Method and system for determining abnormality of differential pressure sensor

Patent metadata

Field	Value
Publication number	US-11111870-B2
Application number	US-202016781231-A
Country	US
Kind code	B2
Filing date	Feb 4, 2020
Priority date	Apr 19, 2019
Publication date	Sep 7, 2021
Grant date	Sep 7, 2021

Abstract

A method of determining an abnormality of a differential pressure sensor which is configured to detect a pressure differential between an upstream side and a downstream side of an EGR valve provided to an EGR passage of an engine, is provided. The method includes the steps of controlling an opening of the EGR valve based on an output value of the differential pressure sensor, determining the abnormality of the differential pressure sensor based on the output value of the differential pressure sensor, controlling at least a throttle valve of the engine toward a closed side so that the pressure differential is maintained at a given pressure or higher when determining, and prohibiting the execution of the abnormality determination when an engine speed is a given engine speed or higher, and permitting the execution of the abnormality determination when the engine speed is less than the given engine speed.

First claim

What is claimed is:

1. A method of determining an abnormality of a differential pressure sensor configured to detect a pressure differential between an upstream side and a downstream side of an exhaust gas recirculation (EGR) valve provided to an EGR passage of an engine, the method comprising the steps of:
controlling an opening of the EGR valve based on an output value of the differential pressure sensor;
determining the abnormality of the differential pressure sensor based on the output value of the differential pressure sensor;
controlling at least a throttle valve of the engine toward a closed side so that the pressure differential between the upstream side and the downstream side of the EGR valve is maintained at greater than or equal to a given pressure when determining the abnormality of the differential pressure sensor; and
prohibiting the execution of the abnormality determination of the differential pressure sensor when an engine speed of the engine is greater than or equal to a given engine speed, and permitting the execution of the abnormality determination of the differential pressure sensor when the engine speed is less than the given engine speed.

2. The method of claim 1 , wherein determining the abnormality of the differential pressure sensor includes determining that the differential pressure sensor is abnormal when a difference between a pressure differential corresponding to the output value of the differential pressure sensor, and a difference between a pressure corresponding to an output value of a pressure sensor provided at the downstream side of the EGR valve and a pressure corresponding to an output value of an atmospheric pressure sensor, is greater than or equal to a given determination threshold.

3. The method of claim 2 , further comprising setting the determination threshold at a higher value as the engine speed increases.

4. The method of claim 1 , wherein the given pressure is 5 kPa.

5. The method of claim 1 , wherein the engine is provided with a supercharger configured to boost intake air supplied to the engine, a bypass passage configured to circulate the intake air while bypassing the supercharger, and a bypass valve provided to the bypass passage, the method further comprising:
setting a target boosting pressure of the supercharger; and
controlling the bypass valve so that the target boosting pressure is achieved,
wherein controlling the bypass valve includes carrying out a feedback control of an opening of the bypass valve based on the target boosting pressure, when the throttle valve is controlled so that the pressure differential between the upstream side and the downstream side of the EGR valve is maintained at greater than or equal to the given pressure in order to determine the abnormality of the differential pressure sensor, so as to compensate a change in a boosting pressure caused by the control of the throttle valve.

6. The method of claim 5 , wherein the supercharger is a mechanical supercharger driven by the engine.

7. The method of claim 1 , wherein the EGR passage recirculates, to an intake passage of the engine, exhaust gas at a downstream side of a catalyst provided to an exhaust passage of the engine.

8. The method of claim 1 , wherein the engine has a first combustion mode in which compression ignition combustion of a mixture gas inside the combustion chamber is carried out by self-ignition in a state where a gas-fuel ratio (G/F) that is a ratio of a total amount of gas inside the combustion chamber including EGR gas from the EGR passage to an amount of fuel inside the combustion chamber is greater than a stoichiometric air-fuel ratio, and an air-fuel ratio (A/F) that is a ratio of an amount of air to the amount of fuel inside the combustion chamber is substantially in agreement with the stoichiometric air-fuel ratio.

9. The method of claim 8 , wherein the engine further has a second combustion mode in which the compression ignition combustion is carried out in a state where the air-fuel ratio is larger than the stoichiometric air-fuel ratio.

10. The method of claim 9 , further comprising prohibiting the first combustion mode and permitting the second combustion mode, when the differential pressure sensor is determined to be abnormal.

11. The method of claim 10 , wherein the second combustion mode is carried out in a low-load low-speed range where a load of the engine is less than a given load and the engine speed is less than a given engine speed, and a third combustion mode, in which jump-spark ignition combustion of the entire mixture gas inside the combustion chamber is carried out by jump-spark ignition, is carried out in other ranges.

12. An abnormality determination system for a differential pressure sensor, comprising:
the differential pressure sensor configured to detect a pressure differential between an upstream side and a downstream side of an exhaust gas recirculation (EGR) valve provided to an EGR passage of an engine; and
a controller comprised of circuitry and configured to determine at least an abnormality of the differential pressure sensor,
wherein the controller is configured to:
control an opening of the EGR valve based on an output value of the differential pressure sensor;
determine the abnormality of the differential pressure sensor based on the output value of the differential pressure sensor;
control at least a throttle valve of the engine toward a closed side so that the pressure differential between the upstream side and the downstream side of the EGR valve is maintained at greater than or equal to a given pressure when determining the abnormality of the differential pressure sensor; and
prohibit the abnormality determination of the differential pressure sensor when an engine speed of the engine is greater than or equal to a given engine speed, and permit the abnormality determination of the differential pressure sensor when the engine speed is less than the given engine speed.

Assignees

• Mazda Motor

Inventors

• Kusunoki Tomokuni

Classifications

• F02D41/222

  relating to the failure of sensors or parameter detection devices · CPC title

• F02D41/22 Primary

  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 title

• G01M15/106

  using pressure sensors · CPC title

• F02M26/06 Primary

  Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream of the compressor · CPC title

• F02D41/1448

  the characteristics being an exhaust gas pressure · CPC title