Control system for internal combustion engine of vehicle

• US 9,856,816 B2
• Filed: 10/30/2014
• Issued: 01/02/2018
• Est. Priority Date: 11/18/2013
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Kojima, Susumu, Suzuki, Yusuke, Onoda, Rui
• Primary Examiner(s): Vilakazi, Sizo
• Assistant Examiner(s): KIRBY, BRIAN R
• Application Number:
  US14/528,226
• Publication Number:
  US 20150142297A1
• Time in Patent Office: 1,160 Days
• Field of Search: 701102-104, 701112-113
• CPC Class Codes: F02D 2200/021 Engine temperature
• CPC Class Codes: F02D 35/025 by determining temperatures inside the cylinder, e.g. combustion temperatures
• CPC Class Codes: F02D 41/0025 Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
• CPC Class Codes: F02D 41/047 Taking into account fuel evaporation or wall wetting; special correction after fuel cut-off F02D41/126
• CPC Class Codes: F02D 41/062 for starting F02D41/061 takes precedence
• CPC Class Codes: F02D 41/068 for warming-up
• CPC Class Codes: F02D 41/3076 with special conditions for selecting a mode of combustion, e.g. for starting, for diagnosing
• CPC Class Codes: F02N 11/0814 comprising means for controlling automatic idle-start-stop

Abstract

When the temperature in a cylinder of an engine is low, the fuel injection amount of fuel that has a low vapor pressure and is less likely to be vaporized is increased, and the fuel injection amount of fuel that has a high vapor pressure and is more likely to be vaporized is reduced, so that the start timing of the engine can be kept constant. When the temperature in the cylinder is high, the fuel injection amount of the fuel that has a low vapor pressure and is more likely to be decomposed is reduced, and the fuel that has a high vapor pressure and is less likely to be burned (decomposed) is increased, so that the start timing of the engine can be kept constant. Thus, the start timing of the engine is kept constant irrespective of the fuel property, and deterioration of the drivability can be curbed.

Claims

1. A control system that automatically stops and automatically restarts an internal combustion engine of a vehicle, the control system comprising:

a vapor pressure sensor that detects a vapor pressure of a fuel; and

an electronic control unit configured to;

a) set a fuel injection amount when the internal combustion engine is automatically restarted such that the fuel injection amount is reduced as a temperature in a cylinder of the internal combustion engine at a time of automatic restart is higher, and

b) set a relationship between the vapor pressure of the fuel and the fuel injection amount by switching between a first map and a second map based on the temperature in the cylinder, the first map is used for determining the fuel injection amount only when the temperature in the cylinder is equal to or lower than a predetermined temperature; and

the second map is used for determining the fuel injection amount only when the temperature in the cylinder exceeds the predetermined temperature, such that a rate of change of the fuel injection amount relative to the vapor pressure increases as the temperature in the cylinder is higher.

2. The control system according to claim 1, wherein the electronic control unit is configured to set the relationship between the vapor pressure of the fuel and the fuel injection amount such that the rate of change is positive when the temperature in the cylinder is equal to or higher than a predetermined value.

3. The control system according to claim 1, wherein the electronic control unit is configured to estimate the temperature in the cylinder based on an engine coolant temperature.

15. The control system according to claim 1, wherein the second map is used for determining the fuel injection amount only when the temperature in the cylinder exceeds the predetermined temperature, such that a rate of change of the fuel injection amount relative to the vapor pressure increases as a sliding scale as the temperature in the cylinder is higher.

4. A control system that automatically stops and automatically restarts an internal combustion engine of a vehicle, the control system comprising:

a vapor pressure sensor that detects a vapor pressure of a fuel; and

an electronic control unit configured to;

a) set a fuel injection amount when the internal combustion engine is automatically restarted such that the fuel injection amount is reduced as a vaporization proportion of the fuel at a time of automatic restart is higher, and

b) set a relationship between the vapor pressure of the fuel and the fuel injection amount by switching between a first map and a second map based on the vaporization proportion of the fuel, the first map is used for determining the fuel injection amount only when the vaporization proportion of the fuel is equal to or lower than a predetermined proportion, such that a rate of change of the fuel injection amount relative to the vapor pressure increases as the vaporization proportion of the fuel is higher.

