Control device for engine

Patent metadata

Field	Value
Publication number	US-11008970-B2
Application number	US-202016922886-A
Country	US
Kind code	B2
Filing date	Jul 7, 2020
Priority date	Jul 17, 2019
Publication date	May 18, 2021
Grant date	May 18, 2021

Abstract

A control device for controlling an engine provided with a fuel pump including a pressurizing chamber, a plunger inserted into the pressurizing chamber and which changes a volume of the pressurizing chamber, and an on-off valve configured to open and close a suction port, is provided. When a pressurizing cycle consists of a period of pressurizing stroke in which the volume of the pressurizing chamber is reduced to allow fuel to be pressurized and a period of suction stroke in which the volume of the pressurizing chamber is increased to allow fuel to be drawn into the pressurizing chamber, a closing cycle of the on-off valve is controlled so that a ratio of the closing cycle to the pressurizing cycle becomes smaller in a second combustion mode where a partial compression-ignition combustion is performed than in a first combustion mode where SI combustion is performed.

First claim

What is claimed is:

1. A control device for controlling an engine provided with a fuel injector configured to inject fuel into a cylinder, a spark plug configured to ignite a mixture gas inside the cylinder, a fuel storage configured to store fuel to be introduced into the fuel injector, a fuel pump configured to pump fuel into the fuel storage, and a low-pressure fuel passage through which fuel to be introduced into the fuel pump flows, the control device comprising:
a processor configured to execute:
a combustion controller to switch a combustion mode of the mixture gas between a first combustion mode and a second combustion mode by controlling each component of the engine according to an operating state of the engine; and
a pump controller to control the fuel pump,

wherein in the first combustion mode, the mixture gas is combusted by SI combustion where the spark plug ignites the mixture gas, and in the second combustion mode, a portion of the mixture gas is combusted by spark ignition (SI) combustion where the spark plug ignites the mixture gas, and then the remaining mixture gas is combusted by compression ignition (CI) combustion where the mixture gas is combusted by self-ignition,
wherein the fuel pump includes:
a pressurizing chamber having a suction port, and into which fuel is introduced from the low-pressure fuel passage via the suction port;
a plunger inserted into the pressurizing chamber and configured to change a volume of the pressurizing chamber;
an on-off valve configured to open and close the suction port; and
a plunger driving part configured to drive the plunger interlocking with the engine so that a suction stroke in which the volume of the pressurizing chamber is increased to allow fuel to be drawn into the pressurizing chamber, and a pressurizing stroke in which the volume of the pressurizing chamber is reduced to allow fuel inside the pressurizing chamber to be pressurized, are performed successively, and

wherein when assuming that a period of time combining a period of the pressurizing stroke and a period of the suction stroke is a pressurizing cycle, the pump controller cyclically closes the on-off valve, and controls a closing cycle of the on-off valve so that a ratio of the closing cycle of the on-off valve to the pressurizing cycle becomes smaller in the second combustion mode than in the first combustion mode.

2. The control device of claim 1 , wherein the combustion controller controls the fuel injector so that an air-fuel ratio of mixture gas in the second combustion mode becomes larger than a stoichiometric air-fuel ratio.

3. The control device of claim 1 ,
wherein the pump controller sets a target variation width that is a target value for a variation width of fuel pressure inside the fuel storage, and controls the closing cycle of the on-off valve so that the variation width becomes the target variation width, and
wherein the target variation width is set to a smaller value in the second combustion mode than in the first combustion mode.

4. The control device of claim 3 , wherein in the second combustion mode, the target variation width is set to a smaller value as an engine load increases.

5. A method for controlling an engine provided with a fuel injector configured to inject fuel into a cylinder, a spark plug configured to ignite a mixture gas inside the cylinder, a fuel storage configured to store fuel to be introduced into the fuel injector, a fuel pump configured to pump fuel into the fuel storage, and a low-pressure fuel passage through which fuel to be introduced into the fuel pump flows, the method comprising the steps of:
switching a combustion mode of mixture gas between a first combustion mode and a second combustion mode by controlling each component of the engine according to an operating state of the engine; and
controlling the fuel pump,
wherein in the first combustion mode, mixture gas is combusted by SI combustion where the spark plug ignites the mixture gas, and in the second combustion mode, a portion of mixture gas is combusted by spark ignition (SI) combustion where the spark plug ignites the mixture gas, and then the rest of the mixture gas is combusted by compression ignition (CI) combustion where the mixture gas is combusted by self-ignition,
wherein the fuel pump includes:
a pressurizing chamber having a suction port, and into which fuel is introduced from the low-pressure fuel passage via the suction port;
a plunger inserted into the pressurizing chamber and configured to change a volume of the pressurizing chamber;
an on-off valve configured to open and close the suction port; and
a plunger driving part configured to drive the plunger interlocking with the engine so that a suction stroke in which the volume of the pressurizing chamber is increased to allow fuel to be drawn into the pressurizing chamber, and a pressurizing stroke in which the volume of the pressurizing chamber is reduced to allow fuel inside the pressurizing chamber to be pressurized, are performed successively, and

wherein when assuming that a period of time combining a period of the pressurizing stroke and a period of the suction stroke is a pressurizing cycle, the on-off valve is cyclically closed, and a closing cycle of the on-off valve is controlled so that a ratio of the closing cycle of the on-off valve to the pressurizing cycle becomes smaller in the second combustion mode than in the first combustion mode.

Assignees

• Mazda Motor

Inventors

• Nishida Masami
• Miyamae Toru
• Yamashita Shigeki
• Takemoto Kazuhiro
• Ito Michio
• Nishimura Kazuhiro
• Kawai Yusuke
• Chikada Tetsuya
• Tokunaga Tatsuhiro

Classifications

• F02M59/46

  Valves · CPC title

• F02M59/10

  characterised by the piston-drive · CPC title

• F02D41/3845

  by controlling the flow into the common rail, e.g. the amount of fuel pumped · CPC title

• F02D41/3818

  for petrol engines · CPC title

• F02D2001/009

  Means for varying the pressure of fuel supply pump according to engine working parameters · CPC title