Pressure Sensor on a Ceramic Substrate

Abstract

A pressure sensor is disclosed. In an embodiment a pressure sensor includes a housing comprising a housing wall, a sensor element arranged inside the housing, a ceramic substrate acting as a carrier of the sensor element and of its electrical connection arranged inside the housing and a first heating element arranged inside the housing or the housing wall.

Claims

1-18. (canceled)

19. A pressure sensor comprising: a housing comprising a housing wall; a sensor element arranged inside the housing; a ceramic substrate acting as a carrier of the sensor element and of its electrical connection arranged inside the housing; and a first heating element arranged inside the housing or the housing wall, wherein the pressure sensor is configured to determine relative or absolute pressure.

20. The pressure sensor according to claim 19, wherein the first heating element is arranged on or in the ceramic substrate.

21. The pressure sensor according to claim 19, wherein the first heating element is arranged on an inner wall of the housing.

22. The pressure sensor according to claim 19, wherein the first heating element is arranged in the housing wall.

23. The pressure sensor according to claim 19, wherein the sensor element is arranged on the ceramic substrate in such a way that only an upper side of the sensor element is exposed to a pressure and only an absolute pressure is measurable.

24. The pressure sensor according to claim 19, wherein the ceramic substrate comprises an aperture, wherein the sensor element is arranged in the aperture such that independent media access is possible from an upper side and a lower side of the sensor element so that a relative pressure is measurable.

25. The pressure sensor according to claim 19, wherein the sensor element comprises a membrane on an upper side, wherein an upwardly open gel container is located on the ceramic substrate, and wherein the gel container has a gel filling that covers the membrane, the gel filling acting as protection for the membrane.

26. The pressure sensor according to claim 25, wherein the first heating element is arranged on the gel container.

27. The pressure sensor according to claim 19, wherein the first heating element comprises an electrically conductive plastic.

28. The pressure sensor according to claim 19, wherein the first heating element comprises a resistive element having a positive temperature coefficient.

29. The pressure sensor according to claim 19, wherein the first heating element is integrated into parts of the housing wall and is configured to generate microwave radiation.

30. The pressure sensor according to claim 19, wherein the first heating element comprises an electricity supply separated from the pressure sensor.

31. The pressure sensor according to claim 19, wherein the sensor element is a MEMS component.

32. The pressure sensor according to claim 19, further comprising a second heating element arranged at a different location than the first heating element.

33. The pressure sensor according to claim 19, wherein the pressure sensor is configured to measure a pressure during a cold engine start in a motor vehicle, and wherein the first heating element is configured to heat the pressure sensor to an established operating temperature at which a first pressure measurement can be carried out.

34. The pressure sensor according to claim 19, wherein the first heating element is configured to heat the pressure sensor to a temperature between 20 C. and 160 C.

35. A method for operating the pressure sensor according to claim 19, the method comprising: turning on the first heating element during a start-up of the pressure sensor in order to heat the pressure sensor until an operating temperature is reached.

36. The method according to claim .sub.35, further comprising turning off the first heating element when the operating temperature is reached.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention and its component parts will be explained in more detail below with the aid of a selection of exemplary embodiments and the associated schematic figures.

[0025] FIG. 1 shows a sectional view of a pressure sensor having a sensor element arranged on a ceramic substrate for absolute pressure measurement together with various positions for arranging a heating element;

[0026] FIG. 2 shows the sectional view of an alternative embodiment of the pressure sensor on a ceramic substrate for relative pressure measurement, with the various positions of a heating element and its possible relative arrangement; and

[0027] FIG. 3 shows the schematic sectional view of a sensor element.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0028] The sectional view shown in FIG. 1 shows the schematic structure of a pressure sensor DS for an absolute pressure measurement. It comprises a housing GH, comprising a housing wall GW. A ceramic substrate KS is fitted inside the housing, and a sensor element SE as well as a gel filling GF inside a gel container GB are arranged thereon. The sensor element is arranged on the ceramic substrate in such a way that pressure can act on the membrane of the sensor element only from one side. This side is the gel-covered upper side of the sensor element. The gel filling protects a pressure-sensitive membrane of the sensor element against moisture. Openings in the housing or the housing wall make it possible for atmospheric pressure also to be set up inside the housing and act on the gel, which transmits the pressure onto the membrane of the sensor element. Since the rear side of the sensor element is closed by the ceramic substrate, an absolute pressure measurement then takes place.

[0029] Furthermore, a plurality of different variants for the possible positioning of one or more heating elements H, in particular at positions A to G, are indicated. The exemplary fitting locations indicated for the heating element are as follows: the heating element may be arranged: [0030] in or on the ceramic substrate (positions A and B); [0031] in the housing, for example, internally on the housing wall (position C); [0032] inside the housing wall (position D); or [0033] on the gel container (position G).

[0034] The sectional view shown in FIG. 2 shows the schematic structure of a pressure sensor for a relative pressure measurement. It comprises a housing GH, comprising a housing wall GW. A ceramic substrate KS and a sensor element SE arranged thereon are fastened in the housing. The ceramic substrate KS comprises an aperture DL. The sensor element is arranged on the ceramic substrate in such a way that the aperture is located below sensor element. Through the aperture, a medium carrying pressure can be fed onto the lower side of the sensor element. The atmospheric pressure enters as a reference pressure through openings in the housing onto the upper side of the sensor element and thus makes a relative pressure measurement possible.

[0035] Furthermore, a plurality of different variants for the possible positioning of one or more heating elements H, in particular at positions A to D, are indicated. The exemplary fitting locations indicated for the heating element are as follows: the heating element may be arranged: [0036] in or on the ceramic substrate (positions A and B); [0037] in the housing, for example, internally on the housing wall (position C); or [0038] inside the housing wall (position D).

[0039] FIG. 3 shows an enlarged sectional view of the sensor element SE. In this case, a membrane of the sensor element MS can be seen, which in this case forms the upper side OS of the sensor element. Arranged opposite the upper side, there is a lower side US of the sensor element, on which a media passage MG to the membrane of the sensor element MS is located.

[0040] The form of the sensor element as represented in FIGS. 1, 2 and 3 is merely exemplary. Other forms or materials may be used in order to design a sensor element or the pressure sensor.

[0041] All representations in FIGS. 1, 2 and 3 are purely schematic and do not imply accurate size ratios of the components respectively represented.