Controller for internal combustion engine

Patent metadata

Field	Value
Publication number	US-10138784-B2
Application number	US-201615187944-A
Country	US
Kind code	B2
Filing date	Jun 21, 2016
Priority date	Aug 18, 2015
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

A PCV valve that ventilates a crankcase is provided. A three-way catalyst and a NOx storage/reduction catalyst are provided in an exhaust passage. An electronic control unit performs a stoichiometric control and a lean control. When a crankcase ventilation request is issued, a relationship between a ventilation amount of ventilation achieved by the PCV valve and a fuel consumption resulting from the ventilation is calculated. Furthermore, an operational condition under which the ventilation amount meets a required ventilation amount and the fuel consumption is minimized is calculated. The operational condition is calculated so that a constant engine torque is maintained and the air-fuel ratio falls within a range that ensures purification.

First claim

The invention claimed is:

1. An internal combustion engine, comprising:
an electronic control unit including a computer and processor for executing programs stored in memory of the computer, the electronic control unit configured to detect the state of the internal combustion engine based on outputs from a plurality of sensors located on the engine and control the state of the internal combustion engine based on the outputs;
a positive crankcase ventilation (PCV) valve that ventilates a crankcase by causing suction of an in-case gas into an intake passage;
a three-way catalyst and an NOx storage/reduction catalyst disposed in an exhaust passage; and
the electronic control unit drives an actuator of the internal combustion engine,
wherein the electronic control unit is programmed to:
perform a stoichiometric control for making the internal combustion engine run in a stoichiometric region including a theoretical air-fuel ratio and a lean control for making the internal combustion engine run in a lean region that is leaner than the stoichiometric region, and,
when it is determined by the electronic control unit that ventilation is necessary for the crankcase, the electronic control unit extracts as a ventilation condition, a combination of an air-fuel ratio of an air-fuel mixture, a fuel injection amount and an intake manifold pressure with which a ventilation amount of the in-case gas per unit time increases among combinations of those, and changes the air-fuel ratio, the fuel injection amount and the intake manifold pressure in accordance with the ventilation condition,
wherein the extraction concerning the air-fuel ratio is performed within an allowable air-fuel ratio range in which the three-way catalyst and the NOx storage/reduction catalyst are capable of purifying an exhaust gas and ensuring in-cylinder combustion of the air-fuel mixture, and
wherein the air-fuel ratio and the fuel injection amount extracted as the ventilation condition meets a relationship that maintains a constant engine torque before and after the change.

2. The internal combustion engine according to claim 1 , wherein the electronic control unit sets a required ventilation amount of the in-case gas per unit time when it is determined by the electronic control unit that ventilation is necessary for the crankcase, and
the ventilation condition is extracted so that the ventilation amount meets the required ventilation amount.

3. The internal combustion engine according to claim 1 , wherein, when it is determined by the electronic control unit that ventilation is necessary for the crankcase, the electronic control unit
(1-1) temporarily determines the air-fuel ratio within the allowable air-fuel ratio range,
(1-2) performs a determination processing for determining the intake manifold pressure that meets the required ventilation amount with the minimum fuel consumption for a combination of the temporarily determined air-fuel ratio and the fuel injection amount that maintains the constant engine torque at the air-fuel ratio,
(2) repeatedly performs the determination processing for each of a plurality of air-fuel ratios included in the allowable air-fuel ratio range, and
(3) extracts, as the ventilation condition, a combination of an intake manifold pressure that provides the minimum fuel consumption among all intake manifold pressures determined in the determination processing and the air-fuel ratio and fuel injection amount used in the determination processing of determining the intake manifold pressure.

4. The internal combustion engine according to claim 2 , wherein the electronic control unit
detects an NOx concentration in the crankcase with at least one of the plurality of sensors, and
sets the required ventilation amount based on the NOx concentration.

5. The internal combustion engine according to claim 2 , wherein the electronic control unit
detects a CO2 concentration in the crankcase with at least one of the plurality of sensors, and
sets the required ventilation amount based on the CO2 concentration.

6. The internal combustion engine according to claim 1 , further comprising:
a throttle valve that controls an intake air amount;
a supercharger provided with a waste gate valve; and
an ejector that ventilates the crankcase by using a pressure difference between before and after a compressor of the supercharger,
wherein the ventilation condition is a combination with which a total ventilation amount per unit time achieved by both the PCV valve and the ejector increases, among combinations of the air-fuel ratio of the air-fuel mixture, the fuel injection amount, the intake manifold pressure, a throttle opening and a waste gate opening angle.

7. The internal combustion engine according to claim 6 , wherein, when the ventilation request is issued, the electronic control unit sets a required ventilation amount of the in-case gas per unit time, and
the ventilation condition is extracted so that the total ventilation amount meets the required ventilation amount.

8. The internal combustion engine according to claim 7 , wherein the ventilation condition is a combination that meets the required ventilation amount with a minimum fuel consumption, among combinations of the air-fuel ratio within the allowable air-fuel ratio range, the fuel injection amount that maintains the constant engine torque, the intake manifold pressure, the throttle opening and the waste gate opening angle.

9. The internal combustion engine according to claim 8 , wherein, when the ventilation request is issued, the electronic control unit
(1-1) temporarily determines the air-fuel ratio within the allowable air-fuel ratio range,
(1-2) temporarily determines the intake manifold pressure within a practical range,
(1-3) performs a determination processing for determining a pair of the throttle opening and the waste gate opening angle that meets the required ventilation amount with the minimum fuel consumption for the combination of the temporarily determined intake manifold pressure and air-fuel ratio and the fuel injection amount that allows generation of the constant torque at the air-fuel ratio, and
(2) repeatedly performs the determination processing for each of a plurality of combinations of a plurality of air-fuel ratios included in the allowable air-fuel ratio range and a plurality of intake manifold pressures included in the practical range.

10. The internal combustion engine according to claim 7 , wherein the electronic control unit
detects an NOx concentration in the crankcase, and
sets the required ventilation amount based on the NOx concentration.

11. The internal combustion engine according to claim 7 , wherein the electronic control unit
detects a CO2 concentration in the crankcase, and
sets the required ventilation amount based on the CO2 concentration.

12. The internal combustion engine according to claim 1 , wherein the electronic control unit
detects an NOx concentration in the crankcase, and
determines that ventilation is necessary for the crankcase when the NOx concentration reaches a threshold.

13. The internal combustion engine according to claim 1 , wherein the electronic control unit
detects a CO2 concentration in the crankcase, and
determines that ventilation is necessary for the crankcase when the CO2 concentration reaches a threshold.

14. The internal combustion engine according to claim 1 , wherein the allowable air-fuel ratio range consists of said stoichiometric region and said lean region,
between said stoichiometric region and said lean region, there is an intermediate region in which NOx in the exhaust gas is not pur

Assignees

• Toyota Motor Co Ltd

Inventors

• Tanaka Takayoshi

Classifications

• F01N3/0842

  Nitrogen oxides · CPC title

• Y02T10/22

  Cross-Sectional Technologies · mapped topic

• F02D2250/08

  Engine blow-by from crankcase chamber · CPC title

• F02D2200/0806

  NOx storage amount, i.e. amount of NOx stored on NOx trap · CPC title

• F01M13/00

  Crankcase ventilating or breathing · CPC title