METHOD FOR DETERMINING THE TEMPERATURE OF AN ELECTRICALLY HEATABLE CATALYTIC CONVERTER

• US 20190331015A1
• Filed: 03/29/2019
• Published: 10/31/2019
• Est. Priority Date: 04/30/2018
• Status: Active Grant

• Current Assignee: Volkswagen AG
• Original Assignee: Volkswagen AG
• Inventors: Naumann, Hardy, Paukner, Stefan
• Granted Patent: US 10,731,533 B2
• Time in Patent Office: Days
• CPC Class Codes: F01N 11/005 the temperature or pressure being estimated, e.g. by means of a theoretical model
• CPC Class Codes: F01N 2240/16 an electric heater, i.e. a resistance heater
• CPC Class Codes: F01N 2390/02 using electric components only
• CPC Class Codes: F01N 2560/12 Other sensor principles, e.g. using electro conductivity of substrate or radio frequency
• CPC Class Codes: F01N 2900/0601 being estimated
• CPC Class Codes: F01N 2900/0602 Electrical exhaust heater signals
• CPC Class Codes: F01N 2900/1602 Temperature of exhaust gas apparatus
• CPC Class Codes: F01N 2900/1626 Catalyst activation temperature
• CPC Class Codes: F01N 3/2013 using electric or magnetic 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: F01N 9/00 Electrical control of exhaust gas treating apparatus monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method for determining the temperature of an electrically heatable catalytic converter having an electric heating element that includes a heating resistor, the electrical resistance of which changes as a function of the component temperature of the electrically heatable catalytic converter. This resistance is determined from the current intensity and the voltage at the electrically heatable catalytic converter, and is used to determine the component temperature of the catalytic converter, based on a characteristic curve stored in the control unit. The energization of the heating resistor for determining the component temperature takes place in each case for only a short time in order to minimize the energy input into the heating resistor and thus avoid overheating of the heating resistor. In addition, by use of the short time interval, the aim is to minimize the energy requirements for determining the component temperature of the electrically heatable catalytic converter.

Claims

1. A method for determining the temperature of an electrically heatable catalytic converter in an exhaust gas system of an internal combustion engine, wherein the electrically heatable catalytic converter includes a heating resistor having a temperature-dependent resistance, comprising:

energizing the electric heating resistor by closing a switch in a circuit that connects a battery to the electric heating resistor, and

determining the component temperature of the electrically heatable catalytic converter from the temperature-dependent electrical resistance of the heating resistor, for a known current intensity and a known voltage.

2. The method according to claim 1, wherein determining the component temperature of the electrically heatable catalytic converter comprises determining the component temperature in an operating phase in which electrical heating is not provided.

3. The method according to claim 2, wherein the energization period for the resistance measurement is selected to be between 50 μ

s and 200 μ

s.

4. The method according to claim 1, further comprising determining a correction factor that takes into account a change in the electrical resistance of the heating resistor due to aging of the electrically heatable catalytic converter.

5. The method according to claim 1, wherein the power input into the measuring circuit takes place by means of a down converter that is controlled by pulse width modulation.

6. The method according to claim 5, further comprising measuring current intensity and voltage at least ten times within a pulse width modulation period.

7. The method according to claim 5, wherein a temperature controller for the electrically heatable catalytic converter utilizes the down converter as a continuous current controller.

8. The method according to claim 1, wherein determining the component temperature of the electrically heatable catalytic converter takes into account the line resistance of the electrical conductor in addition to the electrical resistance of the heating resistor.

9. The method according to claim 1, wherein the resistance measurement is carried out using a four-wire measuring method.

10. An exhaust aftertreatment system for an internal combustion engine having an exhaust gas system in which an electrically heatable catalytic converter is situated, and having a control unit that is configured to carry out a method according to claim 1 when a machine-readable program code is executed by the control unit.