Electrochemical gas sensor with disk-shaped electrodes, which are also electrical contact leads

• US 5,336,390 A
• Filed: 08/11/1993
• Issued: 08/09/1994
• Est. Priority Date: 09/26/1992
• Status: Expired due to Term

• Current Assignee: Dragerwerk AG
• Original Assignee: Dragerwerk AG
• Inventors: Gambert, Rudolf, Lindner, Bernd, Karob, Klaus, Bleichert, Horst-Peter, Busack, Hans-Jurgen
• Primary Examiner(s): Niebling, John
• Assistant Examiner(s): Bell, Bruce F.
• Application Number:
  US08/105,895
• Time in Patent Office: 363 Days
• Field of Search: 204/424, 204/431, 204/432, 204/408, 204/412, 204/415, 204/252, 204/253
• US Class Current: 204/431
• CPC Class Codes: G01N 27/4045 for gases other than oxygen

Abstract

An electrochemical gas sensor for detecting gaseous components in the environment has a diffusion membrane, a measuring electrode, a counterelectrode, and, if desired, a reference electrode, pressed together in a disk stack, which are accommodated in a pot-shaped cover, which in turn is beaded around the sealing edge (6) of a housing pot (1). A compression spring (21) in the housing pot (1) presses a wick disk (20) against the measuring electrode (12), so that a constant and pressurized, intimate and sealed positioning of the disk stack is guaranteed. It is achieved as a result that no additional contact leads from the electrodes to the outer space of the sensor to the measuring and evaluating unit are needed, so that leakage-free sealing of the sensor to the outside is possible, and that a constantly stable, reproducible measured signal is obtained because of the defined and narrow electrolyte film on the surface of the measuring electrode.

Claims

1. An electrochemical gas sensor for detecting gaseous components in a gaseous environment with a disk-shaped measuring electrode, comprising:

a pot-shaped sensor housing having a sealing edge;

a counterelectrode positioned within said sensor housing in electrical contact with said sensor housing;

a pot-shaped cover including a cover edge projecting over said pot-shaped sensor housing;

diffusion path means including an opening in said pot-shaped cover and a diffusion membrane;

a measuring electrode including a contact surface forming a part of an electrode surface of said measuring electrode, said measuring electrode being positioned between said cover and said housing;

a sealing ring positioned around said sealing edge of said pot-shaped sensor housing, said sealing ring establishing electrical insulation between said cover and said pot-shaped sensor housing upon a sealing clamping of said cover on said sealing edge;

an electrolyte filled electrolyte space including an electrolyte impregnated wick including a wick disk positioned between said cover and said housing in contact with an electrolyte-side surface of said measuring electrode;

said measuring electrode and said diffusion membrane each being formed as a disk and cooperating with a sealing disk and/or a pressing disk to form a disk stack, said wick disk being positioned adjacent an electrolyte side surface of said measuring electrode;

a compression spring supported between said wick disk and said pot-shaped sensor housing to press said disk stack, said cover edge being in contact with said contact surface of said measuring electrode to form a contact point.

2. An electrochemical gas sensor according to claim 1, further comprising:

a disk-shaped reference electrode including a contact edge extending beyond said pot-shaped sensor housing edge, sealingly thereabout, said disk-shaped reference electrode being positioned between said measuring electrode and said counterelectrode, said sealing ring acting as an electrical insulation between said disk-shaped reference electrode and said pot-shaped sensor housing;

an insulation piece separating said cover from said disk-shaped reference electrode contact edge, a contact area connected to said contact edge providing access to said contact edge around said edge of said pot-shaped sensor housing.

3. An electrochemical gas sensor according to claim 1, wherein:

said measuring electrode contact surface is designed as a metallic border extending at an outer circumference of said measuring electrode disk.

4. An electrochemical gas sensor according to claim 1, wherein:

said cover is provided with inlet openings for gas to be detected, a porous pressing disk being joined by said diffusion membrane acting as said diffusion path means, said diffusion membrane being followed by said measuring electrode in said disk stack.

5. An electrochemical gas sensor according to claim 1, wherein:

said wick is designed as a hollow body filled with said electrolyte, said compression spring being positioned in said hollow body, said compression spring including an elastic disk in contact with an electrolyte-side surface of said wick disk.

6. An electrochemical gas sensor according to claim 5, wherein:

said elastic disk is provided with a plurality of openings.

7. An electrochemical gas sensor according to claim 1, wherein:

said wick disk is covered on a measuring electrode side with a separating disk, said separating disk leaving free only a partial area of said wick disk in an electrolyte contact with said measuring electrode.

8. An electrochemical gas sensor according to claim 1, wherein:

said measuring electrode is formed as a gold-plated nickel screen having a shell shape with said edge in contact, as a contact surface, with an inner wall of said cover.

9. An electrochemical gas sensor according to claim 1, wherein:

disks of said disk stack are sealed against one another by means of hot-melt adhesive disks (PFA or FEP) and are pressed against each other.

10. An electrochemical gas sensor according to claim 5, wherein:

a gas bubble is provided in said hollow body of said wick.

11. An electrochemical gas sensor according to claim 1, wherein:

said counterelectrode is formed of pressed granular metal and is positioned in a bottom of said pot-shaped housing part, a contact screen being provided in said pressed granular metal and positioned electrically connected to said pot-shaped housing via a contact point.

12. An electrochemical gas sensor according to claim 1, wherein:

said inner wall of said pot-shaped sensor housing is provided with a gold lining.