Pressure sensor for detecting the pressure of a fluid medium

Abstract

A pressure sensor for detecting the pressure of a fluid medium, comprising a sensor housing (3, 2) in which a pressure sensor element (5) for detecting the pressure of the medium is arranged, wherein the sensor housing (2, 3) comprises at least one plug housing part (3) and at least one base housing part (2), wherein the plug housing part (3) is placed on the base housing part (2) in the direction of a central sensor axis (10) and is fixed to the base housing part (2), wherein at least one edge section (21) is formed on the base housing part (2), which edge section projects beyond a support surface (32) of the plug housing part (3) facing away from the base housing part (2), and the edge section (21) has at least one curved locking section (22) which bears against a support surface (32) of the plug housing part (3) facing away from the base housing part (2) and thereby fixes the plug housing part (3) in its position on the base housing part (2), characterized in thatthat the locking section (22) is bent around a bending axis (24) which is not perpendicular to the central sensor axis (10).

Description

State of the art

[0001] Pressure sensors for detecting the pressure of a fluid medium, such as gases and liquids, are well known in the art. The most common method of pressure detection uses a thin membrane as a mechanical intermediate stage for signal acquisition. This membrane is exposed to pressure on one side and deflects more or less under its influence. Its thickness and diameter can be adapted to the respective pressure range within wide limits.

[0002] Known pressure sensors often use a sensor housing with a two-part or multi-part housing, comprising a plug housing part and a steel base housing part, often in the form of a hexagon. A threaded piece is arranged on the base housing part and has a pressure channel in the form of a blind hole. The end region of the blind hole forms a thin membrane, which is provided on the side facing away from the blind hole with at least one sensor element which detects the deformation of the membrane and thus the pressure in the pressure channel. During assembly of the pressure sensor, the end of the threaded piece provided with the sensor element engages through a recess in the base housing part. The plug housing part is placed on from the other side, creating a closed interior space in which the sensor element is arranged.

[0003] Various designs are known for securing the connector housing part to the base housing part. For example, DE 103 15 405 A1 discloses a first embodiment with a sheet metal connecting part arranged between the base housing part and the connector housing part, which is welded to the base housing part and whose outer edge is flanged over a peripheral edge of the connector housing part. Another embodiment of this document discloses a tubular or pot-shaped connecting part, one end of which is integrated into the plastic connector housing part, for example by overmolding, and the other end of which is placed circumferentially on the base housing part and welded to the base housing part. In addition, a peripheral seal is provided between the connecting part and the connector housing part.

[0004] DE 100 14 992 A1 discloses a pressure sensor in which the base housing part has an edge section that is crimped over a bead of the plug housing part. The end of the edge section bent over by the crimping thus forms a locking section, which secures the plug housing part in its position on the base housing part. The seal between the plug housing part and the base housing part is achieved by a circumferential sealing adhesive.

[0005] US 5,595,939 A shows a two-part pressure sensor in which the sensor element is arranged on the connector housing part, and the base housing part is formed by a cover in which the pressure channel is also formed. In this document, the base housing part has a circumferential edge section projecting beyond the connector housing part, which is provided with a curved locking section in the form of a flange. The locking section rests against a support surface of the connector housing part facing away from the base housing part, thereby securing the connector housing part in its position on the base housing part. Furthermore, a sealing ring is inserted between the base housing part and the connector housing part for sealing.

