SENSOR ELEMENT FOR DETECTING AT LEAST ONE PROPERTY OF A FLUID MEDIUM

Abstract

A sensor element is provided for detecting at least one property of a fluid medium. The sensor element includes at least one housing. The housing forms at least one flow channel through which the fluid medium is able to flow. A pressure tap branches off from the flow channel, in which at least one pressure sensor for detecting a pressure of the fluid medium is situated. At least one cavity is situated between the flow channel and the pressure sensor for collecting contaminants in at least one wall of the pressure tap.

Claims

1-11. (canceled)

12. A sensor element for detecting at least one property of a fluid medium, comprising: at least one housing, the housing forming at least one flow channel through which the fluid medium is able to flow, a pressure tap branching off from the flow channel; and at least one pressure sensor being situated in the pressure tap configured to detect a pressure of the fluid medium; wherein at least one cavity is situated between the flow channel and the pressure sensor for collecting contaminants in at least one wall of the pressure tap.

13. The sensor element as recited in claim 12, wherein the sensor element is one of the following: an air mass meter, or a flow rate meter, or a current meter, or an absolute pressure meter, or a differential pressure meter.

14. The sensor element as recited in claim 12, wherein the pressure tap has a bore branching off from the flow channel.

15. The sensor element as recited in claim 14, wherein the bore is entirely or partially a cylindrical bore.

16. The sensor element as recited in claim 14, wherein the pressure tap is a blind-end bore branching off from the flow channel, the pressure sensor being situated on one end of the blind-end bore.

17. The sensor element as recited in claim 14, wherein the cavity is a recess in a wall of the bore).

18. The sensor element as recited in claim 14, wherein the recess has an annular shape.

19. The sensor element as recited in claim 18, wherein the recess having the annular shape has a diameter or equivalent diameter, which is at least 1.2 times the diameter or equivalent diameter of the bore.

20. The sensor element as recited in claim 17, wherein the recess has an undercut.

21. The sensor element as recited in claim 17, wherein the recess has at least one edge at a transition to the wall of the bore.

22. The sensor element as recited in claim 17, wherein between the recess and the pressure sensor, at least one wall section of the wall of the bore is situated, which has no recess.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Additional details and optional features of the present invention are presented in the exemplary embodiments, which are shown schematically in the figures.

[0023] FIG. 1 shows an exemplary embodiment of a sensor element according to the present invention.

[0024] FIGS. 2A and 2B show different illustrations of a sensor element according to the present invention in the form of a plug sensor.

[0025] FIG. 3 shows an induction tract of an internal combustion engine in which the sensor element of the present invention is situated between an intercooler and a throttle valve.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0026] FIG. 1 shows an exemplary embodiment of a sensor element 110 according to the present invention in a schematic sectional view. Sensor element 110 comprises a housing 112, which may be designed in one piece or in multiple pieces. Housing 112 forms at least one flow channel 114 through which the fluid medium is able to flow. Within the scope of the present invention there exist multiple possibilities as to how this housing 112 forms the flow channel 114. Thus flow channel 114 may be fully enclosed by housing 112 for example so that flow channel 114 is situated entirely in housing 112, for example. Alternatively or additionally, however, housing 112 may merely have or form at least one flow channel wall 116, across which the fluid medium is able to flow. Flow channel 114 may accordingly be designed as a flow tube for example or for example as an open space, which is formed at least on one side by flow channel wall 116.

[0027] At least one pressure tap 118 is formed in flow channel wall 116. Pressure tap 118 may be designed in particular entirely or partially as a bore 119. This pressure tap 118 branches off from the flow channel. For this purpose, pressure tap 118 may have for example, as shown in FIG. 1, a bore, which branches off from flow channel 114 preferably at a right angle with respect to flow channel wall 116. For example, it is possible for flow channel 114 to be designed in such a way that the fluid medium is able to flow through it in a main flow direction 120, which may be formed parallel to flow channel wall 116, for example. Pressure tap 118 and/or an axis 122 of pressure tap 118, for example a cylinder axis, may run for example generally perpendicularly with respect to this main flow direction 120. However, other embodiments are fundamentally also possible.

