Pressure sensor arrangement

Abstract

A pressure sensor arrangement (1) for measuring a pressure of a fluid is described, the sensor arrangement (1) comprising a connector housing (2) having a fluid opening (3) and a fluid chamber (4) in connection with the fluid opening (3), at least one pressure sensitive element (5), a membrane (9) arranged between the pressure sensitive element (5) and the fluid chamber (4), and pressure attenuation means (10). Such a pressure sensor arrangement should be able to protect the measuring membrane from high frequency pressure pulsations with low costs. To this end the pressure attenuation means (10) are arranged in the fluid chamber (4) in direct contact with the membrane (9) separating the membrane (9) from the fluid in the fluid chamber and comprise a homogenous incompressible material having a mechanical loss factor of 0.1 or higher at frequencies of 200 Hz or higher.

Claims

1. A pressure sensor arrangement for measuring a pressure of a fluid, comprising a connector housing having a fluid opening and a fluid chamber in connection with the fluid opening, at least one pressure sensitive element, a membrane arranged between the pressure sensitive element and the fluid chamber, and pressure attenuation means wherein the pressure attenuation means are arranged in the fluid chamber in direct contact with the membrane separating the membrane from the fluid in the fluid chamber and comprise a homogenous incompressible material having a mechanical loss factor of 0.1 or higher at frequencies of 200 Hz or higher.

2. The pressure sensor arrangement according to claim 1, wherein the material has a mechanical loss factor of 0.10 or higher at frequencies of 1 kHz or higher.

3. The pressure sensor arrangement according to claim 1, wherein the material has the mechanical loss factor in a temperature range at least from −40° C. to +250° C.

4. The pressure sensor arrangement according to claim 1, wherein the material is an elastomer.

5. The pressure sensor arrangement according to claim 1, wherein the material comprises a shore hardness of 20 Shore A or lower.

6. The pressure sensor arrangement according to claim 1, wherein the membrane is a sealing diaphragm of an oil filled MEMS sensor.

7. The pressure sensor arrangement according to claim 1, wherein the membrane is a measuring membrane of a thinfilm pressure sensor element.

8. The pressure sensor arrangement according to claim 7, wherein the membrane is part of the housing.

9. The pressure sensor arrangement according to claim 1, wherein the membrane is made of metal.

10. The pressure sensor arrangement according to claim 2, wherein the material has the mechanical loss factor in a temperature range at least from −40° C. to +250° C.

11. The pressure sensor arrangement according to claim 2, wherein the material is an elastomer.

12. The pressure sensor arrangement according to claim 3, wherein the material is an elastomer.

13. The pressure sensor arrangement according to claim 2, wherein the material comprises a shore hardness of 20 Shore A or lower.

14. The pressure sensor arrangement according to claim 3, wherein the material comprises a shore hardness of 20 Shore A or lower.

15. The pressure sensor arrangement according to claim 4, wherein the material comprises a shore hardness of 20 Shore A or lower.

16. The pressure sensor arrangement according to claim 2, wherein the membrane is a sealing diaphragm of an oil filled MEMS sensor.

17. The pressure sensor arrangement according to claim 3, wherein the membrane is a sealing diaphragm of an oil filled MEMS sensor.

18. The pressure sensor arrangement according to claim 4, wherein the membrane is a sealing diaphragm of an oil filled MEMS sensor.

19. The pressure sensor arrangement according to claim 5, wherein the membrane is a sealing diaphragm of an oil filled MEMS sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments of the invention will now be described in more detail with reference to the drawing, in which:

(2) FIG. 1 shows a first embodiment of a pressure sensor,

(3) FIG. 2 shows a comparison of pressure spike attenuation with and without the incompressible material,

(4) FIG. 3 shows a second embodiment of the pressure sensor arrangement, and

(5) FIG. 4 shows a comparison of pressure spike attenuation with and without the incompressible material.

