Relative pressure sensor having an atmosphere-side damper

• US 7,243,550 B2
• Filed: 10/31/2003
• Issued: 07/17/2007
• Est. Priority Date: 11/05/2002
• Status: Active Grant

• Current Assignee: Endress + Hauser GmbH + Company KG (Endress+Hauser AG)
• Original Assignee: Endress + Hauser GmbH + Company KG (Endress+Hauser AG)
• Inventors: Burczyk, Dietfried, Dannhauer, Wolfgang
• Primary Examiner(s): Lefkowitz; Edward
• Assistant Examiner(s): JENKINS, JERMAINE L
• Application Number:
  US10/533,253
• Publication Number:
  US 20060169047A1
• Time in Patent Office: 1,355 Days
• Field of Search: 73700-756, 3612831-2834
• US Class Current: 73/715
• CPC Class Codes: G01L 19/0609 Pressure pulsation damping arrangements
• CPC Class Codes: G01L 19/0645 using isolation membranes, specially adapted for protection

Abstract

A relative pressure sensor comprises two chambers and two separating membranes respectively provided for a process pressure and an ambient pressure. The chambers are separated by a pressure-sensitive element and are filled with a transmission medium. In order to attenuate process-side overload pulses, which act upon the first separating membrane, a hydraulic damper is provided that is placed on the side of the atmosphere between the second separating membrane and the pressure-sensitive element. The pressure-sensitive element is a piezoresistive silicon chip, the transmission medium consists of silicone oil, and the damper is comprised of a filter element made of sintered bronze having 29% porosity and an 11 micrometer pore diameter. The filter element has a length of 8 mm and a diameter of 2 mm.

Claims

1. A relative pressure sensor for measuring a pressure difference between a process pressure and an ambient pressure, comprising a measuring unit, having:

a first chamber, which is sealed by a first separating membrane and filled with a transmission medium, said first separating membrane being loadable with the process pressure;

a second chamber, which is sealed by a second separating membrane and filled with a transmission medium, said second separating membrane being loadable with the ambient pressure;

a pressure-sensitive element, which separates said first chamber from said second chamber; and

a damper arranged only between said pressure-sensitive element and said second separating membrane, wherein;

said damper protects said pressure-sensitive element against the effect of excess-pressure pulses acting on said first separating membrane.

2. The relative pressure sensor as claimed in claim 1, wherein:

the transmission medium is a hydraulic liquid, especially a silicone oil.

3. The relative pressure sensor as claimed in claim 1, wherein:

said pressure-sensitive element comprises a measuring membrane, especially a piezoresistive silicon chip with a measuring membrane.

4. The relative pressure sensor as claimed in claim 1, wherein:

said damper comprises a sintered body.

5. The relative pressure sensor as claimed in claim 4, wherein;

the sintered body is a metallic or ceramic, sintered body.

6. The relative pressure sensor as claimed in claim 4, wherein:

the sintered body has an essentially cylindrical form and the length of the sintered body in the axial direction is at least twice as large as the diameter.

7. The relative pressure sensor as claimed in claim 1, wherein:

said damper has a porous structure.

8. The relative pressure sensor as claimed in claim 7, wherein:

the porous structure has a flow-effective pore diameter of not less than 4 μ

m and not more than 28 μ

m, preferably between 8 μ

m and 16 μ

m.

9. The relative pressure sensor as claimed in claim 8, wherein:

the porous structure has a porosity between 15 vol. % and 50 vol. %, preferably between 25 vol. % and 35 vol. %.