WO2013083320A1

WO2013083320A1 - Pressure sensor arrangement for detecting a pressure of a fluid medium in a measuring space

Info

Publication number: WO2013083320A1
Application number: PCT/EP2012/070181
Authority: WO
Inventors: Ralf Kaiser
Original assignee: Robert Bosch Gmbh
Priority date: 2011-12-08
Filing date: 2012-10-11
Publication date: 2013-06-13
Also published as: DE102011088044A1

Abstract

The invention relates to a pressure sensor arrangement (10) for detecting a pressure of a fluid medium in a measuring space. The pressure sensor arrangement (10) comprises a sensor housing (12), at least one sensor element (18) that is arranged in or on the sensor housing (12) in such a way that it can be exposed to the medium in order to measure a pressure of the medium, a pressure connection (14), by means of which the pressure sensor arrangement (10) can be mounted on or in the measuring space, and a housing base (16), on which the sensor housing (12) is arranged. The housing base (16) is connected to the pressure connection (14) by at least one connection, selected from a friction-fit connection or a form-fit connection.

Description

Description title

Pressure sensor arrangement for detecting a pressure of a fluid medium in a measuring space

State of the art

Various devices and methods for detecting pressures of fluid media, such as gases and liquids, are known in the art. The measurand pressure is a occurring in gases and liquids, all-around, non-directed force effect. To measure the pressures, there are dynamically and statically acting transducers or

Sensors. Dynamically acting pressure sensors are only used to measure pressure oscillations in gaseous or liquid media. The pressure measurement can, for example, directly, via membrane deformation or by a

Force sensor done. In particular, to measure very high pressures, it would be fundamentally possible to expose an electrical resistance to the medium, because many known electrical resistances show a pressure dependence. In this case, however, the suppression of the simultaneous dependence of the resistances on the temperature and the pressure-tight implementation of the electrical connections from the pressure medium out are difficult.

A widespread method of pressure detection is therefore used for

Signaling first a thin membrane as a mechanical

Intermediate, which is exposed to pressure on one side and bends under its influence. It can be adapted within wide limits of thickness and diameter of the respective pressure range. Low pressure ranges result in comparatively large diaphragms with deflections that can range from 0.1 mm to 1 mm. However, high pressures require thicker, smaller diameter membranes, usually few

Bend micrometer. Such pressure sensors are for example in Konrad Reif (ed.): Sensors in motor vehicles, 1. Edition 2010, pages 80-82 and pages 134-136.

To attach the pressure sensors in or on the measuring chamber, they usually have a pressure connection. The pressure connection can

be executed for example as a threaded connector and screwed into a wall of a measuring chamber. The actual transducer or the actual sensor element is either directly or indirectly via a

Intermediate carrier arranged on a housing base. The housing base is formed either integrally or integrally with the pressure port, as disclosed for example in DE 01 2009 054 689 A1, or the

Housing base and the pressure port are separate components that are permanently connected to each other by means of a weld, as disclosed for example in EP 1 518 098 B1.

Despite the numerous advantages of the pressure arrangements known from the prior art, these still contain room for improvement. For example, the one-piece design of housing base and

Pressure connection relatively expensive to produce. In the case of two-part training, on the other hand, care must generally be taken to ensure that the materials used can be welded together. In addition, care must be taken to ensure a very accurate weld, otherwise the stability of the connection decreases and this can break with appropriate torque transmission when screwed into the wall of the measuring chamber.

Disclosure of the invention

It is therefore proposed a pressure sensor arrangement which avoids the disadvantages of known pressure sensors at least largely and the simple and inexpensive connection between the housing base and the

Pressure connection allows. The invention is fundamentally suitable for detecting a pressure at any place of use, in particular in the region of the pressures to be measured in a motor vehicle, in particular the high pressures prevailing, for example, in a common rail. One idea of the invention is the torque transmission, which is generally required for attaching and / or fixing the sensor arrangement to a measuring space, by means of a simple non-positive and / or positive connection between the pressure connection and the

Realize housing base.

The proposed pressure sensor arrangement serves to detect a pressure of a fluid medium in a measuring space. The pressure can basically be recorded as absolute pressure and / or as differential pressure. In addition, with appropriate integration of respective components, one or more other physical and / or chemical properties of the fluid medium may be determined, including, for example, a temperature, a further pressure, a flow characteristic, or one or more other properties. In principle, the measuring space can be any space in which the fluid medium, that is to say a gas and / or a liquid, is suspended or flowing. In particular, the measuring space may be a part of a fuel system. The pressure sensor arrangement can thus be used or configured in particular for detecting a fuel pressure.

