate, and - FIGS. 15, 16, 17 and 18 represent t, according to simulated sectional views in Figure 1, four alternative embodiments of a sensor device according to the present invention.

 The sensor assembly according to the present invention, shown in FIGS. 1 to 4 appended, essentially comprises - a sensor capsule 100, - a metal shielding box 200, - an external box body 300, and - a resin of coating 400.

 The capsule 100 and the sensor housed therein can be the subject of numerous variant embodiments.

 Preferably as shown in the appended figures, in particular in Figures 1 and 10, the sensor comprises a capsule 100 made of plastic material. This capsule 100 has two main faces 110, 111 which are generally planar, mutually parallel and perpendicular to a central axis 102 of the housing 100. The peripheral surface 120 of the housing 100 is generally convex and of revolution around the axis 102. More precisely, this peripheral surface 120 is formed of five facets: a central facet 121 generally cylindrical of revolution around the axis 102 and parallel to it, two secondary facets 122, 123, arranged on either side of the central facet 121 , and two external facets 124, 125 placed respectively on either side of the aforementioned facets 122, 123.

 The secondary facets 122, 123 are symmetrical with respect to a median plane which is orthogonal to the axis 102. They are of frustoconical shape and converge towards the axis 102 away from the central facet 121. The external facets 124, 125 are cylindrical of revolution about the axis 102 and parallel to it.

 The housing 100 thus formed defines an internal chamber centered on the axis 102 designed to receive a semiconductor wafer, for example silicon. A gauging structure is installed in the pellet. It is generally a Wheatstone bridge with four elements, arranged so that the resistance of the elements of the bridge varies according to the pressure. The semiconductor chip may also include a signal processing circuit.

 The design of this sensor is however not limited to this particular arrangement. Other gauging configurations implanted in pellets are known to those skilled in the art and can be retained within the scope of the present invention.

 Pins 130 pass through the housing 100, perpendicular to the axis 102, along the above-mentioned median plane. The pins 130 emerge in the internal chamber of the housing 100 and also open onto the external surface 120 of the housing 100 at the level of the central facet 121. The semiconductor chip is connected to the pins 130 by means of welded connecting wires. .

 Generally, the external pressure is transmitted to the semiconductor wafer placed in the housing 100, via a silicone gel which coats the wafer in said internal chamber.

 The chamber housing the semiconductor wafer is generally closed by a cover plate placed in a recess 140 of the housing. A through passage 142 centered on the axis 102 is provided in the cover plate to transmit the external pressure to the semiconductor wafer. To properly understand the structure of the housing 100 and the sensor placed therein, reference may usefully be made to document FR-A2678066 and more particularly to FIG. 1 of this document.

 We will now describe the structure of the shielding box 200 according to the preferred embodiment of the present invention shown in FIGS. 5 to 9.

 As indicated above, according to an important characteristic of the invention, this metal shielding box 200 is formed of a one-piece element closed by folding on the capsule of the sensor 100 to elastically pinch the latter.

 Thanks to this direct elastic clamping of the capsule 100, the latter is immobilized inside the shielding box 200.

 Preferably, the metal shielding box 200 is formed by stamping a steel strip.

 Essentially, the metal shielding box 200 consists of a base 210 and a cover 250.

 The base 210 essentially comprises a bottom wall 220 and a peripheral wall 230.

 The bottom wall 220 is flat. Its surface corresponds substantially to the juxtaposition of a rectangle and a semicircle of the same diameter as the width of the abovementioned rectangle, which semicircle is centered on an axis 222 orthogonal to the wall 220. The bottom wall 220 is provided with a through passage 224 centered on the axis 222. After assembly, as seen for example in FIG. 10, the passage 224 is placed opposite the passage 142 formed in the housing 100.

 The peripheral wall 230 of the housing 200 surrounds the bottom wall 220 over its entire contour, with the exception of the straight edge 226 of this wall opposite the aforementioned semicircle.

 Thus, the peripheral wall 230 essentially consists of a semi-cylindrical wall 232 centered on the axis 222 and extended respectively on either side by two parallel flat walls 234, 236.

