METHOD AND DEVICE FOR SETTING AN EMERGENCY OPERATIONAL MODE IN A SYSTEM WHICH DETECTS PRE-IGNITIONS IN A COMBUSTION ENGINE, AND WHICH CONTAINS ERRORS

• US 20130166184A1
• Filed: 08/01/2011
• Published: 06/27/2013
• Est. Priority Date: 09/06/2010
• Status: Abandoned Application

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Wuerth, Juergen, Kluth, Carsten, Haeming, Werner, Luo, Li
• Application Number:
  US13/820,443
• Publication Number:
  US 20130166184A1
• Time in Patent Office: Days
• US Class Current: 701/111
• CPC Class Codes: F02D 2041/227 Limping Home, i.e. taking specific engine control measures at abnormal conditions
• CPC Class Codes: F02D 35/02 on interior conditions
• CPC Class Codes: F02D 35/023 by determining the cylinder pressure
• CPC Class Codes: F02D 35/027 using knock sensors
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: F02D 41/266 the computer being backed-up or assisted by another circuit, e.g. analogue
• CPC Class Codes: G01D 3/08 with provision for safeguarding the apparatus, e.g. against abnormal operation, against breakdown

Abstract

The invention relates to a method for setting an emergency operational mode in a system which detects pre-ignitions in a combustion engine and which contains errors. The system consists of at least one sensor (17) and/or at least one sensor cable (24) and/or a sensor signal evaluation device (20), and is subject to a diagnosis to detect an error. In order to prevent damage to the combustion engine if the system for detecting pre-ignitions does contain an error, a standard path (26), which comprises sensor signal capturing, sensor signal evaluation, detection of pre-ignitions and initiation of measures to counter the pre-ignitions, is interrupted when the diagnosis detects an error in the system (17, 24, 29), and a safety path (27) is activated as an emergency operational mode.

Claims

1. A method for activating an emergency operational mode in a system which detects pre-ignition in a combustion engine and which contains a fault, wherein, in order to detect the fault, the system, which of includes at least one sensor, is subjected to a diagnosis, characterized in that, if a fault in a standard path (26) of the system (17, 24, 20) is detected by the diagnosis, a safety path (27) is activated as an emergency operational mode.

2. The method as claimed in claim 1, characterized in that, in the safety path (27), measures which reliably prevent the occurrence of pre-ignition in the combustion engine (1) are activated.

3. The method as claimed in claim 2, characterized in that, in order to prevent the occurrence of pre-ignition, a temperature in a combustion chamber of the combustion engine (1) is lowered.

4. The method as claimed in claim 3, characterized in that the temperature in the combustion chamber of the combustion engine (1) is lowered by a fuel enrichment in the combustion engine (1).

5. The method as claimed in claim 3, characterized in that the temperature in the combustion chamber of the combustion engine (1) is lowered by an air enrichment in the combustion engine (1).

6. The method as claimed in claim 3, characterized in that the temperature in the combustion chamber of the combustion engine (1) is decreased by lowering the charging of the combustion engine (1) by reducing the air supply.

7. The method as claimed in claim 3, characterized in that the temperature in the combustion chamber of the combustion engine (1) is decreased by reducing an internal residual gas in the combustion engine (1) by reducing the overlap of the timing of an inlet (15) and an exhaust valve (16) of the combustion engine (1).

8. The method as claimed in claim 16, characterized in that, in order to diagnose the sensor (17), standardized reference levels are determined from the sensor signal and are compared with an upper and a lower threshold value in order to detect a fault, a fault being detected if the sensor signal lies outside the signal band formed by the upper and the lower threshold value.

9. The method as claimed in claim 16, characterized in that, in order to diagnose the sensor cable (24), a short-circuit test is carried out and, if a short circuit of the sensor cable (24) to a battery voltage or to an earth is present, a fault is detected.

10. The method as claimed in claim 16, characterized in that the diagnosis of the sensor signal evaluation device (20) is carried out by monitoring the computer hardware with respect to signal capture and signal evaluation, a fault being detected if implausibilities have occurred during the signal capture or signal evaluation.

11. The method as claimed in claim 8, characterized in that the fault is stored in an error memory for evaluation in a workshop.

16. The method as claimed in claim 1, wherein the system at least one sensor (17) and/or a sensor cable (24) and/or a sensor signal evaluation device (20).

17. The method as claimed in claim 1, wherein the standard path (26) of the system (17, 24, 20) includes-sensor signal capture, sensor signal evaluation, detection of pre-ignition and initiation of measures to counter the pre-ignition.

18. The method as claimed in claim 1, wherein the standard path (26) is interrupted or completed or partially switched off.

19. The method as claimed in claim 3, characterized in that the temperature in the combustion chamber of the combustion engine (1) is decreased by reducing an internal residual gas in the combustion engine (1) by reducing the overlap of the timing of an inlet (15) of the combustion engine (1).

20. The method as claimed in claim 3, characterized in that the temperature in the combustion chamber of the combustion engine (1) is decreased by reducing an internal residual gas in the combustion engine (1) by reducing the overlap of the timing an exhaust valve (16) of the combustion engine (1).

12. A device for setting an emergency operational mode in a system which detects pre-ignition in a combustion engine and which contains faults, wherein, in order to detect a fault, the system, which consists of at least one sensor (17) and/or at least one sensor cable (24) and/or a sensor signal evaluation device (20), is subjected to a diagnosis, characterized in that an evaluator (18, 25) is present which, upon detection of a fault in the system (17, 24, 20) by the diagnosis, interrupt or completely or partially switch off a standard path (26), comprising sensor signal capture, sensor signal evaluation, detection of pre-ignition and initiation of measures to counter pre-ignition, and activate a safety path (27) as an emergency operational mode.

13. The device as claimed in claim 12, characterized in that the evaluator includes a control and evaluation device (18) for the combustion engine (1) which triggers signals for a diagnosis of the at least one sensor (17) and/or the at least one sensor cable (24) and/or the sensor signal evaluation device (20) and evaluates the response signals received in dependence on these signals, the standard path (26) for detecting pre-ignition being interrupted and the safety path (27) being activated upon detection of a fault.

14. The device as claimed in claim 12, characterized in that the sensor (17) is a knock sensor arranged on the cylinder of the combustion engine (1), a pressure sensor arranged in the combustion chamber of the combustion engine (1) or a rotational speed sensor detecting the rotational speed of the crankshaft of the combustion engine (1).

15. The device as claimed in claim 12, characterized in that each cylinder of the combustion engine (1) has as actuators an inlet valve (15) for admitting air and an exhaust valve (16) for discharging a combustion waste gas, the opening times of which are set by a respective camshaft, the control and evaluation device (18) activating the camshaft in such a way that the opening times of the inlet (15) and exhaust valve (16) do not overlap or overlap only slightly.