The pressure sensor arrangement according to the invention comprises a sensor housing, at least one sensor element which is arranged in or on the sensor housing such that it can be exposed to the medium for measuring a pressure of the medium, a pressure connection by means of which the pressure sensor arrangement can be attached to or in the measurement space, and a housing base on which the sensor housing is arranged. The housing base is connected to the pressure port by at least one compound which is selected from a non-positive connection and a positive connection. The housing base may be connected to the pressure port by means of a press connection. The press connection may comprise a radial compression to a longitudinal axis of the pressure sensor arrangement. The pressure connection may comprise a pressure pipe which can be introduced into the measuring chamber. Of the

Housing socket can radially surround the pressure port in at least one section. The connection may be formed in the portion in which the housing base radially surrounds the pressure port. Of the Pressure port may have a portion with a knurled and the housing base may have an opening whose edge is provided with a knurled, wherein the portion with the knurled of the pressure port is disposed in the opening of the housing base. The knurl may be formed entirely in a circumferential direction of the portion of the pressure port and the opening. The knurls can be longitudinal knurls. Between the

Housing socket and the pressure port can be provided a seal. The seal can be provided by a corresponding geometric design of the portion with the knurled of the pressure port, a sealing ring and / or a sealing adhesive. The housing base may be formed at least partially in the form of a hexagon. The sensor element can be designed as a pressure measuring cell made of steel, in particular stainless steel. An evaluation circuit for outputting a signal which indicates the pressure acting on the sensor element can be arranged in the housing, wherein the evaluation circuit is arranged so as to be media-tight outside the medium. The pressure port may be formed as a threaded connector. The pressure connection can be fixed in particular by means of one or more connecting elements in the wall of the measuring space, for example by means of at least one external thread which engages in an internal thread of the wall of the measuring space. However, other fixations are generally possible alternatively or additionally. The fixation can be done in particular pressure-tight and / or media-tight.

In the context of the present invention, a non-positive connection is to be understood as meaning a connection which presupposes a normal force on the surfaces to be joined together, ie. H. a force perpendicular to the surfaces or with at least one component perpendicular to the surfaces. The mutual displacement of the surfaces is prevented, as long as caused by the static friction counterforce is not exceeded. Under a positive connection is within the scope of the present

Invention to understand a compound in which one of the connection partners blocks movement of the other connection partner in at least one direction. Primarily, only two components are positively connected to each other, but this is often achieved by means of a third part, the special connection element. For example, the connection is two overlapping To mention sheet metal edges by means of rivets or screws as a special fastener.

This should be distinguished from the cohesive connections. Cohesive compounds are compounds in which the connection partners are held together by atomic or molecular forces. They are at the same time non-detachable connections, which can only be separated by destruction of the connecting means. Examples include brazing, welding, gluing and vulcanization. Cohesive connections between a housing base and a pressure port are expressly not provided in the present invention and are avoided.

Under a press connection is in the context of the present invention, a compound of two parts on the principle of constant elastic

To understand biasing force by excess in the contact surfaces of parts to be joined. By means of the friction force generated in the connection during assembly, external loads are transmitted. This frictional force is caused by internal normal forces, which as a result of the elastic

Deformations of the parts to be joined arise and can also be referred to as pressing forces. Even after elimination of an external load, the internal normal forces are maintained, so that the connection is maintained even in this state. The internal normal forces can be generated, for example, by deformation, e.g. is generated mechanically or thermally, for example by a pressing operation or a choice of suitable materials with different thermal

Expansion coefficient. Most materials expand when heated. So can two parts that have been cooled and so on

are firmly connected after assuming the room temperature, since they have been firmly wedged by the expansion. This is also called cold stretching. In contrast, if one of the parts is heated before it is assembled with another part, it is called shrinking. Press connections are among the frictional

Connections, but are usually accompanied by a positive connection. Under a knurl is in the context of the present invention, a in a

Workpiece embossed pattern to understand. When knurling, a distinction is made between the non-cutting knurl pressing and the cutting knurl milling. Under a longitudinal knurl is therefore to be understood as a knurl with axially parallel grooves or längsachsparallelen grooves. The longitudinal knurl can be formed, for example, in a component with an axis, such as a longitudinal axis, completely or partially or in sections in the circumferential direction about the axis. The longitudinal knurl, for example in the form of a