 At its apex opposite to the bottom wall 220, the peripheral wall 230 has indentations 238. By way of nonlimiting example, four cutouts 238 are thus provided in the top of the peripheral wall 230: two cutouts in the semi-cylindrical part 232 and a cutout 238 respectively in each of the flat walls 234, 236. This example is not , of course, not limiting.

 Note that to facilitate the engagement of the cover 250 in the peripheral wall 230, preferably the top of the latter is slightly flared towards the outside as referenced at 239.

 Furthermore, the engagement edges of the cutouts 238 are preferably slightly beveled as referenced at 237. The cover 250 is planar. It has a contour identical to the bottom wall 220. The base surface of the cover 250 is thus formed by the juxtaposition of a rectangle and a semicircle with the same radius as the width of the above-mentioned rectangle. The outer edge of the cover 250 is preferably slightly inclined towards the outside of the housing 200, as can be seen in particular in FIGS. 5, 8 and 9, to facilitate the engagement of the cover 250 in the peripheral wall 230.

 The cover 250 is provided on its periphery with projecting tabs 252, in a number equal to the number of cutouts 238 formed in the peripheral wall 230 and coinciding geometrically with these. These tabs 252 are also preferably inclined towards the outside of the housing 240, ie away from the wall 220.

 The cover 250 is articulated by its rectilinear edge 254 opposite the semicircle on the bottom wall 220, by means of a flap 270. The flap 270 is planar. Thus, the cover 250 is articulated on the bottom wall 220 by means of two folding or articulation lines, one corresponding to the zone 226 of connection between the bottom wall 220 and the flap 270, the other to the connection zone 254 between the flap 270 and the cover 250.

 As can be seen in FIG. 9, the flap 270 is provided with through passages 272 designed to receive the pins 130 emerging from the sensor housing 100. These passages 272 are preferably produced before folding and stamping of the housing 200. According to the mode of embodiment shown in the accompanying figures, there are provided three pins 130 emerging from the sensor housing 100 and therefore three passages 272 in the housing 200. This arrangement is not, however, limiting.

 We also see in Figures 7 and 9, two tabs 274 projecting from the edges of the flap 270 orthogonal to the fold lines 226, 254. As seen in Figures 7 and 9, these tabs 274 come to rest against the edge 235 of the walls 234, 236, perpendicular to the bottom wall 220. Thus, the tabs 274 make it possible to guarantee perfect perpendicularity of the flap 270 relative to the bottom wall 220 when the shielding box 200 is closed. As is seen in Figures 10 and 11, according to the invention ceramic capacities 280 are preferably placed around the pins 130 at the through passages 272. These capacities 280 preferably comprise a ceramic body generally cylindrical of revolution. More specifically, the ceramic body of the capacities 280 comprises two axially juxtaposed portions 281, 282 of different diameter defining at their junction a recess in the outer ring. The body of the capacitors 280 has a central through channel 283 suitable for receiving a pin 130. In addition, the body of the capacitors 280 is provided with an internal metallization at the level of the through channel 283 as well as an external metallization on its surfaces. revolution. The outside diameter of the portion 281 of smaller cross section is complementary to the diameter of the through passages 272 formed in the flap 270.

 Thus, when the capacities 280 are placed, through the interior of the housing 200, in the through passages 272, the capacities 280 are automatically immobilized in position, the recess formed between the parts 281, 282 coming to rest on the internal surface of the shutter 270 , as seen in Figure 10.

 Once the capacitors 280 are thus positioned, it remains to introduce a sensor box 100 into the shielding box 200, taking care to position the pins 130 respectively in the channels 283 of said capacitors 280.

 As can be seen in FIG. 11 in particular, preferably the pins 130 are themselves provided along their length, with a recess 132 adapted to rest against the capacities 280, the said recess 132 being positioned to guarantee alignment of the passage 142 formed in the housing 100 on the passage 224 formed in the base of the shielding housing 200, as seen in FIG. 10.

 The shielding box 200 can then be closed as shown in FIG. 10, to elastically pinch the box 100 directly at these main faces 110, 111. Thanks to the intrinsic elasticity of the material making up the box 200, this simultaneously gives on the one hand a firm hold on the housing 100 and moreover, and on the other hand a perfect seal between the internal surface of the shielding housing 200 and respectively the main faces 110, 111 of the sensor housing 100.

