Claims
- 1. A vortex flow sensor for measuring a flow velocity and a volume flow rate of a fluid flowing in a measuring tube in one direction including,
- a bluff body for generating Karman vortices which is arranged along a diameter of said measuring tube, said bluff body being connected to said measuring tube at at least one fixing location,
- a capacitive vortex sensing element inserted into a hole in said measuring tube downstream of said bluff body and responding to pressure fluctuations generated by said vortices, said capacitive vortex sensing element sealing off said hole in said measuring tube, the center of said hole and the center of said fixing location lying on a longitudinal axis of said measuring tube, said capacitive vortex sensing element comprising:
- a diaphragm covering said hole and having a first surface facing toward said fluid and a second surface facing away from said fluid,
- a flexurally stiff thin sensor vane attached to said first surface of said diaphragm and being shorter than said diameter of said measuring tube, said sensor vane having flat main surfaces aligned with said axis of said measuring tube,
- a sleeve-shaped first electrode arrangement attached to said second surface of said diaphragm, said first electrode arrangement having at least one electrode,
- a housing cap surrounding said first electrode arrangement and said diaphragm, said housing cap being fixed on said measuring tube and containing a second electrode arrangement having at least one counterelectrode,
- the mass of said sensor vane being greater than the mass of said first electrode arrangement,
- the geometrical moment of inertia of said sensor vane at said first surface of said diaphragm being approximately equal to the geometrical moment of inertia of said first electrode arrangement at said second surface of said diaphragm, and
- said housing cap being of sufficient flexural stiffness to resist bending when a maximum permissible acceleration acts on said measuring tube.
- 2. A vortex flow sensor for measuring a flow velocity and a velocity and a volume flow rate of a fluid flowing in a measuring tube in one direction including,
- a bluff body for generating Karman vortices which is arranged along a diameter of said measuring tube, said bluff body being connected to said measuring tube at at least one fixing location,
- a capacitive vortex sensing element inserted into a hole in said measuring tube downstream of said bluff body and responding to pressure fluctuations generated by said vortices, said capacitive vortex sensing element sealing off said hole in said measuring tube, the center of said hole and the center of said fixing location lying on a longitudinal axis of said measuring tube, said capacitive vortex sensing element comprising:
- a diaphragm covering said hole and having a first surface facing toward said fluid and a second surface facing away from said fluid,
- a flexurally stiff thin sensor sleeve attached to said first surface of said diaphragm and being shorter than said diameter of said measuring tube,
- a sleeve-shaped first electrode arrangement attached to said second surface of said diaphragm, said first electrode arrangement having at least one electrode,
- a housing cap surrounding said first electrode arrangement and said diaphragm, said housing cap being fixed on said measuring tube and containing a second electrode arrangement having at least one counterelectrode,
- the mass of said sensor sleeve being greater than the mass of said first electrode arrangement,
- the geometrical moment of inertia of said sensor sleeve at said first surface of said diaphragm being approximately equal to the geometrical moment of inertia of said first electrode arrangement at said second surface of said diaphragm, and
- said housing cap being of sufficient flexural stiffness to resist bending when a maximum permissible acceleration acts on said measuring tube.
Priority Claims (2)
Number |
Date |
Country |
Kind |
96117892 |
Nov 1996 |
EPX |
|
97810765 |
Oct 1997 |
EPX |
|
Parent Case Info
This application claims benefit of Provisional Appl. Ser. No. 60/030,465, filed Nov. 13, 1996.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4716770 |
Herzog |
Jan 1988 |
|
5347873 |
Vander Heyden |
Sep 1994 |
|
Foreign Referenced Citations (7)
Number |
Date |
Country |
0 240 100 A1 |
Oct 1987 |
EPX |
0 549 945 A2 |
Jul 1993 |
EPX |
35 44 198 A1 |
Jun 1987 |
DEX |
41 43 202 C1 |
Feb 1993 |
DEX |
57-189015 |
Nov 1982 |
JPX |
1 483 818 |
Aug 1977 |
GBX |
WO 9408211 |
Apr 1994 |
WOX |