To be formed toothing. By forming the knurl in the form of a toothing on a first component, the knurling of a second component, which is to be connected to the first component, in the connected state, a meshing can be realized similar to gears with appropriate training. By such a mesh, for example, forces or torques between the components with a high

Efficiency can be transmitted safely. The grooves or the grooves lying between them can be uniform or non-uniform

be spaced apart. For example, the grooves may be one length, i. H. a dimension in an axis-parallel or längsachsparallelen direction of 2 mm to 10 mm, preferably from 3 mm to 8 mm and more preferably from 5 mm to 6 mm, for example, 5.5 mm. For example, the grooves may have a height, i. H. have a dimension in a radial direction of from 0.2 mm to 4 mm, preferably from 0.3 mm to 2 mm and more preferably from 0.5 mm to 1 mm, for example 0.75 mm. In the context of the present invention, a discharge nozzle is to be understood as meaning a projection or tube piece with at least one bore through which the fluid medium can be conducted to the sensor element, for example a cylindrical bore in a cylindrical nozzle. The discharge nozzle may be formed as a pressure-resistant nozzle, so as not to be damaged by the high pressures occurring in a fuel line.

In the pressure sensor arrangement according to the invention a simple and inexpensive connection between the joining partners pressure port and housing base, which may be at least partially designed as a hexagon created. Both joining partners may consist of different materials, so that in particular the material of the pressure connection to the can be adapted to the respective site or customer. The

Compound is safe with respect to a torsional stress with appropriate geometric design, such as in the form of Längsrändeln. Brief description of the drawings

Further optional details and features of the invention will become apparent from the following description of preferred embodiments, which are shown schematically in the figures.

Show it

Figure 1 is an exploded view of an inventive

Pressure sensor arrangement and

Figure 2 is a sectional view of the pressure sensor arrangement according to the invention. EMBODIMENTS OF THE INVENTION FIG. 1 shows an exemplary embodiment of a pressure sensor arrangement 10 according to the invention in an exploded view. The

Pressure sensor assembly 10 may be formed, for example, for detecting a pressure of fuel in a fuel line of an internal combustion engine. The pressure sensor assembly 10 includes a sensor housing 12, a

Pressure port 14, a housing base 16 in the form of a hexagon and a sensor element 18. A circuit board 20 with a not shown in detail

Evaluation circuit which is adapted to output a signal indicating a pressure acting on the sensor element 18 is attached to the housing base 16, for example by means of an adhesive film 22. The pressure connection 14 may be made of metal and can be used as a cylindrical pressure connection, in particular as a threaded connection. be formed, the cylinder axis coincides with a longitudinal axis 24 of the pressure sensor assembly 10. The pressure port 14 has at one end an opening 26 for the pressurized medium to be measured, which is located in a measuring space, not shown, such as a fuel line. In one embodiment of the pressure port 14 as a threaded connector this may have an external thread, which serves to attach the pressure port 14 on or in a wall of the measuring chamber, wherein the external thread engages in a suitably shaped internal thread of the wall of the measuring space. The housing base 16 may also be made of metal. The sensor element 18 can be connected to the pressure port 14 by means of a

Welded connection be connected. In its interior, the discharge nozzle 14 has a channel 28 adjoining the opening 26 (FIG. 2). The channel 28 extends coaxially to the cylinder axis of the pressure port 14 and the longitudinal axis 24 of the pressure sensor assembly 10. Through the channel 28, the medium passes from the opening 26, starting to the sensor element 18. At the opposite end of the opening 26 of the pressure port 14, the pressure port 14 on its outer side or on its outer circumference a section 30 with a knurl 32. The knurl 32 is in the section 30 in particular completely in the circumferential direction about the cylinder axis of the

Pressure port 14 and the longitudinal axis 24 and formed as a longitudinal knurl, so that their grooves extend parallel to the longitudinal axis 24. As a result, the section 30 is formed overall in the form of a toothing.

The housing base 16 has in its center an opening 34, whose

Center may lie on the longitudinal axis 24 and the housing base 16 can penetrate completely in the direction of the longitudinal axis 24. The opening 34 may thus be formed as a through hole. An edge 36 of the opening 34 has a knurl 38 which is formed as a longitudinal knurl and is thus formed as internal toothing. The knurl 38 of the housing base 16 is formed so that it can engage in the knurls 32 of the portion 30 at the pressure port 14 and is therefore complementary to this. The knurls 32, 38 can be realized such that the knurls 32 on the

Pressure connection 14 is provided via a turning operation and the knurl 38 is introduced into the housing base 16 by a punching process or an injection process.