5. The control system according to claim 4, wherein the electronic control unit is configured to set the relationship between the vapor pressure of the fuel and the fuel injection amount such that the rate of change is positive when the vaporization proportion of the fuel is equal to or larger than a predetermined value.

16. The control system according to claim 4, wherein the second map is used for determining the fuel injection amount only when the vaporization proportion of the fuel exceeds the predetermined proportion, such that a rate of change of the fuel injection amount relative to the vapor pressure increases as a sliding scale as the vaporization proportion of the fuel is higher.

6. A control system that automatically stops and automatically restarts an internal combustion engine of a vehicle, the control system comprising:

an electronic control unit configured to;

a) estimate a vapor pressure of a fuel,

b) set a fuel injection amount when the internal combustion engine is automatically restarted such that the fuel injection amount is reduced as a temperature in a cylinder of the internal combustion engine at a time of automatic restart is higher, and

c) set a relationship between the vapor pressure of the fuel and the fuel injection amount by switching between a first map and a second map based on the temperature in the cylinder, the first map is used for determining the fuel injection amount only when the temperature in the cylinder is equal to or lower than a predetermined temperature, such that a rate of change of the fuel injection amount relative to the vapor pressure increases as the temperature in the cylinder is higher.

7. The control system according to claim 6, wherein the electronic control unit is configured to set the relationship between the vapor pressure of the fuel and the fuel injection amount such that the rate of change is positive when the temperature in the cylinder is equal to or higher than a predetermined value.

8. The control system according to claim 6, wherein the electronic control unit is configured to estimate the temperature in the cylinder based on an engine coolant temperature.

9. The control system according to claim 6, wherein the electronic control unit estimates the vapor pressure of the fuel based on a fuel temperature and an internal pressure in a fuel tank.

10. The control system according to claim 6, wherein the electronic control unit estimates the vapor pressure of the fuel based on a rate of change of an engine speed at a time of a cold start.

17. The control system according to claim 6, wherein the second map is used for determining the fuel injection amount only when the temperature in the cylinder exceeds the predetermined temperature, such that a rate of change of the fuel injection amount relative to the vapor pressure increases as a sliding scale as the temperature in the cylinder is higher.

11. A control system that automatically stops and automatically restarts an internal combustion engine of a vehicle, the control system comprising:

an electronic control unit configured to;

a) estimate a vapor pressure of a fuel,

b) set a fuel injection amount when the internal combustion engine is automatically restarted such that the fuel injection amount is reduced as a vaporization proportion of the fuel at a time of automatic restart is higher, and

c) set a relationship between the vapor pressure of the fuel and the fuel injection amount by switching between a first map and a second map based on the vaporization proportion of the fuel, the first map is used for determining the fuel injection amount only when the vaporization proportion of the fuel is equal to or lower than a predetermined proportion, such that a rate of change of the fuel injection amount relative to the vapor pressure increases as the vaporization proportion of the fuel is higher.

12. The control system according to claim 11, wherein the electronic control unit is configured to set the relationship between the vapor pressure of the fuel and the fuel injection amount such that the rate of change is positive when the vaporization proportion of the fuel is equal to or larger than a predetermined value.

13. The control system according to claim 11, wherein the electronic control unit estimates the vapor pressure of the fuel based on a fuel temperature and an internal pressure of a fuel tank.

14. The control system according to claim 11, wherein the electronic control unit estimates the vapor pressure of the fuel based on a rate of change of an engine speed at a time of a cold start.

18. The control system according to claim 11, wherein the second map is used for determining the fuel injection amount only when the vaporization proportion of the fuel exceeds the predetermined proportion, such that a rate of change of the fuel injection amount relative to the vapor pressure increases as a sliding scale as the vaporization proportion of the fuel is higher.