# US 8,783,227 B2 · Engine control method and apparatus

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- Number: US 8,783,227 B2
- Document ID: US8783227B2
- Status: Granted
- Kind: B2
- Application number: 13/012,406
- Filed: 2011-01-24
- Published: 2011-07-28
- Granted: 2014-07-22
- Earliest claimed: 2010-01-27
- Assignees: Mazda Motor Corporation
- Applicants: Masahisa Yamakawa; Kouhei Iwai; Shuji Oba
- Inventors: Masahisa Yamakawa; Kouhei Iwai; Shuji Oba
- Web page: https://patentgrep.com/patent/US8783227B2

## CPC

- F02B 3/06: with compression ignition (compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02)
- F02D 13/0211: {the change of valve timing is caused by the change in valve lift, i.e. both valve lift and timing are functionally related}
- F02D 13/0238: {by shifting the phase, i.e. the opening periods of the valves are constant}
- F02D 13/0265: {Negative valve overlap for temporarily storing residual gas in the cylinder}
- F02D 13/0269: {Controlling the valves to perform a Miller-Atkinson cycle}
- F02D 15/04: by alteration of volume of compression space without changing piston stroke
- F02D 41/006: {using internal EGR (control of valve overlap for internal EGR F02D13/0261; arrangements for internal EGR F02M26/01)}
- F02D 41/3035: {a mode being the premixed charge compression-ignition mode}
- F02M 26/01: Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages
- F02B 3/08: Methods of operating (F02B3/12 takes precedence)
- F02B 29/0437: {Liquid cooled heat exchangers}
- F02B 2075/125: {Direct injection in the combustion chamber for spark ignition engines, i.e. not in pre-combustion chamber}
- F02D 35/023: {by determining the cylinder pressure}
- F02D 35/026: {using an estimation}
- F02D 41/0007: {for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12)}
- F02D 41/0057: {Specific combustion modes (combustion modes per se F02D41/3017)}
- Y02T 10/12: Improving ICE efficiencies
- Y02T 10/40: Engine management systems
- 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)
- F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

An engine is designed to allow a compression self-ignition combustion under an air-fuel ratio leaner than a stoichiometric air-fuel ratio to be performed at least in a partial-load range of the engine. Under a condition that an engine speed varies at a same load in an engine operating region of the compression self-ignition combustion, a compression end temperature Tx, which is an in-cylinder temperature just before an air-fuel mixture self-ignites, is controlled to be raised higher in a higher engine speed side than in a lower engine speed side. As one example of control for the compression end temperature Tx, an internal EGR amount is controlled to be increased larger in the higher engine speed side than in the lower engine speed side, to raise a compression initial temperature T0 which is an in-cylinder temperature at a start timing of a compression stroke. This makes it possible to perform the compression self-ignition combustion under a lean air-fuel ratio in a wider engine speed range to effectively enhance engine thermal efficiency.

## Claims

### Claim 1

A method for controlling an engine, comprising steps of:
allowing a compression self-ignition combustion under an air-fuel ratio leaner than a stoichiometric air-fuel ratio to be performed at least in a partial-load range of the engine, and
acquiring a compression end temperature which is an in-cylinder temperature just before an air-fuel mixture self-ignites,
wherein, under a condition that an engine speed varies at a same load in an engine operating region of the compression self-ignition combustion, the compression end temperature is controlled to be raised higher in a higher engine speed side than in a lower engine speed side.

### Claim 2 (depends on 1)

The method as defined in claim 1, wherein the control for raising the compression end temperature includes a control for raising a compression initial temperature which is an in-cylinder temperature at a start timing of a compression stroke, and wherein, the compression initial temperature is controlled to be raised higher in the higher engine speed side than in the lower engine speed side.

### Claim 3 (depends on 2)

The method as defined in claim 2, wherein the control for raising the compression initial temperature includes a control for performing internal EGR for causing burned gas to remain in a cylinder, and wherein, an internal EGR amount is controlled to be increased larger in the higher engine speed side than in the lower engine speed side.

### Claim 4 (depends on 3)

The method as defined in claim 3, wherein, when the internal EGR is performed at a same engine speed, the internal EGR amount is increased as the load becomes lower.

### Claim 5 (depends on 2)

The method as defined in claim 2, further comprising a step of raising a compression initial pressure which is an in-cylinder pressure at a start timing of a compression stroke, according to a rise in the compression initial temperature, by means of supercharging.

### Claim 6 (depends on 1)

The method as defined in claim 1, further comprising a step of setting a geometric compression ratio of the engine to 16 or more.

### Claim 7 (depends on 1)

The method as defined in claim 1, wherein, throughout the engine operating region subject to the compression self-ignition combustion, an excess air ratio λ which is a ratio of an actual air-fuel ratio to the stoichiometric air-fuel ratio, is set to 2 or more.

### Claim 8

An apparatus for controlling an engine, comprising:
a controller adapted to control respective sections of the engine to allow a compression self-ignition combustion under an air-fuel ratio leaner than a stoichiometric air-fuel ratio to be performed at least in a partial-load range of the engine,
wherein the controller is operable, under a condition that an engine speed varies at a same load in an engine operating region of the compression self-ignition combustion, to control a compression end temperature, which is an in-cylinder temperature just before an air-fuel mixture self-ignites, in such a manner that it is raised higher in a higher engine speed side than in a lower engine speed side.

### Claim 9 (depends on 8)

The apparatus as defined in claim 8, wherein the control for raising the compression end temperature includes a control for raising a compression initial temperature which is an in-cylinder temperature at a start timing of a compression stroke, and wherein the controller is operable to control the compression initial temperature in such a manner that it is raised higher in the higher engine speed side than in the lower engine speed side.

### Claim 10 (depends on 9)

The apparatus as defined in claim 9, wherein the control for raising the compression initial temperature includes a control for performing internal EGR for causing burned gas to remain in a cylinder, and wherein the controller is operable to control an internal EGR amount in such a manner that it is increased larger in the higher engine speed side than in the lower engine speed side.

### Claim 11 (depends on 10)

The apparatus as defined in claim 10, wherein the controller is operable, when the internal EGR is performed at a same engine speed, to increase the internal EGR amount as the load becomes lower.

### Claim 12 (depends on 9)

The apparatus as defined in claim 9, wherein the engine is equipped with a supercharger operable to supercharge fresh air, and wherein the controller is operable to activate the supercharger to raise a compression initial pressure which is an in-cylinder pressure at a start timing of a compression stroke, according to a rise in the compression initial temperature.

### Claim 13 (depends on 8)

The apparatus as defined in claim 8, wherein a geometric compression ratio of the engine is set to 16 or more.

### Claim 14 (depends on 8)

The apparatus as defined in claim 8, wherein the controller is operable, throughout the engine operating region subject to the compression self-ignition combustion, to set an excess air ratio λ which is a ratio of an actual air-fuel ratio to the stoichiometric air-fuel ratio, to 2 or more.