FIG. 2 shows a sectional view of the pressure sensor arrangement 10 in FIG

assembled condition. As can be seen from the illustration of FIG. 2, the pressure port 14 is connected to the section 30 in the opening 34 of FIG

Housing socket 16 received or arranged. The housing base 16 thus encloses the pressure port 14 radially in the section 30. Of the Pressure port 14 is thus connected positively to the housing base 16 as seen in the radial direction with respect to the longitudinal axis 24, ie the pressure port 14 can not move in the connected state in the radial direction relative to the housing base 16. Thus, the housing base 16 and the pressure port 14 are firmly connected, there is a particular between the pressure port 14 and the housing base 16

non-positive connection, as a press connection, in particular as

Press connection in the radial direction with respect to the longitudinal axis 24, is provided. The housing base 16 can be fixed on the portion 30 of the pressure port 14, for example, by heating the housing base 16 and, in the heated state with the opening 34, being pushed onto the pressure port 14, in particular the portion 30, and by cooling,

for example, to room temperature, the non-positive press connection is realized. Of course, it is alternatively or additionally possible to cool the pressure port 14 and to push the housing base 16 onto the section 30. Due to the knurls 32 in the section 30 and the knurls 38 in the edge 36 of the opening 34 in the housing base 16 an interlocking toothing is formed. Thus, the housing base 16 and the pressure port 14 are torsionally connected. The pressure port 14 and the housing base 16 may be made of the same or different materials. Important with regard to the choice of material for the respective place of use is that the positive connection by appropriate choice of

Thermal expansion coefficient of the respective materials over the entire temperature range occurring during use remains and a different expansion behavior during use can not lead to a release of the compound. For example, if the pressure sensor assembly 10 is to be used in an environment whose temperature is permanently or predominantly higher than a common room temperature of 20 ° C to 25 ° C, the pressure port 14 may be made of a material whose thermal expansion coefficient is higher than the thermal expansion coefficient of the housing base 16. As a result, the pressure port 14 expands more with increasing temperature than the housing base 16 and the portion 30 pushes more against the edge 36 of the opening 34. Thus increases with increasing temperature, the strength of the connection between the

Pressure port 14 and the housing base 16. Accordingly, must

Connecting the pressure port 14 and the housing base 16, the temperature the housing base 16 may be higher than the temperature of the pressure port 14, so that the housing base 16 is more expanded, a diameter of the opening 34 is greater than a diameter of the pressure port in the section 30, and the housing base 16 can be pushed onto the pressure port 14. If the pressure sensor assembly 10 is to be used, for example, in an environment whose temperature is permanently or predominantly lower than a standard room temperature of 20 ° C to 25 ° C, for example 10 ° C or less, the above-mentioned embodiments apply correspondingly reversed. In this case, the thermal expansion coefficient of the pressure port 14 may be smaller than the thermal expansion coefficient of the housing base 16. A cohesive connection between the

Housing socket 16 and the pressure port 14 is in the context of

expressly not provided for in the present invention. The printed circuit board 20 is fixed to the housing base 16 by means of the adhesive film 22. The sensor housing 12 has at its end facing the housing base 16 a beading 40 which extends in a circumferential direction about the longitudinal axis 24 and is inserted into a suitably shaped groove 42 on the housing base 16 on the side facing away from the pressure port 14 side. The housing base 16 has, seen in the radial direction, further outwardly than the groove 42 and adjacent to the groove 42 also a beading edge 44, which is connected to the beaded edge 40 of the sensor housing 12 by crimping. As a result, the sensor housing 12 is attached to the

Housing base 16 attached.

The sensor element 18 is therefore located in the interior of the sensor housing 12. The sensor element 18 is arranged in particular in or on the sensor housing 12 such that it can be exposed to the medium for measuring the pressure of the medium. This can be realized in that the medium can reach the sensor element 18 through the opening 26 and the channel 28 in the pressure connection 14. In the interior of the sensor housing 12 is also the adhesive film 22 and the circuit board 20. The sensor element 18 penetrates in particular the adhesive film 22 and the circuit board 20 by being passed through a corresponding opening 46 in the adhesive film 22 and a corresponding opening 48 of the circuit board 20 , The adhesive film 22 and the printed circuit board 20 are thus arranged coaxially with the sensor element 18. The Evaluation circuit on the circuit board 20 is thus arranged media-tight outside the medium. The sensor element 18 can, for example, as