 The elastic locking of the shielding box 200 is obtained by virtue of the complementary geometry of the contour of the cover 250 and of the internal surface of the peripheral wall 230. Furthermore, the blocking of the box 200 in the closed position is guaranteed thanks to the inclination towards the outside of the peripheral edge of the cover 250 as indicated above and visible in particular in FIG. 10, which edge of the cover 250 comes into engagement with the internal surface of the peripheral wall 230.

 The external metallization of the capacitors 280 is welded to the shielding box 200 and the internal metallization of the capacitors 280 is welded to a respective pin 130.

 The shielding box 200 fitted with the sensor 100 can then be placed in the external box body 300. This sensor body 300 is preferably made of plastic. It is designed to fix the system on a suitable support.

 In the context of a particular but nonlimiting application, the sensor 100 comprises a piezoresistive silicon force transducer as indicated above and the sensor body 300 is designed to fix the assembly on an air intake pipe. motor vehicle engine to measure the pressure therein.

 The geometry of the sensor body 300 can be the subject of numerous variant embodiments. It will therefore not be described in detail below.

 However, it will be noted that this sensor body 300 essentially defines - a chamber 310, - a plunger 320, - a connector 330, and - a fixing flange 340.

 The chamber 310 is a blind chamber adapted to receive the shielding box 200. More precisely, as can be seen in FIG. 2, the chamber 310 has low walls 312, 314 serving to support the free outer edges 253 of the tabs 252 formed on the periphery of the cover 250. Thus, the shielding box 200 is driven into the chamber 310 and maintained by means of the fixing lugs 252 which come to rest by elastic deformation on the internal wall of this chamber 310, more precisely on the internal wall of the low walls 312, 314.

 here again, removal of the shielding box 200 from the chamber 310 is forbidden by virtue of the inclination of the tabs 252 towards the outside of the box 200, that is to say away from the bottom wall 220 as can be seen in the attached figures.

 It should also be noted that the chamber 310 is provided at its base with a circular rib 316 which surrounds the through passage 224 formed in the bottom wall 220.

Thus, thanks to the presence of the rib 316 on the bottom of the chamber 310, to the elasticity of the material making up the shield 200 and to the fixing lugs 252, one obtains during the engagement of the shielding box 200 in the chamber 310, a reinforcement or deformation of the bottom wall 220 which makes it possible to guarantee the seal between the base of the chamber 310 and the bottom wall 220, at the level of the top of the rib 316.

 According to the particular embodiment shown in Figure 1, this rib 316 is generally frustoconical. However, the invention is not limited to this particular embodiment.

 The plunger 320 projects from the body 300. It is generally cylindrical of revolution and centered around an axis 322 passing through the center of the aforementioned rib 316. The plunger 320 is designed to be engaged in a complementary channel formed in the receiving support, for example the air intake manifold.

 The plunger 320 is provided with a through channel 324 centered on the axis 322, and which opens into the chamber 310, opposite the passages 224 and 142 formed respectively in the shielding box 200 and the sensor box 100 to allow the application of the external pressure to the transducer housed in the housing 100.

 Preferably, the plunger 320 is provided with an external groove 326 suitable for receiving an O-ring seal 328.

 In Figure 1, there is shown a protective tip 329 placed on the plunger 320. This protective tip 329 is removed before implantation of the sensor.

 The sensor body 300 is molded onto connection pins 332 in a number equal to the number of output pins 130 mentioned above. Thus, three connection pins 332 are provided according to the particular and nonlimiting embodiment shown in the appended figures.

 These pins 332 emerge, on the one hand inside the chamber 310 receiving the shielding box 200, on the other hand at the level of the assembly 330 shaped into connector body 330. The geometry of the connection pins 332 can be the subject of numerous variant embodiments and will therefore not be described in detail below.

 The fixing flange 340 can also be the subject of numerous variants. Preferably, the fixing flange 340 is provided with a through passage 342 equipped with a metal ring 344, for example made of brass.

