Housing for at least one pressure sensor

Abstract

Housing for at least one pressure sensor for determining pressure in pneumatic systems of vehicles, with a support element (1) to which a plate-shaped element (5) is attached, and at least one pressure sensor (7) is attached to the plate-shaped element (5), and a channel (8) leads from a compressed air connection to the plate-shaped element (5), wherein the support element (1) is gas-tightly connected to a cover element (2) in a form-fitting and material-locking manner, and the cover element (2) is attached to an assembly of a pneumatic system by means of a screw connection at least at two positions; and wherein for the insertion of screws, an opening (9) is formed in the cover element (2) for each screw, and a base surface of the cover element (2) and areas of the base surface of the support element (1) are aligned with each other and the base surface of the cover element (2) together with the aligned areas of the base surface of the support element (1) are pre-tensioned against a surface of the respective assembly of the pneumatic system by means of the screw connection, characterized by the fact that a circumferential rib-shaped elevation (14) is formed on the support element (1), which is inserted in a form-fitting manner into a complementarily formed groove-shaped recess (15) which is formed on the cover element (2).

Description

[0001] The invention relates to a housing for at least one pressure sensor that can be used to determine the pressure of pneumatic systems, in particular vehicle braking systems. This is preferably a technical solution with two pressure sensors, with which a pressure or differential pressure determination can be performed at two positions.

[0002] Such pneumatic systems are subject to elevated internal pressures, which also fluctuate frequently. With the commonly used measuring principle, in which the internal pressure is determined via the deformation of an elastically deformable element, there is a risk of leakage in the respective pneumatic system if an elastically deformable element used to determine the pressure is destroyed. In the event of such destruction, additional protection against leakage is required to ensure the operational reliability of the pneumatic system, which is particularly important in pneumatic braking systems due to the safety aspect. Conventional solutions still have significant deficiencies in this regard, so this problem has not yet been satisfactorily resolved.

[0003] For example, WO 2012 / 014830 A1 describes a device for determining pressure.

[0004] JP H11 351 994 A also concerns a pressure measuring device.

[0005] It is therefore an object of the invention to provide possibilities with which the negative effect of a leak in the area of ​​pressure determination on a pneumatic system of a vehicle can be avoided, or at least its effect can be significantly reduced.

[0006] According to the invention, this object is achieved with a housing having the features of claim 1. Advantageous embodiments and further developments of the invention can be realized with features defined in subordinate claims.

[0007] The housing according to the invention consists of a support element connected to a cover element. At least one pressure sensor, for determining the pressure in pneumatic systems of vehicles, is mounted on a plate-shaped element, and the plate-shaped element is fastened to the support element.

[0008] In addition, a channel is led from a compressed air connection to the plate-shaped element.

[0009] The support element and the cover element are connected to each other in a form-fitting and gas-tight manner. The cover element can be attached to a component of the pneumatic system by means of a screw connection in at least two positions; To allow the passage of screws, a hole is provided in the cover element for each screw, and the base of the cover element and the areas of the base of the support element are aligned flush with each other. The base of the cover element can thus be pre-tensioned together with the aligned areas of the base of the support element by means of the screw connection against the surface of the respective component of the pneumatic system.

[0010] The support element and cover element are preferably made of a polymer, which can be done by plastic injection molding.

[0011] The screw connection allows both the cover element and the support element to be preloaded together with the same force or moment against the support surface on the pneumatic assembly.

[0012] Preferably, a sleeve-shaped element is guided through each opening; each sleeve-shaped element has an end face that is preferably aligned with the base surface of the cover element in the area around the opening. The opposite end face of the sleeve-shaped elements should project beyond the edge of the cover element, thus forming a collar-like element for supporting a screw. As a result, the maximum force transmission for fastening the housing occurs at least predominantly via the sleeve-shaped elements, and the support element, together with the cover element, is held preloaded against a support surface. With the same tightening torques for the screws, a uniform preload force can also be achieved.

[0013] The sleeve-shaped elements are preferably made of metal and can be incorporated into the polymer during plastic injection molding, which counteracts a reduction in the preload forces.

[0014] As already mentioned, two pressure sensors can be housed in a support element, each located on a plate-shaped element. A channel is then connected to each plate-shaped element, through which the pressure to be measured acts as a compressive force on the plate-shaped element.

[0015] A pressure sensor, which can preferably be formed with silicon, can advantageously be arranged on a plate-shaped element, with which a change in an electrical measuring signal proportional to the pressure of the pneumatic system can be detected via the deformation of an introduced membrane.

