Gas sensor, in particular for determining the oxygen content in exhaust gases of internal combustion engines

• US 6,235,174 B1
• Filed: 01/27/1999
• Issued: 05/22/2001
• Est. Priority Date: 01/29/1998
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Jaürnig, Udo
• Primary Examiner(s): TUNG, TA HSUNG
• Application Number:
  US09/238,341
• Time in Patent Office: 846 Days
• Field of Search: 204/421-429
• US Class Current: 204/427
• CPC Class Codes: G01N 27/407 for investigating or analysing gases G01N27/411 takes precedence

Abstract

A gas sensor, in particular for determining the oxygen content in exhaust gases of internal combustion engines, is described. The gas sensor includes a sensing element sealedly fastened in a housing, whose segment on the measured gas side has at least one electrode exposed to a measured gas, at least one electrode exposed to a reference gas, and a reference gas conduit, extending in the longitudinal direction of the sensing element, which terminates at the segment of the sensing element remote from the measured gas and is connected to a reference gas source; and having contacts remote from the measured gas for making contact to the electrodes of the sensing element. Provision is made for the reference gas conduit to terminate at a large surface of the sensing element and to be sealed with a planar sealing fit.

Claims

1. A gas sensor, comprising:

a housing;

a sensing element sealedly coupled in the housing, the sensing element including a segment portion and a reference gas conduit, the segment portion being situated on a measured gas side of the housing, the segment portion has been added after including at least one first electrode which is exposed to a measured gas and at least one second electrode which is exposed to a reference gas, the reference gas conduit extending in a longitudinal direction of the sensing element and terminating at a second segment portion remote from the measured gas, the reference gas conduit being connected to a reference gas source, the reference gas conduit terminating at an outlet at a longitudinal side surface of the sensing element and is sealed with a planar sealing fit, the longitudinal side surface extending in the longitudinal direction of the sensing element; and

first contacts situated at a second predetermined distance from the measured gas, the first contacts being adapted to be electrically connected to the at least one first electrode and the at least one second electrode.

2. The gas sensor according to claim 1, wherein the gas sensor is utilized to determine an oxygen content in an exhaust gas of an internal combustion engine.

3. The gas sensor according to claim 1, further comprising:

a ceramic shaped element immobilizing the sensing element in the housing and forming a reference gas guidance element.

4. The gas sensor according to claim 3, wherein the ceramic shaped element includes a conduit which connects the reference gas conduit to the reference gas source via the outlet at the longitudinal side surface of the sensing element, the conduit being sealed with the reference gas conduit via the planar sealing fit.

5. The gas sensor according to claim 4, wherein the conduit is integrated into the ceramic shaped element.

6. The gas sensor according to claim 4, wherein the ceramic shaped element constitutes a receptacle for the sensing element, the outlet of the reference gas conduit and an outlet of the conduit of the ceramic shaped element are opposite to one another inside of a recess.

7. The gas sensor according to claim 6, wherein at least one of the reference gas conduit outlet and the ceramic shaped element conduit outlet is surrounded by a sealing edge.

8. The gas sensor according to claim 4, wherein the ceramic shaped element has geometrical features to ensure a correctly polarized contacts of the first contacts of the sensor.

9. The gas sensor according to claim 8, wherein the geometrical features include a collar surrounding the conduit.

10. The gas sensor according to claim 3, wherein the sensing element is retained in a surface contact with the ceramic shaped element via a compressive force which acts radially to the longitudinal extension of the sensing element.

11. The gas sensor according to claim 10, further comprising:

a locking ring surrounding an extension of the ceramic shaped element to apply the compressive force, the ceramic shaped element forming a receptacle; and

a locking wedge for compressing the locking ring.

12. The gas sensor according to claim 3, further comprising:

a plastically deformable sealing element situated between the sensing element and one of the ceramic shaped element and a shaped element, at least at the outlet at the longitudinal side surface of the sensing element and at an outlet region of the one of the ceramic shaped element and the shaped element.

13. The gas sensor according to claim 12, wherein the shaped element is of an electrically conductive material.

14. The gas sensor according to claim 3, wherein the ceramic shaped element includes a pressure-tight passthrough contact, a connecting contact of the sensing element being coupled to the at least one of the first contacts of the sensor using the pressure-tight passthrough contacts.

15. The gas sensor according to claim 3, wherein the first contacts of the sensor are situated on an end surface of the ceramic shaped element.

16. The gas sensor according to claim 15, wherein the end surface has geometrical features to enlarge an available contact area of the first contacts of the sensor.

17. The gas sensor according to claim 1, further comprising an electrically conductive shaped element including a conduit connecting the reference gas conduit to the reference gas source, the shaped element providing an electrical contacting to a connecting contact of the sensing element.

18. The gas sensor according to claim 1, wherein the outlet at the longitudinal side surface of the sensing element meets a second conduit.