 After removal of the shielding box 200 fitted with the sensor 100, in the chamber 310, the pins 130 coming from the sensor box 100 are welded respectively to the connection pins 332 as that is referenced at 333 in FIGS. 1 and 2.

 To complete the assembly of the assembly, it remains to inject the mass of resin 400 into the chamber 310 of the housing 300. The resin 400 is preferably an epoxy resin.

 During the injection, this resin penetrates into the shielding box 200 to ensure the immobilization of the sensor box 100 in the shielding box 200.

 For this purpose preferably, the height of the cutouts 238 formed in the peripheral wall 230 of the shielding box 200 is adapted to one day leave under the tabs 252 and facilitate the penetration of the resin 400 into the shielding box 200.

 Furthermore, the resin 400 fills the chamber 310 as seen in FIG. 1 and also ensures the immobilization of the shielding box 200 in the chamber 310.

 Thus, coating with resin 400 makes it possible to avoid any vibration of the transducer placed in the housing 100.

 If necessary, if necessary, an O-ring can be added between the base of the chamber 310 and the bottom wall 220 of the shielding box 200, around the rib 316.

 If necessary, a seal can also be placed inside the shielding box 200, between the bottom wall 220 and the base of the box 100.

 Of course the present invention is not limited to the particular embodiment which has just been described but extends to any variant in accordance with its spirit.

 Thus, for example, as shown in FIG. 15, the shielding box 200 can be maintained in the chamber 310 of the external body 300 by means of a plate 500 driven itself into the chamber 310 of the body 300.

Such a plate 500 can replace the wise eye obtained using the tabs 252 according to the embodiment described previously, if these tabs 252 are removed, or even complete the hunting obtained using these tabs 252.

 The plate 500 can be the subject of numerous variant embodiments. Preferably, it conforms to the arrangements illustrated in FIGS. 12 to 14.

 The plate 500 shown in these figures generally conforms to the geometry of the cover 250 previously described.

 The plate 500 is thus designed to come to rest against the cover 250 inside the peripheral wall 230 of the shielding box 200.

 In fact, in FIGS. 12 to 14, we find a generally flat plate 500 whose surface is formed by the juxtaposition of a rectangle and a semicircle with a diameter equal to the width of the rectangle.

 The plate 500 is provided on its periphery with anchoring lugs 510 homologous with the lugs 252 provided on the cover 250 and adapted like these to be placed in the cutouts 238 formed in the peripheral wall 230 of the shielding box. Preferably, the plate 500 is also provided with an additional anchoring lug 512 at its straight edge 502 opposite the semicircle and adjacent to the connection zone 254 of the cover 250 in use.

 In addition, to avoid any play between the spring plate 500 and the cover 250 of the shielding box 200, the plate 500 is preferably provided with at least one elastic tongue 520 cut in its mass. More specifically, according to the nonlimiting embodiment shown in FIGS. 12 to 14, two elastic tongues 520 are thus provided cut out from the mass of the wafer 500 and elastically deformed towards the bottom of the chamber 310, ie towards the cover 250 .

 It should be noted that according to the variant shown in FIG. 15, the spring plate 500 and the shielding box 200 are coated with an epoxy resin 400 as described above.

 We find in the embodiment shown in Figure 16 a shielding housing 200 housing a sensor housing 100 and coated with an epoxy resin 400 in the chamber 310 of the housing 300. However according to the variant shown in Figure 16, the chamber 310 is closed by a cover 600. The cover 600 is fixed to the housing 300 by any suitable means, such as for example by ultrasonic bonding or welding. The cover 600 can be fixed on the housing 300 after injection of the coating resin 400. However, preferably, the cover 600 is fixed on the housing 300 before injection of the said resin. For this, the injection is carried out through the cover 600 by means of injection holes 610 formed therein.

 FIG. 17 shows an alternative embodiment according to which no coating resin 400 is injected into the chamber 310. Preferably, to perfect the anchoring of the shielding box 200, a hunting plate 500 conforming to that described opposite Figures 12 to 15 is used. Furthermore, preferably, the chamber 310 is closed by a cover 600 devoid of injection hole 610.