[0006] DE 10 2013 226 060 A1 discloses an electrical device with a variable housing having a groove in which an edge portion of a printed circuit board is held. The housing comprises a cover and two tubular housing parts that are plug-connected to each other. Disclosure of the invention

[0007] The invention relates to a pressure sensor for detecting the pressure of a fluid medium. The pressure sensor has a sensor housing in which a pressure sensor element for detecting the pressure of the medium is arranged. The sensor housing comprises at least one connector housing part and at least one base housing part, but can also have more than two parts. As in the prior art, the connector housing part is placed on the base housing part in the direction of a central sensor axis and is secured to the base housing part. At least one edge section is formed on the base housing part, which edge section projects beyond a support surface of the connector housing part facing away from the base housing part, and the edge section has at least one curved locking section, which bears against a support surface of the connector housing part facing away from the base housing part and thereby fixes the connector housing part in its position on the base housing part.According to the invention, it is proposed that the locking section is bent around a bending axis that is not perpendicular to the central sensor axis. Advantages of the invention

[0008] In the solutions known in the prior art, the locking section is always bent around a bending axis perpendicular to the central sensor axis. This is particularly true for solutions with circumferential flanging. With this technology, the quality and strength of the connection depend both on the precise distance between the support surface of the connector housing part and the contact area on the base housing part and on the height of the edge section that projects beyond the connector housing part. Manufacturing tolerances are difficult to compensate for because, with large tolerances, bending the locking section around an axis perpendicular to the central sensor axis is not sufficient to compensate for the tolerances. This disadvantage exists regardless of whether the locking section consists of a flanged edge or of tabs that are bent in a direction perpendicular to the central sensor axis.

[0009] According to the invention, the locking section is instead bent around a bending axis that is not perpendicular to the central sensor axis, for example around a bending axis parallel to the central sensor axis. In this bending direction, the locking section is advantageously guided with its lower edge laterally and approximately parallel over the support surface of the plug housing part until the lower edge rests firmly against the support surface. The counterforces absorbed by the contact of the locking section with the support surface and resulting from the normal basic elasticity of the material of the plug housing part and base housing part and an optionally intermediate sealing ring and directed in the direction of the central sensor axis, advantageously do not act perpendicular to the bending axis due to the bending direction, unlike in the prior art, so that the locking sections cannot be bent back by the counterforces.This makes the entire attachment of the plug housing part to the base housing part particularly secure.

[0010] Advantageous embodiments and further developments of the invention are made possible by the features mentioned in the dependent claims.

[0011] Advantageously, the locking portion has an edge facing the support surface and resting on the support surface. The edge can, for example, simply be formed by the underside of a narrow sheet metal tab formed on the edge portion of the base housing part.

[0012] Because the edge is formed at an angle α greater than 0° and less than 90° to an imaginary plane running perpendicularly through the central sensor axis 10, tolerances in the geometric dimensions of the joining partners can be easily compensated for when bending the locking sections. It is therefore sufficient to bend the respective locking section around its bending axis until the locking section presses securely against the support surface with the angled edge.

[0013] A particularly advantageous embodiment is one in which the support surface of the connector housing part has at least one run-on bevel that interacts with the edge of the locking section, and the beveled edge runs onto the support surface via the run-on bevel when the locking section is bent around the bending axis. The run-on bevels on the connector housing part and the beveled edge of the locking section advantageously compensate for the play between these two joining partners and the always present component tolerances particularly easily when the locking section is bent.

[0014] In an inexpensive and easily manufactured embodiment, the base housing part is flanked on its periphery by two or more edge sections of the base housing part, in particular by diametrically opposed edge sections. The connector housing part is then advantageously inserted between the edge sections when placed on the base housing part and laterally aligned in its position.

[0015] It is particularly simple if an edge section, for example, has two locking sections protruding laterally from it, so that each edge section provides a double hold for the plug housing part.

[0016] The base housing part can further be designed as a hexagon, wherein a threaded piece can also be arranged on the hexagon from the side of the base housing part facing away from the plug housing part.