[0028] FIGS. 2A and 2B illustrate how housing 112 and pressure tap 118 may be designed. These figures thus show different illustrations of a sensor element 110 according to the present invention, which in the exemplary embodiments shown is designed as a plug sensor 124. Plug sensor 124 may project into flow channel 114 for example so that a flow channel wall 116 is partially formed by housing 112 of the plug sensor. FIG. 2A shows an embodiment of plug sensor 124 having a closed cover, whereas in the embodiment shown in FIG. 2B a cover is removed so that a channel section 126 situated in housing 112 is visible, into which fluid medium is able to enter through an opening 128. For possible embodiments of sensor element 110, it is possible to refer to the above-cited document DE 10 2007 053 273 A1, by way of example. However, other embodiments are fundamentally also possible. As may be seen in these figures, sensor element 110 may have multiple pressure taps 118, which may be situated within channel section 126 and/or on an outer side of plug sensor 124. Thus, any area of housing 112, which is reachable by the fluid medium and over which the fluid medium is able to flow, may act as a flow channel wall 116, which has at least one pressure tap 118. For example, in the example shown, two pressure taps may be situated on an outer side of housing 112, that is, on an outer side of plug sensor 124, and one pressure tap 118 may be situated in the interior of channel section 126. Various embodiments are possible.

[0029] As may be further seen in FIG. 1, at least one pressure sensor 130 is situated in pressure tap 118. For example, pressure tap 118 may be designed essentially cylindrically around axis 122, and pressure sensor 130 may be situated for example at one end of cylindrically designed pressure tap 118. For example, pressure tap 118 may be designed accordingly as a blind hole, having a side that is open toward flow channel 114 and a end face facing away from this open side, which is closed and on which pressure sensor 130 is situated.

[0030] Pressure tap 118 furthermore comprises a wall 132, which may be designed as cylinder wall 132 for example. This wall 132 may be designed for example in a circular-cylindrical manner. A polygonal cross section is fundamentally also possible however. In the exemplary embodiment shown, a cavity 134 is situated in this wall 132. This cavity 134, preferably has at least one sharp edge 136 so that cavity 134 preferably forms an undercut in cylindrical pressure tap 118. Cavity 134 may be accordingly developed for example as recess 138, for example as an annular groove, for example as a cylindrical annular groove. Cavity 134 may be for example axially symmetrical with respect to axis 122 and may have for example a diameter or equivalent diameter D.sub.K, whereas the cylindrical bore of the pressure tap 118 itself may have for example a diameter or equivalent diameter D.sub.D. Furthermore, along axis 122, cavity 134 may have for example a height, for example a cylinder height, H.sub.K. Between recess 138 and pressure sensor 130 and/or the end face of pressure tap 118, a wall section 140 may be situated for example, which is developed without recess and without cavity 134. Accordingly, cavity 134 may be developed for example at a distance from pressure sensor 130.

[0031] Sensor element 110, for example the sensor element 110 developed as plug sensor 124 as shown in FIGS. 2A and 2B, may be situated in an air system 142 of an internal combustion engine 144 for example, which is schematically shown in FIG. 3. As may be seen in FIG. 3, this air system 142 comprises an induction tract 144 having an air filter 146, an intercooler 148 and a throttle valve 150 as well as an exhaust tract 152 having an exhaust flap 154. Furthermore, optionally, an exhaust-gas recirculation system 156 may be provided. Sensor element 110 may be situated for example between intercooler 148 and throttle valve 150 and may be designed for example as a pressure-based air mass meter.

[0032] In the system shown, water and dirt particles are able to advance with the flow to pressure taps 118 of sensor element 110. Cavity 134 as shown in FIG. 1 is provided in order to protect the at least one pressure sensor 130, which is able to act as an absolute pressure sensor and/or as a differential pressure sensor, against water and/or dirt deposits. This may be developed as an undercut and may in this way be integrated into the pressure tap, whereby cavity 134 is formed. Drops of water that penetrate pressure tap 118 and run down wall 132 toward pressure sensor 130 are diverted by the undercut into cavity 134. Due to adhesion forces, the water remains in cavity 134 and does not advance to pressure sensor 130, as a result of which pressure sensor 130 remains protected against water and dirt particles until cavity 134 is completely filled. So that the water remains by adhesion in the cavity, the cavity height H.sub.K should not exceed 4 to 6 mm. Thus, generally, in this exemplary embodiment or also in other exemplary embodiments, cavity 134 may have a height H.sub.K, which preferably does not exceed 4 to 6 mm.

[0033] The protection against water may be increased by a greater cavity diameter D.sub.K. Alternatively or additionally, the cavity cross section A.sub.K may be improved while maintaining a maximum cavity height H.sub.K.

[0034] Furthermore, in this or also in other exemplary embodiments of sensor element 110, multiple cavities may be provided instead of a single cavity 134. Thus, for example, multiple recesses 134 may be provided, for example in the form of multiple sequentially arranged annular grooves, which are arranged along axis 118 in wall 132.