 The pins 130 and 332 not being coated with epoxy resin, preferably the welds 333, the capacities 280 as well as the pins 130 and 332 are protected by a varnish, a gel, an oil or any equivalent means.

 Finally, FIG. 18 shows another alternative embodiment devoid of coating resin 400, but comprising a chasing plate 500 and a cover 600 devoid of opening as described for FIG. 17. FIG. 18 differs from the embodiment shown in FIG. 17 by the presence of an O-ring seal 700 between the base of the chamber 310, around the rib 316 and the bottom wall 220 of the armor housing on the one hand, and d a seal, for example an elastomer molded seal, 710, between the bottom wall 220 of the shielding box 200 and the base wall 111 of the sensor box 100.

 The sensor obtained in the context of the present invention proves to be particularly advantageous due to its low number of parts, the excellent immunity to vibrations obtained and the tightness. Note also the ease of assembly of the assembly.

Claims (44)

 1. Device of the sensor type comprising - a sensor placed in a capsule (100), and - a metal shielding box (200) which surrounds the sensor capsule (100), characterized in that the metal shielding box (200 ) is formed of a one-piece metal element closed by folding on the sensor capsule (100) to elastically pinch the latter.  2. Device according to claim 1, characterized in that the metal shielding box (200) is self-locking.  3. Device according to one of claims 1 or 2, characterized in that the metal shielding housing (200) is placed in an external housing body (300).  4. Device according to one of claims 1 to 3, characterized in that it comprises a coating resin (400) placed in the metal shielding box (200) to prevent any vibration of the sensor capsule (100 ) In this one.  5. Device according to claim 3, characterized in that it comprises a coating resin in the outer casing body (300) to avoid any vibration of the metal shielding casing (200) therein.  6. Device according to one of claims 1 to 5, characterized in that the metal shielding housing (200) is stamped.  7. Device according to one of claims 1 to 6, characterized in that the metal shielding box (200) comprises a base composed of a bottom wall (220) generally planar and a peripheral wall (230) on the one hand, and a cover (250) articulated on the bottom wall (220) by means of a flap (270) on the other hand.  8. Device according to one of claims 1 to 7, characterized in that the metal shielding box (200) comprises through passages (272) for the electrical outputs of the sensor.  9. Device according to claims 7 and 8 taken in combination, characterized in that the through passages are formed in the articulation flap (270).  10. Device according to one of claims 1 to 9, characterized in that the metal shielding housing (200) comprises fixing lugs (252) in a chamber (310) formed in an external housing body (300) .  11. Device according to claims 7 and 10 taken in combination, characterized in that the fixing lugs (252) are formed projecting from the periphery of the cover (250).  12. Device according to one of claims 1 to 11 taken in combination with claim 7, characterized in that the peripheral wall (230) of the shielding box (200) has at its apex cutouts (238) in niche.  13. Device according to one of claims 1 to 12, characterized in that it comprises ceramic capacities (280) engaged on the output pins of the sensor at the passages (272) formed in the metal shielding box (200).  14. Device according to claim 13, characterized in that the capacitors (280) have internal and external metallizations and by the fact that there is provided a weld between the external metallization and the metal shielding housing (200) of on the one hand, and between the internal metallizations and the output pins (130) on the other hand.  15. Device according to one of claims 1 to 14, characterized in that the metal shielding box (200) is placed in a chamber (310) of an external box body (300) of thermoplastic material overmolded on connection pins (332).  16. Device according to one of claims 1 to 15, characterized in that the external housing body (300) receiving the metal shielding housing (200) has a circular rib (316) serving as a support for the base of the shielding box (200) to arm the latter and guarantee sealing between the outer case body (300) and the shielding case (200).  17. Device according to one of claims 1 to 16 taken in combination with one of claims 4 or 5, characterized in that the resin (400) is an epoxy resin.  18. Device according to one of claims 1 to 17, characterized in that it comprises a seal (710) between the base (220) of the shielding box (200) and the sensor box (100) .  19. Device according to one of claims 1 to 18 taken in combination with claim 3, characterized in that it comprises a seal (700) interposed between the base of the chamber (310) receiving the sensor housing (100 ) and the latter.  