Pressure measuring cell be made of stainless steel, which has on the side facing away from the medium resistors in thin-film technology. These may be connected to a Wheatstone bridge whose resistance changes due to the applied pressure. The processing and signal amplification of the pressure signal by means of the not shown in detail evaluation circuit on the circuit board 20, which may be in the form of an application-specific integrated circuit (English, application-specific integrated circuit, ASIC), also called custom chip, or realized by a hybrid , An ASIC is one

electronic circuit that has been realized as an integrated circuit. The function of an ASIC is therefore no longer manipulatable. The contacting of the pressure measuring cell to the evaluation circuit on the printed circuit board 20 can be realized either via a flex foil soldered or glued to the electrical contact surfaces or via an additional intermediate carrier (spacer). The intermediate carrier is thereby using bonds with the

Contact pressure cell. The placed on the intermediate carrier

Evaluation circuit is soldered, for example. The contacting of the evaluation circuit on the circuit board 20 in a device plug, not shown, which is inserted or inserted into the housing base 16 remote from the end of the sensor housing 12, either via soldered flexible lines or directly via connector pins 50, in the transition from the sensor housing 12 to the device connector be sealed by soft rubber, which may be disposed inside the sensor housing 12. Another way to make electrical contact is by a coil spring or an S-shaped leaf spring 52, which allows a simple, automated assembly of the device connector. An additional seal between the pressure port 14 and the

Housing base 16 can be done either via a turned-sealing geometry on the pressure port 14, a sealing ring or a subsequent sealing gluing. For example, the pressure port 14 at its

Outer circumferential surface has a groove 54 for an O-ring, which in

Circumferentially extending and adjacent to the section 30. When screwing the pressure port 14 into the wall of the measuring space of the O-ring is then between the wall of the measuring chamber and the housing base 16 is pressed so that no fluid medium between the portion 30 at the pressure port 14 and the edge 36 of the opening 34 in the housing base 16 can penetrate. It is to be expressly understood that all features disclosed in the specification and / or claims are intended to be separate and independent of each other for the purpose of original disclosure as well as for the purpose of limiting the claimed invention independently of the claims

Feature combinations in the embodiments and / or the claims are to be considered. It is explicitly stated that all

Range indications or indications of groups of units disclose every possible intermediate value or subgroups of units for the purpose of the original disclosure as well as for the purpose of restricting the claimed invention, in particular also as a limit of a range indication.

Claims

claims

1 . Pressure sensor arrangement (10) for detecting a pressure of a fluid

Medium in a measuring chamber, comprising a sensor housing (12), at least one sensor element (18) arranged in or on the sensor housing (12) such that it can be exposed to the medium for measuring a pressure of the medium, a pressure port (14) , by means of which the pressure sensor arrangement (10) can be attached to or in the measuring space, and a housing base (16) on which the sensor housing (12) is arranged, characterized in that

the housing base (16) is connected to the pressure port (14) by at least one connection selected from a non-positive connection and a positive connection.

2. Pressure sensor arrangement (10) according to the preceding claim, wherein the housing base (16) with the pressure port (14) by means of a

Press connection is connected.

3. pressure sensor assembly (10) according to the preceding claim, wherein the press connection comprises a radial compression to a longitudinal axis (24) of the pressure sensor assembly (10).

4. Pressure sensor arrangement (10) according to any one of the preceding claims, wherein the pressure port (14) comprises a can be introduced into the measuring chamber pressure port.

5. Pressure sensor arrangement (10) according to one of the preceding claims, wherein the housing base (16) radially surrounds the pressure connection (14) in at least one section (30).

6. Pressure sensor assembly (10) according to the preceding claim, wherein the compound in the portion (30) is formed, in which the

Housing socket (16) radially surrounds the pressure port (14).

7. pressure sensor assembly (10) according to any one of the preceding claims, wherein the pressure port (14) has a portion (30) with a knurled edge (32) and the housing base (16) has an opening (34) whose edge (36) with a Knurl (38) is provided, wherein the portion (30) with the knurls (32) of the pressure port (14) in the opening (34) of the

Housing socket (16) is arranged.

8. Pressure sensor assembly (10) according to the preceding claim, wherein the knurls (32, 38) are formed completely in a circumferential direction of the portion (30) of the pressure port (14) and the opening (34).

9. pressure sensor assembly (10) according to one of the two preceding

Claims, wherein the knurls (32, 38) are longitudinal knurls.

10. Pressure sensor arrangement (10) according to any one of the preceding claims, wherein between the housing base (16) and the pressure port (14) is provided a seal.