Method for recognizing a state of change of a fuel injector

Patent metadata

Field	Value
Publication number	US-10578043-B2
Application number	US-201615748061-A
Country	US
Kind code	B2
Filing date	Jul 7, 2016
Priority date	Aug 4, 2015
Publication date	Mar 3, 2020
Grant date	Mar 3, 2020

Abstract

A method for recognizing a state change of a fuel injector of an internal combustion engine, in which fuel from a high-pressure accumulator is injected into a combustion chamber with the aid of the fuel injector. A value that is representative of a static flow rate of fuel through the fuel injector is ascertained. A state change of the fuel injector is deduced when the representative value differs from a comparative value by more than a first threshold value.

First claim

What is claimed is:

1. A method for recognizing a functional impairment of a fuel injector of an internal combustion engine in a motor vehicle, in which fuel from a high-pressure accumulator is injected into a combustion chamber using the fuel injector, the method comprising:
measuring during a fuel injection by the fuel injector using a pressure sensor, a pressure drop in the high-pressure accumulator;
ascertaining a value that is representative of a static flow rate of fuel through the fuel injector, the representative value being ascertained as a ratio of the measured pressure drop to a time period of the fuel injection;
comparing the representative value to a comparative value, the comparative value being an average of representative values of: (i) all fuel injectors of the internal combustion engine, or (ii) all fuel injectors of the internal combustion engine except the fuel injector, wherein each of the representative values is a ratio of a measured pressure drop during a fuel injection of a respective one of the fuel injectors to a time period of the fuel injection of the respective one of the fuel injectors;
determining functional impairment of the fuel injector when the representative value deviates from the comparative value by greater than a first threshold value; and
based on determining the functional impairment, performing at least one of the following: (i) storing information about the functional impairment of the fuel injector in memory, (ii) sending a warning message to a driver of the motor vehicle about the functional impairment of the fuel injector, the sending of the warning message including activating a warning light in the motor vehicle or displaying a notification in the motor vehicle about the functional impairment, (iii) adapting a flow rate of the fuel injector, (iv) performing a cleaning operation of the fuel injector by changing combustion conditions in the internal combustion engine.

2. The method as recited in claim 1 , wherein a defect that has been present since the fuel injector began operation is determined as the functional impairment when the representative value deviates from the comparative value without a preceding adaptation of the flow rate of the fuel injector.

3. The method as recited in claim 1 , wherein a defect during operation of the fuel injector is determined as the functional impairment when the representative value deviates from the comparative value after a preceding adaptation of the flow rate of the fuel injector.

4. The method as recited in claim 1 , wherein carbonization is determined as the functional impairment when the representative value deviates from the comparative value after multiple preceding adaptations of the flow rate of the fuel injector, in each case in the same direction.

5. The method as recited in claim 1 , further comprising:
detecting that the fuel injector has been replaced by comparing representative values of the fuel injector ascertained in successive driving cycles, and determining the representative values deviate from each other by more than a threshold value.

6. The method as recited in claim 1 , wherein based on determining the functional impairment, the information about the functional impairment is stored in the memory.

7. The method as recited in claim 1 , wherein based on determining the functional impairment, the warning message is sent to the driver.

8. The method as recited in claim 1 , wherein the comparative value is repeatedly or continuously updated.

9. The method as recited in claim 1 , wherein a curve of the deviation of the representative value from the comparative value is detected and stored over a service life of the internal combustion engine.

10. The method as recited in claim 1 , wherein the first threshold is 10% of the comparative value.

11. The method as recited in claim 1 , wherein the first threshold is 25% of the comparative value.

12. The method as recited in claim 1 , wherein based on determining the functional impairment, the flow rate of the fuel injector is adapted.

13. The method as recited in claim 1 , wherein based on determining the functional impairment, the cleaning operation of the fuel injector is performed by changing the combustion conditions in the internal combustion engine.

14. A processing unit configured for recognizing a functional impairment of a fuel injector of an internal combustion engine in a motor vehicle, in which fuel from a high-pressure accumulator is injected into a combustion chamber using the fuel injector, the processing unit configured to:
measuring during a fuel injection by the fuel injector using a pressure sensor, a pressure drop in the high-pressure accumulator;
ascertain a value that is representative of a static flow rate of fuel through the fuel injector, the representative value being ascertained as a ratio of the measured pressure drop to a time period of the fuel injection;
compare the representative value to a comparative value, the comparative value is an average of representative values of: (i) all fuel injectors of the internal combustion engine, or (ii) all fuel injectors of the internal combustion engine except the fuel injector, wherein each of the representative values is a ratio of a measured pressure drop during a fuel injection of a respective one of the fuel injectors to a time period of the fuel injection of the respective one of the fuel injectors;
determine a functional impairment of the fuel injector when the representative value deviates from the comparative value by greater than a first threshold value; and
based on determining the functional impairment, perform at least one of the following: (i) store information about the functional impairment of the fuel injector in memory, (ii) send a warning message to a driver of the motor vehicle about the functional impairment of the fuel injector, the sending of the warning message including activation of a warning light in the motor vehicle or display of a notification in the motor vehicle about the functional impairment, (iii) adapt a flow rate of the fuel injector, (iv) perform a cleaning operation of the fuel injector by changing combustion conditions in the internal combustion engine.

15. The processing unit as recited in claim 14 , wherein the first threshold is 10% of the comparative value.

16. The processing unit as recited in claim 14 , wherein the first threshold is 25% of the comparative value.

17. A non-transitory machine-readable memory medium on which is stored a computer program for recognizing a functional impairment of a fuel injector of an internal combustion engine in a motor vehicle, in which fuel from a high-pressure accumulator is injected into a combustion chamber using the fuel injector, the computer program, when executed by a processor, causing the processor to perform:
measuring during a fuel injection by the fuel injector using a pressure sensor, a pressure drop in the high-pressure accumulator;
ascertaining a value that is representative of a static flow rate of fuel through the fuel injector, the representative value being ascertained as a ratio of the measured pressure drop to a time period of the fuel injection;
comparing the representative value to a comparative value, the comparative value being an average of representative values of: (i) all fuel injectors of the internal combustion engine, or (ii) all fuel injectors of the internal combustion engine except the fuel injector, wherein each of the representative values is a ratio of a measured pressure drop during a fuel injection of a respective one of the fuel injectors to a

Assignees

• Bosch Gmbh Robert

Inventors

• Hirchenhein Achim
• Schenck Zu Schweinsberg Alexander
• Joos Klaus

Classifications

• F02M2200/247

  Pressure sensors · CPC title

• F02D41/2467

  for injectors · CPC title

• F02M2200/06

  Fuel-injection apparatus having means for preventing coking, e.g. of fuel injector discharge orifices or valve needles · CPC title

• F02D2200/0614

  Actual fuel mass or fuel injection amount · CPC title

• F02D41/3809

  Common rail control systems (common rail apparatus F02M55/025, F02M63/0225) · CPC title