20. Device according to one of claims 1 to 19, characterized in that it comprises a spring plate (500) driven into the chamber of an external housing body (300) to immobilize the metal shielding housing (200 ).  21. Device according to one of claims 1 to 20, characterized in that it further comprises a cover (600) closing the chamber (310) of the outer housing body (300).  22. Device according to claim 21, characterized in that the cover (600) is provided with at least one through passage (610) for the injection of a coating resin (400).  23. Device according to one of claims 1 to 22, characterized in that the sensor (100) comprises a piezoresistive silicon transducer.  24. A method of manufacturing a sensor comprising the steps which consist in - placing a sensor capsule (100) in a metal shielding casing (200) provided with through passages (272), - placing the metal casing (200) provided of the sensor capsule (100) in an external housing body (300), and - introducing a coating resin (400) into said external housing body (300) in order to immobilize the sensor capsule (100) ) in the metal shielding box (200), on the other hand immobilize the metal shielding box (200) in the external box body (300).  25. The method of claim 24, characterized in that the metal shielding housing (200) is formed of a one-piece metal element closed by folding on the sensor capsule (100) to pinch it elastically.  26. The method of claim 25, characterized in that the metal shielding housing (200) is self-locking.  27. Method according to one of claims 24 to 26, characterized in that the metal shielding housing (200) is stamped.  28. Method according to one of claims 24 to 27, characterized in that the metal shielding box (200) comprises a base composed of a bottom wall (220) generally planar and a peripheral wall (230) on the one hand, and a cover (250) articulated on the bottom wall (220) by means of a flap (270).  29. Method according to one of claims 24 to 28, characterized in that the metal shielding box (200) comprises through passages (272) for the electrical outputs of the sensor.  30. Method according to claims 28 and 29 taken in combination, characterized in that the through passages are formed in the articulation flap (270).  31. Method according to one of claims 24 to 30, characterized in that the metal shielding housing (200) comprises fixing lugs (252) in a chamber (310) formed in an external housing body (300) .  32. Method according to claims 28 and 31 taken in combination, characterized in that the fixing lugs (252) are formed projecting from the periphery of the cover (250).  33. Method according to one of claims 24 to 32 taken in combination with claim 28, characterized in that the peripheral wall (230) of the shielding box (200) has at its apex cut-outs (238).  34. Method according to one of claims 24 to 33, characterized in that it comprises ceramic capacities (280) engaged on the output pins of the sensor at the level of the passages (272) formed in the metal shielding casing (200).  35. Method according to claim 34, characterized in that the capacitors (280) have internal and external metallizations and by the fact that a weld is provided between the external metallization and the metal shielding casing (200) of on the one hand, and between the internal metallizations and the output pins (130) on the other hand.  36. Method according to one of claims 24 to 35, characterized in that the metal shielding box (200) is placed in a chamber (310) of an external box body (300) of thermoplastic material overmolded on connection pins (332).  37. Method according to one of claims 24 to 36, characterized in that the external housing body (300) receiving the metal shielding housing (200) has a circular rib (316) serving as a support for the base of the shielding box (200) to arm the latter and guarantee sealing between the outer case body (300) and the shielding case (200).  38. Method according to one of claims 24 to 37, characterized in that the resin (400) is an epoxy resin.  39. Method according to one of claims 24 to 38, characterized in that it comprises a seal (710) between the base (220) of the shielding housing (200) and the sensor housing (100) .  40. Method according to one of claims 24 to 39, characterized in that it comprises a seal (700) interposed between the base of the chamber (310) receiving the sensor housing (100) and the latter.  41. Method according to one of claims 24 to 40, characterized in that it comprises a spring plate (500) driven into the chamber of an external housing body (300) to immobilize the metal shielding housing (200 ).  42. Method according to one of claims 24 to 41, characterized in that it further comprises a cover (600) closing the chamber (310) of the outer housing body (300).  43. Method according to claim 42, characterized in that the cover (600) is provided with at least one through passage (610) for the injection of the coating resin (400).  44. Method according to one of claims 24 to 43, characterized in that the sensor (100) comprises a piezoresistive silicon transducer.