Method for Producing a Subminiature "Micro-Chip" Oxygen Sensor for Control of Internal Combustion Engines or Other Combustion Processes, Oxygen Sensor and an Exhaust Safety Switch

• US 20110186446A1
• Filed: 12/29/2010
• Published: 08/04/2011
• Est. Priority Date: 01/29/2010
• Status: Active Grant

• Current Assignee: Kerdea Technologies, Inc.
• Original Assignee: Fosaaen Technologies, LLC
• Inventors: Fosaaen, Ken Ervin
• Granted Patent: US 8,586,394 B2
• Time in Patent Office: Days
• US Class Current: 205/784.5
• CPC Class Codes: F01N 11/002 the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
• CPC Class Codes: F01N 2560/025 for measuring or detecting O2, e.g. lambda sensors
• CPC Class Codes: F01N 2560/20 Sensor having heating means
• CPC Class Codes: F01N 3/2026 directly electrifying the catalyst substrate, i.e. heating the electrically conductive catalyst substrate by joule effect
• CPC Class Codes: F02D 41/042 for stopping the engine
• CPC Class Codes: G01M 15/104 using oxygen or lambda-sensors testing catalytic converters F01N3/18, F01N11/007
• CPC Class Codes: G01N 27/4067 Means for heating or controlling the temperature of the solid electrolyte

Abstract

A method of making a sub-miniature “micro-chip” oxygen sensor is provided where multiple sensor elements are applied to a dielectric ceramic substrate consisting of a heater pattern, followed by a dielectric layer. Intermeshing electrodes are then applied either over the heater pattern/dielectric layers or on the opposite side of the substrate. The space between the intermeshing electrodes is filled with an n-type or p-type high temperature semiconductor which is covered by a porous protection layer. After singulation (dicing), the sensor element is assembled having conductors applied to the contact pads on the element and is packaged in an assembly for introduction to the exhaust stream of a combustion process. A large step-wise change in the resistance of the element takes place as a result of changes in oxygen content in the exhaust whereby one can determine if the exhaust is rich or lean for use in an engine management or combustion management systems for emissions control. A circuit is proposed to convert the change in resistance to a voltage signal to be used for control algorithms in engine or combustion control. Utilizing multiple units of the device for individual cylinder control of multi-cylinder engines is described. A method of using one embodiment of the invention for use as a safety switch is also revealed.

Claims

1. A method of making an oxygen sensor, comprising:

depositing on a dielectric substrate multiple resistive heater circuits;

depositing second dielectric layers on the resistive heater circuits;

depositing conductive intermeshing comb electrodes on the dielectric layer or on the substrate on the opposite side of the heater pattern;

applying one of n-type or p-type high temperature semiconductors on the comb electrodes bridging the gap between the legs of the combs;

applying porous dielectric protective layers containing catalytic precious metals on the semiconductors; and

isolating individual elements via a singulation process to produce multiple individual oxygen or gas sensor elements.

2. The method of claim 1, wherein a heater pattern is placed on a ceramic substrate with the sensing element on the same side of the substrate as the heater having a dielectric barrier printed or otherwise deposited between the two.

3. The method of claim 1, wherein physical vapor deposition is used to deposit conductive materials for heater patterns and/or electrodes on the sub-miniature oxygen or gas sensors.

4. The method of claim 1, wherein electroless plating is used to deposit conductive materials for heater patterns and/or electrodes on the sub-miniature oxygen or gas sensors.

5. The method of claim 1, wherein physical vapor deposition is used to deposit dielectric materials to electrically insulate the heater circuit from the sensor circuit of the oxygen sensor.

6. The method of claim 1, wherein Direct-Write Technology is used to deposit the dielectric, semiconducting, or porous cover layer materials to the oxygen sensor elements.

7. The method of claim 1, wherein ink-jet printing is used to deposit the dielectric, semiconducting, or porous cover layer materials to the oxygen sensor elements.

21. The method of using the sensor made according to claim 1 as safety switch for the purpose of alarming and/or disabling engines or other combustion systems in the event they begin operating under rich-burn conditions.

8. An oxygen sensor for sensing exhaust gases from a combination process, comprising:

a fired ceramic dielectric substrate;

at least one heater circuit adhered to a surface of the substrate, with at least one dielectric layer encapsulating the heater circuit to provide electrical isolation; and

at least one electrode adhered on the substrate apart from the dielectric layer encapsulated pattern of heater circuit.

9. The sensor of claim 8, wherein the semiconducting material is composed of a n-type high temperature semiconductor for use as an oxygen sensor for stoichiometric engine control or a safety switch for lean-burn engine applications.

10. The sensor of claim 8, wherein the semiconducting material is composed of a p-type high temperature semiconductor for use as a safety switch in lean-burn engine applications or as an oxygen sensor for Stoichiometric engine control.

11. The sensor of claim 8, further comprising an n or p type semiconducting material on the electrode and adjacent the electrode.

12. The sensor of claim 8, further comprising a porous protective dielectric layer applied to the electrode over the semiconducting layer.

13. The sensor of claim 8, further comprising a housing assembly for holding the sensor in a manner exposed to exhaust gases from a combustion process.

14. The sensor of claim 13, further comprising wires connected to the heater circuit and to at least one electrode for heating the sensor and detecting a resistance change representative of sensed exhaust gases.

15. The sensor of claim 8, wherein said substrate is made of aluminum oxide and the electrode is made of platinum, palladium, or a combination.

16. A method of converting the resistance change in the sensor of claim 8, to a voltage signal, comprising applying a voltage to the sensor via a voltage divider contained in an electronic control unit.

17. A method of converting the resistance change in the sensor of claim 8, to a voltage signal comprising by applying a voltage to the sensor via a voltage divider contained in a wire harness connector between the sensor element and an electronic control unit of the engine.

18. A method of converting the resistance change in the sensor of claim 8, to a voltage signal comprising by applying a voltage to the sensor via a voltage divider contained in an assembly of the sensor.

19. A method of converting the resistance change in the sensor of claim 8, to a voltage signal comprising by applying a voltage to the sensor via a voltage divider contained on a sensing element of the sensor.

20. A method of use of the sensor made according to claim 16 for the purpose of individual cylinder control for multi-cylinder engines.