[0016] Plate-shaped elements can be made of ceramic material and secured in the material of the support element by means of a form-fitting connection. This can also be achieved during production using plastic injection molding. A combination of form-fitting and material-fitting connections is also possible. In this case, a plate-shaped element can be additionally bonded or welded to the support element.

[0017] It is possible to close an opening in the support element with a cap that can be rotated and fixed in the support element by means of a positive fit. The cap can be connected to the support element by a 90° rotation, thereby closing an opening in the support element. For this purpose, an outer contour is formed on the cap and a complementary contour is formed on the opening, which engage behind each other when fixed.

[0018] One or more cavities present in the support element or inside the housing should be filled with a polymer. This can be a polyurethane, which can be used to fill one or more cavities. This reduces the surface area available for force transmission due to the pressure that increases when a plate-shaped element is destroyed. This prevents the risk of destruction of the entire housing or the escape of the pressurized medium of the pneumatic system, or at least significantly reduces its impact.

[0019] It is advantageous if electrical contact pins, which are preferably embedded in a polymer and connected to the cover element, are led through the cover element from the outside to an electrical conductor track formed on the carrier element when the carrier and cover elements are connected to one another. The electrical conductor track and pressure sensors as well as any integrated control and evaluation electronics can thus be electrically contacted to the outside. The electrically conductive connection between the contact pins and the conductor track can be established without any further action when connecting the cover element to the carrier element. Contact pins can be inserted into receptacles which are designed like bores, for example. An electrically conductive material which belongs to the electrical conductor track or is connected to it is then present on the edges or inside the receptacles.

[0020] However, it is also possible to design contact pins with a spring element on at least one side. The spring elements are then pressed against the surface of a conductor track with a compressive force to create a secure electrically conductive connection. The contact pins can be connected to the electrical conductors by welding or soldering.

[0021] It is also possible to attach a protective cap element above a pressure sensor mounted on a plate-shaped element. This can extend over the entire surface of the respective plate-shaped element. It can serve as protection in the event of a bursting of the plate-shaped element and protect the housing from destruction or unwanted opening.

[0022] The cover element is additionally connected to the support element by a circumferential ridge-like protrusion formed on the support element, which can be inserted into a complementary groove-like recess on the cover element. Preferably, the surfaces of the ridge-like protrusion and the groove-like recess can be joined together in a material-to-material and gas-tight manner. A material-to-material connection can also be achieved by gluing or welding.

[0023] The circumferential ridge-like protrusion and groove-like recess should be aligned parallel to the direction of force exerted during assembly, including with the screws used to connect and secure the housing. A correspondingly adapted conical cross-section of the protrusion and recess can also be selected, which can facilitate insertion into each other when connecting the cover and support elements.

[0024] The inventive design makes it possible to ensure a largely gas-tight seal of the housing, even if a plate-shaped element bursts. At the very least, the resulting pressure drop in a pneumatic system can be significantly reduced, since sealing can also be achieved by individual or all interacting parts of the housing.

[0025] In addition, the housing represents a safe and cost-effective solution.

[0026] The invention will be explained in more detail below by way of example.

[0027] Showing: Fig. 1 a sectional view of an example of a housing according to the invention along the line AA of the Fig. 2 shown top view and Fig. 2 a top view of the example according to Fig. 1.

[0028] In Fig.Figure 1 shows a sectional view through an example of a housing according to the invention. A cover element 2 and a support element 1 are positively connected to one another. For this connection, a groove-shaped recess 15 is formed on the cover element 2, which runs circumferentially around the cover element 2, following the outer edge contour. A complementary web-shaped elevation 14 is also formed circumferentially on the support element 1. Both are conical in shape so that they can be easily inserted into one another. The depth and length of the recess 15 and the elevation 14 are dimensioned such that the end face of the elevation 14 inserted into the recess 15 does not touch the bottom or base of the recess 14 when the cover element 2 is correctly connected to the support element 1. The cover element 2 and the support element 1 are manufactured by plastic injection molding from PBT with 30% glass fibers (polybutylene terephthalate).

[0029] However, a recess 15 and a protrusion 14 can also be formed on the other element, i.e. a recess 15 on the support element 1 and a protrusion 14 on the cover element 2.

