PRESSURE SENSOR HAVING A MEMBRANE HAVING SENSOR CHIPS HAVING MEASURING BRIDGES HAVING SENSOR ELEMENTS

Abstract

The invention relates to pressure sensors having a membrane having sensor chips having measuring bridges having sensor elements, wherein the membrane is fastened in a housing, with a carrier or as part of a housing, to which membrane a working medium can be applied. The pressure sensors are characterised in particular in that the mechanical stresses resulting from a fastening and/or an installation of the pressure sensors do not influence the measurement result and/or the measurement signal. To this end, at least two sensor chips, which are spaced apart from one another and are offset at an angle to one another, are located at least on a side of the membrane that bends on application of pressure. The measuring bridges are designed and/or connected to a controller in such a manner that at least one force resulting from the fastening of the membrane and thus acting on the membrane is or will be compensated.

Claims

1. A pressure sensor having a circular membrane (1) having sensor chips (2, 3) arranged on a circular ring of the same diameter having measuring bridges having sensor elements, wherein a working medium can be applied to the membrane (1) and wherein at least two sensor chips (2, 3), which are spaced apart from one another and are offset at right angles to one another, are located at least on a side of the membrane (1) that bends on application of pressure, as a result of which mechanical stresses which arise when the pressure sensor is screwed in are compensated, in that the changes in the bridge stress from the bending load in the two sensor chips (2, 3) are almost the same, but have opposite signs in terms of amplitude and, as a result, cancel one another out.

2. The pressure sensor according to claim 1, characterized in that the measuring bridges of the sensor chips (2, 3) are connected in parallel to one another in such a manner that at least one force resulting from the fastening of the membrane (1) and thus acting on the membrane (1) and the at least one mechanical stress resulting therefrom can be compensated.

3. (canceled)

4. The pressure sensor according to claim 1, characterized in that the sensor elements of the measuring bridges are monolithic silicon bridge arrangements or the sensor elements of the measuring bridges consist of a piezoelectric element (30).

5. The pressure sensor according to claim 1, characterized in that the sensor chips (2, 3) are arranged off-center on the membrane (1).

6. (canceled)

7. The pressure sensor according to claim 1, characterized in that the membrane (1) is arranged in such a manner that a working medium can be applied to said membrane on one side or both sides.

8. The pressure sensor according to claim 1, characterized in that the at least two sensor chips (2, 3) having the measuring bridges having the sensor elements, which sensor chips are spaced apart from one another and are offset at an angle to one another, are located on the side of the membrane (1), to which the working medium can be applied on one side, said side facing away from the working medium.

9. The pressure sensor according to claim 1, characterized in that the sensor chips (2, 3) are arranged on the membrane (1) in such a manner that the same mechanical stresses emanating from the working medium are applied to the sensor chips (2, 3).

10. The pressure sensor according to claim 1, characterized in that the membrane (1) is arranged in a housing (4), the housing (4) has a cavity covered with a region of the membrane (1), which cavity has an opening and/or a channel for a working medium to pass through, wherein the cavity is located on the side of the membrane (1) opposite the side having the sensor chips (2, 3).

11. The pressure sensor according to claim 1, characterized in that the membrane (1) is a wall or a part of a wall of a housing (4), the housing (4) has a cavity covered with the wall and the sensor chips (2, 3) are located on the surface of the membrane (1) pointing into the cavity.

12. The pressure sensor according to claim 11, characterized in that the membrane (1) is conical or frustoconical or the membrane (1) is located in a frustoconical ring.

Description

[0027] Therein:

[0028] FIG. 1 shows a membrane of a pressure sensor,

[0029] FIG. 2 shows a pressure sensor having a housing and a threaded piece as a fastening element,

[0030] FIG. 3 shows the pressure sensor having a membrane, and

[0031] FIG. 4 shows a pressure sensor having a membrane on the front.

[0032] A pressure sensor substantially consists of a membrane 1 having sensor chips 2, 3 having measuring bridges having sensor elements.

[0033] FIG. 1 shows a membrane 1 of a pressure sensor in a basic representation.

[0034] Two sensor chips 2, 3, which are spaced apart from one another and are offset at an angle to one another, are arranged on the membrane 1. The measuring bridges of the sensor chips 2, 3 are designed and/or connected to a controller in such a manner that at least one force resulting from the fastening of the membrane 1 and thus acting on the membrane 1 can be compensated and thus is compensated or will be compensated. To this end, the measuring bridges can be connected in parallel to one another in such a manner that mechanical disturbances can be compensated. The measuring bridges can, furthermore, be offset at right angles to one another. The sensor elements of the measuring bridges are monolithic silicon bridge arrangements.

[0035] The forces resulting from the fastening of the membrane 1 and thus acting on the membrane 1 are in particular mechanical disturbances from mechanical stresses of approximately the same amplitude and the opposing working direction in the sensor chips 2, 3. Therefore, the stress on the membrane resulting from the bending load, with the same radius and measuring bridges arranged at right angles to one another and, thus, the sensor chips, is the same amount but has opposite signs, whereas the stresses on the measuring bridges of the sensor chips caused by the pressure to be measured are of the same sign. By connecting the measuring bridges, which are arranged on the same radius of the membrane and at right angles to one another, in parallel, said measuring bridges consequently supply two stresses which are averaged by the parallel connection. The stresses of the measuring bridges resulting from the bending cancel one another out due to the opposite signs, so that they compensate one another.

[0036] FIG. 2 shows a pressure sensor having a housing 4 and a threaded piece 5 as a fastening element, and

[0037] FIG. 3 shows the pressure sensor having a membrane 1, in each case, in a basic representation.

[0038] The membrane 1 is fastened in a housing 4 with a threaded piece 5 and a hexagon 6. The housing 4 has a cavity covered with a region of the membrane 1, which cavity has an opening and/or a channel for a working medium to pass through. The cavity is located on the side of the membrane 1 opposite the side having the sensor chips 2, 3.

[0039] When the housing 4 having the pressure sensor device is screwed into an engine block, for example, mechanical stresses and, thus, forces acting on the membrane 1 arise, which lead to measurement errors. As a result of the sensor chips 2, 3 being arranged at an angle and spaced apart from one another, the changes in the bridge stress from the bending load in the two sensor chips 2, 3 are virtually the same, but have opposite signs in terms of amplitude. This arrangement is thus suitable for compensating the bending stresses resulting from the fastening of the membrane 1 and, thus, the forces acting on the membrane 1. The stresses resulting from the pressure have the same signs in both sensor chips 2, 3.

[0040] FIG. 4 shows a pressure sensor having a membrane 1 on the front in a basic illustration.

[0041] In one embodiment, the membrane 1 can be a wall or a part of a wall of a housing 4. The housing 4 has a cavity covered with the membrane 1 as a wall. The sensor chips 2, 3 are located on the surface of the membrane 1 pointing into the cavity. To this end, the membrane 1 can be conical or can be located in a frustoconical ring.