Turbocharger compressor diagnostic system

• US 6,298,718 B1
• Filed: 03/08/2000
• Issued: 10/09/2001
• Est. Priority Date: 03/08/2000
• Status: Expired due to Term

• Current Assignee: Cummins Engine Company Incorporated (Cummins Incorporated)
• Original Assignee: Cummins Engine Company Incorporated (Cummins Incorporated)
• Inventors: Wang, Yue Yun
• Primary Examiner(s): MCCALL, ERIC SCOTT
• Application Number:
  US09/521,873
• Time in Patent Office: 580 Days
• Field of Search: 731/12, 731/16, 731/171, 731/172, 731/173, 731/174, 731/181, 701/99, 701/100, 701/101
• US Class Current: 73/114.01
• CPC Class Codes: F02D 41/0007 for control of turbo-charged or super-charged engines control of the pumps per se F02B37/12
• 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: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A system and method for detecting abnormal operation of a turbocharger compressor reads data from a plurality of sensors and first conducts a series of rationality tests on the sensor data. The tests determine whether the data generated by certain ones of the sensors is accurate or compromised. If a particular sensor fails its corresponding rationality test, an error signal is generated. On the other hand, if all sensor data passes the rationality tests, the compressor performance data is compared to a compressor operation map, and more particularly to surge and choke regions defined by boundary lines on the map. If certain compressor performance data falls into either the surge or choke region, an appropriate abnormal performance signal is generated. In certain embodiments of the invention, the sensor rationality tests are based on a predetermined second order polynomial relationship between two compressor operating parameter, such as mass air flow, boost pressure, turbo speed, etc. In another aspect, a third order polynomial relationship between mass air flow and compressor pressure ratio is used to diagnose an abnormal compressor condition.

Claims

1. For a turbocharged engine having an engine control module operable to control engine operation in response to data received from a plurality of sensors, a method for diagnosing abnormal turbocharger compressor operation, comprising the steps of:

storing, in a memory, data corresponding to a compressor operation map defining a region of normal compressor operation between a surge line and a choke line, a surge region outside the surge line and a choke region outside the choke line, the surge line and choke line being defined according to a predetermined relationship between a first and a second compressor operating parameter;

conducting a rationality test on the data received from selected ones of the plurality of sensors and generating an error signal if one or more of the selected sensors fails the rationality test;

if all sensors pass the rationality test, generating actual values for the first and second operating parameters from the sensor data; and

comparing the actual values with the compressor operation map and generating an abnormal operation signal if the actual values fall outside a predetermined relationship with the choke line or the surge line.

2. The method according to claim 1, wherein said step of conducting a rationality test includes conducting the tests in a predetermined order among the selected sensors.

3. The method according to claim 2, wherein the rationality test for successive sensors in the predetermined order utilize data from one or more of the prior sensors in the predetermined order.

4. The method according to claim 3, wherein the selected ones of the sensors include, in said predetermined order, sensors for boost pressure, ambient pressure, turbo speed and mass air flow at the engine air intake.

5. The method according to claim 4, wherein the rationality test for the turbo speed sensor utilizes data from the boost pressure and ambient pressure sensors.

6. The method according to claim 4, wherein the rationality test for the mass air flow sensor utilizes data from the boost pressure and ambient pressure sensors.

7. The method according to claim 1, wherein the rationality test includes:

storing, in the memory, data corresponding to a sensor rationality map defining a region of acceptable sensor performance between an upper boundary line and a lower boundary line, the upper and lower boundary lines being defined according to a predetermined relationship between a third and a fourth compressor operating parameter;

generating, from the sensor data, actual values for the third and fourth compressor operating parameters; and

comparing the actual values with the sensor rationality map and generating a failure signal if the actual values fall outside either the upper or lower boundary line.

8. The method according to claim 7, wherein the upper and lower boundary lines are defined by a second order polynomial relationship between the third and fourth operating parameters.

9. The method according to claim 8, wherein:

a selected one of the plurality of sensors is the turbo speed sensor;

the third compressor operating parameter is the compressor pressure ratio (PR);

the fourth compressor operating parameter is the turbo speed (N_c); and

the second order polynomial has the form;

10. The method according to claim 8, wherein:

a selected one of the plurality of sensors is the mass air flow sensor;

the third compressor operating parameter is the turbo speed (N_c);

the fourth compressor operating parameter is the mass air flow (MAF); and

the second order polynomial has the form;

11. The method according to claim 10, wherein the third compressor operating parameter is a corrected turbo speed in which the actual turbo speed value from the turbo speed sensor is normalized as a function of the sensor value from the ambient temperature sensor.

12. The method according to claim 7, wherein:

the upper and lower boundary lines are defined by a predetermined relationship between the third and fourth operating parameters; and

the step of comparing the actual values with the sensor rationality map includes;

applying the actual value for the third operating parameter to the predetermined relationship to obtain a calculated value for the fourth operating parameter; and

comparing the actual and calculated values for the fourth operating parameter.

13. The method according to claim 1, wherein the surge line and the choke line are defined by a third order polynomial relationship between the first and second operating parameters.

14. The method according to claim 13, wherein:

the first compressor operating parameter is the mass air flow (MAF) at the engine air intake;

the second compressor operating parameter is the compressor pressure ratio (PR); and

the third order polynomial relationship has the form;

15. The method according to claim 1, wherein:

the first compressor operating parameter is the mass air flow (MAF) at the engine air intake;

the second compressor operating parameter is the compressor pressure ratio (PR); and

the step of comparing the actual values with the compressor operation map includes;

obtaining an actual value for the mass air flow from the sensor data;

calculating an actual compressor pressure ratio from the sensor data;

applying the actual compressor ratio to the predetermined relationship to obtain a calculated value for the mass air flow; and

comparing the actual and calculated values for the mass air flow.

16. The method according to claim 15, wherein the step of comparing the actual values with the compressor operation map further includes detecting a surge or choke trend by comparing the absolute value of the difference between the actual and calculated values for the mass air flow to a predetermined limit value.

17. The method according to claim 15, wherein the step of comparing the actual values with the compressor operation map further includes detecting a surge or choke cycle by comparing the difference between the actual and calculated values for the mass air flow at a first time with the difference between the actual and calculated values for the mass air flow at a second different time.

18. The method according to claim 17, wherein the step of comparing the actual values with the compressor operation map includes generating an abnormal operation signal if the sign of the difference at the first time is different from the sign of the difference at the second time.

19. For a turbocharged engine having an engine control module operable to control engine operation in response to data received from a plurality of sensors, a method for diagnosing abnormal turbocharger compressor operation, comprising the steps of:

storing, in a memory, data corresponding to a compressor operation map defining a region of normal compressor operation between a surge line and a choke line, a surge region outside the surge line and a choke region outside the choke line, the surge line and choke line being defined according to a predetermined relationship between a first and a second compressor operating parameter;

generating actual values for the first and second operating parameters from the sensor data; and

applying the actual value for the first operating parameter to the predetermined relationship to obtain a calculated value for the second operating parameter;

comparing the actual and calculated values for the second operating parameter and generating an abnormal operation signal if the comparison exceeds a predetermined limit.

20. The method according to claim 19, wherein the step of comparing the actual and calculated values includes comparing the difference between the actual and calculated values for the second operating parameter to a predetermined limit value.