[0030] The support element 1 has two channels 8 through which the pressurized medium of the pneumatic system communicates with a plate-shaped element 5 made of ceramic, on which a pressure sensor is mounted. Depending on the level of the internal pressure in the respective channel 8, a pressure sensor 7 or a part of a pressure sensor 7 can deform to a greater or lesser extent. The respective deformation, or a constant, unchanged deformation at a constant internal pressure, can be detected with a pressure sensor 7 attached to the plate-shaped element 5 and used as a measure of the respective internal pressure.

[0031] In this example, a protective cap element 13 is present above the pressure sensors 7.

[0032] Electrical contact pins 12 are guided through the cover element 2, which here are guided outwards in a connection body 16 and up to an electrical conductor track (not shown here) which is formed on a region of the carrier element 1, into the interior of the housing.

[0033] On the cover element 2, two openings 9 are formed for screw fastening, into each of which a sleeve-shaped element 9.1 made of aluminum or another metal is inserted and is connected to the cover element 2 in a material and form-fitting manner during plastic injection molding.

[0034] The outer edge region of the cover element 2 points towards a pneumatic assembly (not shown) to which the housing is to be connected, the outer edge regions of the support element 1 pointing in the same direction, and the end faces of the sleeve-shaped elements 9.1 pointing in this direction are aligned with one another in a plane when the cover element 2 and the support element 1 are connected to one another as previously explained. If the housing is now fastened to the pneumatic assembly by means of the screw connection, these surface areas are pressed evenly with a constant force against the surface of the pneumatic assembly. Thus, no force transmission is required via the connection of the cover element 2 to the support element 1 in the area of ​​the elevation 14 and the depression 15.

[0035] In this example, there is an opening between the two channels 8, which can be closed with a cap 10. The cap 10 is simply rotated by 90°, and a secure, positive connection can be created using contour elements on the cap and on the support element 1 in the area of ​​the opening.

[0036] A cavity 11 is actually present between the cap 10 and the interior of the support element 1 in the area of ​​the opening. However, this cavity can be filled as completely as possible with polyurethane or another polymer in order to reduce the surface area exposed to increased internal pressure in the event of damage to one or both plate-shaped elements 5.

Claims

[1] Housing for at least one pressure sensor for determining a pressure in pneumatic systems of vehicles, with a carrier element (1) to which a plate-shaped element (5) is fastened, and the at least one pressure sensor (7) is attached to the plate-shaped element (5), and a channel (8) is guided from a compressed air connection to the plate-shaped element (5), wherein the carrier element (1) is connected in a form-fitting and material-locking manner to a cover element (2) and the cover element (2) is fastened to an assembly of a pneumatic system by means of a screw connection in at least two positions; and wherein for the passage of screws, an opening (9) is formed in the cover element (2) for each screw and a base surface of the cover element (2) and areas of the base surface of the support element (1) are aligned with each other and the base surface of the cover element (2) is fastened together with the aligned areas of the base surface of the support element (1) by means of the screw connection against a surface of the respective assembly of the pneumatic system, characterized by , that a circumferential web-shaped elevation (14) is formed on the carrier element (1), which is positively inserted into a complementarily formed groove-shaped recess (15) formed on the cover element (2). [2] Housing according to claim 1, characterized by in that a sleeve-shaped element (9.1) is guided through each opening (9); wherein the sleeve-shaped element (9.1) has an end face which is preferably aligned with the base surface of the cover element (2). [3] Housing according to claim 1 or 2, characterized bythat two plate-shaped elements (5), each with a pressure sensor (7), are attached to the carrier element (1) and a channel (8) is led to each plate-shaped element (5). [4] Housing according to one of the preceding claims, characterized by that the plate-shaped element(s) (5) is / are formed from a ceramic material. [5] Housing according to one of the preceding claims, characterized by that an opening of the carrier element (1) can be closed by positive locking with a cap (10) which can be rotatably fixed in the carrier element (1). [6] Housing according to one of claims 1 to 4, characterized by that an opening of the carrier element (1) is sealed gas-tight with an adhesive, a seal and / or a closure element. [7] Housing according to one of the preceding claims, characterized by that one or more cavities (11) in the housing are filled with a polymer. [8] Housing according to one of the preceding claims, characterized by that electrical contact pins (12) which are connected to the cover element (2) and are guided from the outside to an electrical conductor track formed on the carrier element (1) are guided through the cover element (2). [9] Housing according to one of the preceding claims, characterized by that a protective cap element (13) is mounted above a pressure sensor (7) arranged on a plate-shaped element (5). [10] Housing according to one of the preceding claims, characterized by that the surfaces of the web-shaped elevation (14) and the groove-shaped depression (15) are connected to one another in a materially bonded and gas-tight manner.

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