# US 2019/0170072 A1 · Controller and control method for internal combustion engine

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- Number: US 2019/0170072 A1
- Document ID: US20190170072A1
- Status: Published application
- Kind: A1
- Application number: 16/190,365
- Filed: 2018-11-14
- Published: 2019-06-06
- Earliest claimed: 2017-12-06
- Assignees: Toyota Jidosha Kabushiki Kaisha
- Applicants: Toyota Jidosha Kabushiki Kaisha
- Inventors: Yuya YOSHIKAWA; Isao Nakajima; Akihiro Katayama; Ryo Suzuki; Sohichi Imai; Eiichiro Kido
- Web page: https://patentgrep.com/patent/US20190170072A1

## CPC

- F02D 41/008: {Controlling each cylinder individually}
- F02D 41/1408: {Dithering techniques}
- F02D 41/1475: {Regulating the air fuel ratio at a value other than stoichiometry}
- F02D 41/1497: {With detection of the mechanical response of the engine}
- F02D 41/2458: {with an additional dither signal}
- F02D 41/263: {the program execution being modifiable by physical parameters}
- F02D 41/38: of the high pressure type
- F02D 41/401: {Controlling injection timing (F02D41/402 takes precedence)}
- F02P 5/045: {combined with electronic control of other engine functions, e.g. fuel injection (in general F02D37/02)}
- F02P 5/15: Digital data processing
- F02P 5/1502: {using one central computing unit}
- F02D 41/1498: {measuring engine roughness}
- F02D 2200/0614: Actual fuel mass or fuel injection amount
- F02D 2200/1002: Output torque
- F02D 2200/1015: Engines misfires
- Y02T 10/40: Engine management systems
- 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)
- F02P: IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES ({anti-pollution means for internal-combustion engines F02B17/00}; specially adapted for rotary-piston or oscillating-piston engines F02B53/12; {ignition of gas turbine plants F02C7/26; ignition of jet propulsion plants F02K9/95; starting of combustion engines F02N9/00}; ignition of combustion apparatus in general, glowing plugs F23Q; measuring of physical variables in general G01; controlling in general G05; data processing in general G06; electrical components in general see Section H; {ignition coils H01F38/12}; sparking plugs H01T13/00)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A first limit requesting process limits a dither control process of fuel injection valves in such a manner that the absolute value of the difference between the air-fuel ratios of the cylinders becomes smaller when the degree of variation of the injection amounts of the fuel injection valves provided for respective cylinders is great than when the degree of variation is small. A second limit requesting process limits the dither control process in such a manner that the absolute value is smaller when the torque fluctuation amount of the internal combustion engine is great than when the torque fluctuation amount is small. The limiting process limits the dither control process in accordance with one of requests generated by the first limit requesting process and the second limit requesting process that causes the absolute value to be smaller than the other.

## Claims

### Claim 1

A controller for an internal combustion engine, wherein the internal combustion engine includes an exhaust purifying device, which purifies exhaust gas discharged from a plurality of cylinders, and fuel injection valves provided for the respective cylinders, and the controller being configured to execute
a dither control process of operating the fuel injection valves in such a manner that at least one of the cylinders is designated as a rich combustion cylinder and at least another one of the cylinders is designated as a lean combustion cylinder, an air-fuel ratio of the rich combustion cylinder being richer than a stoichiometric air-fuel ratio, and an air-fuel ratio of the lean combustion cylinder being leaner than a stoichiometric air-fuel ratio,
a first limit requesting process of, in a case in which the fuel injection valves are operated to control air-fuel ratios of the respective cylinders to be equal to each other, requesting to limit the dither control process in such a manner that an absolute value of a difference between the air-fuel ratios of the cylinders is when a degree of variation of the injection amounts of the fuel injection valves of the respective cylinders is great than when the degree of variation is small,
a second limit requesting process of requesting to limit the dither control process in such a manner that the absolute value is smaller when a torque fluctuation amount of the internal combustion engine is great than when the torque fluctuation amount is small, and
a limiting process of limiting the dither control process in such a manner that the absolute value decreases in accordance with one of requests generated by the first limit requesting process and the second limit requesting process that causes the absolute value to be smaller than the other.