[0017] The base housing part can be manufactured cost-effectively as a deep-drawn part with the edge sections and the locking sections. Short description of the drawings

[0018] It shows Fig. 1 is an exploded view of a prior art construction of a pressure sensor not according to the invention, Fig. 2 a perspective view of a pressure sensor according to the invention in the finished state, Fig. 3a an enlarged detailed view of the pressure sensor Fig. 2 during assembly before bending the locking sections, Fig. 3a an enlarged detailed view of the pressure sensor Fig. 2 during assembly after bending the locking sections, Fig. 4a and Fig. 4b the assembly steps Fig. 3a and Fig. 3b shows an embodiment with run-up slopes on the support surface of the plug housing part. Embodiments of the invention

[0019] Fig. Figure 1 shows a conventional construction of a pressure sensor, as known, for example, from DE 103 15 405 A1, in an exploded view. A sensor housing of the pressure sensor 1 has a connector housing part 3 and a base housing part 2. The base housing part 2 is designed as a hexagon made of steel. A threaded piece 4 is fixed to the underside of the base housing part 2. The approximately cylindrical threaded piece 4 has Fig. 1 concealed underside, an invisible central blind hole-like pressure channel which extends along a sensor axis 10 to a membrane closing the pressure channel at the other end of the threaded piece. This membrane is preferably formed by a thin metal wall. On the side of the membrane facing away from the pressure channel, a pressure sensor element 5 is arranged, which detects a measured value resulting from a bending or vibration of the membrane under pressure load. The sensor element 5 can, for example, comprise a Wheatstone bridge circuit. The base housing part 2 has a central opening 27. During assembly, the sensor element 5, which is arranged on a protruding dome at the end of the threaded piece 4, extends through this opening 27. On the side of the base housing part 2 facing away from the threaded piece 4, a printed circuit board 6 with electronic components 62 of an evaluation circuit is arranged.This evaluation circuit is electrically connected to the pressure sensor element 5 via bonding wires (not shown). Contact springs 61 are also provided on the circuit board 6 for electrically contacting the connector housing part 3.

[0020] The connector housing part 3 has Fig. 1 has connecting elements not visible, which are injected into the plastic. In addition, for example, a tubular metallic connecting part 31 can also be injected into the plastic. The plug housing part 3 is placed along the central sensor axis 10 onto the base housing part 2, so that an encapsulated interior space is created between the plug housing part 3 and the base housing part 2, in which the sensor element 5 is arranged. When placed on, the contact springs 61 contact the connecting elements (not shown), which are led outwards through the plastic of the plug housing part 3 and are provided there as plug lugs or plug pins for connection to, for example, a control unit.

[0021] In Fig. 1 shows the central sensor axis 10. The pressure sensor is essentially rotationally symmetrical to the sensor axis 10. As can be seen, the connector housing part 3 is placed on the base housing part 2 in the direction of the sensor axis. To secure the connector housing part 3, the connecting part 31 is welded circumferentially onto the base housing part.

[0022] Fig. 2 shows a first embodiment of a pressure sensor 1 according to the invention. In comparison to Fig. 1, corresponding parts are provided with the same reference numerals. Here, too, the sensor housing comprises a base housing part 2 and a connector housing part 3. The connector housing part 3 is, in comparison to Fig. 1 without the connecting part 31 and is made of plastic, into which the connecting elements (not shown) are embedded. Fig. 2, which covers the base housing part 2, forms a support surface 32.

[0023] The threaded piece 4, which is fixed to the base housing part 2, for example by a weld seam, can be identical to the Fig. 1, so it need not be discussed in more detail here.

[0024] The base housing part 2 is in contrast to Fig. 1, however, is not designed as a plate-shaped hexagonal part, but as a metallic deep-drawn part that forms a kind of pot. The outer peripheral wall 28 of the pot again has a hexagonal cross-section, so that Fig. 2 the base housing part 2 forms a hexagon 26. The base housing part 2 has an opening in the bottom of this pot similar to that in Fig. 1 shown opening 27 for the passage of the sensor element 5.

