# US 11,111,870 B2 · Method and system for determining abnormality of differential pressure sensor

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- Number: US 11,111,870 B2
- Document ID: US11111870B2
- Status: Granted
- Kind: B2
- Application number: 16/781,231
- Filed: 2020-02-04
- Published: 2020-10-22
- Granted: 2021-09-07
- Earliest claimed: 2019-04-19
- Assignees: Mazda Motor Corporation
- Applicants: Mazda Motor Corporation
- Inventors: Tomokuni Kusunoki
- Web page: https://patentgrep.com/patent/US11111870B2

## CPC

- 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)}
- F02D 41/0007: {for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12)}
- F02D 41/0077: {Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position (EGR valve position sensor F02M26/48)}
- F02D 41/1448: {the characteristics being an exhaust gas pressure}
- F02D 41/222: {relating to the failure of sensors or parameter detection devices}
- F02M 26/10: having means to increase the pressure difference between the exhaust and intake system, e.g. venturis, variable geometry turbines, check valves using pressure pulsations or throttles in the air intake or exhaust system
- F02M 26/49: Detecting, diagnosing or indicating an abnormal function of the EGR system
- G01L 27/007: {Malfunction diagnosis, i.e. diagnosing a sensor defect}
- G01M 15/106: {using pressure sensors}
- F02M 26/06: 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
- F02M 26/47: the characteristics being temperatures, pressures or flow rates
- Y02T 10/12: Improving ICE efficiencies
- F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W)
- F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## 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.

## Claims

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 2)

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

### Claim 4 (depends on 1)

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

### Claim 5 (depends on 1)

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.

### Claim 6 (depends on 5)

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

### Claim 7 (depends on 1)

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.

### Claim 8 (depends on 1)

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.

### Claim 9 (depends on 8)

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.

### Claim 10 (depends on 9)

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.

### Claim 11 (depends on 10)

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.

### Claim 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.