# US 10,480,479 B2 · Control device for engine

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- Number: US 10,480,479 B2
- Document ID: US10480479B2
- Status: Granted
- Kind: B2
- Application number: 16/058,122
- Filed: 2018-08-08
- Published: 2019-02-28
- Granted: 2019-11-19
- Earliest claimed: 2017-08-25
- Assignees: Mazda Motor Corporation
- Applicants: Mazda Motor Corporation
- Inventors: Kenichi Nakashima; Keitaro Ezumi; Yuichiro Tsumura; Daisuke Tanaka; Taiki Maiguma; Takuji Okumura; Kensuke Ashikaga; Masayoshi Higashio
- Web page: https://patentgrep.com/patent/US10480479B2

## CPC

- F02P 5/152: dependent on pinking (detecting or indicating knocks in internal-combustion engines G01L23/22)
- F02B 1/12: with compression ignition (with fuel-air charge ignited by compression ignition of an additional fuel F02B7/00)
- F02B 7/00: Engines characterised by the fuel-air charge being ignited by compression ignition of an additional fuel (characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition F02B11/00)
- F02D 35/023: {by determining the cylinder pressure}
- F02D 37/02: one of the functions being ignition
- F02D 41/3041: {with means for triggering compression ignition, e.g. spark plug}
- F02P 5/1502: {using one central computing unit}
- F02P 5/153: dependent on combustion pressure
- F02D 2041/0015: {for engines with means for controlling swirl or tumble flow, e.g. by using swirl valves}
- F02D 2200/025: Engine noise, e.g. determined by using an acoustic sensor
- F02D 2200/0602: Fuel pressure
- F02P 5/045: {combined with electronic control of other engine functions, e.g. fuel injection (in general F02D37/02)}
- Y02T 10/12: Improving ICE efficiencies
- Y02T 10/40: Engine management systems
- 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)
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)
- 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)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A control device for an engine in which partial compression-ignition combustion including SI combustion performed by forcibly combusting a portion of mixture gas inside a cylinder followed by CI combustion performed by causing the rest of the mixture gas inside the cylinder to self-ignite is executed within a part of an operating range of the engine, is provided. The device includes a detector configured to detect a parameter related to noise caused by the combustion inside the cylinder, a memory configured to store a characteristic defining a relationship between a start timing of the CI combustion and a combustion noise index, and a processor configured to specify a given combustion noise index value based on the detection value of the detector, and control the start timing of the CI combustion.

## Claims

### Claim 1

A control system for a compression-ignition engine, comprising:
an engine including a cylinder, a piston, a cylinder head, and a combustion chamber formed by the cylinder, the piston, and the cylinder head;
a spark plug disposed in the combustion chamber;
a fuel injection valve disposed to be oriented into the combustion chamber;
an in-cylinder pressure sensor connected to the combustion chamber and configured to detect pressure inside the combustion chamber; and
a control unit including a processor connected to the spark plug, the fuel injection valve, and the pressure sensor, and configured to output a control signal to the spark plug, the fuel injection valve, and the pressure sensor, respectively, the control unit executing:
a combustion noise index value calculating module to calculate, based on the output value of the in-cylinder pressure sensor, a first combustion noise index value that is an in-cylinder pressure level at a given high frequency, and a second combustion noise index value that is an in-cylinder pressure level at a given low frequency;
a limit value calculating module to calculate a limit value of a start timing of the CI combustion based on the first combustion noise index value and the second combustion noise index value;
an ignition timing setting module to set an ignition timing so that the start timing of the CI combustion does not advance beyond the limit value; and
a spark plug controlling module to output an ignition instruction to the spark plug at the ignition timing set by the ignition timing setting module.

### Claim 2 (depends on 1)

The control system of claim 1, wherein the control unit obtains a distribution of a plurality of combustion noise index values calculated at a plurality of time points, sets an allowable limit of the first and second combustion noise index values based on the distribution, determines a target θci that is a target start timing of the CI combustion based on the allowable limit and a characteristic, and controls the combustion inside the cylinder to achieve the determined target θci.

### Claim 3 (depends on 1)

The control system of claim 1,
wherein the control unit is further configured to execute:
a detection period setting module to set a crank angle period in which the in-cylinder pressure sensor sequentially performs the detection; and
an amplitude value calculating module to calculate an amplitude value of the in-cylinder pressure for each frequency based on an output value of the in-cylinder pressure sensor during the detection period,
wherein the combustion noise index value calculating module calculates the first combustion noise index value and the second combustion noise index value based on an output value of the amplitude value calculating module.

### Claim 4 (depends on 3)

The control system of claim 3, wherein the limit value calculating module calculates the start timing limit value of the CI combustion based on an allowable limit map in which the allowable value of the first combustion noise index value is set higher as an engine speed increases, and an allowable limit map in which the allowable value of the second combustion noise index value is set higher as the engine speed increases.

### Claim 5 (depends on 3)

The control system of claim 3, wherein the limit value calculating module calculates the start timing limit value of the CI combustion based on an allowable limit map in which the allowable value of the first combustion noise index value is set higher as an engine load increases, and an allowable limit map in which the allowable value of the second combustion noise index value is set higher as the engine load increases.