[0025] As in Fig. 2, the plug housing part 3 engages in the peripheral wall 28 in such a way that an overhanging edge 34 of the support surface 32 comes to rest on the peripheral wall 28 and thereby closes the base housing part 2 as a cover, so that between the plug housing part 3 and the base housing part 2 there is a protected interior space in which the sensor element 5 is located, which is similar to Fig. 1 is contacted with the connection elements of the plug housing part 3 via a printed circuit board and contact springs.

[0026] In addition, a circumferential seal (not shown), for example in sealing adhesive or a sealing ring, for example similar to DE 100 14 992 A1, can be arranged between the plug housing part 3 and the base housing part 2 in order to reliably seal the interior of the sensor housing.

[0027] In Fig. 2 it can be seen that the base housing part 2 further has, for example, two edge sections 21 at the edges, which flank the plug housing part 3. Starting from the peripheral wall 28, each of the two edge sections 21 projects beyond the support surface 32 of the plug housing part 3 facing away from the base housing part 2 and protrudes from the peripheral wall 28 in the direction of the central sensor axis 10. As in Fig. 2, each of the two edge sections 21 has two locking sections 22. These locking sections are designed, for example, as tabs that protrude laterally from the respective edge section 21. The locking sections 22, together with the edge sections 21 and the base housing part 2, are formed in one piece as a deep-drawn part made of metal, for example, from a metal sheet.

[0028] During assembly, as in Fig. 3a and Fig. 3b. The connector housing part 3 is first moved along the central sensor axis 10, which is Fig. 2 forms the z-axis, and thus in the direction of arrow 100 in Fig. 3a is inserted into the cup of the base housing part 2. The projecting edge 34 of the support surface 32 slides between the two edge regions 21 in the direction of the arrow 100 until the projecting edge 34 rests against the peripheral wall 28 of the base housing part 2. In this position, the locking sections 22 are designed according to the peripheral contour of the hexagon 26. It can be seen in Fig. 3a, that the locking sections, starting from the edge section 21 at a corner of the hexagon 26, are aligned along two surfaces of the hexagon 26, so that they do not reach inwards in the direction of the z-axis and consequently do not hinder the penetration of the plug housing part 3 into the base housing part 2

[0029] After inserting the plug housing part 3 into the peripheral wall 28 of the base housing part 2, as shown in Fig. As shown in Figure 3b, the locking sections 22 are each bent around a bending axis 24. The respective bending axis 24 is preferably parallel to the central sensor axis 10 and therefore parallel to the z-direction. However, it is also possible for the bending axis not to run parallel to the central sensor axis 10, as long as it is not oriented perpendicular to the central sensor axis.

[0030] By bending the locking section 22 sideways in the direction of the arrows 101 in Fig. 3b, each locking section 22 is pivoted with its lower edge 23 laterally and approximately parallel to the xy plane over the support surface 32 of the plug housing part 3, which in this exemplary embodiment runs in this plane, until the lower edge 23 rests firmly against the support surface 32. The counterforces absorbed by the contact of the locking section 22 with the support surface 32 and resulting, for example, from the basic elasticity of the material of the plug housing part 3 and base housing part 2 and a sealing ring shown between the plug housing part 3 and base housing part 2, advantageously act parallel to the bending axes 24, so that the locking sections 22 cannot be bent back by the counterforces. In addition, the edges 23 of the respective locking sections 22 can, for example, claw into the plastic of the support surface 32.

[0031] In contrast, the flanged locking sections known from the prior art, or the locking section in the form of a flanged edge known from the prior art, is always bent perpendicular to the central sensor axis at all points of the peripheral wall there, so that the counterforces load the locking sections in the direction of their bending.

[0032] A particularly advantageous embodiment is shown in Fig. 4a and Fig. 4b. In this embodiment, as shown in Fig. 4a, the supporting surface 32 and in the secured state of the Fig. 4b, the edge 23 resting on the support surface 32 is formed at an angle α greater than 0° and less than 90° to an imaginary plane running perpendicularly through the central sensor axis 10, which corresponds to the xy-plane of the Fig. 2. The increase in Fig. 4a, starting from the edge portion 21, the distance between the edge 23 and the peripheral wall 28 is continuous due to the bevel of the edge 23. Corresponding to the inclination of the edge 23, the support surface 32 is also inclined by a similar or identical angle α greater than 0° and less than 90°.