DETAILED DESCRIPTION

(6) FIG. 1 shows schematically a pressure sensor arrangement 1 comprising a connector housing 2 having a fluid opening 3 and a fluid chamber 4 in connection with the fluid opening. A pressure sensor die 5 of a MEMS sensor (micro electronic mechanical system sensor) is arranged in a recess 6 of a body part 7. The recess is filled with an oil volume 8. The oil volume 8 is sealed by means of a sealing diaphragm 9. The sealing diaphragm 9 is arranged between the pressure sensor die 5 and the fluid chamber 4.

(7) Furthermore, pressure attenuation means 10 are arranged in the fluid chamber in direct contact with the diaphragm 9 and separates the diaphragm 9 from the fluid in the fluid chamber 4. The pressure attenuation means comprise a homogenous incompressible material having a mechanical loss factor of 0.10 or higher at frequencies of 200 Hz or higher, preferably at frequencies of 500 Hz or higher and most preferably at least 1.000 Hz or higher.

(8) Furthermore, the material of the attenuation means 10 keeps this loss factor over a rather large temperature range which may be e.g. −40° C. t+250° C.

(9) The material of the attenuation mean is preferably an elastomer, e.g. rubber or silicon rubber material like Wacker Elastosil LR 3003.

(10) Furthermore, the material of the attenuation means can comprise a shore hardness of 20 Shore A or lower.

(11) The body part 7 can be made of metal. It forms a part of a subassembly 11 comprising the pressure sensor die 5 which can have, for example, a piezo-resistive measuring bridge. The oil in the oil volume 8 protects the sensor die 5 and transfers the pressure acting on the sealing diaphragm 9 to the sensor die 5.

(12) The attenuation means 10 on the other hand damp pressure pulses so that the diaphragm 9 is protected against damage which can be caused by a too fast increase of pressure in the fluid chamber 4.

(13) FIG. 2 shows a comparison of the pressure spike attenuation with and without the attenuation means 10 in form of the elastomer potting in the pressure sensor cavity, i.e. in the fluid chamber 4. A graph 12 shows a pressure spike attenuation with the attenuation means 10 of the element shown in FIG. 1. A graph 13 shows under the same conditions the pressure spike attenuation without the attenuation means 10 in the embodiment of FIG. 1.

(14) It can be seen that the pressure spike attenuation is much faster and better with the attenuation means 10.

(15) The material of the attenuation means 10 is applied in the fluid chamber 4 in contact to the sealing diaphragm 9. Otherwise, cavitation could occur in the fluid enclosed between the attenuation device 10 and the diaphragm 9.

(16) The material of the attenuation means 10 transfers the fluid pressure acting on the surface the attenuation means facing the fluid chamber 4 or the fluid opening 3 to the sensing diaphragm 9 without influencing or hindering the movement of the diaphragm 9 caused by changes in fluid pressure.

(17) FIG. 3 shows a second embodiment in which the same elements are denoted with the same reference numerals.

(18) In this case the pressure sensing device 1 comprises a metallic thinfilm pressure sensor element 14 with a measuring membrane 15. The measuring membrane is part of the body part 7. The measuring membrane 15 is a wall section of the body part 7 having a rather small thickness.

(19) The pressure sensitive elements can be formed, e.g. by piezo-resistive thinfilm resistors, which can be, e.g. coupled in a Wheatstone bridge configuration. They are deposited on the side of the measuring membrane 15 facing away from a fluid supply chamber 4.

(20) The pressure propagation into the fluid chamber 4 is symbolized by an arrow 16.

(21) FIG. 4 shows the pressure spike attenuation with and without the attenuation means 10. A curve 17 shows the attenuation when the attenuation means 10 are used. A curve 18 shows the attenuation when under the same conditions the attenuation means 20 are not used.

(22) In FIGS. 2 and 4 it can be seen that, when a sudden change of fluid pressure occurs, the attenuation means 10 reduce the occurring pressure spikes.

(23) While the present disclosure has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this disclosure may be made without departing from the spirit and scope of the present disclosure.