### Claim 6

A control device for an engine in which partial compression-ignition combustion including spark ignition (SI) combustion performed by forcibly combusting a portion of mixture gas inside a cylinder followed by compression ignition (CI) combustion performed by causing the rest of the mixture gas inside the cylinder to self-ignite is executed within a part of an operating range of the engine, comprising:
a detector configured to detect a parameter related to noise caused by the combustion inside the cylinder;
a memory configured to store a characteristic defining a relationship between a start timing of the CI combustion and a combustion noise index; and
a processor configured to:
specify a given combustion noise index value based on the detection value of the detector; and
control the start timing of the CI combustion based on the characteristic and the combustion noise index value.

### Claim 7 (depends on 6)

The control device of claim 6, wherein the processor obtains a distribution of a plurality of combustion noise index values calculated at a plurality of time points, sets an allowable limit of the combustion noise index value based on the distribution, determines a target θci that is a target start timing of the CI combustion based on the allowable limit and the characteristic, and controls the combustion inside the cylinder to achieve the determined target θci.

### Claim 8 (depends on 7)

The control device of claim 7, wherein the processor specifies, based on the detection value of the detector, an SI knock index value correlated with SI knock in which unburned gas outside an area of the cylinder where the SI combustion of the mixture gas occurs combusts rapidly by abnormal local self-ignition, and a CI knock index value correlated with CI knock in which noise at a lower frequency than that in the SI knock occurs during the CI combustion, as the combustion noise index value,
wherein the memory stores, as the characteristic, a first characteristic defining the relationship between the start timing of the CI combustion and the SI knock index value, and a second characteristic defining the relationship between the start timing of the CI combustion and the CI knock index value, and
wherein the processor sets an allowable limit of the SI knock index value based on a distribution of a plurality of SI knock index values specified at a plurality of time points and the first characteristic, and an allowable limit of the CI knock index value based on a distribution of a plurality of CI knock index values specified at a plurality of time points and the second characteristic, obtains a first θci limit that is a limit of the start timing of the CI combustion by which the SI knock index value is kept below the allowable limit based on the first characteristic stored in the memory, obtains a second θci limit that is a limit of the start timing of the CI combustion by which the CI knock index value is kept below the allowable limit based on the first characteristic stored in the memory, determines a timing that is the same as or later than either one of the first θci limit and the second θci limit as the target θci, and controls the combustion inside the cylinder so that the determined target θci is achieved.

### Claim 9 (depends on 8)

The control device of claim 8, wherein the processor calculates a standard deviation among the plurality of SI knock index values; sets, as the allowable limit of the SI knock index value, a value obtained by subtracting the standard deviation among the SI knock index values from a given reference limit of the SI knock index value; calculates a standard deviation among the plurality of CI knock index values; and sets, as the allowable limit of the CI knock index value, a value obtained by subtracting the standard deviation among the CI knock index values from a given reference limit of the CI knock index value.

### Claim 10

A method of controlling a compression-ignition engine including a cylinder, a piston, a cylinder head, a combustion chamber formed by the cylinder, the piston, and the cylinder head, a spark plug disposed in the combustion chamber, and a fuel injection valve disposed to be oriented into the combustion chamber, comprising:
detecting an in-cylinder pressure that is a pressure inside the combustion chamber;
calculating, based on the detected in-cylinder pressure, a first combustion noise index value that is an in-cylinder pressure level at a given high frequency, and a second combustion noise index value that is an in-cylinder pressure level at a given low frequency;
calculating a limit value of a start timing of the CI combustion based on the first combustion noise index value and the second combustion noise index value;
setting an ignition timing so that the start timing of the CI combustion does not advance beyond the limit value; and
causing the spark plug to ignite at the set ignition timing.

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
obtaining a distribution of a plurality of combustion noise index values calculated at a plurality of time points;
setting an allowable limit of the first and second combustion noise index values based on the distribution;
determining a target θci that is a target start timing of the CI combustion based on the allowable limit and a characteristic; and
controlling the combustion inside the cylinder to achieve the determined target θci.

### Claim 12 (depends on 10)

The method of claim 10, further comprising:
setting a crank angle period in which the in-cylinder pressure is sequentially detected;
calculating an amplitude value of the in-cylinder pressure for each frequency based on the detected in-cylinder pressure during the detection period; and
calculating the first combustion noise index value and the second combustion noise index value based on the calculated amplitude value.

### Claim 13 (depends on 12)

The method of claim 12, wherein the start timing limit value of the CI combustion is calculated based on an allowable limit map in which the allowable value of the first combustion noise index value is set higher as an engine speed increases, and an allowable limit map in which the allowable value of the second combustion noise index value is set higher as the engine speed increases.

### Claim 14 (depends on 12)

The method of claim 12, wherein the start timing limit value of the CI combustion is calculated based on an allowable limit map in which the allowable value of the first combustion noise index value is set higher as an engine load increases, and an allowable limit map in which the allowable value of the second combustion noise index value is set higher as the engine load increases.