Spark-ignition direct injection engine

Patent metadata

Field	Value
Publication number	US-9261041-B2
Application number	US-201313954881-A
Country	US
Kind code	B2
Filing date	Jul 30, 2013
Priority date	Aug 29, 2012
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

A spark-ignition direct injection engine is provided. The engine includes an engine body, a fuel injection valve, a fuel pressure setting mechanism, an ignition plug, and a controller. The controller operates the engine to perform compression-ignition combustion within a first operating range, and controls the ignition plug to operate the engine to perform spark-ignition combustion within a second operating range. Within a specific part of the first range, the controller sets the fuel pressure to 30 MPa or above, and retards the compression ignition to after a compression top dead center by controlling the injection valve to inject fuel into a cylinder in a period from a late stage of compression stroke to an early stage of expansion stroke. Below the specific part, the controller controls the fuel injection valve to inject the fuel into the cylinder in a period from intake stroke to a mid-stage of the compression stroke.

First claim

The invention claimed is:

1. A spark-ignition direct injection engine, comprising:
an engine body having a cylinder;
a fuel injection valve for injecting fuel into the cylinder;
a fuel pressure setting mechanism for setting a pressure of the fuel to be injected by the fuel injection valve;
an ignition plug arranged to be oriented toward an inside of the cylinder and for igniting mixture gas within the cylinder; and
a controller for operating the engine body by controlling at least the fuel injection valve, the fuel pressure setting mechanism, and the ignition plug,
wherein when an operating state of the engine body is within a first range that is a predetermined low engine load range, the controller operates the engine body to perform compression-ignition combustion where the mixture gas within the cylinder is compressed to ignite,
wherein when the operating state of the engine body is within a second range where the engine load is higher than the first range where the compression-ignition combustion is performed, the controller controls the ignition plug at a predetermined timing so as to operate the engine body to perform spark-ignition combustion,
wherein when the operating state of the engine body is within a specific high engine load part of the first range including a boundary between the first and second ranges, the controller sets the fuel pressure to be a high fuel pressure of 30 MPa or above by the fuel pressure setting mechanism, and the controller retards the compression ignition to after a compression top dead center by controlling the fuel injection valve to perform the fuel injection into the cylinder at least in a period from a late stage of compression stroke to an early stage of expansion stroke, and
wherein when the operating state of the engine body is within a part of the first range where the engine load is below the specific part, the controller controls the fuel injection valve to perform the fuel injection into the cylinder at least in a period from intake stroke to a middle stage of the compression stroke.

2. The engine of claim 1 , further comprising an exhaust recirculator for introducing exhaust gas into the cylinder,
wherein the controller controls the exhaust recirculator to change an EGR ratio, the EGR ratio corresponding to a ratio of an amount of exhaust gas with respect to the entire gas amount within the cylinder,
wherein when the operating state of the engine body is within a lowest engine load part of the first range, the controller sets a highest EGR ratio and reduces the EGR ratio according to an increase of the engine load, and
wherein between the specific part of the first range and a low engine load part of the second range including the boundary between the first and second ranges, the controller continuously reduces the EGR ratio according to the increase of the engine load.

3. The engine of claim 2 , wherein the exhaust recirculator introduces into the cylinder, a cooled EGR gas that is cooled exhaust gas, and a hot EGR gas having a higher temperature than the cooled EGR gas, and
wherein when the operating state of the engine body is within the lowest engine load part of the first range, the controller only introduces the hot EGR gas into the cylinder through the exhaust recirculator, and when the operating state of the engine body is within the low engine load part of the second range including the boundary between the first and second ranges, the controller at least introduces the cooled EGR gas into the cylinder.

4. The engine of claim 1 , wherein when the operating state of the engine body is within the part of the first range where the engine load is below the specific part, the controller sets the fuel pressure to be a low fuel pressure of below 30 MPa by the fuel pressure setting mechanism, and the controller controls the fuel injection valve to perform the fuel injection at least in the period from intake stroke to the middle stage of the compression stroke.

5. The engine of claim 4 , wherein the fuel pressure setting mechanism includes a high pressure fuel pump that is operated by the engine body, and the high pressure fuel pump adjusts the pressure of the fuel to be injected from the fuel injection valve.

6. The engine of claim 1 , wherein a piston is reciprocatably inserted into the cylinder, and a concaved cavity is formed on a top face of the piston, and
wherein when the operating state of the engine body is within the specific part of the first range, the controller controls the fuel injection valve to perform the fuel injection into the cylinder at least in the period from the late stage of the compression stroke to the early stage of the expansion stroke so that the fuel is injected into the cavity.

7. The engine of claim 6 , wherein the fuel injection valve is a multi-hole type and arranged in a center part of a combustion chamber of the engine body, and the fuel injection valve is set to radially inject the fuel within the cavity in the period from the late stage of the compression stroke to the early stage of the expansion stroke.

8. The engine of claim 2 , wherein the exhaust recirculator introduces into the cylinder, a cooled EGR gas that is cooled exhaust gas, and a hot EGR gas having a higher temperature than the cooled EGR gas, and
wherein when the operating state of the engine body is between the specific part of the first range and a low engine load part of the second range including the boundary between the first and second ranges, the exhaust recirculator introduces both the cooled and hot EGR gas into the cylinder and, as the engine load increases, reduces the EGR ratio by reducing a ratio of the hot EGR gas amount with respect to the entire gas amount within the cylinder while increasing a ratio of the cooled EGR gas with respect to the entire gas amount within the cylinder, the EGR ratio corresponding to the ratio of the total EGR gas amount including the cooled EGR gas and the hot EGR gas with respect to the entire gas amount within the cylinder.

Assignees

• Mazda Motor

Inventors

• Iwai Kouhei
• Yamakawa Masahisa
• Nagatsu Kazuhiro
• Youso Takashi

Classifications

• F02D13/0219

  by shifting the phase, i.e. the opening periods of the valves are constant · CPC title

• F02M25/0728

  Mechanical Engineering · mapped topic

• F02D13/0273

  Multiple actuations of a valve within an engine cycle · CPC title

• Y02T10/18

  Cross-Sectional Technologies · mapped topic

• Y02T10/146

  Cross-Sectional Technologies · mapped topic