[0033] In order to facilitate the sliding of the respective edges 23 onto the inclined support surfaces 32, the support surface 32 in this embodiment is provided with two run-on slopes 33, each run-on slope 33 cooperating with a locking section 22, as shown in Fig.4b. When the respective locking section 22 is bent about its bending axis 24, the edges 23 of this locking section 22 slide over the associated run-on bevel 33 onto the inclined support surface 32. The run-on bevel 33 thus serves as a sliding ramp, which facilitates the lateral sliding of the edges 23 onto the support surface 32. The combination of the inclination of the edge 23 and the run-on bevel 33 makes it particularly easy to compensate for tolerances in the geometric dimensions of the joining partners when bending the locking sections 22. It is therefore sufficient to bend the respective locking section 22 around the bending axis 24 until the edge 23 slides over the run-on bevel 33 onto the support surface 32 and presses securely against the support surface.

[0034] Of course, further embodiments are possible. For example, more than two edge sections 21 or just one edge section may be provided.

[0035] Likewise, each edge section can have only one locking section or more than two locking sections. The shape of the locking sections can be different from the illustrated tab. In principle, various embodiments are conceivable.

Claims

[1] A pressure sensor for detecting the pressure of a fluid medium, comprising a sensor housing (3, 2) in which a pressure sensor element (5) for detecting the pressure of the medium is arranged, wherein the sensor housing (2, 3) comprises at least one plug housing part (3) and at least one base housing part (2), wherein the plug housing part (3) is placed on the base housing part (2) in the direction of a central sensor axis (10) and is fixed to the base housing part (2), wherein at least one edge portion (21) is formed on the base housing part (2), which edge portion (21) projects beyond a support surface (32) of the plug housing part (3) facing away from the base housing part (2), and the edge portion (21) has at least one curved locking portion (22) which bears against a support surface (32) of the plug housing part (3) facing away from the base housing part (2) and thereby fixes the plug housing part (3) in its position on the base housing part (2), characterized bythat the locking section (22) is bent around a bending axis (24) which is not perpendicular to the central sensor axis (10). [2] Pressure sensor according to claim 1, characterized by that the locking section (22) is bent around a bending axis (24) parallel to the sensor axis (10). [3] Pressure sensor according to claim 1 or 2, characterized by that the locking portion (22) has an edge (23) facing the support surface (32) and resting on the support surface (32). [4] Pressure sensor according to claim 3, characterized by that the edge (23) is formed at an angle (α) greater than 0° and less than 90° to an imaginary plane (xy) running perpendicularly through the central sensor axis (10). [5] Pressure sensor according to claim 4, characterized bythat the support surface (32) has at least one run-on bevel (33) cooperating with the edge (23) and that by bending the locking section (22) about the bending axis (24) the beveled edge (23) is pushed onto the support surface (32) via the run-on bevel (33). [6] Pressure sensor according to one of the preceding claims, characterized by that the base housing part (2) is flanked on its circumference by two or more edge sections (21) which are formed on the base housing part (2), in particular by diametrically opposite edge sections (21). [7] Pressure sensor according to one of the preceding claims, characterized by that the at least one edge portion (21) is provided with two locking portions (22) projecting laterally from the edge portion (21). [8] Pressure sensor according to one of the preceding claims, characterized by that the base housing part (2) is designed as a hexagon (26). [9] Pressure sensor according to claim 8, characterized by that a threaded piece (4) is arranged on the hexagon (26) from the side of the base housing part (2) facing away from the plug housing part (3). [10] Pressure sensor according to one of the preceding claims, characterized by that the base housing part (2) is manufactured as a deep-drawn part.

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