### Claim 2 (depends on 1)

The controller for an internal combustion engine according to claim 1, wherein the controller is further configured to execute
an advancing process of advancing an ignition timing more when the torque fluctuation amount of the internal combustion engine is great than when the torque fluctuation amount is small, and
an adjustment process of executing the limiting process prior to the execution of the advancing process when the torque fluctuation amount increases during execution of the dither control process.

### Claim 3 (depends on 2)

The controller for an internal combustion engine according to claim 2, wherein
the controller is further configured to execute a retardation requirement amount setting process of setting a requested retardation amount of the ignition timing in accordance with a rotational speed and a load of a crankshaft of the internal combustion engine, and
the advancing process corrects the requested retardation amount to decrease in accordance with the torque fluctuation amount.

### Claim 4 (depends on 2)

The controller for an internal combustion engine according to claim 2, wherein the advancing process includes a process of advancing the ignition timing more when the degree of variation is great than when the degree of variation is small.

### Claim 5 (depends on 2)

The controller for an internal combustion engine according to claim 2, wherein the second limit requesting process includes a process of causing a changing speed of a request for the absolute value in response to a case in which the torque fluctuation amount is changed from a great value to a small value to be lower than a changing speed of a request for the absolute value in response to a case in which the torque fluctuation amount is changed from a small value to a great value.

### Claim 6

A control method for an internal combustion engine, wherein the internal combustion engine includes an exhaust purifying device, which purifies exhaust gas discharged from a plurality of cylinders, and fuel injection valves provided for the respective cylinders, the control method comprising:
a dither control process of operating the fuel injection valves in such a manner that at least one of the cylinders is designated as a rich combustion cylinder and at least another one of the cylinders is designated as a lean combustion cylinder, an air-fuel ratio of the rich combustion cylinder being richer than a stoichiometric air-fuel ratio, and an air-fuel ratio of the lean combustion cylinder being leaner than a stoichiometric air-fuel ratio;
a first limit requesting process of, in a case in which the fuel injection valves are operated to control air-fuel ratios of the respective cylinders to be equal to each other, requesting to limit the dither control process in such a manner that an absolute value of a difference between the air-fuel ratios of the cylinders is when a degree of variation of the injection amounts of the fuel injection valves of the respective cylinders is great than when the degree of variation is small;
a second limit requesting process of requesting to limit the dither control process in such a manner that the absolute value is smaller when a torque fluctuation amount of the internal combustion engine is great than when the torque fluctuation amount is small; and
a limiting process of limiting the dither control process in such a manner that the absolute value decreases in accordance with one of requests generated by the first limit requesting process and the second limit requesting process that causes the absolute value to be smaller than the other.

### Claim 7

A non-transitory computer readable medium that stores a program for causing a processor to execute a control process for an internal combustion engine, wherein the internal combustion engine includes an exhaust purifying device, which purifies exhaust gas discharged from a plurality of cylinders, and fuel injection valves provided for the respective cylinders, the control process includes
a dither control process of operating the fuel injection valves in such a manner that at least one of the cylinders is designated as a rich combustion cylinder and at least another one of the cylinders is designated as a lean combustion cylinder, an air-fuel ratio of the rich combustion cylinder being richer than a stoichiometric air-fuel ratio, and an air-fuel ratio of the lean combustion cylinder being leaner than a stoichiometric air-fuel ratio,
a first limit requesting process of, in a case in which the fuel injection valves are operated to control air-fuel ratios of the respective cylinders to be equal to each other, requesting to limit the dither control process in such a manner that an absolute value of a difference between the air-fuel ratios of the cylinders is when a degree of variation of the injection amounts of the fuel injection valves of the respective cylinders is great than when the degree of variation is small,
a second limit requesting process of requesting to limit the dither control process in such a manner that the absolute value is smaller when a torque fluctuation amount of the internal combustion engine is great than when the torque fluctuation amount is small, and
a limiting process of limiting the dither control process in such a manner that the absolute value decreases in accordance with one of requests generated by the first limit requesting process and the second limit requesting process that causes the absolute value to be smaller than the other.